Commits
Chris Wilson committed 8ba306a6a36
drm/i915: Share per-timeline HWSP using a slab suballocator If we restrict ourselves to only using a cacheline for each timeline's HWSP (we could go smaller, but want to avoid needless polluting cachelines on different engines between different contexts), then we can suballocate a single 4k page into 64 different timeline HWSP. By treating each fresh allocation as a slab of 64 entries, we can keep it around for the next 64 allocation attempts until we need to refresh the slab cache. John Harrison noted the issue of fragmentation leading to the same worst case performance of one page per timeline as before, which can be mitigated by adopting a freelist. v2: Keep all partially allocated HWSP on a freelist This is still without migration, so it is possible for the system to end up with each timeline in its own page, but we ensure that no new allocation would needless allocate a fresh page! v3: Throw a selftest at the allocator to try and catch invalid cacheline reuse. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: John Harrison <John.C.Harrison@Intel.com> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20190128181812.22804-4-chris@chris-wilson.co.uk