]> git.baikalelectronics.ru Git - kernel.git/commit
drm/i915/gt: Shrink i915_page_directory's slab bucket
authorChris Wilson <chris@chris-wilson.co.uk>
Wed, 29 Jul 2020 16:42:19 +0000 (17:42 +0100)
committerJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Mon, 7 Sep 2020 11:24:23 +0000 (14:24 +0300)
commit82adf901138cc0564656dc8dc3a47862a546cb2a
treea91ebb7a3198d28b64c2ef17b78cdfe8e5a6c248
parent89351925a477441ae5fdd0136aec80b49ea1c53c
drm/i915/gt: Shrink i915_page_directory's slab bucket

kmalloc uses power-of-two slab buckets for small allocations (up to a
few pages). Since i915_page_directory is a page of pointers, plus a
couple more, this is rounded up to 8K, and we waste nearly 50% of that
allocation. Long terms this leads to poor memory utilisation, bloating
the kernel footprint, but the problem is exacerbated by our conservative
preallocation scheme for binding VMA. As we are required to allocate all
levels for each vma just in case we need to insert them upon binding,
this leads to a large multiplication factor for a single page vma. By
halving the allocation we need for the page directory structure, we
halve the impact of that factor, bringing workloads that once fitted into
memory, hopefully back to fitting into memory.

We maintain the split between i915_page_directory and i915_page_table as
we only need half the allocation for the lowest, most populous, level.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200729164219.5737-3-chris@chris-wilson.co.uk
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
drivers/gpu/drm/i915/gt/gen6_ppgtt.c
drivers/gpu/drm/i915/gt/gen8_ppgtt.c
drivers/gpu/drm/i915/gt/intel_gtt.h
drivers/gpu/drm/i915/gt/intel_ppgtt.c