diff mbox

[v8,02/12] drm/i915: Add i915 perf infrastructure

Message ID 20161028021430.2177-3-robert@sixbynine.org (mailing list archive)
State New, archived
Headers show

Commit Message

Robert Bragg Oct. 28, 2016, 2:14 a.m. UTC
Adds base i915 perf infrastructure for Gen performance metrics.

This adds a DRM_IOCTL_I915_PERF_OPEN ioctl that takes an array of uint64
properties to configure a stream of metrics and returns a new fd usable
with standard VFS system calls including read() to read typed and sized
records; ioctl() to enable or disable capture and poll() to wait for
data.

A stream is opened something like:

  uint64_t properties[] = {
      /* Single context sampling */
      DRM_I915_PERF_PROP_CTX_HANDLE,        ctx_handle,

      /* Include OA reports in samples */
      DRM_I915_PERF_PROP_SAMPLE_OA,         true,

      /* OA unit configuration */
      DRM_I915_PERF_PROP_OA_METRICS_SET,    metrics_set_id,
      DRM_I915_PERF_PROP_OA_FORMAT,         report_format,
      DRM_I915_PERF_PROP_OA_EXPONENT,       period_exponent,
   };
   struct drm_i915_perf_open_param parm = {
      .flags = I915_PERF_FLAG_FD_CLOEXEC |
               I915_PERF_FLAG_FD_NONBLOCK |
               I915_PERF_FLAG_DISABLED,
      .properties_ptr = (uint64_t)properties,
      .num_properties = sizeof(properties) / 16,
   };
   int fd = drmIoctl(drm_fd, DRM_IOCTL_I915_PERF_OPEN, &param);

Records read all start with a common { type, size } header with
DRM_I915_PERF_RECORD_SAMPLE being of most interest. Sample records
contain an extensible number of fields and it's the
DRM_I915_PERF_PROP_SAMPLE_xyz properties given when opening that
determine what's included in every sample.

No specific streams are supported yet so any attempt to open a stream
will return an error.

v2:
    use i915_gem_context_get() - Chris Wilson
v3:
    update read() interface to avoid passing state struct - Chris Wilson
    fix some rebase fallout, with i915-perf init/deinit
v4:
    s/DRM_IORW/DRM_IOW/ - Emil Velikov

Signed-off-by: Robert Bragg <robert@sixbynine.org>
---
 drivers/gpu/drm/i915/Makefile    |   3 +
 drivers/gpu/drm/i915/i915_drv.c  |   4 +
 drivers/gpu/drm/i915/i915_drv.h  |  91 ++++++++
 drivers/gpu/drm/i915/i915_perf.c | 443 +++++++++++++++++++++++++++++++++++++++
 include/uapi/drm/i915_drm.h      |  67 ++++++
 5 files changed, 608 insertions(+)
 create mode 100644 drivers/gpu/drm/i915/i915_perf.c

Comments

Matthew Auld Oct. 28, 2016, 2:27 p.m. UTC | #1
> +/* Note we copy the properties from userspace outside of the i915 perf
> + * mutex to avoid an awkward lockdep with mmap_sem.
> + *
> + * Note this function only validates properties in isolation it doesn't
> + * validate that the combination of properties makes sense or that all
> + * properties necessary for a particular kind of stream have been set.
> + */
> +static int read_properties_unlocked(struct drm_i915_private *dev_priv,
> +                                   u64 __user *uprops,
> +                                   u32 n_props,
> +                                   struct perf_open_properties *props)
> +{
> +       u64 __user *uprop = uprops;
> +       int i;
> +
> +       memset(props, 0, sizeof(struct perf_open_properties));
> +
> +       if (!n_props) {
> +               DRM_ERROR("No i915 perf properties given");
> +               return -EINVAL;
> +       }
> +
> +       if (n_props > DRM_I915_PERF_PROP_MAX) {
Ah but DRM_I915_PERF_PROP_MAX is not a property itself.
Robert Bragg Oct. 31, 2016, 4:27 p.m. UTC | #2
On Fri, Oct 28, 2016 at 3:27 PM, Matthew Auld <
matthew.william.auld@gmail.com> wrote:

> > +/* Note we copy the properties from userspace outside of the i915 perf
> > + * mutex to avoid an awkward lockdep with mmap_sem.
> > + *
> > + * Note this function only validates properties in isolation it doesn't
> > + * validate that the combination of properties makes sense or that all
> > + * properties necessary for a particular kind of stream have been set.
> > + */
> > +static int read_properties_unlocked(struct drm_i915_private *dev_priv,
> > +                                   u64 __user *uprops,
> > +                                   u32 n_props,
> > +                                   struct perf_open_properties *props)
> > +{
> > +       u64 __user *uprop = uprops;
> > +       int i;
> > +
> > +       memset(props, 0, sizeof(struct perf_open_properties));
> > +
> > +       if (!n_props) {
> > +               DRM_ERROR("No i915 perf properties given");
> > +               return -EINVAL;
> > +       }
> > +
> > +       if (n_props > DRM_I915_PERF_PROP_MAX) {
> Ah but DRM_I915_PERF_PROP_MAX is not a property itself.
>

I'm not sure I follow what your implied concern is?

This is just a sanity check for the number properties given by userspace,
based on the assumption that there's currently no reason for multiple
values with a particular property id.
Matthew Auld Oct. 31, 2016, 5:13 p.m. UTC | #3
On 31 October 2016 at 16:27, Robert Bragg <robert@sixbynine.org> wrote:
>
>
> On Fri, Oct 28, 2016 at 3:27 PM, Matthew Auld
> <matthew.william.auld@gmail.com> wrote:
>>
>> > +/* Note we copy the properties from userspace outside of the i915 perf
>> > + * mutex to avoid an awkward lockdep with mmap_sem.
>> > + *
>> > + * Note this function only validates properties in isolation it doesn't
>> > + * validate that the combination of properties makes sense or that all
>> > + * properties necessary for a particular kind of stream have been set.
>> > + */
>> > +static int read_properties_unlocked(struct drm_i915_private *dev_priv,
>> > +                                   u64 __user *uprops,
>> > +                                   u32 n_props,
>> > +                                   struct perf_open_properties *props)
>> > +{
>> > +       u64 __user *uprop = uprops;
>> > +       int i;
>> > +
>> > +       memset(props, 0, sizeof(struct perf_open_properties));
>> > +
>> > +       if (!n_props) {
>> > +               DRM_ERROR("No i915 perf properties given");
>> > +               return -EINVAL;
>> > +       }
>> > +
>> > +       if (n_props > DRM_I915_PERF_PROP_MAX) {
>> Ah but DRM_I915_PERF_PROP_MAX is not a property itself.
>
>
> I'm not sure I follow what your implied concern is?
>
> This is just a sanity check for the number properties given by userspace,
> based on the assumption that there's currently no reason for multiple values
> with a particular property id.
>
All I meant was should it not be n_props >= DRM_I915_PERF_PROP_MAX ?

So with that fixed, or if I'm completely mad:
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Robert Bragg Oct. 31, 2016, 6:54 p.m. UTC | #4
On Mon, Oct 31, 2016 at 5:13 PM, Matthew Auld <
matthew.william.auld@gmail.com> wrote:

> On 31 October 2016 at 16:27, Robert Bragg <robert@sixbynine.org> wrote:
> >
> >
> > On Fri, Oct 28, 2016 at 3:27 PM, Matthew Auld
> > <matthew.william.auld@gmail.com> wrote:
> >>
> >> > +/* Note we copy the properties from userspace outside of the i915
> perf
> >> > + * mutex to avoid an awkward lockdep with mmap_sem.
> >> > + *
> >> > + * Note this function only validates properties in isolation it
> doesn't
> >> > + * validate that the combination of properties makes sense or that
> all
> >> > + * properties necessary for a particular kind of stream have been
> set.
> >> > + */
> >> > +static int read_properties_unlocked(struct drm_i915_private
> *dev_priv,
> >> > +                                   u64 __user *uprops,
> >> > +                                   u32 n_props,
> >> > +                                   struct perf_open_properties
> *props)
> >> > +{
> >> > +       u64 __user *uprop = uprops;
> >> > +       int i;
> >> > +
> >> > +       memset(props, 0, sizeof(struct perf_open_properties));
> >> > +
> >> > +       if (!n_props) {
> >> > +               DRM_ERROR("No i915 perf properties given");
> >> > +               return -EINVAL;
> >> > +       }
> >> > +
> >> > +       if (n_props > DRM_I915_PERF_PROP_MAX) {
> >> Ah but DRM_I915_PERF_PROP_MAX is not a property itself.
> >
> >
> > I'm not sure I follow what your implied concern is?
> >
> > This is just a sanity check for the number properties given by userspace,
> > based on the assumption that there's currently no reason for multiple
> values
> > with a particular property id.
> >
> All I meant was should it not be n_props >= DRM_I915_PERF_PROP_MAX ?


> So with that fixed, or if I'm completely mad:
> Reviewed-by: Matthew Auld <matthew.auld@intel.com>
>

Ah, I see. Actually tbh I think either is reasonable...

The check is mainly about ruling out the silly large values that could be
given, imposing a upper-bound to the number of properties expected from
userspace. It might help catch userspace giving garbage/undefined data, or
block attempts to get the kernel parsing huge amounts of property data
which should never be necessary for configuring a stream. It doesn't e.g.
stop userspace specifying duplicate property IDs even if they supply less
than the maximum allowed. So even if it allowed say 2x the number of
properties I think it would still pretty much do its job.

I could imagine in the future the same check might become much more fuzzy
if we have a case where userspace might need to legitimately specify the
same property ID multiple times (where the sequential order is relevant).

_PERF_PROP_MAX is the last in the enum whereby we can interpret it as an
upper bound on the number of properties while we don't currently expect to
see property IDs duplicated.

The detail here though is that ID 0 is reserved so _PERF_PROP_MAX is more
like ('the maximum number of properties' + 1) - and so this is what you're
essentially highlighting.

I can change this - maybe with a comment about ID 0 being reserved and
explaining the assumption that property ID duplicates aren't currently
expected

Thanks for the review!
sourab.gupta@intel.com Nov. 4, 2016, 8:59 a.m. UTC | #5
On Thu, 2016-10-27 at 19:14 -0700, Robert Bragg wrote:
> Adds base i915 perf infrastructure for Gen performance metrics.
> 
> This adds a DRM_IOCTL_I915_PERF_OPEN ioctl that takes an array of uint64
> properties to configure a stream of metrics and returns a new fd usable
> with standard VFS system calls including read() to read typed and sized
> records; ioctl() to enable or disable capture and poll() to wait for
> data.
> 
> A stream is opened something like:
> 
>   uint64_t properties[] = {
>       /* Single context sampling */
>       DRM_I915_PERF_PROP_CTX_HANDLE,        ctx_handle,
> 
>       /* Include OA reports in samples */
>       DRM_I915_PERF_PROP_SAMPLE_OA,         true,
> 
>       /* OA unit configuration */
>       DRM_I915_PERF_PROP_OA_METRICS_SET,    metrics_set_id,
>       DRM_I915_PERF_PROP_OA_FORMAT,         report_format,
>       DRM_I915_PERF_PROP_OA_EXPONENT,       period_exponent,
>    };
>    struct drm_i915_perf_open_param parm = {
>       .flags = I915_PERF_FLAG_FD_CLOEXEC |
>                I915_PERF_FLAG_FD_NONBLOCK |
>                I915_PERF_FLAG_DISABLED,
>       .properties_ptr = (uint64_t)properties,
>       .num_properties = sizeof(properties) / 16,
>    };
>    int fd = drmIoctl(drm_fd, DRM_IOCTL_I915_PERF_OPEN, &param);
> 
> Records read all start with a common { type, size } header with
> DRM_I915_PERF_RECORD_SAMPLE being of most interest. Sample records
> contain an extensible number of fields and it's the
> DRM_I915_PERF_PROP_SAMPLE_xyz properties given when opening that
> determine what's included in every sample.
> 
> No specific streams are supported yet so any attempt to open a stream
> will return an error.
> 
> v2:
>     use i915_gem_context_get() - Chris Wilson
> v3:
>     update read() interface to avoid passing state struct - Chris Wilson
>     fix some rebase fallout, with i915-perf init/deinit
> v4:
>     s/DRM_IORW/DRM_IOW/ - Emil Velikov
> 
> Signed-off-by: Robert Bragg <robert@sixbynine.org>
> ---
>  drivers/gpu/drm/i915/Makefile    |   3 +
>  drivers/gpu/drm/i915/i915_drv.c  |   4 +
>  drivers/gpu/drm/i915/i915_drv.h  |  91 ++++++++
>  drivers/gpu/drm/i915/i915_perf.c | 443 +++++++++++++++++++++++++++++++++++++++
>  include/uapi/drm/i915_drm.h      |  67 ++++++
>  5 files changed, 608 insertions(+)
>  create mode 100644 drivers/gpu/drm/i915/i915_perf.c
> 
> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> index 6123400..8d4e25f 100644
> --- a/drivers/gpu/drm/i915/Makefile
> +++ b/drivers/gpu/drm/i915/Makefile
> @@ -113,6 +113,9 @@ i915-$(CONFIG_DRM_I915_CAPTURE_ERROR) += i915_gpu_error.o
>  # virtual gpu code
>  i915-y += i915_vgpu.o
>  
> +# perf code
> +i915-y += i915_perf.o
> +
>  ifeq ($(CONFIG_DRM_I915_GVT),y)
>  i915-y += intel_gvt.o
>  include $(src)/gvt/Makefile
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index af3559d..685c96e 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -836,6 +836,8 @@ static int i915_driver_init_early(struct drm_i915_private *dev_priv,
>  
>  	intel_detect_preproduction_hw(dev_priv);
>  
> +	i915_perf_init(dev_priv);
> +
>  	return 0;
>  
>  err_workqueues:
> @@ -849,6 +851,7 @@ static int i915_driver_init_early(struct drm_i915_private *dev_priv,
>   */
>  static void i915_driver_cleanup_early(struct drm_i915_private *dev_priv)
>  {
> +	i915_perf_fini(dev_priv);
>  	i915_gem_load_cleanup(&dev_priv->drm);
>  	i915_workqueues_cleanup(dev_priv);
>  }
> @@ -2556,6 +2559,7 @@ static const struct drm_ioctl_desc i915_ioctls[] = {
>  	DRM_IOCTL_DEF_DRV(I915_GEM_USERPTR, i915_gem_userptr_ioctl, DRM_RENDER_ALLOW),
>  	DRM_IOCTL_DEF_DRV(I915_GEM_CONTEXT_GETPARAM, i915_gem_context_getparam_ioctl, DRM_RENDER_ALLOW),
>  	DRM_IOCTL_DEF_DRV(I915_GEM_CONTEXT_SETPARAM, i915_gem_context_setparam_ioctl, DRM_RENDER_ALLOW),
> +	DRM_IOCTL_DEF_DRV(I915_PERF_OPEN, i915_perf_open_ioctl, DRM_RENDER_ALLOW),
>  };
>  
>  static struct drm_driver driver = {
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 5a260db..7a65c0b 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1767,6 +1767,84 @@ struct intel_wm_config {
>  	bool sprites_scaled;
>  };
>  
> +struct i915_perf_stream;
> +
> +struct i915_perf_stream_ops {
> +	/* Enables the collection of HW samples, either in response to
> +	 * I915_PERF_IOCTL_ENABLE or implicitly called when stream is
> +	 * opened without I915_PERF_FLAG_DISABLED.
> +	 */
> +	void (*enable)(struct i915_perf_stream *stream);
> +
> +	/* Disables the collection of HW samples, either in response to
> +	 * I915_PERF_IOCTL_DISABLE or implicitly called before
> +	 * destroying the stream.
> +	 */
> +	void (*disable)(struct i915_perf_stream *stream);
> +
> +	/* Return: true if any i915 perf records are ready to read()
> +	 * for this stream.
> +	 */
> +	bool (*can_read)(struct i915_perf_stream *stream);
> +
> +	/* Call poll_wait, passing a wait queue that will be woken
> +	 * once there is something ready to read() for the stream
> +	 */
> +	void (*poll_wait)(struct i915_perf_stream *stream,
> +			  struct file *file,
> +			  poll_table *wait);
> +
> +	/* For handling a blocking read, wait until there is something
> +	 * to ready to read() for the stream. E.g. wait on the same
> +	 * wait queue that would be passed to poll_wait() until
> +	 * ->can_read() returns true (if its safe to call ->can_read()
> +	 * without the i915 perf lock held).
> +	 */
> +	int (*wait_unlocked)(struct i915_perf_stream *stream);
> +
> +	/* read - Copy buffered metrics as records to userspace
> +	 * @buf: the userspace, destination buffer
> +	 * @count: the number of bytes to copy, requested by userspace
> +	 * @offset: zero at the start of the read, updated as the read
> +	 *          proceeds, it represents how many bytes have been
> +	 *          copied so far and the buffer offset for copying the
> +	 *          next record.
> +	 *
> +	 * Copy as many buffered i915 perf samples and records for
> +	 * this stream to userspace as will fit in the given buffer.
> +	 *
> +	 * Only write complete records; returning -ENOSPC if there
> +	 * isn't room for a complete record.
> +	 *
> +	 * Return any error condition that results in a short read
> +	 * such as -ENOSPC or -EFAULT, even though these may be
> +	 * squashed before returning to userspace.
> +	 */
> +	int (*read)(struct i915_perf_stream *stream,
> +		    char __user *buf,
> +		    size_t count,
> +		    size_t *offset);
> +
> +	/* Cleanup any stream specific resources.
> +	 *
> +	 * The stream will always be disabled before this is called.
> +	 */
> +	void (*destroy)(struct i915_perf_stream *stream);
> +};
> +
> +struct i915_perf_stream {
> +	struct drm_i915_private *dev_priv;
> +
> +	struct list_head link;
> +
> +	u32 sample_flags;
> +
> +	struct i915_gem_context *ctx;
> +	bool enabled;
> +
> +	struct i915_perf_stream_ops *ops;
> +};
> +
>  struct drm_i915_private {
>  	struct drm_device drm;
>  
> @@ -2069,6 +2147,12 @@ struct drm_i915_private {
>  
>  	struct i915_runtime_pm pm;
>  
> +	struct {
> +		bool initialized;
> +		struct mutex lock;
> +		struct list_head streams;
> +	} perf;
> +
>  	/* Abstract the submission mechanism (legacy ringbuffer or execlists) away */
>  	struct {
>  		void (*resume)(struct drm_i915_private *);
> @@ -3482,6 +3566,9 @@ int i915_gem_context_setparam_ioctl(struct drm_device *dev, void *data,
>  int i915_gem_context_reset_stats_ioctl(struct drm_device *dev, void *data,
>  				       struct drm_file *file);
>  
> +int i915_perf_open_ioctl(struct drm_device *dev, void *data,
> +			 struct drm_file *file);
> +
>  /* i915_gem_evict.c */
>  int __must_check i915_gem_evict_something(struct i915_address_space *vm,
>  					  u64 min_size, u64 alignment,
> @@ -3607,6 +3694,10 @@ int intel_engine_cmd_parser(struct intel_engine_cs *engine,
>  			    u32 batch_len,
>  			    bool is_master);
>  
> +/* i915_perf.c */
> +extern void i915_perf_init(struct drm_i915_private *dev_priv);
> +extern void i915_perf_fini(struct drm_i915_private *dev_priv);
> +
>  /* i915_suspend.c */
>  extern int i915_save_state(struct drm_device *dev);
>  extern int i915_restore_state(struct drm_device *dev);
> diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
> new file mode 100644
> index 0000000..c45cf92
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/i915_perf.c
> @@ -0,0 +1,443 @@
> +/*
> + * Copyright © 2015-2016 Intel Corporation
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> + * IN THE SOFTWARE.
> + *
> + * Authors:
> + *   Robert Bragg <robert@sixbynine.org>
> + */
> +
> +#include <linux/anon_inodes.h>
> +
> +#include "i915_drv.h"
> +
> +struct perf_open_properties {
> +	u32 sample_flags;
> +
> +	u64 single_context:1;
> +	u64 ctx_handle;
> +};
> +
> +static ssize_t i915_perf_read_locked(struct i915_perf_stream *stream,
> +				     struct file *file,
> +				     char __user *buf,
> +				     size_t count,
> +				     loff_t *ppos)
> +{
> +	/* Note we keep the offset (aka bytes read) separate from any
> +	 * error status so that the final check for whether we return
> +	 * the bytes read with a higher precedence than any error (see
> +	 * comment below) doesn't need to be handled/duplicated in
> +	 * stream->ops->read() implementations.
> +	 */
> +	size_t offset = 0;
> +	int ret = stream->ops->read(stream, buf, count, &offset);
> +
> +	/* If we've successfully copied any data then reporting that
> +	 * takes precedence over any internal error status, so the
> +	 * data isn't lost.
> +	 *
> +	 * For example ret will be -ENOSPC whenever there is more
> +	 * buffered data than can be copied to userspace, but that's
> +	 * only interesting if we weren't able to copy some data
> +	 * because it implies the userspace buffer is too small to
> +	 * receive a single record (and we never split records).
> +	 *
> +	 * Another case with ret == -EFAULT is more of a grey area
> +	 * since it would seem like bad form for userspace to ask us
> +	 * to overrun its buffer, but the user knows best:
> +	 *
> +	 *   http://yarchive.net/comp/linux/partial_reads_writes.html
> +	 */
> +	return offset ?: (ret ?: -EAGAIN);
> +}
> +
> +static ssize_t i915_perf_read(struct file *file,
> +			      char __user *buf,
> +			      size_t count,
> +			      loff_t *ppos)
> +{
> +	struct i915_perf_stream *stream = file->private_data;
> +	struct drm_i915_private *dev_priv = stream->dev_priv;
> +	ssize_t ret;
> +
> +	if (!(file->f_flags & O_NONBLOCK)) {
> +		/* Allow false positives from stream->ops->wait_unlocked.
> +		 */
> +		do {
> +			ret = stream->ops->wait_unlocked(stream);
> +			if (ret)
> +				return ret;
> +
> +			mutex_lock(&dev_priv->perf.lock);

Should interruptible version be used here, to allow for reads to be
interrupted?
> +			ret = i915_perf_read_locked(stream, file,
> +						    buf, count, ppos);
> +			mutex_unlock(&dev_priv->perf.lock);
> +		} while (ret == -EAGAIN);
> +	} else {
> +		mutex_lock(&dev_priv->perf.lock);
Likewise.

> +		ret = i915_perf_read_locked(stream, file, buf, count, ppos);
> +		mutex_unlock(&dev_priv->perf.lock);
> +	}
> +
> +	return ret;
> +}
> +
> +static unsigned int i915_perf_poll_locked(struct i915_perf_stream *stream,
> +					  struct file *file,
> +					  poll_table *wait)
> +{
> +	unsigned int streams = 0;
> +
> +	stream->ops->poll_wait(stream, file, wait);
> +
> +	if (stream->ops->can_read(stream))
> +		streams |= POLLIN;
> +
> +	return streams;
> +}
> +
> +static unsigned int i915_perf_poll(struct file *file, poll_table *wait)
> +{
> +	struct i915_perf_stream *stream = file->private_data;
> +	struct drm_i915_private *dev_priv = stream->dev_priv;
> +	int ret;
> +
> +	mutex_lock(&dev_priv->perf.lock);
Same question. Can interruptible versions be used here, and likewise
other instances in the patch?

> +	ret = i915_perf_poll_locked(stream, file, wait);
> +	mutex_unlock(&dev_priv->perf.lock);
> +
> +	return ret;
> +}
> +
> +static void i915_perf_enable_locked(struct i915_perf_stream *stream)
> +{
> +	if (stream->enabled)
> +		return;
> +
> +	/* Allow stream->ops->enable() to refer to this */
> +	stream->enabled = true;
> +
> +	if (stream->ops->enable)
> +		stream->ops->enable(stream);
> +}
> +
> +static void i915_perf_disable_locked(struct i915_perf_stream *stream)
> +{
> +	if (!stream->enabled)
> +		return;
> +
> +	/* Allow stream->ops->disable() to refer to this */
> +	stream->enabled = false;
> +
> +	if (stream->ops->disable)
> +		stream->ops->disable(stream);
> +}
> +
> +static long i915_perf_ioctl_locked(struct i915_perf_stream *stream,
> +				   unsigned int cmd,
> +				   unsigned long arg)
> +{
> +	switch (cmd) {
> +	case I915_PERF_IOCTL_ENABLE:
> +		i915_perf_enable_locked(stream);
> +		return 0;
> +	case I915_PERF_IOCTL_DISABLE:
> +		i915_perf_disable_locked(stream);
> +		return 0;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static long i915_perf_ioctl(struct file *file,
> +			    unsigned int cmd,
> +			    unsigned long arg)
> +{
> +	struct i915_perf_stream *stream = file->private_data;
> +	struct drm_i915_private *dev_priv = stream->dev_priv;
> +	long ret;
> +
> +	mutex_lock(&dev_priv->perf.lock);
> +	ret = i915_perf_ioctl_locked(stream, cmd, arg);
> +	mutex_unlock(&dev_priv->perf.lock);
> +
> +	return ret;
> +}
> +
> +static void i915_perf_destroy_locked(struct i915_perf_stream *stream)
> +{
> +	struct drm_i915_private *dev_priv = stream->dev_priv;
> +
> +	if (stream->enabled)
> +		i915_perf_disable_locked(stream);
> +
> +	if (stream->ops->destroy)
> +		stream->ops->destroy(stream);
> +
> +	list_del(&stream->link);
> +
> +	if (stream->ctx) {
> +		mutex_lock(&dev_priv->drm.struct_mutex);
> +		i915_gem_context_put(stream->ctx);
> +		mutex_unlock(&dev_priv->drm.struct_mutex);
> +	}
> +
> +	kfree(stream);
> +}
> +
> +static int i915_perf_release(struct inode *inode, struct file *file)
> +{
> +	struct i915_perf_stream *stream = file->private_data;
> +	struct drm_i915_private *dev_priv = stream->dev_priv;
> +
> +	mutex_lock(&dev_priv->perf.lock);
> +	i915_perf_destroy_locked(stream);
> +	mutex_unlock(&dev_priv->perf.lock);
> +
> +	return 0;
> +}
> +
> +
> +static const struct file_operations fops = {
> +	.owner		= THIS_MODULE,
> +	.llseek		= no_llseek,
> +	.release	= i915_perf_release,
> +	.poll		= i915_perf_poll,
> +	.read		= i915_perf_read,
> +	.unlocked_ioctl	= i915_perf_ioctl,
> +};
> +
> +
> +static struct i915_gem_context *
> +lookup_context(struct drm_i915_private *dev_priv,
> +	       struct drm_i915_file_private *file_priv,
> +	       u32 ctx_user_handle)
> +{
> +	struct i915_gem_context *ctx;
> +	int ret;
> +
> +	ret = i915_mutex_lock_interruptible(&dev_priv->drm);
> +	if (ret)
> +		return ERR_PTR(ret);
> +
> +	ctx = i915_gem_context_lookup(file_priv, ctx_user_handle);
> +	if (!IS_ERR(ctx))
> +		i915_gem_context_get(ctx);
> +
> +	mutex_unlock(&dev_priv->drm.struct_mutex);
> +
> +	return ctx;
> +}
> +
> +static int
> +i915_perf_open_ioctl_locked(struct drm_i915_private *dev_priv,
> +			    struct drm_i915_perf_open_param *param,
> +			    struct perf_open_properties *props,
> +			    struct drm_file *file)
> +{
> +	struct i915_gem_context *specific_ctx = NULL;
> +	struct i915_perf_stream *stream = NULL;
> +	unsigned long f_flags = 0;
> +	int stream_fd;
> +	int ret;
> +
> +	if (props->single_context) {
> +		u32 ctx_handle = props->ctx_handle;
> +		struct drm_i915_file_private *file_priv = file->driver_priv;
> +
> +		specific_ctx = lookup_context(dev_priv, file_priv, ctx_handle);
> +		if (IS_ERR(specific_ctx)) {
> +			ret = PTR_ERR(specific_ctx);
> +			if (ret != -EINTR)
> +				DRM_ERROR("Failed to look up context with ID %u for opening perf stream\n",
> +					  ctx_handle);
> +			goto err;
> +		}
> +	}
> +
> +	if (!specific_ctx && !capable(CAP_SYS_ADMIN)) {
> +		DRM_ERROR("Insufficient privileges to open system-wide i915 perf stream\n");
> +		ret = -EACCES;
> +		goto err_ctx;
> +	}
> +
> +	stream = kzalloc(sizeof(*stream), GFP_KERNEL);
> +	if (!stream) {
> +		ret = -ENOMEM;
> +		goto err_ctx;
> +	}
> +
> +	stream->sample_flags = props->sample_flags;
> +	stream->dev_priv = dev_priv;
> +	stream->ctx = specific_ctx;
> +
> +	/*
> +	 * TODO: support sampling something
> +	 *
> +	 * For now this is as far as we can go.
> +	 */
> +	DRM_ERROR("Unsupported i915 perf stream configuration\n");
> +	ret = -EINVAL;
> +	goto err_alloc;
> +
> +	list_add(&stream->link, &dev_priv->perf.streams);
> +
> +	if (param->flags & I915_PERF_FLAG_FD_CLOEXEC)
> +		f_flags |= O_CLOEXEC;
> +	if (param->flags & I915_PERF_FLAG_FD_NONBLOCK)
> +		f_flags |= O_NONBLOCK;
> +
> +	stream_fd = anon_inode_getfd("[i915_perf]", &fops, stream, f_flags);
> +	if (stream_fd < 0) {
> +		ret = stream_fd;
> +		goto err_open;
> +	}
> +
> +	if (!(param->flags & I915_PERF_FLAG_DISABLED))
> +		i915_perf_enable_locked(stream);
> +
> +	return stream_fd;
> +
> +err_open:
> +	list_del(&stream->link);
> +	if (stream->ops->destroy)
> +		stream->ops->destroy(stream);
> +err_alloc:
> +	kfree(stream);
> +err_ctx:
> +	if (specific_ctx) {
> +		mutex_lock(&dev_priv->drm.struct_mutex);
> +		i915_gem_context_put(specific_ctx);
> +		mutex_unlock(&dev_priv->drm.struct_mutex);
> +	}
> +err:
> +	return ret;
> +}
> +
> +/* Note we copy the properties from userspace outside of the i915 perf
> + * mutex to avoid an awkward lockdep with mmap_sem.
> + *
> + * Note this function only validates properties in isolation it doesn't
> + * validate that the combination of properties makes sense or that all
> + * properties necessary for a particular kind of stream have been set.
> + */
> +static int read_properties_unlocked(struct drm_i915_private *dev_priv,
> +				    u64 __user *uprops,
> +				    u32 n_props,
> +				    struct perf_open_properties *props)
> +{
> +	u64 __user *uprop = uprops;
> +	int i;
> +
> +	memset(props, 0, sizeof(struct perf_open_properties));
> +
> +	if (!n_props) {
> +		DRM_ERROR("No i915 perf properties given");
> +		return -EINVAL;
> +	}
> +
> +	if (n_props > DRM_I915_PERF_PROP_MAX) {
> +		DRM_ERROR("More i915 perf properties specified than exist");
> +		return -EINVAL;
> +	}
> +
> +	for (i = 0; i < n_props; i++) {
> +		u64 id, value;
> +		int ret;
> +
> +		ret = get_user(id, uprop);
> +		if (ret)
> +			return ret;
> +
> +		ret = get_user(value, uprop + 1);
> +		if (ret)
> +			return ret;
> +
> +		switch ((enum drm_i915_perf_property_id)id) {
> +		case DRM_I915_PERF_PROP_CTX_HANDLE:
> +			props->single_context = 1;
> +			props->ctx_handle = value;
> +			break;
> +		default:
> +			MISSING_CASE(id);
> +			DRM_ERROR("Unknown i915 perf property ID");
> +			return -EINVAL;
> +		}
> +
> +		uprop += 2;
> +	}
> +
> +	return 0;
> +}
> +
> +int i915_perf_open_ioctl(struct drm_device *dev, void *data,
> +			 struct drm_file *file)
> +{
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +	struct drm_i915_perf_open_param *param = data;
> +	struct perf_open_properties props;
> +	u32 known_open_flags;
> +	int ret;
> +
> +	if (!dev_priv->perf.initialized) {
> +		DRM_ERROR("i915 perf interface not available for this system");
> +		return -ENOTSUPP;
> +	}
> +
> +	known_open_flags = I915_PERF_FLAG_FD_CLOEXEC |
> +			   I915_PERF_FLAG_FD_NONBLOCK |
> +			   I915_PERF_FLAG_DISABLED;
> +	if (param->flags & ~known_open_flags) {
> +		DRM_ERROR("Unknown drm_i915_perf_open_param flag\n");
> +		return -EINVAL;
> +	}
> +
> +	ret = read_properties_unlocked(dev_priv,
> +				       u64_to_user_ptr(param->properties_ptr),
> +				       param->num_properties,
> +				       &props);
> +	if (ret)
> +		return ret;
> +
> +	mutex_lock(&dev_priv->perf.lock);
> +	ret = i915_perf_open_ioctl_locked(dev_priv, param, &props, file);
> +	mutex_unlock(&dev_priv->perf.lock);
> +
> +	return ret;
> +}
> +
> +void i915_perf_init(struct drm_i915_private *dev_priv)
> +{
> +	INIT_LIST_HEAD(&dev_priv->perf.streams);
> +	mutex_init(&dev_priv->perf.lock);
> +
> +	dev_priv->perf.initialized = true;
> +}
> +
> +void i915_perf_fini(struct drm_i915_private *dev_priv)
> +{
> +	if (!dev_priv->perf.initialized)
> +		return;
> +
> +	/* Currently nothing to clean up */
> +
> +	dev_priv->perf.initialized = false;
> +}
> diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
> index 03725fe..98cd493 100644
> --- a/include/uapi/drm/i915_drm.h
> +++ b/include/uapi/drm/i915_drm.h
> @@ -258,6 +258,7 @@ typedef struct _drm_i915_sarea {
>  #define DRM_I915_GEM_USERPTR		0x33
>  #define DRM_I915_GEM_CONTEXT_GETPARAM	0x34
>  #define DRM_I915_GEM_CONTEXT_SETPARAM	0x35
> +#define DRM_I915_PERF_OPEN		0x36
>  
>  #define DRM_IOCTL_I915_INIT		DRM_IOW( DRM_COMMAND_BASE + DRM_I915_INIT, drm_i915_init_t)
>  #define DRM_IOCTL_I915_FLUSH		DRM_IO ( DRM_COMMAND_BASE + DRM_I915_FLUSH)
> @@ -311,6 +312,7 @@ typedef struct _drm_i915_sarea {
>  #define DRM_IOCTL_I915_GEM_USERPTR			DRM_IOWR (DRM_COMMAND_BASE + DRM_I915_GEM_USERPTR, struct drm_i915_gem_userptr)
>  #define DRM_IOCTL_I915_GEM_CONTEXT_GETPARAM	DRM_IOWR (DRM_COMMAND_BASE + DRM_I915_GEM_CONTEXT_GETPARAM, struct drm_i915_gem_context_param)
>  #define DRM_IOCTL_I915_GEM_CONTEXT_SETPARAM	DRM_IOWR (DRM_COMMAND_BASE + DRM_I915_GEM_CONTEXT_SETPARAM, struct drm_i915_gem_context_param)
> +#define DRM_IOCTL_I915_PERF_OPEN	DRM_IOW(DRM_COMMAND_BASE + DRM_I915_PERF_OPEN, struct drm_i915_perf_open_param)
>  
>  /* Allow drivers to submit batchbuffers directly to hardware, relying
>   * on the security mechanisms provided by hardware.
> @@ -1222,6 +1224,71 @@ struct drm_i915_gem_context_param {
>  	__u64 value;
>  };
>  
> +enum drm_i915_perf_property_id {
> +	/**
> +	 * Open the stream for a specific context handle (as used with
> +	 * execbuffer2). A stream opened for a specific context this way
> +	 * won't typically require root privileges.
> +	 */
> +	DRM_I915_PERF_PROP_CTX_HANDLE = 1,
> +
> +	DRM_I915_PERF_PROP_MAX /* non-ABI */
> +};
> +
> +struct drm_i915_perf_open_param {
> +	__u32 flags;
> +#define I915_PERF_FLAG_FD_CLOEXEC	(1<<0)
> +#define I915_PERF_FLAG_FD_NONBLOCK	(1<<1)
> +#define I915_PERF_FLAG_DISABLED		(1<<2)
> +
> +	/** The number of u64 (id, value) pairs */
> +	__u32 num_properties;
> +
> +	/**
> +	 * Pointer to array of u64 (id, value) pairs configuring the stream
> +	 * to open.
> +	 */
> +	__u64 __user properties_ptr;
> +};
> +
> +#define I915_PERF_IOCTL_ENABLE	_IO('i', 0x0)
> +#define I915_PERF_IOCTL_DISABLE	_IO('i', 0x1)
> +
> +/**
> + * Common to all i915 perf records
> + */
> +struct drm_i915_perf_record_header {
> +	__u32 type;
> +	__u16 pad;
> +	__u16 size;
> +};
> +
> +enum drm_i915_perf_record_type {
> +
> +	/**
> +	 * Samples are the work horse record type whose contents are extensible
> +	 * and defined when opening an i915 perf stream based on the given
> +	 * properties.
> +	 *
> +	 * Boolean properties following the naming convention
> +	 * DRM_I915_PERF_SAMPLE_xyz_PROP request the inclusion of 'xyz' data in
> +	 * every sample.
> +	 *
> +	 * The order of these sample properties given by userspace has no
> +	 * affect on the ordering of data within a sample. The order will be
> +	 * documented here.
> +	 *
> +	 * struct {
> +	 *     struct drm_i915_perf_record_header header;
> +	 *
> +	 *     TODO: itemize extensible sample data here
> +	 * };
> +	 */
> +	DRM_I915_PERF_RECORD_SAMPLE = 1,
> +
> +	DRM_I915_PERF_RECORD_MAX /* non-ABI */
> +};
> +
>  #if defined(__cplusplus)
>  }
>  #endif
Robert Bragg Nov. 4, 2016, 1:19 p.m. UTC | #6
On Fri, Nov 4, 2016 at 8:59 AM, sourab gupta <sourab.gupta@intel.com> wrote:

> On Thu, 2016-10-27 at 19:14 -0700, Robert Bragg wrote:
> > Adds base i915 perf infrastructure for Gen performance metrics.
> >
> > This adds a DRM_IOCTL_I915_PERF_OPEN ioctl that takes an array of uint64
> > properties to configure a stream of metrics and returns a new fd usable
> > with standard VFS system calls including read() to read typed and sized
> > records; ioctl() to enable or disable capture and poll() to wait for
> > data.
> >
> > A stream is opened something like:
> >
> >   uint64_t properties[] = {
> >       /* Single context sampling */
> >       DRM_I915_PERF_PROP_CTX_HANDLE,        ctx_handle,
> >
> >       /* Include OA reports in samples */
> >       DRM_I915_PERF_PROP_SAMPLE_OA,         true,
> >
> >       /* OA unit configuration */
> >       DRM_I915_PERF_PROP_OA_METRICS_SET,    metrics_set_id,
> >       DRM_I915_PERF_PROP_OA_FORMAT,         report_format,
> >       DRM_I915_PERF_PROP_OA_EXPONENT,       period_exponent,
> >    };
> >    struct drm_i915_perf_open_param parm = {
> >       .flags = I915_PERF_FLAG_FD_CLOEXEC |
> >                I915_PERF_FLAG_FD_NONBLOCK |
> >                I915_PERF_FLAG_DISABLED,
> >       .properties_ptr = (uint64_t)properties,
> >       .num_properties = sizeof(properties) / 16,
> >    };
> >    int fd = drmIoctl(drm_fd, DRM_IOCTL_I915_PERF_OPEN, &param);
> >
> > Records read all start with a common { type, size } header with
> > DRM_I915_PERF_RECORD_SAMPLE being of most interest. Sample records
> > contain an extensible number of fields and it's the
> > DRM_I915_PERF_PROP_SAMPLE_xyz properties given when opening that
> > determine what's included in every sample.
> >
> > No specific streams are supported yet so any attempt to open a stream
> > will return an error.
> >
> > v2:
> >     use i915_gem_context_get() - Chris Wilson
> > v3:
> >     update read() interface to avoid passing state struct - Chris Wilson
> >     fix some rebase fallout, with i915-perf init/deinit
> > v4:
> >     s/DRM_IORW/DRM_IOW/ - Emil Velikov
> >
> > Signed-off-by: Robert Bragg <robert@sixbynine.org>
> > ---
> >  drivers/gpu/drm/i915/Makefile    |   3 +
> >  drivers/gpu/drm/i915/i915_drv.c  |   4 +
> >  drivers/gpu/drm/i915/i915_drv.h  |  91 ++++++++
> >  drivers/gpu/drm/i915/i915_perf.c | 443 ++++++++++++++++++++++++++++++
> +++++++++
> >  include/uapi/drm/i915_drm.h      |  67 ++++++
> >  5 files changed, 608 insertions(+)
> >  create mode 100644 drivers/gpu/drm/i915/i915_perf.c
> >
> > diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/
> Makefile
> > index 6123400..8d4e25f 100644
> > --- a/drivers/gpu/drm/i915/Makefile
> > +++ b/drivers/gpu/drm/i915/Makefile
> > @@ -113,6 +113,9 @@ i915-$(CONFIG_DRM_I915_CAPTURE_ERROR) +=
> i915_gpu_error.o
> >  # virtual gpu code
> >  i915-y += i915_vgpu.o
> >
> > +# perf code
> > +i915-y += i915_perf.o
> > +
> >  ifeq ($(CONFIG_DRM_I915_GVT),y)
> >  i915-y += intel_gvt.o
> >  include $(src)/gvt/Makefile
> > diff --git a/drivers/gpu/drm/i915/i915_drv.c
> b/drivers/gpu/drm/i915/i915_drv.c
> > index af3559d..685c96e 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.c
> > +++ b/drivers/gpu/drm/i915/i915_drv.c
> > @@ -836,6 +836,8 @@ static int i915_driver_init_early(struct
> drm_i915_private *dev_priv,
> >
> >       intel_detect_preproduction_hw(dev_priv);
> >
> > +     i915_perf_init(dev_priv);
> > +
> >       return 0;
> >
> >  err_workqueues:
> > @@ -849,6 +851,7 @@ static int i915_driver_init_early(struct
> drm_i915_private *dev_priv,
> >   */
> >  static void i915_driver_cleanup_early(struct drm_i915_private
> *dev_priv)
> >  {
> > +     i915_perf_fini(dev_priv);
> >       i915_gem_load_cleanup(&dev_priv->drm);
> >       i915_workqueues_cleanup(dev_priv);
> >  }
> > @@ -2556,6 +2559,7 @@ static const struct drm_ioctl_desc i915_ioctls[] =
> {
> >       DRM_IOCTL_DEF_DRV(I915_GEM_USERPTR, i915_gem_userptr_ioctl,
> DRM_RENDER_ALLOW),
> >       DRM_IOCTL_DEF_DRV(I915_GEM_CONTEXT_GETPARAM,
> i915_gem_context_getparam_ioctl, DRM_RENDER_ALLOW),
> >       DRM_IOCTL_DEF_DRV(I915_GEM_CONTEXT_SETPARAM,
> i915_gem_context_setparam_ioctl, DRM_RENDER_ALLOW),
> > +     DRM_IOCTL_DEF_DRV(I915_PERF_OPEN, i915_perf_open_ioctl,
> DRM_RENDER_ALLOW),
> >  };
> >
> >  static struct drm_driver driver = {
> > diff --git a/drivers/gpu/drm/i915/i915_drv.h
> b/drivers/gpu/drm/i915/i915_drv.h
> > index 5a260db..7a65c0b 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.h
> > +++ b/drivers/gpu/drm/i915/i915_drv.h
> > @@ -1767,6 +1767,84 @@ struct intel_wm_config {
> >       bool sprites_scaled;
> >  };
> >
> > +struct i915_perf_stream;
> > +
> > +struct i915_perf_stream_ops {
> > +     /* Enables the collection of HW samples, either in response to
> > +      * I915_PERF_IOCTL_ENABLE or implicitly called when stream is
> > +      * opened without I915_PERF_FLAG_DISABLED.
> > +      */
> > +     void (*enable)(struct i915_perf_stream *stream);
> > +
> > +     /* Disables the collection of HW samples, either in response to
> > +      * I915_PERF_IOCTL_DISABLE or implicitly called before
> > +      * destroying the stream.
> > +      */
> > +     void (*disable)(struct i915_perf_stream *stream);
> > +
> > +     /* Return: true if any i915 perf records are ready to read()
> > +      * for this stream.
> > +      */
> > +     bool (*can_read)(struct i915_perf_stream *stream);
> > +
> > +     /* Call poll_wait, passing a wait queue that will be woken
> > +      * once there is something ready to read() for the stream
> > +      */
> > +     void (*poll_wait)(struct i915_perf_stream *stream,
> > +                       struct file *file,
> > +                       poll_table *wait);
> > +
> > +     /* For handling a blocking read, wait until there is something
> > +      * to ready to read() for the stream. E.g. wait on the same
> > +      * wait queue that would be passed to poll_wait() until
> > +      * ->can_read() returns true (if its safe to call ->can_read()
> > +      * without the i915 perf lock held).
> > +      */
> > +     int (*wait_unlocked)(struct i915_perf_stream *stream);
> > +
> > +     /* read - Copy buffered metrics as records to userspace
> > +      * @buf: the userspace, destination buffer
> > +      * @count: the number of bytes to copy, requested by userspace
> > +      * @offset: zero at the start of the read, updated as the read
> > +      *          proceeds, it represents how many bytes have been
> > +      *          copied so far and the buffer offset for copying the
> > +      *          next record.
> > +      *
> > +      * Copy as many buffered i915 perf samples and records for
> > +      * this stream to userspace as will fit in the given buffer.
> > +      *
> > +      * Only write complete records; returning -ENOSPC if there
> > +      * isn't room for a complete record.
> > +      *
> > +      * Return any error condition that results in a short read
> > +      * such as -ENOSPC or -EFAULT, even though these may be
> > +      * squashed before returning to userspace.
> > +      */
> > +     int (*read)(struct i915_perf_stream *stream,
> > +                 char __user *buf,
> > +                 size_t count,
> > +                 size_t *offset);
> > +
> > +     /* Cleanup any stream specific resources.
> > +      *
> > +      * The stream will always be disabled before this is called.
> > +      */
> > +     void (*destroy)(struct i915_perf_stream *stream);
> > +};
> > +
> > +struct i915_perf_stream {
> > +     struct drm_i915_private *dev_priv;
> > +
> > +     struct list_head link;
> > +
> > +     u32 sample_flags;
> > +
> > +     struct i915_gem_context *ctx;
> > +     bool enabled;
> > +
> > +     struct i915_perf_stream_ops *ops;
> > +};
> > +
> >  struct drm_i915_private {
> >       struct drm_device drm;
> >
> > @@ -2069,6 +2147,12 @@ struct drm_i915_private {
> >
> >       struct i915_runtime_pm pm;
> >
> > +     struct {
> > +             bool initialized;
> > +             struct mutex lock;
> > +             struct list_head streams;
> > +     } perf;
> > +
> >       /* Abstract the submission mechanism (legacy ringbuffer or
> execlists) away */
> >       struct {
> >               void (*resume)(struct drm_i915_private *);
> > @@ -3482,6 +3566,9 @@ int i915_gem_context_setparam_ioctl(struct
> drm_device *dev, void *data,
> >  int i915_gem_context_reset_stats_ioctl(struct drm_device *dev, void
> *data,
> >                                      struct drm_file *file);
> >
> > +int i915_perf_open_ioctl(struct drm_device *dev, void *data,
> > +                      struct drm_file *file);
> > +
> >  /* i915_gem_evict.c */
> >  int __must_check i915_gem_evict_something(struct i915_address_space
> *vm,
> >                                         u64 min_size, u64 alignment,
> > @@ -3607,6 +3694,10 @@ int intel_engine_cmd_parser(struct
> intel_engine_cs *engine,
> >                           u32 batch_len,
> >                           bool is_master);
> >
> > +/* i915_perf.c */
> > +extern void i915_perf_init(struct drm_i915_private *dev_priv);
> > +extern void i915_perf_fini(struct drm_i915_private *dev_priv);
> > +
> >  /* i915_suspend.c */
> >  extern int i915_save_state(struct drm_device *dev);
> >  extern int i915_restore_state(struct drm_device *dev);
> > diff --git a/drivers/gpu/drm/i915/i915_perf.c
> b/drivers/gpu/drm/i915/i915_perf.c
> > new file mode 100644
> > index 0000000..c45cf92
> > --- /dev/null
> > +++ b/drivers/gpu/drm/i915/i915_perf.c
> > @@ -0,0 +1,443 @@
> > +/*
> > + * Copyright © 2015-2016 Intel Corporation
> > + *
> > + * Permission is hereby granted, free of charge, to any person
> obtaining a
> > + * copy of this software and associated documentation files (the
> "Software"),
> > + * to deal in the Software without restriction, including without
> limitation
> > + * the rights to use, copy, modify, merge, publish, distribute,
> sublicense,
> > + * and/or sell copies of the Software, and to permit persons to whom the
> > + * Software is furnished to do so, subject to the following conditions:
> > + *
> > + * The above copyright notice and this permission notice (including the
> next
> > + * paragraph) shall be included in all copies or substantial portions
> of the
> > + * Software.
> > + *
> > + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
> EXPRESS OR
> > + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
> MERCHANTABILITY,
> > + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT
> SHALL
> > + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
> OTHER
> > + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
> ARISING
> > + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
> DEALINGS
> > + * IN THE SOFTWARE.
> > + *
> > + * Authors:
> > + *   Robert Bragg <robert@sixbynine.org>
> > + */
> > +
> > +#include <linux/anon_inodes.h>
> > +
> > +#include "i915_drv.h"
> > +
> > +struct perf_open_properties {
> > +     u32 sample_flags;
> > +
> > +     u64 single_context:1;
> > +     u64 ctx_handle;
> > +};
> > +
> > +static ssize_t i915_perf_read_locked(struct i915_perf_stream *stream,
> > +                                  struct file *file,
> > +                                  char __user *buf,
> > +                                  size_t count,
> > +                                  loff_t *ppos)
> > +{
> > +     /* Note we keep the offset (aka bytes read) separate from any
> > +      * error status so that the final check for whether we return
> > +      * the bytes read with a higher precedence than any error (see
> > +      * comment below) doesn't need to be handled/duplicated in
> > +      * stream->ops->read() implementations.
> > +      */
> > +     size_t offset = 0;
> > +     int ret = stream->ops->read(stream, buf, count, &offset);
> > +
> > +     /* If we've successfully copied any data then reporting that
> > +      * takes precedence over any internal error status, so the
> > +      * data isn't lost.
> > +      *
> > +      * For example ret will be -ENOSPC whenever there is more
> > +      * buffered data than can be copied to userspace, but that's
> > +      * only interesting if we weren't able to copy some data
> > +      * because it implies the userspace buffer is too small to
> > +      * receive a single record (and we never split records).
> > +      *
> > +      * Another case with ret == -EFAULT is more of a grey area
> > +      * since it would seem like bad form for userspace to ask us
> > +      * to overrun its buffer, but the user knows best:
> > +      *
> > +      *   http://yarchive.net/comp/linux/partial_reads_writes.html
> > +      */
> > +     return offset ?: (ret ?: -EAGAIN);
> > +}
> > +
> > +static ssize_t i915_perf_read(struct file *file,
> > +                           char __user *buf,
> > +                           size_t count,
> > +                           loff_t *ppos)
> > +{
> > +     struct i915_perf_stream *stream = file->private_data;
> > +     struct drm_i915_private *dev_priv = stream->dev_priv;
> > +     ssize_t ret;
> > +
> > +     if (!(file->f_flags & O_NONBLOCK)) {
> > +             /* Allow false positives from stream->ops->wait_unlocked.
> > +              */
> > +             do {
> > +                     ret = stream->ops->wait_unlocked(stream);
> > +                     if (ret)
> > +                             return ret;
> > +
> > +                     mutex_lock(&dev_priv->perf.lock);
>
> Should interruptible version be used here, to allow for reads to be
> interrupted?
>

Now that we don't have the context pin hook on haswell we could /almost/
get away without this lock except for its use to synchronize
i915_perf_register with i915_perf_open_ioctl.

Most of the i915-perf state access is synchronized as a result of being
fops driven, so this perf.lock was added to deal with a few entrypoints
outside of fops such as the contect pinning hook we used to have (though we
avoid it in the hrtimer callback).

Although the recent change to remove the pin hook has made the lock look a
bit redundant for now, I think I'd prefer to leave the locks as they are to
avoid the churn with the gen8+ patches where we do have some other
entrypoints into i915-perf outside of the fops.

Given that though, there's currently not really much argument either way
for them being interruptible. The expectation I have atm is that there
shouldn't be anything running async within i915-perf outside of fops that's
expected to be long running. We will probably also want to consider the
risk of bouncing lots of reads, starving userspace and increasing the risk
of a buffer overflow if this is interruptible.

- Robert
sourab.gupta@intel.com Nov. 7, 2016, 8:40 a.m. UTC | #7
On Fri, 2016-11-04 at 06:19 -0700, Robert Bragg wrote:
> 
> 
> On Fri, Nov 4, 2016 at 8:59 AM, sourab gupta <sourab.gupta@intel.com>
> wrote:
>         On Thu, 2016-10-27 at 19:14 -0700, Robert Bragg wrote:
>         > Adds base i915 perf infrastructure for Gen performance
>         metrics.
>         >
>         > This adds a DRM_IOCTL_I915_PERF_OPEN ioctl that takes an
>         array of uint64
>         > properties to configure a stream of metrics and returns a
>         new fd usable
>         > with standard VFS system calls including read() to read
>         typed and sized
>         > records; ioctl() to enable or disable capture and poll() to
>         wait for
>         > data.
>         >
>         > A stream is opened something like:
>         >
>         >   uint64_t properties[] = {
>         >       /* Single context sampling */
>         >       DRM_I915_PERF_PROP_CTX_HANDLE,        ctx_handle,
>         >
>         >       /* Include OA reports in samples */
>         >       DRM_I915_PERF_PROP_SAMPLE_OA,         true,
>         >
>         >       /* OA unit configuration */
>         >       DRM_I915_PERF_PROP_OA_METRICS_SET,    metrics_set_id,
>         >       DRM_I915_PERF_PROP_OA_FORMAT,         report_format,
>         >       DRM_I915_PERF_PROP_OA_EXPONENT,       period_exponent,
>         >    };
>         >    struct drm_i915_perf_open_param parm = {
>         >       .flags = I915_PERF_FLAG_FD_CLOEXEC |
>         >                I915_PERF_FLAG_FD_NONBLOCK |
>         >                I915_PERF_FLAG_DISABLED,
>         >       .properties_ptr = (uint64_t)properties,
>         >       .num_properties = sizeof(properties) / 16,
>         >    };
>         >    int fd = drmIoctl(drm_fd, DRM_IOCTL_I915_PERF_OPEN,
>         &param);
>         >
>         > Records read all start with a common { type, size } header
>         with
>         > DRM_I915_PERF_RECORD_SAMPLE being of most interest. Sample
>         records
>         > contain an extensible number of fields and it's the
>         > DRM_I915_PERF_PROP_SAMPLE_xyz properties given when opening
>         that
>         > determine what's included in every sample.
>         >
>         > No specific streams are supported yet so any attempt to open
>         a stream
>         > will return an error.
>         >
>         > v2:
>         >     use i915_gem_context_get() - Chris Wilson
>         > v3:
>         >     update read() interface to avoid passing state struct -
>         Chris Wilson
>         >     fix some rebase fallout, with i915-perf init/deinit
>         > v4:
>         >     s/DRM_IORW/DRM_IOW/ - Emil Velikov
>         >
>         > Signed-off-by: Robert Bragg <robert@sixbynine.org>
>         > ---
>         >  drivers/gpu/drm/i915/Makefile    |   3 +
>         >  drivers/gpu/drm/i915/i915_drv.c  |   4 +
>         >  drivers/gpu/drm/i915/i915_drv.h  |  91 ++++++++
>         >  drivers/gpu/drm/i915/i915_perf.c | 443
>         +++++++++++++++++++++++++++++++++++++++
>         >  include/uapi/drm/i915_drm.h      |  67 ++++++
>         >  5 files changed, 608 insertions(+)
>         >  create mode 100644 drivers/gpu/drm/i915/i915_perf.c
>         >
>         > diff --git a/drivers/gpu/drm/i915/Makefile
>         b/drivers/gpu/drm/i915/Makefile
>         > index 6123400..8d4e25f 100644
>         > --- a/drivers/gpu/drm/i915/Makefile
>         > +++ b/drivers/gpu/drm/i915/Makefile
>         > @@ -113,6 +113,9 @@ i915-$(CONFIG_DRM_I915_CAPTURE_ERROR) +=
>         i915_gpu_error.o
>         >  # virtual gpu code
>         >  i915-y += i915_vgpu.o
>         >
>         > +# perf code
>         > +i915-y += i915_perf.o
>         > +
>         >  ifeq ($(CONFIG_DRM_I915_GVT),y)
>         >  i915-y += intel_gvt.o
>         >  include $(src)/gvt/Makefile
>         > diff --git a/drivers/gpu/drm/i915/i915_drv.c
>         b/drivers/gpu/drm/i915/i915_drv.c
>         > index af3559d..685c96e 100644
>         > --- a/drivers/gpu/drm/i915/i915_drv.c
>         > +++ b/drivers/gpu/drm/i915/i915_drv.c
>         > @@ -836,6 +836,8 @@ static int i915_driver_init_early(struct
>         drm_i915_private *dev_priv,
>         >
>         >       intel_detect_preproduction_hw(dev_priv);
>         >
>         > +     i915_perf_init(dev_priv);
>         > +
>         >       return 0;
>         >
>         >  err_workqueues:
>         > @@ -849,6 +851,7 @@ static int i915_driver_init_early(struct
>         drm_i915_private *dev_priv,
>         >   */
>         >  static void i915_driver_cleanup_early(struct
>         drm_i915_private *dev_priv)
>         >  {
>         > +     i915_perf_fini(dev_priv);
>         >       i915_gem_load_cleanup(&dev_priv->drm);
>         >       i915_workqueues_cleanup(dev_priv);
>         >  }
>         > @@ -2556,6 +2559,7 @@ static const struct drm_ioctl_desc
>         i915_ioctls[] = {
>         >       DRM_IOCTL_DEF_DRV(I915_GEM_USERPTR,
>         i915_gem_userptr_ioctl, DRM_RENDER_ALLOW),
>         >       DRM_IOCTL_DEF_DRV(I915_GEM_CONTEXT_GETPARAM,
>         i915_gem_context_getparam_ioctl, DRM_RENDER_ALLOW),
>         >       DRM_IOCTL_DEF_DRV(I915_GEM_CONTEXT_SETPARAM,
>         i915_gem_context_setparam_ioctl, DRM_RENDER_ALLOW),
>         > +     DRM_IOCTL_DEF_DRV(I915_PERF_OPEN,
>         i915_perf_open_ioctl, DRM_RENDER_ALLOW),
>         >  };
>         >
>         >  static struct drm_driver driver = {
>         > diff --git a/drivers/gpu/drm/i915/i915_drv.h
>         b/drivers/gpu/drm/i915/i915_drv.h
>         > index 5a260db..7a65c0b 100644
>         > --- a/drivers/gpu/drm/i915/i915_drv.h
>         > +++ b/drivers/gpu/drm/i915/i915_drv.h
>         > @@ -1767,6 +1767,84 @@ struct intel_wm_config {
>         >       bool sprites_scaled;
>         >  };
>         >
>         > +struct i915_perf_stream;
>         > +
>         > +struct i915_perf_stream_ops {
>         > +     /* Enables the collection of HW samples, either in
>         response to
>         > +      * I915_PERF_IOCTL_ENABLE or implicitly called when
>         stream is
>         > +      * opened without I915_PERF_FLAG_DISABLED.
>         > +      */
>         > +     void (*enable)(struct i915_perf_stream *stream);
>         > +
>         > +     /* Disables the collection of HW samples, either in
>         response to
>         > +      * I915_PERF_IOCTL_DISABLE or implicitly called before
>         > +      * destroying the stream.
>         > +      */
>         > +     void (*disable)(struct i915_perf_stream *stream);
>         > +
>         > +     /* Return: true if any i915 perf records are ready to
>         read()
>         > +      * for this stream.
>         > +      */
>         > +     bool (*can_read)(struct i915_perf_stream *stream);
>         > +
>         > +     /* Call poll_wait, passing a wait queue that will be
>         woken
>         > +      * once there is something ready to read() for the
>         stream
>         > +      */
>         > +     void (*poll_wait)(struct i915_perf_stream *stream,
>         > +                       struct file *file,
>         > +                       poll_table *wait);
>         > +
>         > +     /* For handling a blocking read, wait until there is
>         something
>         > +      * to ready to read() for the stream. E.g. wait on the
>         same
>         > +      * wait queue that would be passed to poll_wait()
>         until
>         > +      * ->can_read() returns true (if its safe to call
>         ->can_read()
>         > +      * without the i915 perf lock held).
>         > +      */
>         > +     int (*wait_unlocked)(struct i915_perf_stream *stream);
>         > +
>         > +     /* read - Copy buffered metrics as records to
>         userspace
>         > +      * @buf: the userspace, destination buffer
>         > +      * @count: the number of bytes to copy, requested by
>         userspace
>         > +      * @offset: zero at the start of the read, updated as
>         the read
>         > +      *          proceeds, it represents how many bytes
>         have been
>         > +      *          copied so far and the buffer offset for
>         copying the
>         > +      *          next record.
>         > +      *
>         > +      * Copy as many buffered i915 perf samples and records
>         for
>         > +      * this stream to userspace as will fit in the given
>         buffer.
>         > +      *
>         > +      * Only write complete records; returning -ENOSPC if
>         there
>         > +      * isn't room for a complete record.
>         > +      *
>         > +      * Return any error condition that results in a short
>         read
>         > +      * such as -ENOSPC or -EFAULT, even though these may
>         be
>         > +      * squashed before returning to userspace.
>         > +      */
>         > +     int (*read)(struct i915_perf_stream *stream,
>         > +                 char __user *buf,
>         > +                 size_t count,
>         > +                 size_t *offset);
>         > +
>         > +     /* Cleanup any stream specific resources.
>         > +      *
>         > +      * The stream will always be disabled before this is
>         called.
>         > +      */
>         > +     void (*destroy)(struct i915_perf_stream *stream);
>         > +};
>         > +
>         > +struct i915_perf_stream {
>         > +     struct drm_i915_private *dev_priv;
>         > +
>         > +     struct list_head link;
>         > +
>         > +     u32 sample_flags;
>         > +
>         > +     struct i915_gem_context *ctx;
>         > +     bool enabled;
>         > +
>         > +     struct i915_perf_stream_ops *ops;
>         > +};
>         > +
>         >  struct drm_i915_private {
>         >       struct drm_device drm;
>         >
>         > @@ -2069,6 +2147,12 @@ struct drm_i915_private {
>         >
>         >       struct i915_runtime_pm pm;
>         >
>         > +     struct {
>         > +             bool initialized;
>         > +             struct mutex lock;
>         > +             struct list_head streams;
>         > +     } perf;
>         > +
>         >       /* Abstract the submission mechanism (legacy
>         ringbuffer or execlists) away */
>         >       struct {
>         >               void (*resume)(struct drm_i915_private *);
>         > @@ -3482,6 +3566,9 @@ int
>         i915_gem_context_setparam_ioctl(struct drm_device *dev, void
>         *data,
>         >  int i915_gem_context_reset_stats_ioctl(struct drm_device
>         *dev, void *data,
>         >                                      struct drm_file *file);
>         >
>         > +int i915_perf_open_ioctl(struct drm_device *dev, void
>         *data,
>         > +                      struct drm_file *file);
>         > +
>         >  /* i915_gem_evict.c */
>         >  int __must_check i915_gem_evict_something(struct
>         i915_address_space *vm,
>         >                                         u64 min_size, u64
>         alignment,
>         > @@ -3607,6 +3694,10 @@ int intel_engine_cmd_parser(struct
>         intel_engine_cs *engine,
>         >                           u32 batch_len,
>         >                           bool is_master);
>         >
>         > +/* i915_perf.c */
>         > +extern void i915_perf_init(struct drm_i915_private
>         *dev_priv);
>         > +extern void i915_perf_fini(struct drm_i915_private
>         *dev_priv);
>         > +
>         >  /* i915_suspend.c */
>         >  extern int i915_save_state(struct drm_device *dev);
>         >  extern int i915_restore_state(struct drm_device *dev);
>         > diff --git a/drivers/gpu/drm/i915/i915_perf.c
>         b/drivers/gpu/drm/i915/i915_perf.c
>         > new file mode 100644
>         > index 0000000..c45cf92
>         > --- /dev/null
>         > +++ b/drivers/gpu/drm/i915/i915_perf.c
>         > @@ -0,0 +1,443 @@
>         > +/*
>         > + * Copyright © 2015-2016 Intel Corporation
>         > + *
>         > + * Permission is hereby granted, free of charge, to any
>         person obtaining a
>         > + * copy of this software and associated documentation files
>         (the "Software"),
>         > + * to deal in the Software without restriction, including
>         without limitation
>         > + * the rights to use, copy, modify, merge, publish,
>         distribute, sublicense,
>         > + * and/or sell copies of the Software, and to permit
>         persons to whom the
>         > + * Software is furnished to do so, subject to the following
>         conditions:
>         > + *
>         > + * The above copyright notice and this permission notice
>         (including the next
>         > + * paragraph) shall be included in all copies or
>         substantial portions of the
>         > + * Software.
>         > + *
>         > + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
>         ANY KIND, EXPRESS OR
>         > + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
>         MERCHANTABILITY,
>         > + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
>         IN NO EVENT SHALL
>         > + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
>         CLAIM, DAMAGES OR OTHER
>         > + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
>         OTHERWISE, ARISING
>         > + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
>         USE OR OTHER DEALINGS
>         > + * IN THE SOFTWARE.
>         > + *
>         > + * Authors:
>         > + *   Robert Bragg <robert@sixbynine.org>
>         > + */
>         > +
>         > +#include <linux/anon_inodes.h>
>         > +
>         > +#include "i915_drv.h"
>         > +
>         > +struct perf_open_properties {
>         > +     u32 sample_flags;
>         > +
>         > +     u64 single_context:1;
>         > +     u64 ctx_handle;
>         > +};
>         > +
>         > +static ssize_t i915_perf_read_locked(struct
>         i915_perf_stream *stream,
>         > +                                  struct file *file,
>         > +                                  char __user *buf,
>         > +                                  size_t count,
>         > +                                  loff_t *ppos)
>         > +{
>         > +     /* Note we keep the offset (aka bytes read) separate
>         from any
>         > +      * error status so that the final check for whether we
>         return
>         > +      * the bytes read with a higher precedence than any
>         error (see
>         > +      * comment below) doesn't need to be
>         handled/duplicated in
>         > +      * stream->ops->read() implementations.
>         > +      */
>         > +     size_t offset = 0;
>         > +     int ret = stream->ops->read(stream, buf, count,
>         &offset);
>         > +
>         > +     /* If we've successfully copied any data then
>         reporting that
>         > +      * takes precedence over any internal error status, so
>         the
>         > +      * data isn't lost.
>         > +      *
>         > +      * For example ret will be -ENOSPC whenever there is
>         more
>         > +      * buffered data than can be copied to userspace, but
>         that's
>         > +      * only interesting if we weren't able to copy some
>         data
>         > +      * because it implies the userspace buffer is too
>         small to
>         > +      * receive a single record (and we never split
>         records).
>         > +      *
>         > +      * Another case with ret == -EFAULT is more of a grey
>         area
>         > +      * since it would seem like bad form for userspace to
>         ask us
>         > +      * to overrun its buffer, but the user knows best:
>         > +      *
>         > +      *
>          http://yarchive.net/comp/linux/partial_reads_writes.html
>         > +      */
>         > +     return offset ?: (ret ?: -EAGAIN);
>         > +}
>         > +
>         > +static ssize_t i915_perf_read(struct file *file,
>         > +                           char __user *buf,
>         > +                           size_t count,
>         > +                           loff_t *ppos)
>         > +{
>         > +     struct i915_perf_stream *stream = file->private_data;
>         > +     struct drm_i915_private *dev_priv = stream->dev_priv;
>         > +     ssize_t ret;
>         > +
>         > +     if (!(file->f_flags & O_NONBLOCK)) {
>         > +             /* Allow false positives from
>         stream->ops->wait_unlocked.
>         > +              */
>         > +             do {
>         > +                     ret =
>         stream->ops->wait_unlocked(stream);
>         > +                     if (ret)
>         > +                             return ret;
>         > +
>         > +                     mutex_lock(&dev_priv->perf.lock);
>         
>         
>         Should interruptible version be used here, to allow for reads
>         to be
>         interrupted?
> 
> 
> Now that we don't have the context pin hook on haswell we
> could /almost/ get away without this lock except for its use to
> synchronize i915_perf_register with i915_perf_open_ioctl.
> 
> 
> Most of the i915-perf state access is synchronized as a result of
> being fops driven, so this perf.lock was added to deal with a few
> entrypoints outside of fops such as the contect pinning hook we used
> to have (though we avoid it in the hrtimer callback).
> 
> 
> 
> Although the recent change to remove the pin hook has made the lock
> look a bit redundant for now, I think I'd prefer to leave the locks as
> they are to avoid the churn with the gen8+ patches where we do have
> some other entrypoints into i915-perf outside of the fops.
> 
> 
> Given that though, there's currently not really much argument either
> way for them being interruptible. The expectation I have atm is that
> there shouldn't be anything running async within i915-perf outside of
> fops that's expected to be long running. We will probably also want to
> consider the risk of bouncing lots of reads, starving userspace and
> increasing the risk of a buffer overflow if this is interruptible.
> 
Well, that makes sense. I'm okay with rest of the interfaces exposed
here (Have been using them for my work too). So,
Reviewed-by: Sourab Gupta <sourab.gupta@intel.com>
> 
> - Robert
>
diff mbox

Patch

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 6123400..8d4e25f 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -113,6 +113,9 @@  i915-$(CONFIG_DRM_I915_CAPTURE_ERROR) += i915_gpu_error.o
 # virtual gpu code
 i915-y += i915_vgpu.o
 
+# perf code
+i915-y += i915_perf.o
+
 ifeq ($(CONFIG_DRM_I915_GVT),y)
 i915-y += intel_gvt.o
 include $(src)/gvt/Makefile
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index af3559d..685c96e 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -836,6 +836,8 @@  static int i915_driver_init_early(struct drm_i915_private *dev_priv,
 
 	intel_detect_preproduction_hw(dev_priv);
 
+	i915_perf_init(dev_priv);
+
 	return 0;
 
 err_workqueues:
@@ -849,6 +851,7 @@  static int i915_driver_init_early(struct drm_i915_private *dev_priv,
  */
 static void i915_driver_cleanup_early(struct drm_i915_private *dev_priv)
 {
+	i915_perf_fini(dev_priv);
 	i915_gem_load_cleanup(&dev_priv->drm);
 	i915_workqueues_cleanup(dev_priv);
 }
@@ -2556,6 +2559,7 @@  static const struct drm_ioctl_desc i915_ioctls[] = {
 	DRM_IOCTL_DEF_DRV(I915_GEM_USERPTR, i915_gem_userptr_ioctl, DRM_RENDER_ALLOW),
 	DRM_IOCTL_DEF_DRV(I915_GEM_CONTEXT_GETPARAM, i915_gem_context_getparam_ioctl, DRM_RENDER_ALLOW),
 	DRM_IOCTL_DEF_DRV(I915_GEM_CONTEXT_SETPARAM, i915_gem_context_setparam_ioctl, DRM_RENDER_ALLOW),
+	DRM_IOCTL_DEF_DRV(I915_PERF_OPEN, i915_perf_open_ioctl, DRM_RENDER_ALLOW),
 };
 
 static struct drm_driver driver = {
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 5a260db..7a65c0b 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1767,6 +1767,84 @@  struct intel_wm_config {
 	bool sprites_scaled;
 };
 
+struct i915_perf_stream;
+
+struct i915_perf_stream_ops {
+	/* Enables the collection of HW samples, either in response to
+	 * I915_PERF_IOCTL_ENABLE or implicitly called when stream is
+	 * opened without I915_PERF_FLAG_DISABLED.
+	 */
+	void (*enable)(struct i915_perf_stream *stream);
+
+	/* Disables the collection of HW samples, either in response to
+	 * I915_PERF_IOCTL_DISABLE or implicitly called before
+	 * destroying the stream.
+	 */
+	void (*disable)(struct i915_perf_stream *stream);
+
+	/* Return: true if any i915 perf records are ready to read()
+	 * for this stream.
+	 */
+	bool (*can_read)(struct i915_perf_stream *stream);
+
+	/* Call poll_wait, passing a wait queue that will be woken
+	 * once there is something ready to read() for the stream
+	 */
+	void (*poll_wait)(struct i915_perf_stream *stream,
+			  struct file *file,
+			  poll_table *wait);
+
+	/* For handling a blocking read, wait until there is something
+	 * to ready to read() for the stream. E.g. wait on the same
+	 * wait queue that would be passed to poll_wait() until
+	 * ->can_read() returns true (if its safe to call ->can_read()
+	 * without the i915 perf lock held).
+	 */
+	int (*wait_unlocked)(struct i915_perf_stream *stream);
+
+	/* read - Copy buffered metrics as records to userspace
+	 * @buf: the userspace, destination buffer
+	 * @count: the number of bytes to copy, requested by userspace
+	 * @offset: zero at the start of the read, updated as the read
+	 *          proceeds, it represents how many bytes have been
+	 *          copied so far and the buffer offset for copying the
+	 *          next record.
+	 *
+	 * Copy as many buffered i915 perf samples and records for
+	 * this stream to userspace as will fit in the given buffer.
+	 *
+	 * Only write complete records; returning -ENOSPC if there
+	 * isn't room for a complete record.
+	 *
+	 * Return any error condition that results in a short read
+	 * such as -ENOSPC or -EFAULT, even though these may be
+	 * squashed before returning to userspace.
+	 */
+	int (*read)(struct i915_perf_stream *stream,
+		    char __user *buf,
+		    size_t count,
+		    size_t *offset);
+
+	/* Cleanup any stream specific resources.
+	 *
+	 * The stream will always be disabled before this is called.
+	 */
+	void (*destroy)(struct i915_perf_stream *stream);
+};
+
+struct i915_perf_stream {
+	struct drm_i915_private *dev_priv;
+
+	struct list_head link;
+
+	u32 sample_flags;
+
+	struct i915_gem_context *ctx;
+	bool enabled;
+
+	struct i915_perf_stream_ops *ops;
+};
+
 struct drm_i915_private {
 	struct drm_device drm;
 
@@ -2069,6 +2147,12 @@  struct drm_i915_private {
 
 	struct i915_runtime_pm pm;
 
+	struct {
+		bool initialized;
+		struct mutex lock;
+		struct list_head streams;
+	} perf;
+
 	/* Abstract the submission mechanism (legacy ringbuffer or execlists) away */
 	struct {
 		void (*resume)(struct drm_i915_private *);
@@ -3482,6 +3566,9 @@  int i915_gem_context_setparam_ioctl(struct drm_device *dev, void *data,
 int i915_gem_context_reset_stats_ioctl(struct drm_device *dev, void *data,
 				       struct drm_file *file);
 
+int i915_perf_open_ioctl(struct drm_device *dev, void *data,
+			 struct drm_file *file);
+
 /* i915_gem_evict.c */
 int __must_check i915_gem_evict_something(struct i915_address_space *vm,
 					  u64 min_size, u64 alignment,
@@ -3607,6 +3694,10 @@  int intel_engine_cmd_parser(struct intel_engine_cs *engine,
 			    u32 batch_len,
 			    bool is_master);
 
+/* i915_perf.c */
+extern void i915_perf_init(struct drm_i915_private *dev_priv);
+extern void i915_perf_fini(struct drm_i915_private *dev_priv);
+
 /* i915_suspend.c */
 extern int i915_save_state(struct drm_device *dev);
 extern int i915_restore_state(struct drm_device *dev);
diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
new file mode 100644
index 0000000..c45cf92
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -0,0 +1,443 @@ 
+/*
+ * Copyright © 2015-2016 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ * Authors:
+ *   Robert Bragg <robert@sixbynine.org>
+ */
+
+#include <linux/anon_inodes.h>
+
+#include "i915_drv.h"
+
+struct perf_open_properties {
+	u32 sample_flags;
+
+	u64 single_context:1;
+	u64 ctx_handle;
+};
+
+static ssize_t i915_perf_read_locked(struct i915_perf_stream *stream,
+				     struct file *file,
+				     char __user *buf,
+				     size_t count,
+				     loff_t *ppos)
+{
+	/* Note we keep the offset (aka bytes read) separate from any
+	 * error status so that the final check for whether we return
+	 * the bytes read with a higher precedence than any error (see
+	 * comment below) doesn't need to be handled/duplicated in
+	 * stream->ops->read() implementations.
+	 */
+	size_t offset = 0;
+	int ret = stream->ops->read(stream, buf, count, &offset);
+
+	/* If we've successfully copied any data then reporting that
+	 * takes precedence over any internal error status, so the
+	 * data isn't lost.
+	 *
+	 * For example ret will be -ENOSPC whenever there is more
+	 * buffered data than can be copied to userspace, but that's
+	 * only interesting if we weren't able to copy some data
+	 * because it implies the userspace buffer is too small to
+	 * receive a single record (and we never split records).
+	 *
+	 * Another case with ret == -EFAULT is more of a grey area
+	 * since it would seem like bad form for userspace to ask us
+	 * to overrun its buffer, but the user knows best:
+	 *
+	 *   http://yarchive.net/comp/linux/partial_reads_writes.html
+	 */
+	return offset ?: (ret ?: -EAGAIN);
+}
+
+static ssize_t i915_perf_read(struct file *file,
+			      char __user *buf,
+			      size_t count,
+			      loff_t *ppos)
+{
+	struct i915_perf_stream *stream = file->private_data;
+	struct drm_i915_private *dev_priv = stream->dev_priv;
+	ssize_t ret;
+
+	if (!(file->f_flags & O_NONBLOCK)) {
+		/* Allow false positives from stream->ops->wait_unlocked.
+		 */
+		do {
+			ret = stream->ops->wait_unlocked(stream);
+			if (ret)
+				return ret;
+
+			mutex_lock(&dev_priv->perf.lock);
+			ret = i915_perf_read_locked(stream, file,
+						    buf, count, ppos);
+			mutex_unlock(&dev_priv->perf.lock);
+		} while (ret == -EAGAIN);
+	} else {
+		mutex_lock(&dev_priv->perf.lock);
+		ret = i915_perf_read_locked(stream, file, buf, count, ppos);
+		mutex_unlock(&dev_priv->perf.lock);
+	}
+
+	return ret;
+}
+
+static unsigned int i915_perf_poll_locked(struct i915_perf_stream *stream,
+					  struct file *file,
+					  poll_table *wait)
+{
+	unsigned int streams = 0;
+
+	stream->ops->poll_wait(stream, file, wait);
+
+	if (stream->ops->can_read(stream))
+		streams |= POLLIN;
+
+	return streams;
+}
+
+static unsigned int i915_perf_poll(struct file *file, poll_table *wait)
+{
+	struct i915_perf_stream *stream = file->private_data;
+	struct drm_i915_private *dev_priv = stream->dev_priv;
+	int ret;
+
+	mutex_lock(&dev_priv->perf.lock);
+	ret = i915_perf_poll_locked(stream, file, wait);
+	mutex_unlock(&dev_priv->perf.lock);
+
+	return ret;
+}
+
+static void i915_perf_enable_locked(struct i915_perf_stream *stream)
+{
+	if (stream->enabled)
+		return;
+
+	/* Allow stream->ops->enable() to refer to this */
+	stream->enabled = true;
+
+	if (stream->ops->enable)
+		stream->ops->enable(stream);
+}
+
+static void i915_perf_disable_locked(struct i915_perf_stream *stream)
+{
+	if (!stream->enabled)
+		return;
+
+	/* Allow stream->ops->disable() to refer to this */
+	stream->enabled = false;
+
+	if (stream->ops->disable)
+		stream->ops->disable(stream);
+}
+
+static long i915_perf_ioctl_locked(struct i915_perf_stream *stream,
+				   unsigned int cmd,
+				   unsigned long arg)
+{
+	switch (cmd) {
+	case I915_PERF_IOCTL_ENABLE:
+		i915_perf_enable_locked(stream);
+		return 0;
+	case I915_PERF_IOCTL_DISABLE:
+		i915_perf_disable_locked(stream);
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+static long i915_perf_ioctl(struct file *file,
+			    unsigned int cmd,
+			    unsigned long arg)
+{
+	struct i915_perf_stream *stream = file->private_data;
+	struct drm_i915_private *dev_priv = stream->dev_priv;
+	long ret;
+
+	mutex_lock(&dev_priv->perf.lock);
+	ret = i915_perf_ioctl_locked(stream, cmd, arg);
+	mutex_unlock(&dev_priv->perf.lock);
+
+	return ret;
+}
+
+static void i915_perf_destroy_locked(struct i915_perf_stream *stream)
+{
+	struct drm_i915_private *dev_priv = stream->dev_priv;
+
+	if (stream->enabled)
+		i915_perf_disable_locked(stream);
+
+	if (stream->ops->destroy)
+		stream->ops->destroy(stream);
+
+	list_del(&stream->link);
+
+	if (stream->ctx) {
+		mutex_lock(&dev_priv->drm.struct_mutex);
+		i915_gem_context_put(stream->ctx);
+		mutex_unlock(&dev_priv->drm.struct_mutex);
+	}
+
+	kfree(stream);
+}
+
+static int i915_perf_release(struct inode *inode, struct file *file)
+{
+	struct i915_perf_stream *stream = file->private_data;
+	struct drm_i915_private *dev_priv = stream->dev_priv;
+
+	mutex_lock(&dev_priv->perf.lock);
+	i915_perf_destroy_locked(stream);
+	mutex_unlock(&dev_priv->perf.lock);
+
+	return 0;
+}
+
+
+static const struct file_operations fops = {
+	.owner		= THIS_MODULE,
+	.llseek		= no_llseek,
+	.release	= i915_perf_release,
+	.poll		= i915_perf_poll,
+	.read		= i915_perf_read,
+	.unlocked_ioctl	= i915_perf_ioctl,
+};
+
+
+static struct i915_gem_context *
+lookup_context(struct drm_i915_private *dev_priv,
+	       struct drm_i915_file_private *file_priv,
+	       u32 ctx_user_handle)
+{
+	struct i915_gem_context *ctx;
+	int ret;
+
+	ret = i915_mutex_lock_interruptible(&dev_priv->drm);
+	if (ret)
+		return ERR_PTR(ret);
+
+	ctx = i915_gem_context_lookup(file_priv, ctx_user_handle);
+	if (!IS_ERR(ctx))
+		i915_gem_context_get(ctx);
+
+	mutex_unlock(&dev_priv->drm.struct_mutex);
+
+	return ctx;
+}
+
+static int
+i915_perf_open_ioctl_locked(struct drm_i915_private *dev_priv,
+			    struct drm_i915_perf_open_param *param,
+			    struct perf_open_properties *props,
+			    struct drm_file *file)
+{
+	struct i915_gem_context *specific_ctx = NULL;
+	struct i915_perf_stream *stream = NULL;
+	unsigned long f_flags = 0;
+	int stream_fd;
+	int ret;
+
+	if (props->single_context) {
+		u32 ctx_handle = props->ctx_handle;
+		struct drm_i915_file_private *file_priv = file->driver_priv;
+
+		specific_ctx = lookup_context(dev_priv, file_priv, ctx_handle);
+		if (IS_ERR(specific_ctx)) {
+			ret = PTR_ERR(specific_ctx);
+			if (ret != -EINTR)
+				DRM_ERROR("Failed to look up context with ID %u for opening perf stream\n",
+					  ctx_handle);
+			goto err;
+		}
+	}
+
+	if (!specific_ctx && !capable(CAP_SYS_ADMIN)) {
+		DRM_ERROR("Insufficient privileges to open system-wide i915 perf stream\n");
+		ret = -EACCES;
+		goto err_ctx;
+	}
+
+	stream = kzalloc(sizeof(*stream), GFP_KERNEL);
+	if (!stream) {
+		ret = -ENOMEM;
+		goto err_ctx;
+	}
+
+	stream->sample_flags = props->sample_flags;
+	stream->dev_priv = dev_priv;
+	stream->ctx = specific_ctx;
+
+	/*
+	 * TODO: support sampling something
+	 *
+	 * For now this is as far as we can go.
+	 */
+	DRM_ERROR("Unsupported i915 perf stream configuration\n");
+	ret = -EINVAL;
+	goto err_alloc;
+
+	list_add(&stream->link, &dev_priv->perf.streams);
+
+	if (param->flags & I915_PERF_FLAG_FD_CLOEXEC)
+		f_flags |= O_CLOEXEC;
+	if (param->flags & I915_PERF_FLAG_FD_NONBLOCK)
+		f_flags |= O_NONBLOCK;
+
+	stream_fd = anon_inode_getfd("[i915_perf]", &fops, stream, f_flags);
+	if (stream_fd < 0) {
+		ret = stream_fd;
+		goto err_open;
+	}
+
+	if (!(param->flags & I915_PERF_FLAG_DISABLED))
+		i915_perf_enable_locked(stream);
+
+	return stream_fd;
+
+err_open:
+	list_del(&stream->link);
+	if (stream->ops->destroy)
+		stream->ops->destroy(stream);
+err_alloc:
+	kfree(stream);
+err_ctx:
+	if (specific_ctx) {
+		mutex_lock(&dev_priv->drm.struct_mutex);
+		i915_gem_context_put(specific_ctx);
+		mutex_unlock(&dev_priv->drm.struct_mutex);
+	}
+err:
+	return ret;
+}
+
+/* Note we copy the properties from userspace outside of the i915 perf
+ * mutex to avoid an awkward lockdep with mmap_sem.
+ *
+ * Note this function only validates properties in isolation it doesn't
+ * validate that the combination of properties makes sense or that all
+ * properties necessary for a particular kind of stream have been set.
+ */
+static int read_properties_unlocked(struct drm_i915_private *dev_priv,
+				    u64 __user *uprops,
+				    u32 n_props,
+				    struct perf_open_properties *props)
+{
+	u64 __user *uprop = uprops;
+	int i;
+
+	memset(props, 0, sizeof(struct perf_open_properties));
+
+	if (!n_props) {
+		DRM_ERROR("No i915 perf properties given");
+		return -EINVAL;
+	}
+
+	if (n_props > DRM_I915_PERF_PROP_MAX) {
+		DRM_ERROR("More i915 perf properties specified than exist");
+		return -EINVAL;
+	}
+
+	for (i = 0; i < n_props; i++) {
+		u64 id, value;
+		int ret;
+
+		ret = get_user(id, uprop);
+		if (ret)
+			return ret;
+
+		ret = get_user(value, uprop + 1);
+		if (ret)
+			return ret;
+
+		switch ((enum drm_i915_perf_property_id)id) {
+		case DRM_I915_PERF_PROP_CTX_HANDLE:
+			props->single_context = 1;
+			props->ctx_handle = value;
+			break;
+		default:
+			MISSING_CASE(id);
+			DRM_ERROR("Unknown i915 perf property ID");
+			return -EINVAL;
+		}
+
+		uprop += 2;
+	}
+
+	return 0;
+}
+
+int i915_perf_open_ioctl(struct drm_device *dev, void *data,
+			 struct drm_file *file)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct drm_i915_perf_open_param *param = data;
+	struct perf_open_properties props;
+	u32 known_open_flags;
+	int ret;
+
+	if (!dev_priv->perf.initialized) {
+		DRM_ERROR("i915 perf interface not available for this system");
+		return -ENOTSUPP;
+	}
+
+	known_open_flags = I915_PERF_FLAG_FD_CLOEXEC |
+			   I915_PERF_FLAG_FD_NONBLOCK |
+			   I915_PERF_FLAG_DISABLED;
+	if (param->flags & ~known_open_flags) {
+		DRM_ERROR("Unknown drm_i915_perf_open_param flag\n");
+		return -EINVAL;
+	}
+
+	ret = read_properties_unlocked(dev_priv,
+				       u64_to_user_ptr(param->properties_ptr),
+				       param->num_properties,
+				       &props);
+	if (ret)
+		return ret;
+
+	mutex_lock(&dev_priv->perf.lock);
+	ret = i915_perf_open_ioctl_locked(dev_priv, param, &props, file);
+	mutex_unlock(&dev_priv->perf.lock);
+
+	return ret;
+}
+
+void i915_perf_init(struct drm_i915_private *dev_priv)
+{
+	INIT_LIST_HEAD(&dev_priv->perf.streams);
+	mutex_init(&dev_priv->perf.lock);
+
+	dev_priv->perf.initialized = true;
+}
+
+void i915_perf_fini(struct drm_i915_private *dev_priv)
+{
+	if (!dev_priv->perf.initialized)
+		return;
+
+	/* Currently nothing to clean up */
+
+	dev_priv->perf.initialized = false;
+}
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index 03725fe..98cd493 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -258,6 +258,7 @@  typedef struct _drm_i915_sarea {
 #define DRM_I915_GEM_USERPTR		0x33
 #define DRM_I915_GEM_CONTEXT_GETPARAM	0x34
 #define DRM_I915_GEM_CONTEXT_SETPARAM	0x35
+#define DRM_I915_PERF_OPEN		0x36
 
 #define DRM_IOCTL_I915_INIT		DRM_IOW( DRM_COMMAND_BASE + DRM_I915_INIT, drm_i915_init_t)
 #define DRM_IOCTL_I915_FLUSH		DRM_IO ( DRM_COMMAND_BASE + DRM_I915_FLUSH)
@@ -311,6 +312,7 @@  typedef struct _drm_i915_sarea {
 #define DRM_IOCTL_I915_GEM_USERPTR			DRM_IOWR (DRM_COMMAND_BASE + DRM_I915_GEM_USERPTR, struct drm_i915_gem_userptr)
 #define DRM_IOCTL_I915_GEM_CONTEXT_GETPARAM	DRM_IOWR (DRM_COMMAND_BASE + DRM_I915_GEM_CONTEXT_GETPARAM, struct drm_i915_gem_context_param)
 #define DRM_IOCTL_I915_GEM_CONTEXT_SETPARAM	DRM_IOWR (DRM_COMMAND_BASE + DRM_I915_GEM_CONTEXT_SETPARAM, struct drm_i915_gem_context_param)
+#define DRM_IOCTL_I915_PERF_OPEN	DRM_IOW(DRM_COMMAND_BASE + DRM_I915_PERF_OPEN, struct drm_i915_perf_open_param)
 
 /* Allow drivers to submit batchbuffers directly to hardware, relying
  * on the security mechanisms provided by hardware.
@@ -1222,6 +1224,71 @@  struct drm_i915_gem_context_param {
 	__u64 value;
 };
 
+enum drm_i915_perf_property_id {
+	/**
+	 * Open the stream for a specific context handle (as used with
+	 * execbuffer2). A stream opened for a specific context this way
+	 * won't typically require root privileges.
+	 */
+	DRM_I915_PERF_PROP_CTX_HANDLE = 1,
+
+	DRM_I915_PERF_PROP_MAX /* non-ABI */
+};
+
+struct drm_i915_perf_open_param {
+	__u32 flags;
+#define I915_PERF_FLAG_FD_CLOEXEC	(1<<0)
+#define I915_PERF_FLAG_FD_NONBLOCK	(1<<1)
+#define I915_PERF_FLAG_DISABLED		(1<<2)
+
+	/** The number of u64 (id, value) pairs */
+	__u32 num_properties;
+
+	/**
+	 * Pointer to array of u64 (id, value) pairs configuring the stream
+	 * to open.
+	 */
+	__u64 __user properties_ptr;
+};
+
+#define I915_PERF_IOCTL_ENABLE	_IO('i', 0x0)
+#define I915_PERF_IOCTL_DISABLE	_IO('i', 0x1)
+
+/**
+ * Common to all i915 perf records
+ */
+struct drm_i915_perf_record_header {
+	__u32 type;
+	__u16 pad;
+	__u16 size;
+};
+
+enum drm_i915_perf_record_type {
+
+	/**
+	 * Samples are the work horse record type whose contents are extensible
+	 * and defined when opening an i915 perf stream based on the given
+	 * properties.
+	 *
+	 * Boolean properties following the naming convention
+	 * DRM_I915_PERF_SAMPLE_xyz_PROP request the inclusion of 'xyz' data in
+	 * every sample.
+	 *
+	 * The order of these sample properties given by userspace has no
+	 * affect on the ordering of data within a sample. The order will be
+	 * documented here.
+	 *
+	 * struct {
+	 *     struct drm_i915_perf_record_header header;
+	 *
+	 *     TODO: itemize extensible sample data here
+	 * };
+	 */
+	DRM_I915_PERF_RECORD_SAMPLE = 1,
+
+	DRM_I915_PERF_RECORD_MAX /* non-ABI */
+};
+
 #if defined(__cplusplus)
 }
 #endif