diff mbox

[7/7] Revert "drm/i915: Enable semaphores on BDW"

Message ID 1407176119-5294-7-git-send-email-rodrigo.vivi@intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Rodrigo Vivi Aug. 4, 2014, 6:15 p.m. UTC
This reverts commit 521e62e49a42661a4ee0102644517dbe2f100a23.

Although POST_SYNC brought a bit of stability to Semaphores on BDW
it didn't solved all issues and some hungs can still occour when
semaphores are enabled on BDW. Also some sloweness can be found on some
igt tests, althoguth it apparently doesn't affect real workloads.

Besides that, no real performance gain was found on our tests with different
and even multiple workloads.

Let's disable it again for now. At least until we are sure it is safe
to re-enable it.

Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
---
 drivers/gpu/drm/i915/i915_drv.c | 4 ++++
 1 file changed, 4 insertions(+)

Comments

Rodrigo Vivi Aug. 7, 2014, 8:05 p.m. UTC | #1
The rest of the series was a reference for the records of what I had and
let semaphores on bdw a bit more stable. But even with them we still get
hungs so please consider only to get the revert for now.


On Mon, Aug 4, 2014 at 11:15 AM, Rodrigo Vivi <rodrigo.vivi@intel.com>
wrote:

> This reverts commit 521e62e49a42661a4ee0102644517dbe2f100a23.
>
> Although POST_SYNC brought a bit of stability to Semaphores on BDW
> it didn't solved all issues and some hungs can still occour when
> semaphores are enabled on BDW. Also some sloweness can be found on some
> igt tests, althoguth it apparently doesn't affect real workloads.
>
> Besides that, no real performance gain was found on our tests with
> different
> and even multiple workloads.
>
> Let's disable it again for now. At least until we are sure it is safe
> to re-enable it.
>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.c
> b/drivers/gpu/drm/i915/i915_drv.c
> index 6c4b25c..ec96f9a 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -481,6 +481,10 @@ bool i915_semaphore_is_enabled(struct drm_device *dev)
>         if (i915.semaphores >= 0)
>                 return i915.semaphores;
>
> +       /* Until we get further testing... */
> +       if (IS_GEN8(dev))
> +               return false;
> +
>  #ifdef CONFIG_INTEL_IOMMU
>         /* Enable semaphores on SNB when IO remapping is off */
>         if (INTEL_INFO(dev)->gen == 6 && intel_iommu_gfx_mapped)
> --
> 1.9.3
>
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
Daniel Vetter Aug. 8, 2014, 7:10 a.m. UTC | #2
On Thu, Aug 07, 2014 at 01:05:52PM -0700, Rodrigo Vivi wrote:
> The rest of the series was a reference for the records of what I had and
> let semaphores on bdw a bit more stable. But even with them we still get
> hungs so please consider only to get the revert for now.

Thanks for the reminder, picked up for -fixes, thanks for the patch.
-Daniel
> 
> 
> On Mon, Aug 4, 2014 at 11:15 AM, Rodrigo Vivi <rodrigo.vivi@intel.com>
> wrote:
> 
> > This reverts commit 521e62e49a42661a4ee0102644517dbe2f100a23.
> >
> > Although POST_SYNC brought a bit of stability to Semaphores on BDW
> > it didn't solved all issues and some hungs can still occour when
> > semaphores are enabled on BDW. Also some sloweness can be found on some
> > igt tests, althoguth it apparently doesn't affect real workloads.
> >
> > Besides that, no real performance gain was found on our tests with
> > different
> > and even multiple workloads.
> >
> > Let's disable it again for now. At least until we are sure it is safe
> > to re-enable it.
> >
> > Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_drv.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_drv.c
> > b/drivers/gpu/drm/i915/i915_drv.c
> > index 6c4b25c..ec96f9a 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.c
> > +++ b/drivers/gpu/drm/i915/i915_drv.c
> > @@ -481,6 +481,10 @@ bool i915_semaphore_is_enabled(struct drm_device *dev)
> >         if (i915.semaphores >= 0)
> >                 return i915.semaphores;
> >
> > +       /* Until we get further testing... */
> > +       if (IS_GEN8(dev))
> > +               return false;
> > +
> >  #ifdef CONFIG_INTEL_IOMMU
> >         /* Enable semaphores on SNB when IO remapping is off */
> >         if (INTEL_INFO(dev)->gen == 6 && intel_iommu_gfx_mapped)
> > --
> > 1.9.3
> >
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> >
> 
> 
> 
> -- 
> Rodrigo Vivi
> Blog: http://blog.vivi.eng.br

> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
Daniel Vetter Aug. 8, 2014, 7:13 a.m. UTC | #3
On Mon, Aug 04, 2014 at 11:15:19AM -0700, Rodrigo Vivi wrote:
> This reverts commit 521e62e49a42661a4ee0102644517dbe2f100a23.
> 
> Although POST_SYNC brought a bit of stability to Semaphores on BDW
> it didn't solved all issues and some hungs can still occour when
> semaphores are enabled on BDW. Also some sloweness can be found on some
> igt tests, althoguth it apparently doesn't affect real workloads.
> 
> Besides that, no real performance gain was found on our tests with different
> and even multiple workloads.
> 
> Let's disable it again for now. At least until we are sure it is safe
> to re-enable it.
> 
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 6c4b25c..ec96f9a 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -481,6 +481,10 @@ bool i915_semaphore_is_enabled(struct drm_device *dev)
>  	if (i915.semaphores >= 0)
>  		return i915.semaphores;
>  
> +	/* Until we get further testing... */
> +	if (IS_GEN8(dev))
> +		return false;

Aside: With this we can't test the code any more at all. The usual
approach for adjusting defaults when it's not the same on all platforms is
to set the module option to -1 (per-platform defaults) and have a
sanitize_foo function call to set it to the correct default. Would be nice
on top of the revert.
-Daniel

> +
>  #ifdef CONFIG_INTEL_IOMMU
>  	/* Enable semaphores on SNB when IO remapping is off */
>  	if (INTEL_INFO(dev)->gen == 6 && intel_iommu_gfx_mapped)
> -- 
> 1.9.3
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
Chris Wilson Aug. 8, 2014, 7:31 a.m. UTC | #4
On Fri, Aug 08, 2014 at 09:13:06AM +0200, Daniel Vetter wrote:
> On Mon, Aug 04, 2014 at 11:15:19AM -0700, Rodrigo Vivi wrote:
> > Besides that, no real performance gain was found on our tests with different
> > and even multiple workloads.

That either means you didn't try hard enough, or that the implementation
is extremely inefficient.
-Chris
diff mbox

Patch

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 6c4b25c..ec96f9a 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -481,6 +481,10 @@  bool i915_semaphore_is_enabled(struct drm_device *dev)
 	if (i915.semaphores >= 0)
 		return i915.semaphores;
 
+	/* Until we get further testing... */
+	if (IS_GEN8(dev))
+		return false;
+
 #ifdef CONFIG_INTEL_IOMMU
 	/* Enable semaphores on SNB when IO remapping is off */
 	if (INTEL_INFO(dev)->gen == 6 && intel_iommu_gfx_mapped)