[PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[Kenneth Graunke]

Haswell significantly improved the performance of sampler_c messages,
but the optimization appears to be off by default.  Later platforms
remove this bit, and apparently always enable the optimization.

Improves performance in "Counter Strike: Global Offensive" by 18%
at default settings on Iris Pro.

This may break sampling of paletted formats (P8/A8P8/P8A8).  It's
unclear whether it affects sampling of paletted formats in general,
or just the sample_c message (which is never used).

While libva does have support for using paletted formats (primarily
for OSDs), that support appears to have been broken for at least a
year, so I couldn't observe a regression from this.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
---
 drivers/gpu/drm/i915/i915_reg.h | 1 +
 drivers/gpu/drm/i915/intel_pm.c | 4 ++++
 2 files changed, 5 insertions(+)

Resubmitting the patch to unconditionally enable this.  I tried to get
libva-intel to use paletted formats, and observe a regression...but the
only thing I found that used it was mplayer's OSD (on screen display).
Even without my patch, the colors were totally wrong with that, and it's
according to a few distro wikis, that's been the case for over a year.

If libva's code for paletted formats /is/ broken, they could always add
code to disable this bit using the command validator when fixing it.

Could we try merging this, and back it out if someone reports a
regression?  I haven't observed any problems.  It's also been quite
stable.

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 40ca873..0f32fd1a 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -6167,6 +6167,7 @@ enum punit_power_well {
 #define  HSW_ROW_CHICKEN3_L3_GLOBAL_ATOMICS_DISABLE    (1 << 6)
 
 #define HALF_SLICE_CHICKEN3		0xe184
+#define   HSW_SAMPLE_C_PERFORMANCE	(1<<9)
 #define   GEN8_CENTROID_PIXEL_OPT_DIS	(1<<8)
 #define   GEN8_SAMPLER_POWER_BYPASS_DIS	(1<<1)
 
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 7d99a9c..17e84dc 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -5974,6 +5974,10 @@ static void haswell_init_clock_gating(struct drm_device *dev)
 	I915_WRITE(GEN7_GT_MODE,
 		   _MASKED_FIELD(GEN6_WIZ_HASHING_MASK, GEN6_WIZ_HASHING_16x4));
 
+	/* Make sample_c messages faster. */
+	I915_WRITE(HALF_SLICE_CHICKEN3,
+		   _MASKED_BIT_ENABLE(HSW_SAMPLE_C_PERFORMANCE));
+
 	/* WaSwitchSolVfFArbitrationPriority:hsw */
 	I915_WRITE(GAM_ECOCHK, I915_READ(GAM_ECOCHK) | HSW_ECOCHK_ARB_PRIO_SOL);
 
-- 
2.2.1

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Re: [PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[shuang.he]

Tested-By: PRC QA PRTS (Patch Regression Test System Contact: shuang.he@intel.com)
-------------------------------------Summary-------------------------------------
Platform          Delta          drm-intel-nightly          Series Applied
PNV                                  363/364              363/364
ILK                 -1              364/366              363/366
SNB              +2-1              443/450              444/450
IVB                                  496/498              496/498
BYT                                  288/289              288/289
HSW              +2-6              542/564              538/564
BDW                                  415/417              415/417
-------------------------------------Detailed-------------------------------------
Platform  Test                                drm-intel-nightly          Series Applied
*ILK  igt_gem_fenced_exec_thrash_no-spare-fences-busy      PASS(2, M37)      DMESG_WARN(1, M37)
*SNB  igt_kms_flip_modeset-vs-vblank-race      DMESG_WARN(2, M35)      PASS(1, M35)
 SNB  igt_kms_flip_modeset-vs-vblank-race-interruptible      DMESG_WARN(2, M35M22)PASS(1, M35)      DMESG_WARN(1, M35)
 SNB  igt_kms_plane_plane-position-hole-pipe-B-plane-1      DMESG_WARN(1, M35)PASS(2, M35M22)      PASS(1, M35)
*HSW  igt_kms_flip_flip-vs-expired-vblank      PASS(2, M40)      DMESG_WARN(1, M40)
*HSW  igt_kms_flip_flip-vs-expired-vblank-interruptible      PASS(2, M40)      DMESG_WARN(1, M40)
*HSW  igt_kms_flip_nonexisting-fb      PASS(2, M40)      DMESG_WARN(1, M40)
*HSW  igt_kms_flip_nonexisting-fb-interruptible      PASS(2, M40)      DMESG_WARN(1, M40)
*HSW  igt_kms_flip_single-buffer-flip-vs-dpms-off-vs-modeset      PASS(3, M40M19)      DMESG_WARN(1, M40)
*HSW  igt_kms_plane_plane-panning-bottom-right-pipe-C-plane-1      TIMEOUT(2, M40)PASS(1, M19)      PASS(1, M40)
*HSW  igt_kms_plane_plane-position-hole-pipe-A-plane-2      PASS(2, M40)      DMESG_WARN(1, M40)
 HSW  igt_pm_rpm_modeset-non-lpsp-stress-no-wait      NSPT(1, M19)DMESG_WARN(1, M40)PASS(1, M40)      PASS(1, M40)
Note: You need to pay more attention to line start with '*'
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Re: [PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[Daniel Vetter]

On Wed, Dec 31, 2014 at 04:23:00PM -0800, Kenneth Graunke wrote:
> Haswell significantly improved the performance of sampler_c messages,
> but the optimization appears to be off by default.  Later platforms
> remove this bit, and apparently always enable the optimization.
> 
> Improves performance in "Counter Strike: Global Offensive" by 18%
> at default settings on Iris Pro.
> 
> This may break sampling of paletted formats (P8/A8P8/P8A8).  It's
> unclear whether it affects sampling of paletted formats in general,
> or just the sample_c message (which is never used).
> 
> While libva does have support for using paletted formats (primarily
> for OSDs), that support appears to have been broken for at least a
> year, so I couldn't observe a regression from this.
> 
> Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
> ---
>  drivers/gpu/drm/i915/i915_reg.h | 1 +
>  drivers/gpu/drm/i915/intel_pm.c | 4 ++++
>  2 files changed, 5 insertions(+)
> 
> Resubmitting the patch to unconditionally enable this.  I tried to get
> libva-intel to use paletted formats, and observe a regression...but the
> only thing I found that used it was mplayer's OSD (on screen display).
> Even without my patch, the colors were totally wrong with that, and it's
> according to a few distro wikis, that's been the case for over a year.
> 
> If libva's code for paletted formats /is/ broken, they could always add
> code to disable this bit using the command validator when fixing it.
> 
> Could we try merging this, and back it out if someone reports a
> regression?  I haven't observed any problems.  It's also been quite
> stable.

Yeah makes sense. When resending please incorporated review feedback
(Ville dug out the wa name), I've done that. And I've pasted the
additional detail about the libva saga, just for reference (since no one
will remember that it's mplayer's OSD which uses this 2 months down the
road).

Also please cc libva mailing lists next time around as an fyi. Done that
too.

Queued for -next, thanks for the patch.
-Daniel

> 
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 40ca873..0f32fd1a 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -6167,6 +6167,7 @@ enum punit_power_well {
>  #define  HSW_ROW_CHICKEN3_L3_GLOBAL_ATOMICS_DISABLE    (1 << 6)
>  
>  #define HALF_SLICE_CHICKEN3		0xe184
> +#define   HSW_SAMPLE_C_PERFORMANCE	(1<<9)
>  #define   GEN8_CENTROID_PIXEL_OPT_DIS	(1<<8)
>  #define   GEN8_SAMPLER_POWER_BYPASS_DIS	(1<<1)
>  
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 7d99a9c..17e84dc 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -5974,6 +5974,10 @@ static void haswell_init_clock_gating(struct drm_device *dev)
>  	I915_WRITE(GEN7_GT_MODE,
>  		   _MASKED_FIELD(GEN6_WIZ_HASHING_MASK, GEN6_WIZ_HASHING_16x4));
>  
> +	/* Make sample_c messages faster. */
> +	I915_WRITE(HALF_SLICE_CHICKEN3,
> +		   _MASKED_BIT_ENABLE(HSW_SAMPLE_C_PERFORMANCE));
> +
>  	/* WaSwitchSolVfFArbitrationPriority:hsw */
>  	I915_WRITE(GAM_ECOCHK, I915_READ(GAM_ECOCHK) | HSW_ECOCHK_ARB_PRIO_SOL);
>  
> -- 
> 2.2.1
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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Re: [PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[Kenneth Graunke]

[-- Attachment #1.1: Type: text/plain, Size: 2309 bytes --]

On Monday, January 05, 2015 02:19:15 PM Daniel Vetter wrote:
> On Wed, Dec 31, 2014 at 04:23:00PM -0800, Kenneth Graunke wrote:
> > Haswell significantly improved the performance of sampler_c messages,
> > but the optimization appears to be off by default.  Later platforms
> > remove this bit, and apparently always enable the optimization.
> > 
> > Improves performance in "Counter Strike: Global Offensive" by 18%
> > at default settings on Iris Pro.
> > 
> > This may break sampling of paletted formats (P8/A8P8/P8A8).  It's
> > unclear whether it affects sampling of paletted formats in general,
> > or just the sample_c message (which is never used).
> > 
> > While libva does have support for using paletted formats (primarily
> > for OSDs), that support appears to have been broken for at least a
> > year, so I couldn't observe a regression from this.
> > 
> > Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
> > ---
> >  drivers/gpu/drm/i915/i915_reg.h | 1 +
> >  drivers/gpu/drm/i915/intel_pm.c | 4 ++++
> >  2 files changed, 5 insertions(+)
> > 
> > Resubmitting the patch to unconditionally enable this.  I tried to get
> > libva-intel to use paletted formats, and observe a regression...but the
> > only thing I found that used it was mplayer's OSD (on screen display).
> > Even without my patch, the colors were totally wrong with that, and it's
> > according to a few distro wikis, that's been the case for over a year.
> > 
> > If libva's code for paletted formats /is/ broken, they could always add
> > code to disable this bit using the command validator when fixing it.
> > 
> > Could we try merging this, and back it out if someone reports a
> > regression?  I haven't observed any problems.  It's also been quite
> > stable.
> 
> Yeah makes sense. When resending please incorporated review feedback
> (Ville dug out the wa name), I've done that. And I've pasted the
> additional detail about the libva saga, just for reference (since no one
> will remember that it's mplayer's OSD which uses this 2 months down the
> road).
> 
> Also please cc libva mailing lists next time around as an fyi. Done that
> too.
> 
> Queued for -next, thanks for the patch.
> -Daniel

Oh, sorry, I missed that in the review.

Thanks, Daniel!

--Ken

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Re: [PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[Xiang, Haihao]

Hi Kenneth,

How did you test OSD ? I can't reproduce the issue you mentioned, OSD
works well for me when using mplayer-vaapi with the latest
libva/libva-intel-driver master branch.

I tried your patch, what surprised me is OSD still works well after
applying your patch. It seems your patch didn't disable the palette.

Thanks
Haihao


> On Monday, January 05, 2015 02:19:15 PM Daniel Vetter wrote:
> > On Wed, Dec 31, 2014 at 04:23:00PM -0800, Kenneth Graunke wrote:
> > > Haswell significantly improved the performance of sampler_c messages,
> > > but the optimization appears to be off by default.  Later platforms
> > > remove this bit, and apparently always enable the optimization.
> > > 
> > > Improves performance in "Counter Strike: Global Offensive" by 18%
> > > at default settings on Iris Pro.
> > > 
> > > This may break sampling of paletted formats (P8/A8P8/P8A8).  It's
> > > unclear whether it affects sampling of paletted formats in general,
> > > or just the sample_c message (which is never used).
> > > 
> > > While libva does have support for using paletted formats (primarily
> > > for OSDs), that support appears to have been broken for at least a
> > > year, so I couldn't observe a regression from this.
> > > 
> > > Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
> > > ---
> > >  drivers/gpu/drm/i915/i915_reg.h | 1 +
> > >  drivers/gpu/drm/i915/intel_pm.c | 4 ++++
> > >  2 files changed, 5 insertions(+)
> > > 
> > > Resubmitting the patch to unconditionally enable this.  I tried to get
> > > libva-intel to use paletted formats, and observe a regression...but the
> > > only thing I found that used it was mplayer's OSD (on screen display).
> > > Even without my patch, the colors were totally wrong with that, and it's
> > > according to a few distro wikis, that's been the case for over a year.
> > > 
> > > If libva's code for paletted formats /is/ broken, they could always add
> > > code to disable this bit using the command validator when fixing it.
> > > 
> > > Could we try merging this, and back it out if someone reports a
> > > regression?  I haven't observed any problems.  It's also been quite
> > > stable.
> > 
> > Yeah makes sense. When resending please incorporated review feedback
> > (Ville dug out the wa name), I've done that. And I've pasted the
> > additional detail about the libva saga, just for reference (since no one
> > will remember that it's mplayer's OSD which uses this 2 months down the
> > road).
> > 
> > Also please cc libva mailing lists next time around as an fyi. Done that
> > too.
> > 
> > Queued for -next, thanks for the patch.
> > -Daniel
> 
> Oh, sorry, I missed that in the review.
> 
> Thanks, Daniel!
> 
> --Ken
> _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/intel-gfx


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Re: [PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[Kenneth Graunke]

[-- Attachment #1.1: Type: text/plain, Size: 896 bytes --]

On Tuesday, January 06, 2015 01:11:53 PM Xiang, Haihao wrote:
> 
> Hi Kenneth,
> 
> How did you test OSD ? I can't reproduce the issue you mentioned, OSD
> works well for me when using mplayer-vaapi with the latest
> libva/libva-intel-driver master branch.
> 
> I tried your patch, what surprised me is OSD still works well after
> applying your patch. It seems your patch didn't disable the palette.
> 
> Thanks
> Haihao

I ran:

mplayer -osdlevel 3 -vo vaapi big_buck_bunny_720p_stereo.ogg

For me, the OSD text is solid green, with hard edges.

If you use "-vo gl" or "-vo xv", the OSD is solid white text with a black
border around it.  I presume that it's supposed to be white with vaapi as
well, but I guess I'm not entirely sure.

It's possible that the optimization doesn't affect the palette as long as
you never use sample_c with the paletted textures.

--Ken

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Re: [PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[Xiang, Haihao]

On Mon, 2015-01-05 at 21:54 -0800, Kenneth Graunke wrote:
> On Tuesday, January 06, 2015 01:11:53 PM Xiang, Haihao wrote:
> > 
> > Hi Kenneth,
> > 
> > How did you test OSD ? I can't reproduce the issue you mentioned, OSD
> > works well for me when using mplayer-vaapi with the latest
> > libva/libva-intel-driver master branch.
> > 
> > I tried your patch, what surprised me is OSD still works well after
> > applying your patch. It seems your patch didn't disable the palette.
> > 
> > Thanks
> > Haihao
> 
> I ran:
> 
> mplayer -osdlevel 3 -vo vaapi big_buck_bunny_720p_stereo.ogg
> 
> For me, the OSD text is solid green, with hard edges.

The OSD text is white for me when using mplayer -osdlevel 3 -vo vaapi
xxx. If possible, could you update your mplayer ?

> 
> If you use "-vo gl" or "-vo xv", the OSD is solid white text with a black
> border around it.  I presume that it's supposed to be white with vaapi as
> well, but I guess I'm not entirely sure.
> 
> It's possible that the optimization doesn't affect the palette as long as
> you never use sample_c with the paletted textures.


I verified the palette takes effect in the following way:

1. Only support P8A8 format in the driver

2. ran the above command and I saw white OSD text

3. Only support P4A4 format in the driver and don't use
3DSTATE_SAMPLER_PALETTE_LOAD0 to load the value to the texture palette,
so the palette keeps unchanged. 

4. ran the above command and I saw black OSD text.

5. Load the right value to the texture palette and ran the above command
again, I saw white OSD text.

Hence I think sample_c with the paletted textures is used in the driver.


> 
> --Ken


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Re: [Intel-gfx] [PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[Xiang, Haihao]

On Tue, 2015-01-06 at 14:39 +0800, Xiang, Haihao wrote:
> On Mon, 2015-01-05 at 21:54 -0800, Kenneth Graunke wrote:
> > On Tuesday, January 06, 2015 01:11:53 PM Xiang, Haihao wrote:
> > > 
> > > Hi Kenneth,
> > > 
> > > How did you test OSD ? I can't reproduce the issue you mentioned, OSD
> > > works well for me when using mplayer-vaapi with the latest
> > > libva/libva-intel-driver master branch.
> > > 
> > > I tried your patch, what surprised me is OSD still works well after
> > > applying your patch. It seems your patch didn't disable the palette.
> > > 
> > > Thanks
> > > Haihao
> > 
> > I ran:
> > 
> > mplayer -osdlevel 3 -vo vaapi big_buck_bunny_720p_stereo.ogg
> > 
> > For me, the OSD text is solid green, with hard edges.
> 
> The OSD text is white for me when using mplayer -osdlevel 3 -vo vaapi
> xxx. If possible, could you update your mplayer ?
> 
> > 
> > If you use "-vo gl" or "-vo xv", the OSD is solid white text with a black
> > border around it.  I presume that it's supposed to be white with vaapi as
> > well, but I guess I'm not entirely sure.
> > 
> > It's possible that the optimization doesn't affect the palette as long as
> > you never use sample_c with the paletted textures.
> 
> 
> I verified the palette takes effect in the following way:
> 
> 1. Only support P8A8 format in the driver
> 
> 2. ran the above command and I saw white OSD text
> 
> 3. Only support P4A4 format in the driver and don't use
> 3DSTATE_SAMPLER_PALETTE_LOAD0 to load the value to the texture palette,
> so the palette keeps unchanged. 
> 
> 4. ran the above command and I saw black OSD text.
> 
> 5. Load the right value to the texture palette and ran the above command
> again, I saw white OSD text.
> 
> Hence I think sample_c with the paletted textures is used in the driver.

Sorry, libva driver doesn't use sample_c message, I mean the paletted
texture is used.  However corroding to the doc, Palette is disabled for
fast mode.


> 
> > 
> > --Ken
> 
> 
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Re: [PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[Kenneth Graunke]

[-- Attachment #1.1: Type: text/plain, Size: 2453 bytes --]

On Tuesday, January 06, 2015 02:39:36 PM Xiang, Haihao wrote:
> On Mon, 2015-01-05 at 21:54 -0800, Kenneth Graunke wrote:
> > On Tuesday, January 06, 2015 01:11:53 PM Xiang, Haihao wrote:
> > > 
> > > Hi Kenneth,
> > > 
> > > How did you test OSD ? I can't reproduce the issue you mentioned, OSD
> > > works well for me when using mplayer-vaapi with the latest
> > > libva/libva-intel-driver master branch.
> > > 
> > > I tried your patch, what surprised me is OSD still works well after
> > > applying your patch. It seems your patch didn't disable the palette.
> > > 
> > > Thanks
> > > Haihao
> > 
> > I ran:
> > 
> > mplayer -osdlevel 3 -vo vaapi big_buck_bunny_720p_stereo.ogg
> > 
> > For me, the OSD text is solid green, with hard edges.
> 
> The OSD text is white for me when using mplayer -osdlevel 3 -vo vaapi
> xxx. If possible, could you update your mplayer ?

Huh.  I'm using the Arch Linux package of mplayer-vaapi 36265-13,
which seems to be the most recent subversion commit ID.  I've never seen
white text on my Haswell system - it seems to be consistently dark green.

> > If you use "-vo gl" or "-vo xv", the OSD is solid white text with a black
> > border around it.  I presume that it's supposed to be white with vaapi as
> > well, but I guess I'm not entirely sure.
> > 
> > It's possible that the optimization doesn't affect the palette as long as
> > you never use sample_c with the paletted textures.
> 
> I verified the palette takes effect in the following way:
> 
> 1. Only support P8A8 format in the driver
> 
> 2. ran the above command and I saw white OSD text
> 
> 3. Only support P4A4 format in the driver and don't use
> 3DSTATE_SAMPLER_PALETTE_LOAD0 to load the value to the texture palette,
> so the palette keeps unchanged. 
> 
> 4. ran the above command and I saw black OSD text.
> 
> 5. Load the right value to the texture palette and ran the above command
> again, I saw white OSD text.
> 
> Hence I think sample_c with the paletted textures is used in the driver.

That sounds like the palette is actually working, then.  Great :)

I doubt that libva would use sample_c - sampling with a shadow comparison?
It looks like it just uses sample and sample+killpix.

I'm pretty sure the sample_c optimization just uses the palette memory as
storage for some stuff, so it's quite possible it just works if you're
only using sample and sample+killpix.

--Ken

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Re: [Intel-gfx] [PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[Xiang, Haihao]

On Mon, 2015-01-05 at 23:03 -0800, Kenneth Graunke wrote:
> On Tuesday, January 06, 2015 02:39:36 PM Xiang, Haihao wrote:
> > On Mon, 2015-01-05 at 21:54 -0800, Kenneth Graunke wrote:
> > > On Tuesday, January 06, 2015 01:11:53 PM Xiang, Haihao wrote:
> > > > 
> > > > Hi Kenneth,
> > > > 
> > > > How did you test OSD ? I can't reproduce the issue you mentioned, OSD
> > > > works well for me when using mplayer-vaapi with the latest
> > > > libva/libva-intel-driver master branch.
> > > > 
> > > > I tried your patch, what surprised me is OSD still works well after
> > > > applying your patch. It seems your patch didn't disable the palette.
> > > > 
> > > > Thanks
> > > > Haihao
> > > 
> > > I ran:
> > > 
> > > mplayer -osdlevel 3 -vo vaapi big_buck_bunny_720p_stereo.ogg
> > > 
> > > For me, the OSD text is solid green, with hard edges.
> > 
> > The OSD text is white for me when using mplayer -osdlevel 3 -vo vaapi
> > xxx. If possible, could you update your mplayer ?
> 
> Huh.  I'm using the Arch Linux package of mplayer-vaapi 36265-13,
> which seems to be the most recent subversion commit ID.  I've never seen
> white text on my Haswell system - it seems to be consistently dark green.

> > > If you use "-vo gl" or "-vo xv", the OSD is solid white text with a black
> > > border around it.  I presume that it's supposed to be white with vaapi as
> > > well, but I guess I'm not entirely sure.
> > > 
> > > It's possible that the optimization doesn't affect the palette as long as
> > > you never use sample_c with the paletted textures.
> > 
> > I verified the palette takes effect in the following way:
> > 
> > 1. Only support P8A8 format in the driver
> > 
> > 2. ran the above command and I saw white OSD text
> > 
> > 3. Only support P4A4 format in the driver and don't use
> > 3DSTATE_SAMPLER_PALETTE_LOAD0 to load the value to the texture palette,
> > so the palette keeps unchanged. 
> > 
> > 4. ran the above command and I saw black OSD text.
> > 
> > 5. Load the right value to the texture palette and ran the above command
> > again, I saw white OSD text.
> > 
> > Hence I think sample_c with the paletted textures is used in the driver.
> 
> That sounds like the palette is actually working, then.  Great :)
> 
> I doubt that libva would use sample_c - sampling with a shadow comparison?
> It looks like it just uses sample and sample+killpix.

You are right, libva driver doesn't use sample_c message. 

> I'm pretty sure the sample_c optimization just uses the palette memory as
> storage for some stuff, so it's quite possible it just works if you're
> only using sample and sample+killpix.

Thanks for the explanation, it makes sense to me.

> 
> --Ken


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Re: [Intel-gfx] [PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[Daniel Vetter]

On Tue, Jan 06, 2015 at 03:15:39PM +0800, Xiang, Haihao wrote:
> On Mon, 2015-01-05 at 23:03 -0800, Kenneth Graunke wrote:
> > On Tuesday, January 06, 2015 02:39:36 PM Xiang, Haihao wrote:
> > > On Mon, 2015-01-05 at 21:54 -0800, Kenneth Graunke wrote:
> > > > On Tuesday, January 06, 2015 01:11:53 PM Xiang, Haihao wrote:
> > > > > 
> > > > > Hi Kenneth,
> > > > > 
> > > > > How did you test OSD ? I can't reproduce the issue you mentioned, OSD
> > > > > works well for me when using mplayer-vaapi with the latest
> > > > > libva/libva-intel-driver master branch.
> > > > > 
> > > > > I tried your patch, what surprised me is OSD still works well after
> > > > > applying your patch. It seems your patch didn't disable the palette.
> > > > > 
> > > > > Thanks
> > > > > Haihao
> > > > 
> > > > I ran:
> > > > 
> > > > mplayer -osdlevel 3 -vo vaapi big_buck_bunny_720p_stereo.ogg
> > > > 
> > > > For me, the OSD text is solid green, with hard edges.
> > > 
> > > The OSD text is white for me when using mplayer -osdlevel 3 -vo vaapi
> > > xxx. If possible, could you update your mplayer ?
> > 
> > Huh.  I'm using the Arch Linux package of mplayer-vaapi 36265-13,
> > which seems to be the most recent subversion commit ID.  I've never seen
> > white text on my Haswell system - it seems to be consistently dark green.
> 
> > > > If you use "-vo gl" or "-vo xv", the OSD is solid white text with a black
> > > > border around it.  I presume that it's supposed to be white with vaapi as
> > > > well, but I guess I'm not entirely sure.
> > > > 
> > > > It's possible that the optimization doesn't affect the palette as long as
> > > > you never use sample_c with the paletted textures.
> > > 
> > > I verified the palette takes effect in the following way:
> > > 
> > > 1. Only support P8A8 format in the driver
> > > 
> > > 2. ran the above command and I saw white OSD text
> > > 
> > > 3. Only support P4A4 format in the driver and don't use
> > > 3DSTATE_SAMPLER_PALETTE_LOAD0 to load the value to the texture palette,
> > > so the palette keeps unchanged. 
> > > 
> > > 4. ran the above command and I saw black OSD text.
> > > 
> > > 5. Load the right value to the texture palette and ran the above command
> > > again, I saw white OSD text.
> > > 
> > > Hence I think sample_c with the paletted textures is used in the driver.
> > 
> > That sounds like the palette is actually working, then.  Great :)
> > 
> > I doubt that libva would use sample_c - sampling with a shadow comparison?
> > It looks like it just uses sample and sample+killpix.
> 
> You are right, libva driver doesn't use sample_c message. 
> 
> > I'm pretty sure the sample_c optimization just uses the palette memory as
> > storage for some stuff, so it's quite possible it just works if you're
> > only using sample and sample+killpix.
> 
> Thanks for the explanation, it makes sense to me.

Thanks for digging into this some more, I've added the above discussion in
a quote to the commit message.

Thanks, Daniel
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Re: [PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[Daniel Vetter]

On Fri, Nov 07, 2014 at 10:46:31AM -0800, Matt Turner wrote:
> On Wed, Oct 29, 2014 at 2:12 PM, Kenneth Graunke <kenneth@whitecape.org> wrote:
> > Haswell significantly improved the performance of sampler_c messages,
> > but the optimization appears to be off by default.  Later platforms
> > remove this bit, and apparently always enable the optimization.
> >
> > Improves performance in "Counter Strike: Global Offensive" by 18%
> > at default settings on Iris Pro.  No Piglit regressions.
> 
> Discussion seems to have ended, but Mesa really needs this.
> 
> So, Kernel Team, how are we going to make sure Mesa gets this 18%
> performance improvement?

Someone writes the patches+tests and everything, gets it all reviewed and
I'll merge it.

I'd prefer if we could do this with the cmd parser, but that thing seems
to be eternally stuck. So a new execbuf flag is imo ok too. execbuf
already tracks a few other lonesome bits and makes sure userspace actually
gets the setting it requests, so should work out.
-Daniel
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Re: [PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[Matt Turner]

On Wed, Oct 29, 2014 at 2:12 PM, Kenneth Graunke <kenneth@whitecape.org> wrote:
> Haswell significantly improved the performance of sampler_c messages,
> but the optimization appears to be off by default.  Later platforms
> remove this bit, and apparently always enable the optimization.
>
> Improves performance in "Counter Strike: Global Offensive" by 18%
> at default settings on Iris Pro.  No Piglit regressions.

Discussion seems to have ended, but Mesa really needs this.

So, Kernel Team, how are we going to make sure Mesa gets this 18%
performance improvement?
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Re: [PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[Dave Gordon]

On 30/10/14 19:26, Ville Syrjälä wrote:
> On Thu, Oct 30, 2014 at 10:32:38AM -0700, Kenneth Graunke wrote:
>> On Thursday, October 30, 2014 01:01:30 PM Ville Syrjälä wrote:
>>> On Thu, Oct 30, 2014 at 02:32:40AM -0700, Kenneth Graunke wrote:
>>>> On Thursday, October 30, 2014 11:00:51 AM Ville Syrjälä wrote:
>>>>> On Thu, Oct 30, 2014 at 10:50:03AM +0200, Ville Syrjälä wrote:
>>>>>> On Wed, Oct 29, 2014 at 03:12:43PM -0700, Kenneth Graunke wrote:
>>>>>>> Haswell significantly improved the performance of sampler_c 
>> messages,
>>>>>>> but the optimization appears to be off by default.  Later platforms
>>>>>>> remove this bit, and apparently always enable the optimization.
>>>>>>>
>>>>>>> Improves performance in "Counter Strike: Global Offensive" by 18%
>>>>>>> at default settings on Iris Pro.  No Piglit regressions.
>>>>>>
>>>>>> Nice. We need more bits like this ;)
>>>>>>
>>>>>>>
>>>>>>> Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
>>>>>>> ---
>>>>>>>  drivers/gpu/drm/i915/i915_reg.h | 1 +
>>>>>>>  drivers/gpu/drm/i915/intel_pm.c | 4 ++++
>>>>>>>  2 files changed, 5 insertions(+)
>>>>>>>
>>>>>>> diff --git a/drivers/gpu/drm/i915/i915_reg.h 
>>>> b/drivers/gpu/drm/i915/i915_reg.h
>>>>>>> index 77fce96..340821a 100644
>>>>>>> --- a/drivers/gpu/drm/i915/i915_reg.h
>>>>>>> +++ b/drivers/gpu/drm/i915/i915_reg.h
>>>>>>> @@ -5952,6 +5952,7 @@ enum punit_power_well {
>>>>>>>  #define  HSW_ROW_CHICKEN3_L3_GLOBAL_ATOMICS_DISABLE    (1 << 6)
>>>>>>>  
>>>>>>>  #define HALF_SLICE_CHICKEN3		0xe184
>>>>>>> +#define   HSW_SAMPLE_C_PERFORMANCE	(1<<9)
>>>>>>>  #define   GEN8_CENTROID_PIXEL_OPT_DIS	(1<<8)
>>>>>>>  #define   GEN8_SAMPLER_POWER_BYPASS_DIS	(1<<1)
>>>>>>>  
>>>>>>> diff --git a/drivers/gpu/drm/i915/intel_pm.c 
>>>> b/drivers/gpu/drm/i915/intel_pm.c
>>>>>>> index 7a69eba..50c72a7 100644
>>>>>>> --- a/drivers/gpu/drm/i915/intel_pm.c
>>>>>>> +++ b/drivers/gpu/drm/i915/intel_pm.c
>>>>>>> @@ -5736,6 +5736,10 @@ static void haswell_init_clock_gating(struct 
>>>> drm_device *dev)
>>>>>>>  	I915_WRITE(GEN7_GT_MODE,
>>>>>>>  		   GEN6_WIZ_HASHING_MASK | GEN6_WIZ_HASHING_16x4);
>>>>>>>  
>>>>>>> +	/* Make sample_c messages faster. */
>>>>>>
>>>>>> I found a name for it in the w/a database.
>>>>>>
>>>>>> WaSampleCChickenBitEnable:hsw
>>>>>>
>>>>>> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
>>>>>
>>>>> Oh actually it says palette won't work when this bit is on. I'm assuming
>>>>> that's the texture palette. Do we have any use of that anywhere?
>>>>
>>>> That's a good point.  3DSTATE_SAMPLER_PALETTE_LOAD and the A8P8/indexed 
>>>> formats aren't used by Mesa or xf86-video-intel, but it looks like they
>>>> might be used by libva.
>>>>
>>>> Can someone confirm that libva does use the sampler palette?
>>>>
>>>> If they do, what do we do about it?
>>>
>>> I suppose the best option then would be to use an LRI from a batch,
>>> which means the register would need to be added to the cmd parser
>>> white list. This is one of the context saved registers so doing the
>>> LRI just once per context should be enough.
>>
>> I don't like that solution.  For one, it's impossible - you can't LRI from 
>> userspace batches, even if you add it to the kernel command parser's 
>> whitelist, because the hardware scanner is still enabled.  Given that I've 
>> been waiting two years for this capability, I want to find a more immediate 
>> solution.
> 
> Ah. I've somehow convinced myself the cmd parser might actually be doing
> something besides just eating CPU cycles these days. But I guess not.
> 
>>
>> Another option is to have some sort of execbuf flag...maybe a 3D/Media "usage" 
>> flag.  If set to 3D, write 0x6000200...if media, write 0x6000000.  Or 
>> something specific.  I do hate adding more junk to the execbuf path, though.
>>
>> Other ideas?
> 
> Fast vs. slow flag? :)
> 
> More seriously, one somewhat crappy option would be to initialize that
> bit to 1 for all explicit contexts, and then have the kernel always turn
> it off before executing something with the default context. It's not
> unlike how we imagined the RS stuff would work since old userspace
> doesn't know to turn RS off when using the default context.
> 
> But if we would do something like this, I think it would be nice if we
> could just add it as a temporary hack and potentially drop it if we
> manage to lose the restore inhibit flag and someone finishes the
> cmd parser. So maybe Mesa could also try to set it from a batch,
> which currently would be a nop or rejected by the cmd parser, but
> when the cmd parser starts to work it might actually do something?
> 
> But always initializing it to 1 for all explicit context in the kernel
> obviously requires that libva doesn't use an explicit context itself.
> In case it does, another idea would be to just add a hack to the cmd
> parser to emit the LRI on the ring when it enconters this register.
> Not very pretty, but should work somewhat. It wouldn't allow mid-batch
> changes to the register value though, but enough for setting it once
> for each context in Mesa. And of course we'd still need the kernel to
> turn it off before any default context will see it.

This looks like a use for the proposed DRM_I915_GEM_CONTEXT_CREATE2
ioctl, which (so far) allows setting of scheduling priority for batches
submitted in the new context, and/or declaring that the context will be
used for GPGPU batches. We could add some more bits so that the creator
could declare the context as being specifically for 3d, or for media,
so that the driver can issue the relevant LRIs for such contexts
without affecting users of the default (or any other) context.

.Dave.

>>> Well that's assuming libva doesn't use the default context. I'm getting
>>> another itch to drop the restore inhibit flag for default contexts.
>>> That would actually make it possible to do these sort of things without
>>> risking breakage to existing userspace. But I think Chris is going
>>> scream unless the patch comes with performance data that shows it
>>> doesn't hurt too much.
>>
>> I suppose it wouldn't affect Mesa much, since we never use the default context 
>> on Gen6+.  But otherwise I'd probably want to see the data, like Chris...
> 
> Yeah. I just have this feeling we're going to have to go there
> eventually since there are plenty of registers in the context. Some of
> those registers might have other interesting bits that certain users
> might want to frob from batches. But I suppose we could always have the
> kernel reset those too once they get added to the cmd parser white
> list. Except on new platforms where the hw scanner itself has a whitelist,
> so we'd have to reset them all basically, unless we want the cmd parser
> to still scan every batch on those platforms.


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Re: [PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[Daniel Vetter]

On Fri, Oct 31, 2014 at 11:27:33AM +0200, Ville Syrjälä wrote:
> On Thu, Oct 30, 2014 at 12:57:04PM -0700, Kenneth Graunke wrote:
> > Before we get too much further...we should check if libva is actually broken.
> > I don't know if this means the sampler palette completely doesn't work, or if
> > it just means sample_c doesn't work with the palette.  If it's the latter,
> > we're probably fine, because I doubt libva uses sample_c.
>
> Yeah if we wouldn't break any existing userspace I guess we could just
> flip the switch in the kernel. If anyone later wants to start doing
> something that no longer works they'd have to deal with disabling the
> bit using an LRI.

It very much looks like libva uses palettes, since it supports C8 and C4
image formats (well some crazy fourcc nonsense, but meh). And it does so
on all generations support by the libva driver, i.e. including hsw afaict

Cc'ing people and lists with more clue who should be able to tell whether
its not just there but actually works ...
-Daniel
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Re: [PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[Jani Nikula]

[off-topic]

On Fri, 31 Oct 2014, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
> On Thu, Oct 30, 2014 at 12:57:04PM -0700, Kenneth Graunke wrote:
>> I don't think HALF_SLICE_CHICKEN3 is part of the logical context, FWIW.
>
> Oh but it is. Lots of chickens like to nest in the context.

In the context of lunch, HALF_SLICE_CHICKEN3 is indeed part of the
context. But it has certainly ceased to nest.


BR,
Jani.


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Re: [PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[Ville Syrjälä]

On Thu, Oct 30, 2014 at 12:57:04PM -0700, Kenneth Graunke wrote:
> On Thursday, October 30, 2014 09:26:01 PM Ville Syrjälä wrote:
> > On Thu, Oct 30, 2014 at 10:32:38AM -0700, Kenneth Graunke wrote:
> > > On Thursday, October 30, 2014 01:01:30 PM Ville Syrjälä wrote:
> > > > On Thu, Oct 30, 2014 at 02:32:40AM -0700, Kenneth Graunke wrote:
> > > > > On Thursday, October 30, 2014 11:00:51 AM Ville Syrjälä wrote:
> > > > > > On Thu, Oct 30, 2014 at 10:50:03AM +0200, Ville Syrjälä wrote:
> > > > > > > On Wed, Oct 29, 2014 at 03:12:43PM -0700, Kenneth Graunke wrote:
> > > > > > > > Haswell significantly improved the performance of sampler_c 
> > > messages,
> > > > > > > > but the optimization appears to be off by default.  Later 
> platforms
> > > > > > > > remove this bit, and apparently always enable the optimization.
> > > > > > > > 
> > > > > > > > Improves performance in "Counter Strike: Global Offensive" by 
> 18%
> > > > > > > > at default settings on Iris Pro.  No Piglit regressions.
> > > > > > > 
> > > > > > > Nice. We need more bits like this ;)
> > > > > > > 
> > > > > > > > 
> > > > > > > > Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
> > > > > > > > ---
> > > > > > > >  drivers/gpu/drm/i915/i915_reg.h | 1 +
> > > > > > > >  drivers/gpu/drm/i915/intel_pm.c | 4 ++++
> > > > > > > >  2 files changed, 5 insertions(+)
> > > > > > > > 
> > > > > > > > diff --git a/drivers/gpu/drm/i915/i915_reg.h 
> > > > > b/drivers/gpu/drm/i915/i915_reg.h
> > > > > > > > index 77fce96..340821a 100644
> > > > > > > > --- a/drivers/gpu/drm/i915/i915_reg.h
> > > > > > > > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > > > > > > > @@ -5952,6 +5952,7 @@ enum punit_power_well {
> > > > > > > >  #define  HSW_ROW_CHICKEN3_L3_GLOBAL_ATOMICS_DISABLE    (1 << 6)
> > > > > > > >  
> > > > > > > >  #define HALF_SLICE_CHICKEN3		0xe184
> > > > > > > > +#define   HSW_SAMPLE_C_PERFORMANCE	(1<<9)
> > > > > > > >  #define   GEN8_CENTROID_PIXEL_OPT_DIS	(1<<8)
> > > > > > > >  #define   GEN8_SAMPLER_POWER_BYPASS_DIS	(1<<1)
> > > > > > > >  
> > > > > > > > diff --git a/drivers/gpu/drm/i915/intel_pm.c 
> > > > > b/drivers/gpu/drm/i915/intel_pm.c
> > > > > > > > index 7a69eba..50c72a7 100644
> > > > > > > > --- a/drivers/gpu/drm/i915/intel_pm.c
> > > > > > > > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > > > > > > > @@ -5736,6 +5736,10 @@ static void 
> haswell_init_clock_gating(struct 
> > > > > drm_device *dev)
> > > > > > > >  	I915_WRITE(GEN7_GT_MODE,
> > > > > > > >  		   GEN6_WIZ_HASHING_MASK | GEN6_WIZ_HASHING_16x4);
> > > > > > > >  
> > > > > > > > +	/* Make sample_c messages faster. */
> > > > > > > 
> > > > > > > I found a name for it in the w/a database.
> > > > > > > 
> > > > > > > WaSampleCChickenBitEnable:hsw
> > > > > > > 
> > > > > > > Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > > > > 
> > > > > > Oh actually it says palette won't work when this bit is on. I'm 
> assuming
> > > > > > that's the texture palette. Do we have any use of that anywhere?
> > > > > 
> > > > > That's a good point.  3DSTATE_SAMPLER_PALETTE_LOAD and the 
> A8P8/indexed 
> > > > > formats aren't used by Mesa or xf86-video-intel, but it looks like 
> they 
> > > might 
> > > > > be used by libva.
> > > > > 
> > > > > Can someone confirm that libva does use the sampler palette?
> > > > > 
> > > > > If they do, what do we do about it?
> > > > 
> > > > I suppose the best option then would be to use an LRI from a batch,
> > > > which means the register would need to be added to the cmd parser
> > > > white list. This is one of the context saved registers so doing the
> > > > LRI just once per context should be enough.
> > > 
> > > I don't like that solution.  For one, it's impossible - you can't LRI from 
> > > userspace batches, even if you add it to the kernel command parser's 
> > > whitelist, because the hardware scanner is still enabled.  Given that I've 
> > > been waiting two years for this capability, I want to find a more 
> immediate 
> > > solution.
> > 
> > Ah. I've somehow convinced myself the cmd parser might actually be doing
> > something besides just eating CPU cycles these days. But I guess not.
> > 
> > > 
> > > Another option is to have some sort of execbuf flag...maybe a 3D/Media 
> "usage" 
> > > flag.  If set to 3D, write 0x6000200...if media, write 0x6000000.  Or 
> > > something specific.  I do hate adding more junk to the execbuf path, 
> though.
> > > 
> > > Other ideas?
> > 
> > Fast vs. slow flag? :)
> > 
> > More seriously, one somewhat crappy option would be to initialize that
> > bit to 1 for all explicit contexts, and then have the kernel always turn
> > it off before executing something with the default context. It's not
> > unlike how we imagined the RS stuff would work since old userspace
> > doesn't know to turn RS off when using the default context.
> 
> Interesting idea - that might work.  We don't need mid-batch changes either.
> 
> I don't think HALF_SLICE_CHICKEN3 is part of the logical context, FWIW.

Oh but it is. Lots of chickens like to nest in the context.

> 
> Before we get too much further...we should check if libva is actually broken.  
> I don't know if this means the sampler palette completely doesn't work, or if 
> it just means sample_c doesn't work with the palette.  If it's the latter, 
> we're probably fine, because I doubt libva uses sample_c.

Yeah if we wouldn't break any existing userspace I guess we could just
flip the switch in the kernel. If anyone later wants to start doing
something that no longer works they'd have to deal with disabling the
bit using an LRI.

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Re: [PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[Kenneth Graunke]

[-- Attachment #1.1: Type: text/plain, Size: 5141 bytes --]

On Thursday, October 30, 2014 09:26:01 PM Ville Syrjälä wrote:
> On Thu, Oct 30, 2014 at 10:32:38AM -0700, Kenneth Graunke wrote:
> > On Thursday, October 30, 2014 01:01:30 PM Ville Syrjälä wrote:
> > > On Thu, Oct 30, 2014 at 02:32:40AM -0700, Kenneth Graunke wrote:
> > > > On Thursday, October 30, 2014 11:00:51 AM Ville Syrjälä wrote:
> > > > > On Thu, Oct 30, 2014 at 10:50:03AM +0200, Ville Syrjälä wrote:
> > > > > > On Wed, Oct 29, 2014 at 03:12:43PM -0700, Kenneth Graunke wrote:
> > > > > > > Haswell significantly improved the performance of sampler_c 
> > messages,
> > > > > > > but the optimization appears to be off by default.  Later 
platforms
> > > > > > > remove this bit, and apparently always enable the optimization.
> > > > > > > 
> > > > > > > Improves performance in "Counter Strike: Global Offensive" by 
18%
> > > > > > > at default settings on Iris Pro.  No Piglit regressions.
> > > > > > 
> > > > > > Nice. We need more bits like this ;)
> > > > > > 
> > > > > > > 
> > > > > > > Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
> > > > > > > ---
> > > > > > >  drivers/gpu/drm/i915/i915_reg.h | 1 +
> > > > > > >  drivers/gpu/drm/i915/intel_pm.c | 4 ++++
> > > > > > >  2 files changed, 5 insertions(+)
> > > > > > > 
> > > > > > > diff --git a/drivers/gpu/drm/i915/i915_reg.h 
> > > > b/drivers/gpu/drm/i915/i915_reg.h
> > > > > > > index 77fce96..340821a 100644
> > > > > > > --- a/drivers/gpu/drm/i915/i915_reg.h
> > > > > > > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > > > > > > @@ -5952,6 +5952,7 @@ enum punit_power_well {
> > > > > > >  #define  HSW_ROW_CHICKEN3_L3_GLOBAL_ATOMICS_DISABLE    (1 << 6)
> > > > > > >  
> > > > > > >  #define HALF_SLICE_CHICKEN3		0xe184
> > > > > > > +#define   HSW_SAMPLE_C_PERFORMANCE	(1<<9)
> > > > > > >  #define   GEN8_CENTROID_PIXEL_OPT_DIS	(1<<8)
> > > > > > >  #define   GEN8_SAMPLER_POWER_BYPASS_DIS	(1<<1)
> > > > > > >  
> > > > > > > diff --git a/drivers/gpu/drm/i915/intel_pm.c 
> > > > b/drivers/gpu/drm/i915/intel_pm.c
> > > > > > > index 7a69eba..50c72a7 100644
> > > > > > > --- a/drivers/gpu/drm/i915/intel_pm.c
> > > > > > > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > > > > > > @@ -5736,6 +5736,10 @@ static void 
haswell_init_clock_gating(struct 
> > > > drm_device *dev)
> > > > > > >  	I915_WRITE(GEN7_GT_MODE,
> > > > > > >  		   GEN6_WIZ_HASHING_MASK | GEN6_WIZ_HASHING_16x4);
> > > > > > >  
> > > > > > > +	/* Make sample_c messages faster. */
> > > > > > 
> > > > > > I found a name for it in the w/a database.
> > > > > > 
> > > > > > WaSampleCChickenBitEnable:hsw
> > > > > > 
> > > > > > Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > > > 
> > > > > Oh actually it says palette won't work when this bit is on. I'm 
assuming
> > > > > that's the texture palette. Do we have any use of that anywhere?
> > > > 
> > > > That's a good point.  3DSTATE_SAMPLER_PALETTE_LOAD and the 
A8P8/indexed 
> > > > formats aren't used by Mesa or xf86-video-intel, but it looks like 
they 
> > might 
> > > > be used by libva.
> > > > 
> > > > Can someone confirm that libva does use the sampler palette?
> > > > 
> > > > If they do, what do we do about it?
> > > 
> > > I suppose the best option then would be to use an LRI from a batch,
> > > which means the register would need to be added to the cmd parser
> > > white list. This is one of the context saved registers so doing the
> > > LRI just once per context should be enough.
> > 
> > I don't like that solution.  For one, it's impossible - you can't LRI from 
> > userspace batches, even if you add it to the kernel command parser's 
> > whitelist, because the hardware scanner is still enabled.  Given that I've 
> > been waiting two years for this capability, I want to find a more 
immediate 
> > solution.
> 
> Ah. I've somehow convinced myself the cmd parser might actually be doing
> something besides just eating CPU cycles these days. But I guess not.
> 
> > 
> > Another option is to have some sort of execbuf flag...maybe a 3D/Media 
"usage" 
> > flag.  If set to 3D, write 0x6000200...if media, write 0x6000000.  Or 
> > something specific.  I do hate adding more junk to the execbuf path, 
though.
> > 
> > Other ideas?
> 
> Fast vs. slow flag? :)
> 
> More seriously, one somewhat crappy option would be to initialize that
> bit to 1 for all explicit contexts, and then have the kernel always turn
> it off before executing something with the default context. It's not
> unlike how we imagined the RS stuff would work since old userspace
> doesn't know to turn RS off when using the default context.

Interesting idea - that might work.  We don't need mid-batch changes either.

I don't think HALF_SLICE_CHICKEN3 is part of the logical context, FWIW.

Before we get too much further...we should check if libva is actually broken.  
I don't know if this means the sampler palette completely doesn't work, or if 
it just means sample_c doesn't work with the palette.  If it's the latter, 
we're probably fine, because I doubt libva uses sample_c.

--Ken

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Re: [PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[Ville Syrjälä]

On Thu, Oct 30, 2014 at 10:32:38AM -0700, Kenneth Graunke wrote:
> On Thursday, October 30, 2014 01:01:30 PM Ville Syrjälä wrote:
> > On Thu, Oct 30, 2014 at 02:32:40AM -0700, Kenneth Graunke wrote:
> > > On Thursday, October 30, 2014 11:00:51 AM Ville Syrjälä wrote:
> > > > On Thu, Oct 30, 2014 at 10:50:03AM +0200, Ville Syrjälä wrote:
> > > > > On Wed, Oct 29, 2014 at 03:12:43PM -0700, Kenneth Graunke wrote:
> > > > > > Haswell significantly improved the performance of sampler_c 
> messages,
> > > > > > but the optimization appears to be off by default.  Later platforms
> > > > > > remove this bit, and apparently always enable the optimization.
> > > > > > 
> > > > > > Improves performance in "Counter Strike: Global Offensive" by 18%
> > > > > > at default settings on Iris Pro.  No Piglit regressions.
> > > > > 
> > > > > Nice. We need more bits like this ;)
> > > > > 
> > > > > > 
> > > > > > Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
> > > > > > ---
> > > > > >  drivers/gpu/drm/i915/i915_reg.h | 1 +
> > > > > >  drivers/gpu/drm/i915/intel_pm.c | 4 ++++
> > > > > >  2 files changed, 5 insertions(+)
> > > > > > 
> > > > > > diff --git a/drivers/gpu/drm/i915/i915_reg.h 
> > > b/drivers/gpu/drm/i915/i915_reg.h
> > > > > > index 77fce96..340821a 100644
> > > > > > --- a/drivers/gpu/drm/i915/i915_reg.h
> > > > > > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > > > > > @@ -5952,6 +5952,7 @@ enum punit_power_well {
> > > > > >  #define  HSW_ROW_CHICKEN3_L3_GLOBAL_ATOMICS_DISABLE    (1 << 6)
> > > > > >  
> > > > > >  #define HALF_SLICE_CHICKEN3		0xe184
> > > > > > +#define   HSW_SAMPLE_C_PERFORMANCE	(1<<9)
> > > > > >  #define   GEN8_CENTROID_PIXEL_OPT_DIS	(1<<8)
> > > > > >  #define   GEN8_SAMPLER_POWER_BYPASS_DIS	(1<<1)
> > > > > >  
> > > > > > diff --git a/drivers/gpu/drm/i915/intel_pm.c 
> > > b/drivers/gpu/drm/i915/intel_pm.c
> > > > > > index 7a69eba..50c72a7 100644
> > > > > > --- a/drivers/gpu/drm/i915/intel_pm.c
> > > > > > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > > > > > @@ -5736,6 +5736,10 @@ static void haswell_init_clock_gating(struct 
> > > drm_device *dev)
> > > > > >  	I915_WRITE(GEN7_GT_MODE,
> > > > > >  		   GEN6_WIZ_HASHING_MASK | GEN6_WIZ_HASHING_16x4);
> > > > > >  
> > > > > > +	/* Make sample_c messages faster. */
> > > > > 
> > > > > I found a name for it in the w/a database.
> > > > > 
> > > > > WaSampleCChickenBitEnable:hsw
> > > > > 
> > > > > Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > > 
> > > > Oh actually it says palette won't work when this bit is on. I'm assuming
> > > > that's the texture palette. Do we have any use of that anywhere?
> > > 
> > > That's a good point.  3DSTATE_SAMPLER_PALETTE_LOAD and the A8P8/indexed 
> > > formats aren't used by Mesa or xf86-video-intel, but it looks like they 
> might 
> > > be used by libva.
> > > 
> > > Can someone confirm that libva does use the sampler palette?
> > > 
> > > If they do, what do we do about it?
> > 
> > I suppose the best option then would be to use an LRI from a batch,
> > which means the register would need to be added to the cmd parser
> > white list. This is one of the context saved registers so doing the
> > LRI just once per context should be enough.
> 
> I don't like that solution.  For one, it's impossible - you can't LRI from 
> userspace batches, even if you add it to the kernel command parser's 
> whitelist, because the hardware scanner is still enabled.  Given that I've 
> been waiting two years for this capability, I want to find a more immediate 
> solution.

Ah. I've somehow convinced myself the cmd parser might actually be doing
something besides just eating CPU cycles these days. But I guess not.

> 
> Another option is to have some sort of execbuf flag...maybe a 3D/Media "usage" 
> flag.  If set to 3D, write 0x6000200...if media, write 0x6000000.  Or 
> something specific.  I do hate adding more junk to the execbuf path, though.
> 
> Other ideas?

Fast vs. slow flag? :)

More seriously, one somewhat crappy option would be to initialize that
bit to 1 for all explicit contexts, and then have the kernel always turn
it off before executing something with the default context. It's not
unlike how we imagined the RS stuff would work since old userspace
doesn't know to turn RS off when using the default context.

But if we would do something like this, I think it would be nice if we
could just add it as a temporary hack and potentially drop it if we
manage to lose the restore inhibit flag and someone finishes the
cmd parser. So maybe Mesa could also try to set it from a batch,
which currently would be a nop or rejected by the cmd parser, but
when the cmd parser starts to work it might actually do something?

But always initializing it to 1 for all explicit context in the kernel
obviously requires that libva doesn't use an explicit context itself.
In case it does, another idea would be to just add a hack to the cmd
parser to emit the LRI on the ring when it enconters this register.
Not very pretty, but should work somewhat. It wouldn't allow mid-batch
changes to the register value though, but enough for setting it once
for each context in Mesa. And of course we'd still need the kernel to
turn it off before any default context will see it.

> 
> > Well that's assuming libva doesn't use the default context. I'm getting
> > another itch to drop the restore inhibit flag for default contexts.
> > That would actually make it possible to do these sort of things without
> > risking breakage to existing userspace. But I think Chris is going
> > scream unless the patch comes with performance data that shows it
> > doesn't hurt too much.
> 
> I suppose it wouldn't affect Mesa much, since we never use the default context 
> on Gen6+.  But otherwise I'd probably want to see the data, like Chris...

Yeah. I just have this feeling we're going to have to go there
eventually since there are plenty of registers in the context. Some of
those registers might have other interesting bits that certain users
might want to frob from batches. But I suppose we could always have the
kernel reset those too once they get added to the cmd parser white
list. Except on new platforms where the hw scanner itself has a whitelist,
so we'd have to reset them all basically, unless we want the cmd parser
to still scan every batch on those platforms.

-- 
Ville Syrjälä
Intel OTC
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Re: [PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[Kenneth Graunke]

[-- Attachment #1.1: Type: text/plain, Size: 4204 bytes --]

On Thursday, October 30, 2014 01:01:30 PM Ville Syrjälä wrote:
> On Thu, Oct 30, 2014 at 02:32:40AM -0700, Kenneth Graunke wrote:
> > On Thursday, October 30, 2014 11:00:51 AM Ville Syrjälä wrote:
> > > On Thu, Oct 30, 2014 at 10:50:03AM +0200, Ville Syrjälä wrote:
> > > > On Wed, Oct 29, 2014 at 03:12:43PM -0700, Kenneth Graunke wrote:
> > > > > Haswell significantly improved the performance of sampler_c 
messages,
> > > > > but the optimization appears to be off by default.  Later platforms
> > > > > remove this bit, and apparently always enable the optimization.
> > > > > 
> > > > > Improves performance in "Counter Strike: Global Offensive" by 18%
> > > > > at default settings on Iris Pro.  No Piglit regressions.
> > > > 
> > > > Nice. We need more bits like this ;)
> > > > 
> > > > > 
> > > > > Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
> > > > > ---
> > > > >  drivers/gpu/drm/i915/i915_reg.h | 1 +
> > > > >  drivers/gpu/drm/i915/intel_pm.c | 4 ++++
> > > > >  2 files changed, 5 insertions(+)
> > > > > 
> > > > > diff --git a/drivers/gpu/drm/i915/i915_reg.h 
> > b/drivers/gpu/drm/i915/i915_reg.h
> > > > > index 77fce96..340821a 100644
> > > > > --- a/drivers/gpu/drm/i915/i915_reg.h
> > > > > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > > > > @@ -5952,6 +5952,7 @@ enum punit_power_well {
> > > > >  #define  HSW_ROW_CHICKEN3_L3_GLOBAL_ATOMICS_DISABLE    (1 << 6)
> > > > >  
> > > > >  #define HALF_SLICE_CHICKEN3		0xe184
> > > > > +#define   HSW_SAMPLE_C_PERFORMANCE	(1<<9)
> > > > >  #define   GEN8_CENTROID_PIXEL_OPT_DIS	(1<<8)
> > > > >  #define   GEN8_SAMPLER_POWER_BYPASS_DIS	(1<<1)
> > > > >  
> > > > > diff --git a/drivers/gpu/drm/i915/intel_pm.c 
> > b/drivers/gpu/drm/i915/intel_pm.c
> > > > > index 7a69eba..50c72a7 100644
> > > > > --- a/drivers/gpu/drm/i915/intel_pm.c
> > > > > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > > > > @@ -5736,6 +5736,10 @@ static void haswell_init_clock_gating(struct 
> > drm_device *dev)
> > > > >  	I915_WRITE(GEN7_GT_MODE,
> > > > >  		   GEN6_WIZ_HASHING_MASK | GEN6_WIZ_HASHING_16x4);
> > > > >  
> > > > > +	/* Make sample_c messages faster. */
> > > > 
> > > > I found a name for it in the w/a database.
> > > > 
> > > > WaSampleCChickenBitEnable:hsw
> > > > 
> > > > Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > > 
> > > Oh actually it says palette won't work when this bit is on. I'm assuming
> > > that's the texture palette. Do we have any use of that anywhere?
> > 
> > That's a good point.  3DSTATE_SAMPLER_PALETTE_LOAD and the A8P8/indexed 
> > formats aren't used by Mesa or xf86-video-intel, but it looks like they 
might 
> > be used by libva.
> > 
> > Can someone confirm that libva does use the sampler palette?
> > 
> > If they do, what do we do about it?
> 
> I suppose the best option then would be to use an LRI from a batch,
> which means the register would need to be added to the cmd parser
> white list. This is one of the context saved registers so doing the
> LRI just once per context should be enough.

I don't like that solution.  For one, it's impossible - you can't LRI from 
userspace batches, even if you add it to the kernel command parser's 
whitelist, because the hardware scanner is still enabled.  Given that I've 
been waiting two years for this capability, I want to find a more immediate 
solution.

Another option is to have some sort of execbuf flag...maybe a 3D/Media "usage" 
flag.  If set to 3D, write 0x6000200...if media, write 0x6000000.  Or 
something specific.  I do hate adding more junk to the execbuf path, though.

Other ideas?

> Well that's assuming libva doesn't use the default context. I'm getting
> another itch to drop the restore inhibit flag for default contexts.
> That would actually make it possible to do these sort of things without
> risking breakage to existing userspace. But I think Chris is going
> scream unless the patch comes with performance data that shows it
> doesn't hurt too much.

I suppose it wouldn't affect Mesa much, since we never use the default context 
on Gen6+.  But otherwise I'd probably want to see the data, like Chris...

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Re: [PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[Ville Syrjälä]

On Thu, Oct 30, 2014 at 02:32:40AM -0700, Kenneth Graunke wrote:
> On Thursday, October 30, 2014 11:00:51 AM Ville Syrjälä wrote:
> > On Thu, Oct 30, 2014 at 10:50:03AM +0200, Ville Syrjälä wrote:
> > > On Wed, Oct 29, 2014 at 03:12:43PM -0700, Kenneth Graunke wrote:
> > > > Haswell significantly improved the performance of sampler_c messages,
> > > > but the optimization appears to be off by default.  Later platforms
> > > > remove this bit, and apparently always enable the optimization.
> > > > 
> > > > Improves performance in "Counter Strike: Global Offensive" by 18%
> > > > at default settings on Iris Pro.  No Piglit regressions.
> > > 
> > > Nice. We need more bits like this ;)
> > > 
> > > > 
> > > > Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
> > > > ---
> > > >  drivers/gpu/drm/i915/i915_reg.h | 1 +
> > > >  drivers/gpu/drm/i915/intel_pm.c | 4 ++++
> > > >  2 files changed, 5 insertions(+)
> > > > 
> > > > diff --git a/drivers/gpu/drm/i915/i915_reg.h 
> b/drivers/gpu/drm/i915/i915_reg.h
> > > > index 77fce96..340821a 100644
> > > > --- a/drivers/gpu/drm/i915/i915_reg.h
> > > > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > > > @@ -5952,6 +5952,7 @@ enum punit_power_well {
> > > >  #define  HSW_ROW_CHICKEN3_L3_GLOBAL_ATOMICS_DISABLE    (1 << 6)
> > > >  
> > > >  #define HALF_SLICE_CHICKEN3		0xe184
> > > > +#define   HSW_SAMPLE_C_PERFORMANCE	(1<<9)
> > > >  #define   GEN8_CENTROID_PIXEL_OPT_DIS	(1<<8)
> > > >  #define   GEN8_SAMPLER_POWER_BYPASS_DIS	(1<<1)
> > > >  
> > > > diff --git a/drivers/gpu/drm/i915/intel_pm.c 
> b/drivers/gpu/drm/i915/intel_pm.c
> > > > index 7a69eba..50c72a7 100644
> > > > --- a/drivers/gpu/drm/i915/intel_pm.c
> > > > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > > > @@ -5736,6 +5736,10 @@ static void haswell_init_clock_gating(struct 
> drm_device *dev)
> > > >  	I915_WRITE(GEN7_GT_MODE,
> > > >  		   GEN6_WIZ_HASHING_MASK | GEN6_WIZ_HASHING_16x4);
> > > >  
> > > > +	/* Make sample_c messages faster. */
> > > 
> > > I found a name for it in the w/a database.
> > > 
> > > WaSampleCChickenBitEnable:hsw
> > > 
> > > Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > Oh actually it says palette won't work when this bit is on. I'm assuming
> > that's the texture palette. Do we have any use of that anywhere?
> 
> That's a good point.  3DSTATE_SAMPLER_PALETTE_LOAD and the A8P8/indexed 
> formats aren't used by Mesa or xf86-video-intel, but it looks like they might 
> be used by libva.
> 
> Can someone confirm that libva does use the sampler palette?
> 
> If they do, what do we do about it?

I suppose the best option then would be to use an LRI from a batch,
which means the register would need to be added to the cmd parser
white list. This is one of the context saved registers so doing the
LRI just once per context should be enough.

Well that's assuming libva doesn't use the default context. I'm getting
another itch to drop the restore inhibit flag for default contexts.
That would actually make it possible to do these sort of things without
risking breakage to existing userspace. But I think Chris is going
scream unless the patch comes with performance data that shows it
doesn't hurt too much.

-- 
Ville Syrjälä
Intel OTC
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Re: [PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[Kenneth Graunke]

[-- Attachment #1.1: Type: text/plain, Size: 2464 bytes --]

On Thursday, October 30, 2014 11:00:51 AM Ville Syrjälä wrote:
> On Thu, Oct 30, 2014 at 10:50:03AM +0200, Ville Syrjälä wrote:
> > On Wed, Oct 29, 2014 at 03:12:43PM -0700, Kenneth Graunke wrote:
> > > Haswell significantly improved the performance of sampler_c messages,
> > > but the optimization appears to be off by default.  Later platforms
> > > remove this bit, and apparently always enable the optimization.
> > > 
> > > Improves performance in "Counter Strike: Global Offensive" by 18%
> > > at default settings on Iris Pro.  No Piglit regressions.
> > 
> > Nice. We need more bits like this ;)
> > 
> > > 
> > > Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
> > > ---
> > >  drivers/gpu/drm/i915/i915_reg.h | 1 +
> > >  drivers/gpu/drm/i915/intel_pm.c | 4 ++++
> > >  2 files changed, 5 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/i915_reg.h 
b/drivers/gpu/drm/i915/i915_reg.h
> > > index 77fce96..340821a 100644
> > > --- a/drivers/gpu/drm/i915/i915_reg.h
> > > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > > @@ -5952,6 +5952,7 @@ enum punit_power_well {
> > >  #define  HSW_ROW_CHICKEN3_L3_GLOBAL_ATOMICS_DISABLE    (1 << 6)
> > >  
> > >  #define HALF_SLICE_CHICKEN3		0xe184
> > > +#define   HSW_SAMPLE_C_PERFORMANCE	(1<<9)
> > >  #define   GEN8_CENTROID_PIXEL_OPT_DIS	(1<<8)
> > >  #define   GEN8_SAMPLER_POWER_BYPASS_DIS	(1<<1)
> > >  
> > > diff --git a/drivers/gpu/drm/i915/intel_pm.c 
b/drivers/gpu/drm/i915/intel_pm.c
> > > index 7a69eba..50c72a7 100644
> > > --- a/drivers/gpu/drm/i915/intel_pm.c
> > > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > > @@ -5736,6 +5736,10 @@ static void haswell_init_clock_gating(struct 
drm_device *dev)
> > >  	I915_WRITE(GEN7_GT_MODE,
> > >  		   GEN6_WIZ_HASHING_MASK | GEN6_WIZ_HASHING_16x4);
> > >  
> > > +	/* Make sample_c messages faster. */
> > 
> > I found a name for it in the w/a database.
> > 
> > WaSampleCChickenBitEnable:hsw
> > 
> > Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> Oh actually it says palette won't work when this bit is on. I'm assuming
> that's the texture palette. Do we have any use of that anywhere?

That's a good point.  3DSTATE_SAMPLER_PALETTE_LOAD and the A8P8/indexed 
formats aren't used by Mesa or xf86-video-intel, but it looks like they might 
be used by libva.

Can someone confirm that libva does use the sampler palette?

If they do, what do we do about it?

--Ken

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Re: [PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[Ville Syrjälä]

On Thu, Oct 30, 2014 at 10:50:03AM +0200, Ville Syrjälä wrote:
> On Wed, Oct 29, 2014 at 03:12:43PM -0700, Kenneth Graunke wrote:
> > Haswell significantly improved the performance of sampler_c messages,
> > but the optimization appears to be off by default.  Later platforms
> > remove this bit, and apparently always enable the optimization.
> > 
> > Improves performance in "Counter Strike: Global Offensive" by 18%
> > at default settings on Iris Pro.  No Piglit regressions.
> 
> Nice. We need more bits like this ;)
> 
> > 
> > Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
> > ---
> >  drivers/gpu/drm/i915/i915_reg.h | 1 +
> >  drivers/gpu/drm/i915/intel_pm.c | 4 ++++
> >  2 files changed, 5 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> > index 77fce96..340821a 100644
> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > @@ -5952,6 +5952,7 @@ enum punit_power_well {
> >  #define  HSW_ROW_CHICKEN3_L3_GLOBAL_ATOMICS_DISABLE    (1 << 6)
> >  
> >  #define HALF_SLICE_CHICKEN3		0xe184
> > +#define   HSW_SAMPLE_C_PERFORMANCE	(1<<9)
> >  #define   GEN8_CENTROID_PIXEL_OPT_DIS	(1<<8)
> >  #define   GEN8_SAMPLER_POWER_BYPASS_DIS	(1<<1)
> >  
> > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> > index 7a69eba..50c72a7 100644
> > --- a/drivers/gpu/drm/i915/intel_pm.c
> > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > @@ -5736,6 +5736,10 @@ static void haswell_init_clock_gating(struct drm_device *dev)
> >  	I915_WRITE(GEN7_GT_MODE,
> >  		   GEN6_WIZ_HASHING_MASK | GEN6_WIZ_HASHING_16x4);
> >  
> > +	/* Make sample_c messages faster. */
> 
> I found a name for it in the w/a database.
> 
> WaSampleCChickenBitEnable:hsw
> 
> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Oh actually it says palette won't work when this bit is on. I'm assuming
that's the texture palette. Do we have any use of that anywhere?

> 
> > +	I915_WRITE(HALF_SLICE_CHICKEN3,
> > +		   _MASKED_BIT_ENABLE(HSW_SAMPLE_C_PERFORMANCE));
> > +
> >  	/* WaSwitchSolVfFArbitrationPriority:hsw */
> >  	I915_WRITE(GAM_ECOCHK, I915_READ(GAM_ECOCHK) | HSW_ECOCHK_ARB_PRIO_SOL);
> >  
> > -- 
> > 2.1.2
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Ville Syrjälä
> Intel OTC

-- 
Ville Syrjälä
Intel OTC
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Re: [PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[Ville Syrjälä]

On Wed, Oct 29, 2014 at 03:12:43PM -0700, Kenneth Graunke wrote:
> Haswell significantly improved the performance of sampler_c messages,
> but the optimization appears to be off by default.  Later platforms
> remove this bit, and apparently always enable the optimization.
> 
> Improves performance in "Counter Strike: Global Offensive" by 18%
> at default settings on Iris Pro.  No Piglit regressions.

Nice. We need more bits like this ;)

> 
> Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
> ---
>  drivers/gpu/drm/i915/i915_reg.h | 1 +
>  drivers/gpu/drm/i915/intel_pm.c | 4 ++++
>  2 files changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 77fce96..340821a 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -5952,6 +5952,7 @@ enum punit_power_well {
>  #define  HSW_ROW_CHICKEN3_L3_GLOBAL_ATOMICS_DISABLE    (1 << 6)
>  
>  #define HALF_SLICE_CHICKEN3		0xe184
> +#define   HSW_SAMPLE_C_PERFORMANCE	(1<<9)
>  #define   GEN8_CENTROID_PIXEL_OPT_DIS	(1<<8)
>  #define   GEN8_SAMPLER_POWER_BYPASS_DIS	(1<<1)
>  
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 7a69eba..50c72a7 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -5736,6 +5736,10 @@ static void haswell_init_clock_gating(struct drm_device *dev)
>  	I915_WRITE(GEN7_GT_MODE,
>  		   GEN6_WIZ_HASHING_MASK | GEN6_WIZ_HASHING_16x4);
>  
> +	/* Make sample_c messages faster. */

I found a name for it in the w/a database.

WaSampleCChickenBitEnable:hsw

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> +	I915_WRITE(HALF_SLICE_CHICKEN3,
> +		   _MASKED_BIT_ENABLE(HSW_SAMPLE_C_PERFORMANCE));
> +
>  	/* WaSwitchSolVfFArbitrationPriority:hsw */
>  	I915_WRITE(GAM_ECOCHK, I915_READ(GAM_ECOCHK) | HSW_ECOCHK_ARB_PRIO_SOL);
>  
> -- 
> 2.1.2
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Ville Syrjälä
Intel OTC
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[PATCH] drm/i915: Make sample_c messages go faster on Haswell.

[Kenneth Graunke]

Haswell significantly improved the performance of sampler_c messages,
but the optimization appears to be off by default.  Later platforms
remove this bit, and apparently always enable the optimization.

Improves performance in "Counter Strike: Global Offensive" by 18%
at default settings on Iris Pro.  No Piglit regressions.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
---
 drivers/gpu/drm/i915/i915_reg.h | 1 +
 drivers/gpu/drm/i915/intel_pm.c | 4 ++++
 2 files changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 77fce96..340821a 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -5952,6 +5952,7 @@ enum punit_power_well {
 #define  HSW_ROW_CHICKEN3_L3_GLOBAL_ATOMICS_DISABLE    (1 << 6)
 
 #define HALF_SLICE_CHICKEN3		0xe184
+#define   HSW_SAMPLE_C_PERFORMANCE	(1<<9)
 #define   GEN8_CENTROID_PIXEL_OPT_DIS	(1<<8)
 #define   GEN8_SAMPLER_POWER_BYPASS_DIS	(1<<1)
 
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 7a69eba..50c72a7 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -5736,6 +5736,10 @@ static void haswell_init_clock_gating(struct drm_device *dev)
 	I915_WRITE(GEN7_GT_MODE,
 		   GEN6_WIZ_HASHING_MASK | GEN6_WIZ_HASHING_16x4);
 
+	/* Make sample_c messages faster. */
+	I915_WRITE(HALF_SLICE_CHICKEN3,
+		   _MASKED_BIT_ENABLE(HSW_SAMPLE_C_PERFORMANCE));
+
 	/* WaSwitchSolVfFArbitrationPriority:hsw */
 	I915_WRITE(GAM_ECOCHK, I915_READ(GAM_ECOCHK) | HSW_ECOCHK_ARB_PRIO_SOL);
 
-- 
2.1.2

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