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  1. 03 9月, 2018 1 次提交
  3. 07 8月, 2018 2 次提交
  5. 07 7月, 2018 3 次提交
  7. 21 6月, 2018 2 次提交
  9. 19 6月, 2018 1 次提交
  11. 14 6月, 2018 1 次提交
  13. 11 6月, 2018 1 次提交
  15. 06 6月, 2018 1 次提交
  17. 04 5月, 2018 1 次提交
    • C
      drm/i915: Lazily unbind vma on close · 3365e226
      由 Chris Wilson 提交于 
      When userspace is passing around swapbuffers using DRI, we frequently
have to open and close the same object in the foreign address space.
This shows itself as the same object being rebound at roughly 30fps
(with a second object also being rebound at 30fps), which involves us
having to rewrite the page tables and maintain the drm_mm range manager
every time.

However, since the object still exists and it is only the local handle
that disappears, if we are lazy and do not unbind the VMA immediately
when the local user closes the object but defer it until the GPU is
idle, then we can reuse the same VMA binding. We still have to be
careful to mark the handle and lookup tables as closed to maintain the
uABI, just allowing the underlying VMA to be resurrected if the user is
able to access the same object from the same context again.

If the object itself is destroyed (neither userspace keeping a handle to
it), the VMA will be reaped immediately as usual.

In the future, this will be even more useful as instantiating a new VMA
for use on the GPU will become heavier. A nuisance indeed, so nip it in
the bud.

v2: s/__i915_vma_final_close/i915_vma_destroy/ etc.
v3: Leave a hint as to why we deferred the unbind on close.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180503195115.22309-1-chris@chris-wilson.co.uk
      3365e226
  19. 18 4月, 2018 1 次提交
  21. 06 4月, 2018 1 次提交
  23. 05 4月, 2018 1 次提交
  25. 01 3月, 2018 2 次提交
  27. 22 2月, 2018 1 次提交
  29. 20 2月, 2018 1 次提交
  31. 16 2月, 2018 1 次提交
  33. 15 2月, 2018 1 次提交
  35. 10 2月, 2018 1 次提交
  37. 08 2月, 2018 1 次提交
  39. 12 12月, 2017 1 次提交
  41. 29 11月, 2017 1 次提交
  43. 20 11月, 2017 2 次提交
  45. 16 11月, 2017 1 次提交
  47. 09 11月, 2017 1 次提交
  49. 03 11月, 2017 1 次提交
  51. 02 11月, 2017 1 次提交
  53. 01 11月, 2017 1 次提交
  55. 10 10月, 2017 2 次提交
  57. 22 9月, 2017 2 次提交
  59. 14 9月, 2017 1 次提交
    • M
      mm: treewide: remove GFP_TEMPORARY allocation flag · 0ee931c4
      由 Michal Hocko 提交于 
      GFP_TEMPORARY was introduced by commit e12ba74d ("Group short-lived
and reclaimable kernel allocations") along with __GFP_RECLAIMABLE.  It's
primary motivation was to allow users to tell that an allocation is
short lived and so the allocator can try to place such allocations close
together and prevent long term fragmentation.  As much as this sounds
like a reasonable semantic it becomes much less clear when to use the
highlevel GFP_TEMPORARY allocation flag.  How long is temporary? Can the
context holding that memory sleep? Can it take locks? It seems there is
no good answer for those questions.

The current implementation of GFP_TEMPORARY is basically GFP_KERNEL |
__GFP_RECLAIMABLE which in itself is tricky because basically none of
the existing caller provide a way to reclaim the allocated memory.  So
this is rather misleading and hard to evaluate for any benefits.

I have checked some random users and none of them has added the flag
with a specific justification.  I suspect most of them just copied from
other existing users and others just thought it might be a good idea to
use without any measuring.  This suggests that GFP_TEMPORARY just
motivates for cargo cult usage without any reasoning.

I believe that our gfp flags are quite complex already and especially
those with highlevel semantic should be clearly defined to prevent from
confusion and abuse.  Therefore I propose dropping GFP_TEMPORARY and
replace all existing users to simply use GFP_KERNEL.  Please note that
SLAB users with shrinkers will still get __GFP_RECLAIMABLE heuristic and
so they will be placed properly for memory fragmentation prevention.

I can see reasons we might want some gfp flag to reflect shorterm
allocations but I propose starting from a clear semantic definition and
only then add users with proper justification.

This was been brought up before LSF this year by Matthew [1] and it
turned out that GFP_TEMPORARY really doesn't have a clear semantic.  It
seems to be a heuristic without any measured advantage for most (if not
all) its current users.  The follow up discussion has revealed that
opinions on what might be temporary allocation differ a lot between
developers.  So rather than trying to tweak existing users into a
semantic which they haven't expected I propose to simply remove the flag
and start from scratch if we really need a semantic for short term
allocations.

[1] http://lkml.kernel.org/r/20170118054945.GD18349@bombadil.infradead.org

[akpm@linux-foundation.org: fix typo]
[akpm@linux-foundation.org: coding-style fixes]
[sfr@canb.auug.org.au: drm/i915: fix up]
  Link: http://lkml.kernel.org/r/20170816144703.378d4f4d@canb.auug.org.au
Link: http://lkml.kernel.org/r/20170728091904.14627-1-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Acked-by: NMel Gorman <mgorman@suse.de>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Neil Brown <neilb@suse.de>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      0ee931c4
  61. 13 9月, 2017 1 次提交
  63. 07 9月, 2017 1 次提交