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. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
