Daniel Vetter <daniel@xxxxxxxx> writes: > On Wed, Jan 11, 2017 at 12:24:59PM +0000, Chris Wilson wrote: >> On Wed, Jan 11, 2017 at 02:07:37PM +0200, Mika Kuoppala wrote: >> > Daniel Vetter <daniel@xxxxxxxx> writes: >> > >> > > On Mon, Jan 09, 2017 at 01:07:56PM -0800, Francisco Jerez wrote: >> > >> 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. >> > >> >> > >> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99256 >> > >> Signed-off-by: Francisco Jerez <currojerez@xxxxxxxxxx> >> > >> Cc: Eero Tamminen <eero.t.tamminen@xxxxxxxxx> >> > >> Cc: Jani Nikula <jani.nikula@xxxxxxxxx> >> > >> Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxx> >> > >> Cc: beignet@xxxxxxxxxxxxxxxxxxxxx >> > > >> > > Don't we need some userspace flag/opt-in scheme to avoid stuff going boom >> > > for compute kernels? Are the patches for mesa compute/beignet >> > > ready&reviewed? >> > >> > This is explicit setting on kbl/E0 only. So one could argue >> > that unless they filter based on PCI-IDs, things would already >> > blow up across the skl/kbl population, if they forgot >> > to set it. The whitelisting is in place and looks sane >> > so this E0 exception is a wart that got in by me reading wa >> > database slavishly without thinking. >> >> Add Fixes then? > > Yeah, cc: stable would be good to make sure it shows up in all supported > kernels, fast. Otherwise we'll get some good wtf bug reports. Agreed -- It would be nice for this to get to stable kernel branches. > -Daniel > -- > Daniel Vetter > Software Engineer, Intel Corporation > http://blog.ffwll.ch
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