diff mbox

[1/3] drm/i915: Provide a timeout to i915_gem_wait_for_idle()

Message ID 20180709104237.21880-1-chris@chris-wilson.co.uk (mailing list archive)
State New, archived
Headers show

Commit Message

Chris Wilson July 9, 2018, 10:42 a.m. UTC
Usually we have no idea about the upper bound we need to wait to catch
up with userspace when idling the device, but in a few situations we
know the system was idle beforehand and can provide a short timeout in
order to very quickly catch a failure, long before hangcheck kicks in.

In the following patches, we will use the timeout to curtain two overly
long waits, where we know we can expect the GPU to complete within a
reasonable time or declare it broken.

In particular, with a broken GPU we expect it to fail during the initial
GPU setup where do a couple of context switches to record the defaults.
This is a task that takes a few milliseconds even on the slowest of
devices, but we may have to wait 60s for hangcheck to give in and
declare the machine inoperable. In this a case where any gpu hang is
unacceptable, both from a timeliness and practical standpoint.

The other improvement is that in selftests, we do not need to arm an
independent timer to inject a wedge, as we can just limit the timeout on
the wait directly.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
 drivers/gpu/drm/i915/i915_debugfs.c           |  6 ++-
 drivers/gpu/drm/i915/i915_drv.h               |  2 +-
 drivers/gpu/drm/i915/i915_gem.c               | 43 +++++++++++--------
 drivers/gpu/drm/i915/i915_gem_evict.c         |  3 +-
 drivers/gpu/drm/i915/i915_gem_gtt.c           |  2 +-
 drivers/gpu/drm/i915/i915_gem_shrinker.c      | 11 +++--
 drivers/gpu/drm/i915/i915_perf.c              |  4 +-
 drivers/gpu/drm/i915/i915_request.c           |  6 ++-
 .../gpu/drm/i915/selftests/i915_gem_context.c |  4 +-
 drivers/gpu/drm/i915/selftests/i915_request.c |  4 +-
 .../gpu/drm/i915/selftests/igt_flush_test.c   |  2 +-
 11 files changed, 56 insertions(+), 31 deletions(-)

Comments

Mika Kuoppala July 9, 2018, 11:38 a.m. UTC | #1
Chris Wilson <chris@chris-wilson.co.uk> writes:

> Usually we have no idea about the upper bound we need to wait to catch
> up with userspace when idling the device, but in a few situations we
> know the system was idle beforehand and can provide a short timeout in
> order to very quickly catch a failure, long before hangcheck kicks in.
>
> In the following patches, we will use the timeout to curtain two overly
> long waits, where we know we can expect the GPU to complete within a
> reasonable time or declare it broken.
>
> In particular, with a broken GPU we expect it to fail during the initial
> GPU setup where do a couple of context switches to record the defaults.
> This is a task that takes a few milliseconds even on the slowest of
> devices, but we may have to wait 60s for hangcheck to give in and
> declare the machine inoperable. In this a case where any gpu hang is
> unacceptable, both from a timeliness and practical standpoint.
>
> The other improvement is that in selftests, we do not need to arm an
> independent timer to inject a wedge, as we can just limit the timeout on
> the wait directly.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_debugfs.c           |  6 ++-
>  drivers/gpu/drm/i915/i915_drv.h               |  2 +-
>  drivers/gpu/drm/i915/i915_gem.c               | 43 +++++++++++--------
>  drivers/gpu/drm/i915/i915_gem_evict.c         |  3 +-
>  drivers/gpu/drm/i915/i915_gem_gtt.c           |  2 +-
>  drivers/gpu/drm/i915/i915_gem_shrinker.c      | 11 +++--
>  drivers/gpu/drm/i915/i915_perf.c              |  4 +-
>  drivers/gpu/drm/i915/i915_request.c           |  6 ++-
>  .../gpu/drm/i915/selftests/i915_gem_context.c |  4 +-
>  drivers/gpu/drm/i915/selftests/i915_request.c |  4 +-
>  .../gpu/drm/i915/selftests/igt_flush_test.c   |  2 +-
>  11 files changed, 56 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index 544e5e7f011f..099f97ef2303 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -4105,7 +4105,8 @@ fault_irq_set(struct drm_i915_private *i915,
>  
>  	err = i915_gem_wait_for_idle(i915,
>  				     I915_WAIT_LOCKED |
> -				     I915_WAIT_INTERRUPTIBLE);
> +				     I915_WAIT_INTERRUPTIBLE,
> +				     MAX_SCHEDULE_TIMEOUT);
>  	if (err)
>  		goto err_unlock;
>  
> @@ -4210,7 +4211,8 @@ i915_drop_caches_set(void *data, u64 val)
>  		if (val & DROP_ACTIVE)
>  			ret = i915_gem_wait_for_idle(dev_priv,
>  						     I915_WAIT_INTERRUPTIBLE |
> -						     I915_WAIT_LOCKED);
> +						     I915_WAIT_LOCKED,
> +						     MAX_SCHEDULE_TIMEOUT);
>  
>  		if (val & DROP_RETIRE)
>  			i915_retire_requests(dev_priv);
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 09ab12458244..bec0a2796c37 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -3154,7 +3154,7 @@ void i915_gem_init_swizzling(struct drm_i915_private *dev_priv);
>  void i915_gem_fini(struct drm_i915_private *dev_priv);
>  void i915_gem_cleanup_engines(struct drm_i915_private *dev_priv);
>  int i915_gem_wait_for_idle(struct drm_i915_private *dev_priv,
> -			   unsigned int flags);
> +			   unsigned int flags, long timeout);
>  int __must_check i915_gem_suspend(struct drm_i915_private *dev_priv);
>  void i915_gem_suspend_late(struct drm_i915_private *dev_priv);
>  void i915_gem_resume(struct drm_i915_private *dev_priv);
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 1a9dab302433..093d98ed7755 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -2267,7 +2267,9 @@ static int i915_gem_object_create_mmap_offset(struct drm_i915_gem_object *obj)
>  
>  	/* Attempt to reap some mmap space from dead objects */
>  	do {
> -		err = i915_gem_wait_for_idle(dev_priv, I915_WAIT_INTERRUPTIBLE);
> +		err = i915_gem_wait_for_idle(dev_priv,
> +					     I915_WAIT_INTERRUPTIBLE,
> +					     MAX_SCHEDULE_TIMEOUT);
>  		if (err)
>  			break;
>  
> @@ -3742,14 +3744,14 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
>  	return ret;
>  }
>  
> -static int wait_for_timeline(struct i915_timeline *tl, unsigned int flags)
> +static long wait_for_timeline(struct i915_timeline *tl,
> +			      unsigned int flags, long timeout)
>  {
>  	struct i915_request *rq;
> -	long ret;
>  
>  	rq = i915_gem_active_get_unlocked(&tl->last_request);
>  	if (!rq)
> -		return 0;
> +		return timeout;
>  
>  	/*
>  	 * "Race-to-idle".
> @@ -3763,10 +3765,10 @@ static int wait_for_timeline(struct i915_timeline *tl, unsigned int flags)
>  	if (flags & I915_WAIT_FOR_IDLE_BOOST)
>  		gen6_rps_boost(rq, NULL);
>  
> -	ret = i915_request_wait(rq, flags, MAX_SCHEDULE_TIMEOUT);
> +	timeout = i915_request_wait(rq, flags, timeout);
>  	i915_request_put(rq);
>  
> -	return ret < 0 ? ret : 0;
> +	return timeout;
>  }
>  
>  static int wait_for_engines(struct drm_i915_private *i915)
> @@ -3782,7 +3784,8 @@ static int wait_for_engines(struct drm_i915_private *i915)
>  	return 0;
>  }
>  
> -int i915_gem_wait_for_idle(struct drm_i915_private *i915, unsigned int flags)
> +int i915_gem_wait_for_idle(struct drm_i915_private *i915,
> +			   unsigned int flags, long timeout)
>  {
>  	GEM_TRACE("flags=%x (%s)\n",
>  		  flags, flags & I915_WAIT_LOCKED ? "locked" : "unlocked");

Did you omit enhancing the trace on purpose?

Eventually i915_request_wait will assert for silly timeout values, but
should we add assertion here too as wait_for_timeline will
return what we put, for nonactive timelines?

> @@ -3798,9 +3801,9 @@ int i915_gem_wait_for_idle(struct drm_i915_private *i915, unsigned int flags)
>  		lockdep_assert_held(&i915->drm.struct_mutex);
>  
>  		list_for_each_entry(tl, &i915->gt.timelines, link) {
> -			err = wait_for_timeline(tl, flags);
> -			if (err)
> -				return err;
> +			timeout = wait_for_timeline(tl, flags, timeout);
> +			if (timeout < 0)
> +				return timeout;
>  		}
>  
>  		err = wait_for_engines(i915);

To truely serve the caller, the remaining timeout could be passed to
wait_for_engines too, but that can be followup.

So the only real thing is the missing trace.
-Mika


> @@ -3812,12 +3815,13 @@ int i915_gem_wait_for_idle(struct drm_i915_private *i915, unsigned int flags)
>  	} else {
>  		struct intel_engine_cs *engine;
>  		enum intel_engine_id id;
> -		int err;
>  
>  		for_each_engine(engine, i915, id) {
> -			err = wait_for_timeline(&engine->timeline, flags);
> -			if (err)
> -				return err;
> +			struct i915_timeline *tl = &engine->timeline;
> +
> +			timeout = wait_for_timeline(tl, flags, timeout);
> +			if (timeout < 0)
> +				return timeout;
>  		}
>  	}
>  
> @@ -5052,7 +5056,8 @@ int i915_gem_suspend(struct drm_i915_private *dev_priv)
>  		ret = i915_gem_wait_for_idle(dev_priv,
>  					     I915_WAIT_INTERRUPTIBLE |
>  					     I915_WAIT_LOCKED |
> -					     I915_WAIT_FOR_IDLE_BOOST);
> +					     I915_WAIT_FOR_IDLE_BOOST,
> +					     MAX_SCHEDULE_TIMEOUT);
>  		if (ret && ret != -EIO)
>  			goto err_unlock;
>  
> @@ -5356,7 +5361,9 @@ static int __intel_engines_record_defaults(struct drm_i915_private *i915)
>  	if (err)
>  		goto err_active;
>  
> -	err = i915_gem_wait_for_idle(i915, I915_WAIT_LOCKED);
> +	err = i915_gem_wait_for_idle(i915,
> +				     I915_WAIT_LOCKED,
> +				     MAX_SCHEDULE_TIMEOUT);
>  	if (err)
>  		goto err_active;
>  
> @@ -5421,7 +5428,9 @@ static int __intel_engines_record_defaults(struct drm_i915_private *i915)
>  	if (WARN_ON(i915_gem_switch_to_kernel_context(i915)))
>  		goto out_ctx;
>  
> -	if (WARN_ON(i915_gem_wait_for_idle(i915, I915_WAIT_LOCKED)))
> +	if (WARN_ON(i915_gem_wait_for_idle(i915,
> +					   I915_WAIT_LOCKED,
> +					   MAX_SCHEDULE_TIMEOUT)))
>  		goto out_ctx;
>  
>  	i915_gem_contexts_lost(i915);
> diff --git a/drivers/gpu/drm/i915/i915_gem_evict.c b/drivers/gpu/drm/i915/i915_gem_evict.c
> index 54814a196ee4..02b83a5ed96c 100644
> --- a/drivers/gpu/drm/i915/i915_gem_evict.c
> +++ b/drivers/gpu/drm/i915/i915_gem_evict.c
> @@ -69,7 +69,8 @@ static int ggtt_flush(struct drm_i915_private *i915)
>  
>  	err = i915_gem_wait_for_idle(i915,
>  				     I915_WAIT_INTERRUPTIBLE |
> -				     I915_WAIT_LOCKED);
> +				     I915_WAIT_LOCKED,
> +				     MAX_SCHEDULE_TIMEOUT);
>  	if (err)
>  		return err;
>  
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> index 2ad319e17e39..abd81fb9b0b6 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> @@ -2793,7 +2793,7 @@ void i915_gem_gtt_finish_pages(struct drm_i915_gem_object *obj,
>  	struct i915_ggtt *ggtt = &dev_priv->ggtt;
>  
>  	if (unlikely(ggtt->do_idle_maps)) {
> -		if (i915_gem_wait_for_idle(dev_priv, 0)) {
> +		if (i915_gem_wait_for_idle(dev_priv, 0, MAX_SCHEDULE_TIMEOUT)) {
>  			DRM_ERROR("Failed to wait for idle; VT'd may hang.\n");
>  			/* Wait a bit, in hopes it avoids the hang */
>  			udelay(10);
> diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c b/drivers/gpu/drm/i915/i915_gem_shrinker.c
> index 55e84e71f526..c61f5b80fee3 100644
> --- a/drivers/gpu/drm/i915/i915_gem_shrinker.c
> +++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c
> @@ -172,7 +172,9 @@ i915_gem_shrink(struct drm_i915_private *i915,
>  	 * we will free as much as we can and hope to get a second chance.
>  	 */
>  	if (flags & I915_SHRINK_ACTIVE)
> -		i915_gem_wait_for_idle(i915, I915_WAIT_LOCKED);
> +		i915_gem_wait_for_idle(i915,
> +				       I915_WAIT_LOCKED,
> +				       MAX_SCHEDULE_TIMEOUT);
>  
>  	trace_i915_gem_shrink(i915, target, flags);
>  	i915_retire_requests(i915);
> @@ -392,7 +394,8 @@ shrinker_lock_uninterruptible(struct drm_i915_private *i915, bool *unlock,
>  	unsigned long timeout = jiffies + msecs_to_jiffies_timeout(timeout_ms);
>  
>  	do {
> -		if (i915_gem_wait_for_idle(i915, 0) == 0 &&
> +		if (i915_gem_wait_for_idle(i915,
> +					   0, MAX_SCHEDULE_TIMEOUT) == 0 &&
>  		    shrinker_lock(i915, unlock))
>  			break;
>  
> @@ -466,7 +469,9 @@ i915_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr
>  		return NOTIFY_DONE;
>  
>  	/* Force everything onto the inactive lists */
> -	ret = i915_gem_wait_for_idle(i915, I915_WAIT_LOCKED);
> +	ret = i915_gem_wait_for_idle(i915,
> +				     I915_WAIT_LOCKED,
> +				     MAX_SCHEDULE_TIMEOUT);
>  	if (ret)
>  		goto out;
>  
> diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
> index 447407fee3b8..6bf10952c724 100644
> --- a/drivers/gpu/drm/i915/i915_perf.c
> +++ b/drivers/gpu/drm/i915/i915_perf.c
> @@ -1836,7 +1836,9 @@ static int gen8_configure_all_contexts(struct drm_i915_private *dev_priv,
>  	 * So far the best way to work around this issue seems to be draining
>  	 * the GPU from any submitted work.
>  	 */
> -	ret = i915_gem_wait_for_idle(dev_priv, wait_flags);
> +	ret = i915_gem_wait_for_idle(dev_priv,
> +				     wait_flags,
> +				     MAX_SCHEDULE_TIMEOUT);
>  	if (ret)
>  		goto out;
>  
> diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
> index 3248369dbcfb..5c2c93cbab12 100644
> --- a/drivers/gpu/drm/i915/i915_request.c
> +++ b/drivers/gpu/drm/i915/i915_request.c
> @@ -206,7 +206,8 @@ static int reset_all_global_seqno(struct drm_i915_private *i915, u32 seqno)
>  	/* Carefully retire all requests without writing to the rings */
>  	ret = i915_gem_wait_for_idle(i915,
>  				     I915_WAIT_INTERRUPTIBLE |
> -				     I915_WAIT_LOCKED);
> +				     I915_WAIT_LOCKED,
> +				     MAX_SCHEDULE_TIMEOUT);
>  	if (ret)
>  		return ret;
>  
> @@ -735,7 +736,8 @@ i915_request_alloc(struct intel_engine_cs *engine, struct i915_gem_context *ctx)
>  		/* Ratelimit ourselves to prevent oom from malicious clients */
>  		ret = i915_gem_wait_for_idle(i915,
>  					     I915_WAIT_LOCKED |
> -					     I915_WAIT_INTERRUPTIBLE);
> +					     I915_WAIT_INTERRUPTIBLE,
> +					     MAX_SCHEDULE_TIMEOUT);
>  		if (ret)
>  			goto err_unreserve;
>  
> diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_context.c b/drivers/gpu/drm/i915/selftests/i915_gem_context.c
> index 5fbe15f4effd..ab2590242033 100644
> --- a/drivers/gpu/drm/i915/selftests/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/selftests/i915_gem_context.c
> @@ -478,7 +478,9 @@ static int __igt_switch_to_kernel_context(struct drm_i915_private *i915,
>  		}
>  	}
>  
> -	err = i915_gem_wait_for_idle(i915, I915_WAIT_LOCKED);
> +	err = i915_gem_wait_for_idle(i915,
> +				     I915_WAIT_LOCKED,
> +				     MAX_SCHEDULE_TIMEOUT);
>  	if (err)
>  		return err;
>  
> diff --git a/drivers/gpu/drm/i915/selftests/i915_request.c b/drivers/gpu/drm/i915/selftests/i915_request.c
> index 43995fc3534d..c4aac6141e04 100644
> --- a/drivers/gpu/drm/i915/selftests/i915_request.c
> +++ b/drivers/gpu/drm/i915/selftests/i915_request.c
> @@ -286,7 +286,9 @@ static int begin_live_test(struct live_test *t,
>  	t->func = func;
>  	t->name = name;
>  
> -	err = i915_gem_wait_for_idle(i915, I915_WAIT_LOCKED);
> +	err = i915_gem_wait_for_idle(i915,
> +				     I915_WAIT_LOCKED,
> +				     MAX_SCHEDULE_TIMEOUT);
>  	if (err) {
>  		pr_err("%s(%s): failed to idle before, with err=%d!",
>  		       func, name, err);
> diff --git a/drivers/gpu/drm/i915/selftests/igt_flush_test.c b/drivers/gpu/drm/i915/selftests/igt_flush_test.c
> index 0d06f559243f..09ab037ce803 100644
> --- a/drivers/gpu/drm/i915/selftests/igt_flush_test.c
> +++ b/drivers/gpu/drm/i915/selftests/igt_flush_test.c
> @@ -64,7 +64,7 @@ int igt_flush_test(struct drm_i915_private *i915, unsigned int flags)
>  	}
>  
>  	wedge_on_timeout(&w, i915, HZ)
> -		i915_gem_wait_for_idle(i915, flags);
> +		i915_gem_wait_for_idle(i915, flags, MAX_SCHEDULE_TIMEOUT);
>  
>  	return i915_terminally_wedged(&i915->gpu_error) ? -EIO : 0;
>  }
> -- 
> 2.18.0
Chris Wilson July 9, 2018, 11:47 a.m. UTC | #2
Quoting Mika Kuoppala (2018-07-09 12:38:10)
> Chris Wilson <chris@chris-wilson.co.uk> writes:
> > -int i915_gem_wait_for_idle(struct drm_i915_private *i915, unsigned int flags)
> > +int i915_gem_wait_for_idle(struct drm_i915_private *i915,
> > +                        unsigned int flags, long timeout)
> >  {
> >       GEM_TRACE("flags=%x (%s)\n",
> >                 flags, flags & I915_WAIT_LOCKED ? "locked" : "unlocked");
> 
> Did you omit enhancing the trace on purpose?

Didn't even consider it. I personally only use it as a breadcrumb in the
trace.
 
> Eventually i915_request_wait will assert for silly timeout values, but
> should we add assertion here too as wait_for_timeline will
> return what we put, for nonactive timelines?
> 
> > @@ -3798,9 +3801,9 @@ int i915_gem_wait_for_idle(struct drm_i915_private *i915, unsigned int flags)
> >               lockdep_assert_held(&i915->drm.struct_mutex);
> >  
> >               list_for_each_entry(tl, &i915->gt.timelines, link) {
> > -                     err = wait_for_timeline(tl, flags);
> > -                     if (err)
> > -                             return err;
> > +                     timeout = wait_for_timeline(tl, flags, timeout);
> > +                     if (timeout < 0)
> > +                             return timeout;
> >               }
> >  
> >               err = wait_for_engines(i915);
> 
> To truely serve the caller, the remaining timeout could be passed to
> wait_for_engines too, but that can be followup.

I don't think so. The timeout we employ there is specific to the CSB
delay and we need to employ that irrespective of the caller timeout.
At this point, we have successfully waited for all requests, and now
just have to drain any HW queues -- imo, we have completed the task the
caller set out for us (requests completed within the timeout). And now
onto the followup retirement optimisations.
-Chris
Mika Kuoppala July 9, 2018, 11:52 a.m. UTC | #3
Chris Wilson <chris@chris-wilson.co.uk> writes:

> Quoting Mika Kuoppala (2018-07-09 12:38:10)
>> Chris Wilson <chris@chris-wilson.co.uk> writes:
>> > -int i915_gem_wait_for_idle(struct drm_i915_private *i915, unsigned int flags)
>> > +int i915_gem_wait_for_idle(struct drm_i915_private *i915,
>> > +                        unsigned int flags, long timeout)
>> >  {
>> >       GEM_TRACE("flags=%x (%s)\n",
>> >                 flags, flags & I915_WAIT_LOCKED ? "locked" : "unlocked");
>> 
>> Did you omit enhancing the trace on purpose?
>
> Didn't even consider it. I personally only use it as a breadcrumb in the
> trace.
>  
>> Eventually i915_request_wait will assert for silly timeout values, but
>> should we add assertion here too as wait_for_timeline will
>> return what we put, for nonactive timelines?
>> 
>> > @@ -3798,9 +3801,9 @@ int i915_gem_wait_for_idle(struct drm_i915_private *i915, unsigned int flags)
>> >               lockdep_assert_held(&i915->drm.struct_mutex);
>> >  
>> >               list_for_each_entry(tl, &i915->gt.timelines, link) {
>> > -                     err = wait_for_timeline(tl, flags);
>> > -                     if (err)
>> > -                             return err;
>> > +                     timeout = wait_for_timeline(tl, flags, timeout);
>> > +                     if (timeout < 0)
>> > +                             return timeout;
>> >               }
>> >  
>> >               err = wait_for_engines(i915);
>> 
>> To truely serve the caller, the remaining timeout could be passed to
>> wait_for_engines too, but that can be followup.
>
> I don't think so. The timeout we employ there is specific to the CSB
> delay and we need to employ that irrespective of the caller timeout.
> At this point, we have successfully waited for all requests, and now
> just have to drain any HW queues -- imo, we have completed the task the
> caller set out for us (requests completed within the timeout). And now
> onto the followup retirement optimisations.

Agreed, my mistake. At that point all the requests are already done.
If the engine hw flush timeouts, that is catastrophic, regardless
of caller preferences.

Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>

> -Chris
Chris Wilson July 9, 2018, 1:06 p.m. UTC | #4
Quoting Mika Kuoppala (2018-07-09 12:52:51)
> Chris Wilson <chris@chris-wilson.co.uk> writes:
> 
> > Quoting Mika Kuoppala (2018-07-09 12:38:10)
> >> Chris Wilson <chris@chris-wilson.co.uk> writes:
> >> > -int i915_gem_wait_for_idle(struct drm_i915_private *i915, unsigned int flags)
> >> > +int i915_gem_wait_for_idle(struct drm_i915_private *i915,
> >> > +                        unsigned int flags, long timeout)
> >> >  {
> >> >       GEM_TRACE("flags=%x (%s)\n",
> >> >                 flags, flags & I915_WAIT_LOCKED ? "locked" : "unlocked");
> >> 
> >> Did you omit enhancing the trace on purpose?
> >
> > Didn't even consider it. I personally only use it as a breadcrumb in the
> > trace.
> >  
> >> Eventually i915_request_wait will assert for silly timeout values, but
> >> should we add assertion here too as wait_for_timeline will
> >> return what we put, for nonactive timelines?
> >> 
> >> > @@ -3798,9 +3801,9 @@ int i915_gem_wait_for_idle(struct drm_i915_private *i915, unsigned int flags)
> >> >               lockdep_assert_held(&i915->drm.struct_mutex);
> >> >  
> >> >               list_for_each_entry(tl, &i915->gt.timelines, link) {
> >> > -                     err = wait_for_timeline(tl, flags);
> >> > -                     if (err)
> >> > -                             return err;
> >> > +                     timeout = wait_for_timeline(tl, flags, timeout);
> >> > +                     if (timeout < 0)
> >> > +                             return timeout;
> >> >               }
> >> >  
> >> >               err = wait_for_engines(i915);
> >> 
> >> To truely serve the caller, the remaining timeout could be passed to
> >> wait_for_engines too, but that can be followup.
> >
> > I don't think so. The timeout we employ there is specific to the CSB
> > delay and we need to employ that irrespective of the caller timeout.
> > At this point, we have successfully waited for all requests, and now
> > just have to drain any HW queues -- imo, we have completed the task the
> > caller set out for us (requests completed within the timeout). And now
> > onto the followup retirement optimisations.
> 
> Agreed, my mistake. At that point all the requests are already done.
> If the engine hw flush timeouts, that is catastrophic, regardless
> of caller preferences.
> 
> Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>

Added the timeout info to the GEM_TRACE and pushed. Thanks for the review,
-Chris
diff mbox

Patch

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 544e5e7f011f..099f97ef2303 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -4105,7 +4105,8 @@  fault_irq_set(struct drm_i915_private *i915,
 
 	err = i915_gem_wait_for_idle(i915,
 				     I915_WAIT_LOCKED |
-				     I915_WAIT_INTERRUPTIBLE);
+				     I915_WAIT_INTERRUPTIBLE,
+				     MAX_SCHEDULE_TIMEOUT);
 	if (err)
 		goto err_unlock;
 
@@ -4210,7 +4211,8 @@  i915_drop_caches_set(void *data, u64 val)
 		if (val & DROP_ACTIVE)
 			ret = i915_gem_wait_for_idle(dev_priv,
 						     I915_WAIT_INTERRUPTIBLE |
-						     I915_WAIT_LOCKED);
+						     I915_WAIT_LOCKED,
+						     MAX_SCHEDULE_TIMEOUT);
 
 		if (val & DROP_RETIRE)
 			i915_retire_requests(dev_priv);
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 09ab12458244..bec0a2796c37 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -3154,7 +3154,7 @@  void i915_gem_init_swizzling(struct drm_i915_private *dev_priv);
 void i915_gem_fini(struct drm_i915_private *dev_priv);
 void i915_gem_cleanup_engines(struct drm_i915_private *dev_priv);
 int i915_gem_wait_for_idle(struct drm_i915_private *dev_priv,
-			   unsigned int flags);
+			   unsigned int flags, long timeout);
 int __must_check i915_gem_suspend(struct drm_i915_private *dev_priv);
 void i915_gem_suspend_late(struct drm_i915_private *dev_priv);
 void i915_gem_resume(struct drm_i915_private *dev_priv);
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 1a9dab302433..093d98ed7755 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2267,7 +2267,9 @@  static int i915_gem_object_create_mmap_offset(struct drm_i915_gem_object *obj)
 
 	/* Attempt to reap some mmap space from dead objects */
 	do {
-		err = i915_gem_wait_for_idle(dev_priv, I915_WAIT_INTERRUPTIBLE);
+		err = i915_gem_wait_for_idle(dev_priv,
+					     I915_WAIT_INTERRUPTIBLE,
+					     MAX_SCHEDULE_TIMEOUT);
 		if (err)
 			break;
 
@@ -3742,14 +3744,14 @@  i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
 	return ret;
 }
 
-static int wait_for_timeline(struct i915_timeline *tl, unsigned int flags)
+static long wait_for_timeline(struct i915_timeline *tl,
+			      unsigned int flags, long timeout)
 {
 	struct i915_request *rq;
-	long ret;
 
 	rq = i915_gem_active_get_unlocked(&tl->last_request);
 	if (!rq)
-		return 0;
+		return timeout;
 
 	/*
 	 * "Race-to-idle".
@@ -3763,10 +3765,10 @@  static int wait_for_timeline(struct i915_timeline *tl, unsigned int flags)
 	if (flags & I915_WAIT_FOR_IDLE_BOOST)
 		gen6_rps_boost(rq, NULL);
 
-	ret = i915_request_wait(rq, flags, MAX_SCHEDULE_TIMEOUT);
+	timeout = i915_request_wait(rq, flags, timeout);
 	i915_request_put(rq);
 
-	return ret < 0 ? ret : 0;
+	return timeout;
 }
 
 static int wait_for_engines(struct drm_i915_private *i915)
@@ -3782,7 +3784,8 @@  static int wait_for_engines(struct drm_i915_private *i915)
 	return 0;
 }
 
-int i915_gem_wait_for_idle(struct drm_i915_private *i915, unsigned int flags)
+int i915_gem_wait_for_idle(struct drm_i915_private *i915,
+			   unsigned int flags, long timeout)
 {
 	GEM_TRACE("flags=%x (%s)\n",
 		  flags, flags & I915_WAIT_LOCKED ? "locked" : "unlocked");
@@ -3798,9 +3801,9 @@  int i915_gem_wait_for_idle(struct drm_i915_private *i915, unsigned int flags)
 		lockdep_assert_held(&i915->drm.struct_mutex);
 
 		list_for_each_entry(tl, &i915->gt.timelines, link) {
-			err = wait_for_timeline(tl, flags);
-			if (err)
-				return err;
+			timeout = wait_for_timeline(tl, flags, timeout);
+			if (timeout < 0)
+				return timeout;
 		}
 
 		err = wait_for_engines(i915);
@@ -3812,12 +3815,13 @@  int i915_gem_wait_for_idle(struct drm_i915_private *i915, unsigned int flags)
 	} else {
 		struct intel_engine_cs *engine;
 		enum intel_engine_id id;
-		int err;
 
 		for_each_engine(engine, i915, id) {
-			err = wait_for_timeline(&engine->timeline, flags);
-			if (err)
-				return err;
+			struct i915_timeline *tl = &engine->timeline;
+
+			timeout = wait_for_timeline(tl, flags, timeout);
+			if (timeout < 0)
+				return timeout;
 		}
 	}
 
@@ -5052,7 +5056,8 @@  int i915_gem_suspend(struct drm_i915_private *dev_priv)
 		ret = i915_gem_wait_for_idle(dev_priv,
 					     I915_WAIT_INTERRUPTIBLE |
 					     I915_WAIT_LOCKED |
-					     I915_WAIT_FOR_IDLE_BOOST);
+					     I915_WAIT_FOR_IDLE_BOOST,
+					     MAX_SCHEDULE_TIMEOUT);
 		if (ret && ret != -EIO)
 			goto err_unlock;
 
@@ -5356,7 +5361,9 @@  static int __intel_engines_record_defaults(struct drm_i915_private *i915)
 	if (err)
 		goto err_active;
 
-	err = i915_gem_wait_for_idle(i915, I915_WAIT_LOCKED);
+	err = i915_gem_wait_for_idle(i915,
+				     I915_WAIT_LOCKED,
+				     MAX_SCHEDULE_TIMEOUT);
 	if (err)
 		goto err_active;
 
@@ -5421,7 +5428,9 @@  static int __intel_engines_record_defaults(struct drm_i915_private *i915)
 	if (WARN_ON(i915_gem_switch_to_kernel_context(i915)))
 		goto out_ctx;
 
-	if (WARN_ON(i915_gem_wait_for_idle(i915, I915_WAIT_LOCKED)))
+	if (WARN_ON(i915_gem_wait_for_idle(i915,
+					   I915_WAIT_LOCKED,
+					   MAX_SCHEDULE_TIMEOUT)))
 		goto out_ctx;
 
 	i915_gem_contexts_lost(i915);
diff --git a/drivers/gpu/drm/i915/i915_gem_evict.c b/drivers/gpu/drm/i915/i915_gem_evict.c
index 54814a196ee4..02b83a5ed96c 100644
--- a/drivers/gpu/drm/i915/i915_gem_evict.c
+++ b/drivers/gpu/drm/i915/i915_gem_evict.c
@@ -69,7 +69,8 @@  static int ggtt_flush(struct drm_i915_private *i915)
 
 	err = i915_gem_wait_for_idle(i915,
 				     I915_WAIT_INTERRUPTIBLE |
-				     I915_WAIT_LOCKED);
+				     I915_WAIT_LOCKED,
+				     MAX_SCHEDULE_TIMEOUT);
 	if (err)
 		return err;
 
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 2ad319e17e39..abd81fb9b0b6 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -2793,7 +2793,7 @@  void i915_gem_gtt_finish_pages(struct drm_i915_gem_object *obj,
 	struct i915_ggtt *ggtt = &dev_priv->ggtt;
 
 	if (unlikely(ggtt->do_idle_maps)) {
-		if (i915_gem_wait_for_idle(dev_priv, 0)) {
+		if (i915_gem_wait_for_idle(dev_priv, 0, MAX_SCHEDULE_TIMEOUT)) {
 			DRM_ERROR("Failed to wait for idle; VT'd may hang.\n");
 			/* Wait a bit, in hopes it avoids the hang */
 			udelay(10);
diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c b/drivers/gpu/drm/i915/i915_gem_shrinker.c
index 55e84e71f526..c61f5b80fee3 100644
--- a/drivers/gpu/drm/i915/i915_gem_shrinker.c
+++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c
@@ -172,7 +172,9 @@  i915_gem_shrink(struct drm_i915_private *i915,
 	 * we will free as much as we can and hope to get a second chance.
 	 */
 	if (flags & I915_SHRINK_ACTIVE)
-		i915_gem_wait_for_idle(i915, I915_WAIT_LOCKED);
+		i915_gem_wait_for_idle(i915,
+				       I915_WAIT_LOCKED,
+				       MAX_SCHEDULE_TIMEOUT);
 
 	trace_i915_gem_shrink(i915, target, flags);
 	i915_retire_requests(i915);
@@ -392,7 +394,8 @@  shrinker_lock_uninterruptible(struct drm_i915_private *i915, bool *unlock,
 	unsigned long timeout = jiffies + msecs_to_jiffies_timeout(timeout_ms);
 
 	do {
-		if (i915_gem_wait_for_idle(i915, 0) == 0 &&
+		if (i915_gem_wait_for_idle(i915,
+					   0, MAX_SCHEDULE_TIMEOUT) == 0 &&
 		    shrinker_lock(i915, unlock))
 			break;
 
@@ -466,7 +469,9 @@  i915_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr
 		return NOTIFY_DONE;
 
 	/* Force everything onto the inactive lists */
-	ret = i915_gem_wait_for_idle(i915, I915_WAIT_LOCKED);
+	ret = i915_gem_wait_for_idle(i915,
+				     I915_WAIT_LOCKED,
+				     MAX_SCHEDULE_TIMEOUT);
 	if (ret)
 		goto out;
 
diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
index 447407fee3b8..6bf10952c724 100644
--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -1836,7 +1836,9 @@  static int gen8_configure_all_contexts(struct drm_i915_private *dev_priv,
 	 * So far the best way to work around this issue seems to be draining
 	 * the GPU from any submitted work.
 	 */
-	ret = i915_gem_wait_for_idle(dev_priv, wait_flags);
+	ret = i915_gem_wait_for_idle(dev_priv,
+				     wait_flags,
+				     MAX_SCHEDULE_TIMEOUT);
 	if (ret)
 		goto out;
 
diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
index 3248369dbcfb..5c2c93cbab12 100644
--- a/drivers/gpu/drm/i915/i915_request.c
+++ b/drivers/gpu/drm/i915/i915_request.c
@@ -206,7 +206,8 @@  static int reset_all_global_seqno(struct drm_i915_private *i915, u32 seqno)
 	/* Carefully retire all requests without writing to the rings */
 	ret = i915_gem_wait_for_idle(i915,
 				     I915_WAIT_INTERRUPTIBLE |
-				     I915_WAIT_LOCKED);
+				     I915_WAIT_LOCKED,
+				     MAX_SCHEDULE_TIMEOUT);
 	if (ret)
 		return ret;
 
@@ -735,7 +736,8 @@  i915_request_alloc(struct intel_engine_cs *engine, struct i915_gem_context *ctx)
 		/* Ratelimit ourselves to prevent oom from malicious clients */
 		ret = i915_gem_wait_for_idle(i915,
 					     I915_WAIT_LOCKED |
-					     I915_WAIT_INTERRUPTIBLE);
+					     I915_WAIT_INTERRUPTIBLE,
+					     MAX_SCHEDULE_TIMEOUT);
 		if (ret)
 			goto err_unreserve;
 
diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_context.c b/drivers/gpu/drm/i915/selftests/i915_gem_context.c
index 5fbe15f4effd..ab2590242033 100644
--- a/drivers/gpu/drm/i915/selftests/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/selftests/i915_gem_context.c
@@ -478,7 +478,9 @@  static int __igt_switch_to_kernel_context(struct drm_i915_private *i915,
 		}
 	}
 
-	err = i915_gem_wait_for_idle(i915, I915_WAIT_LOCKED);
+	err = i915_gem_wait_for_idle(i915,
+				     I915_WAIT_LOCKED,
+				     MAX_SCHEDULE_TIMEOUT);
 	if (err)
 		return err;
 
diff --git a/drivers/gpu/drm/i915/selftests/i915_request.c b/drivers/gpu/drm/i915/selftests/i915_request.c
index 43995fc3534d..c4aac6141e04 100644
--- a/drivers/gpu/drm/i915/selftests/i915_request.c
+++ b/drivers/gpu/drm/i915/selftests/i915_request.c
@@ -286,7 +286,9 @@  static int begin_live_test(struct live_test *t,
 	t->func = func;
 	t->name = name;
 
-	err = i915_gem_wait_for_idle(i915, I915_WAIT_LOCKED);
+	err = i915_gem_wait_for_idle(i915,
+				     I915_WAIT_LOCKED,
+				     MAX_SCHEDULE_TIMEOUT);
 	if (err) {
 		pr_err("%s(%s): failed to idle before, with err=%d!",
 		       func, name, err);
diff --git a/drivers/gpu/drm/i915/selftests/igt_flush_test.c b/drivers/gpu/drm/i915/selftests/igt_flush_test.c
index 0d06f559243f..09ab037ce803 100644
--- a/drivers/gpu/drm/i915/selftests/igt_flush_test.c
+++ b/drivers/gpu/drm/i915/selftests/igt_flush_test.c
@@ -64,7 +64,7 @@  int igt_flush_test(struct drm_i915_private *i915, unsigned int flags)
 	}
 
 	wedge_on_timeout(&w, i915, HZ)
-		i915_gem_wait_for_idle(i915, flags);
+		i915_gem_wait_for_idle(i915, flags, MAX_SCHEDULE_TIMEOUT);
 
 	return i915_terminally_wedged(&i915->gpu_error) ? -EIO : 0;
 }