On Sun, Aug 04, 2013 at 11:47:29PM -0700, Ben Widawsky wrote: > The default LLC age was changed: > commit 0d8ff15e9a15f2b393e53337a107b7a1e5919b6d > Author: Ben Widawsky <benjamin.widawsky@xxxxxxxxx> > Date: Thu Jul 4 11:02:03 2013 -0700 > > drm/i915/hsw: Set correct Haswell PTE encodings. > > On the surface it would seem setting a default age wouldn't matter > because all GEM BOs are aged similarly, so the order in which objects > are evicted would not be subject to aging. The current working theory as > to why this caused a regression though is that LLC is a bit special in > that it is shared with the CPU. Presumably (not verified) the CPU > fetches cachelines with age 3, and therefore recently cached GPU objects > would be evicted before similar CPU object first when the LLC is full. > It stands to reason therefore that this would negatively impact CPU > bound benchmarks - but those seem to be low on the priority list. > > eLLC OTOH does not have this same property as LLC. It should be used > entirely for the GPU, and so the age really shouldn't matter. > Furthermore, we have no evidence to suggest one is better than another > on eLLC. Since we've never properly supported eLLC before no, there > should be no regression. If the GPU client really wants "younger" > objects, they should use MOCS. > > v2: Drop the extra #define (Chad) > > v3: Actually git add > > v4: Pimped commit message > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=67062 > Signed-off-by: Ben Widawsky <ben@xxxxxxxxxxxx> > Reviewed-by: Chad Versace <chad.versace@xxxxxxxxxxxxxxx> Queued for -next, thanks for the patch. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
