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From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Chris Wilson <chris@chris-wilson.co.uk>
Cc: "Intel GFX" <intel-gfx@lists.freedesktop.org>,
	"Marcin Ślusarz" <marcin.slusarz@gmail.com>
Subject: Re: [Intel-gfx] [PATCH] drm/i915: Disable atomics in L3 for gen9
Date: Mon, 9 Nov 2020 22:48:47 +0200	[thread overview]
Message-ID: <20201109204847.GP6112@intel.com> (raw)
In-Reply-To: <160495290548.21258.15679039374837190397@build.alporthouse.com>

On Mon, Nov 09, 2020 at 08:15:05PM +0000, Chris Wilson wrote:
> Quoting Jason Ekstrand (2020-11-09 19:52:26)
> > We need to land this patch.  The number of bugs we have piling up in
> > Mesa gitlab related to this is getting a lot larger than I'd like.
> > I've gone back and forth with various HW and SW people internally for
> > countless e-mail threads and there is no other good workaround.  Yes,
> > the perf hit to atomics sucks but, fortunately, most games don't use
> > them heavily enough for it to make a significant impact.  We should
> > just eat the perf hit and fix the hangs.
> 
> Drat, I thought you had found an alternative fix in the
> bad GEN9_DISABLE_OCL_OOB_SUPPRESS_LOGIC w/a.
> 
> So be it.

I don't suppose this could be just lack of programming the magic
MOCS entry for L3 evictions?

--- a/drivers/gpu/drm/i915/gt/intel_mocs.c
+++ b/drivers/gpu/drm/i915/gt/intel_mocs.c
@@ -132,6 +132,9 @@ static const struct drm_i915_mocs_entry skl_mocs_table[] = {
        MOCS_ENTRY(I915_MOCS_CACHED,
                   LE_3_WB | LE_TC_2_LLC_ELLC | LE_LRUM(3),
                   L3_3_WB)
+       MOCS_ENTRY(63,
+                  LE_3_WB | LE_TC_1_LLC | LE_LRUM(3),
+                  L3_1_UC)
 };
 
 /* NOTE: the LE_TGT_CACHE is not used on Broxton */

The code seems to claim we can't even program that on gen9, but there's
nothing in the current spec to back that up AFAICS.

-- 
Ville Syrjälä
Intel
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Intel-gfx mailing list
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  reply	other threads:[~2020-11-09 20:48 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20190720143132.17522-1-chris@chris-wilson.co.uk>
     [not found] ` <65da19be-2696-8d60-e055-63a37101cf6b@linux.intel.com>
     [not found]   ` <156388293186.31349.1576327527372090940@skylake-alporthouse-com>
     [not found]     ` <87pnm0qtr2.fsf@riseup.net>
     [not found]       ` <156397886241.31349.9195166642161638629@skylake-alporthouse-com>
     [not found]         ` <87a7d3qjzx.fsf@riseup.net>
2020-11-09 19:52           ` [Intel-gfx] [PATCH] drm/i915: Disable atomics in L3 for gen9 Jason Ekstrand
2020-11-09 20:15             ` Chris Wilson
2020-11-09 20:48               ` Ville Syrjälä [this message]
2021-01-25 21:52 [Intel-gfx] [CI] " Chris Wilson
2021-01-25 22:01 ` [Intel-gfx] [PATCH] " Chris Wilson

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