Quoting Joonas Lahtinen (2017-07-26 11:19:26) > On pe, 2017-07-21 at 15:50 +0100, Chris Wilson wrote: > > The goal here was to minimise doing any thing or any check inside the > > kernel that was not strictly required. For a userspace that assumes > > complete control over the cache domains, the kernel is usually using > > outdated information and may trigger clflushes where none were > > required. > > > > However, swapping is a situation where userspace has no knowledge of the > > domain transfer, and will leave the object in the CPU cache. The kernel > > must flush this out to the backing storage prior to use with the GPU. As > > we use an asynchronous task tracked by an implicit fence for this, we > > also need to cancel the ASYNC flag on the object so that the object will > > wait for the clflush to complete before being executed. This also absolves > > userspace of the responsibility imposed by commit 77ae9957897d ("drm/i915: > > Enable userspace to opt-out of implicit fencing") that its needed to ensure > > that the object was out of the CPU cache prior to use on the GPU. > > > > Fixes: 77ae9957897d ("drm/i915: Enable userspace to opt-out of implicit fencing") > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101571 > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx> > > Cc: Jason Ekstrand <jason@xxxxxxxxxxxxxx> > > Reviewed-by: Jason Ekstrand <jason@xxxxxxxxxxxxxx> > > All explained out, makes perfect sense. > > Reviewed-by: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx> And finally pushed, hopefully making it to v4.12.y before too many people hit the vk-on-(bsw,bxt,glk) bug. -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx