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Chris Wilson authored
When dealing with a working set larger than the GATT, or even the mappable aperture when touching through the GTT, we end up with evicting objects only to rebind them at a new offset again later. Moving an object into and out of the GTT requires clflushing the pages, thus causing a double-clflush penalty for rebinding. To avoid having to clflush on rebinding, we can track the pages as they are evicted from the GTT and only relinquish those pages on memory pressure. As usual, if it were not for the handling of out-of-memory condition and having to manually shrink our own bo caches, it would be a net reduction of code. Alas. Note: The patch also contains a few changes to the last-hope evict_everything logic in i916_gem_execbuffer.c - we no longer try to only evict the purgeable stuff in a first try (since that's superflous and only helps in OOM corner-cases, not fragmented-gtt trashing situations). Also, the extraction of the get_pages retry loop from bind_to_gtt (and other callsites) to get_pages should imo have been a separate patch. v2: Ditch the newly added put_pages (for unbound objects only) in i915_gem_reset. A quick irc discussion hasn't revealed any important reason for this, so if we need this, I'd like to have a git blame'able explanation for it. v3: Undo the s/drm_malloc_ab/kmalloc/ in get_pages that Chris noticed. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> [danvet: Split out code movements and rant a bit in the commit message with a few Notes. Done v2] Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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