|author||Francisco Jerez <email@example.com>||2017-01-12 12:44:54 +0200|
|committer||Greg Kroah-Hartman <firstname.lastname@example.org>||2017-02-01 08:33:14 +0100|
drm/i915: Remove WaDisableLSQCROPERFforOCL KBL workaround.
commit 4fc020d864647ea3ae8cb8f17d63e48e87ebd0bf upstream. The WaDisableLSQCROPERFforOCL workaround has the side effect of disabling an L3SQ optimization that has huge performance implications and is unlikely to be necessary for the correct functioning of usual graphic workloads. Userspace is free to re-enable the workaround on demand, and is generally in a better position to determine whether the workaround is necessary than the DRM is (e.g. only during the execution of compute kernels that rely on both L3 fences and HDC R/W requests). The same workaround seems to apply to BDW (at least to production stepping G1) and SKL as well (the internal workaround database claims that it does for all steppings, while the BSpec workaround table only mentions pre-production steppings), but the DRM doesn't do anything beyond whitelisting the L3SQCREG4 register so userspace can enable it when it sees fit. Do the same on KBL platforms. Improves performance of the GFXBench4 gl_manhattan31 benchmark by 60%, and gl_4 (AKA car chase) by 14% on a KBL GT2 running Mesa master -- This is followed by a regression of 35% and 10% respectively for the same benchmarks and platform caused by my recent patch series switching userspace to use the dataport constant cache instead of the sampler to implement uniform pull constant loads, which caused us to hit more heavily the L3 cache (and on platforms other than KBL had the opposite effect of improving performance of the same two benchmarks). The overall effect on KBL of this change combined with the recent userspace change is respectively 4.6% and 2.6%. SynMark2 OglShMapPcf was affected by the constant cache changes (though it improved as it did on other platforms rather than regressing), but is not significantly affected by this patch (with statistical significance of 5% and sample size 20). v2: Drop some more code to avoid unused variable warning. Fixes: 738fa1b3123f ("drm/i915/kbl: Add WaDisableLSQCROPERFforOCL") Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99256 Signed-off-by: Francisco Jerez <email@example.com> Cc: Matthew Auld <firstname.lastname@example.org> Cc: Eero Tamminen <email@example.com> Cc: Jani Nikula <firstname.lastname@example.org> Cc: Mika Kuoppala <email@example.com> Cc: firstname.lastname@example.org Reviewed-by: Mika Kuoppala <email@example.com> [Removed double Fixes tag] Signed-off-by: Mika Kuoppala <firstname.lastname@example.org> Link: http://email@example.com (cherry picked from commit 8726f2faa371514fba2f594d799db95203dfeee0) Signed-off-by: Jani Nikula <firstname.lastname@example.org> [ Francisco Jerez: Rebase on v4.9 branch. ] Signed-off-by: Francisco Jerez <email@example.com> Signed-off-by: Greg Kroah-Hartman <firstname.lastname@example.org>
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