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| author | Michal Hocko <mhocko@suse.com> | 2017-06-02 14:46:19 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-06-02 15:07:37 -0700 |
| commit | 4f4f2ba9c531b3d7cee293dd3654ba3b86e7d220 (patch) | |
| tree | e76d33e876e50dcbeb4dc88a919003657911b785 /mm/util.c | |
| parent | 60b0a8c3d2480f3b57282b47b7cae7ee71c48635 (diff) | |
| download | linux-4f4f2ba9c531b3d7cee293dd3654ba3b86e7d220.tar.gz | |
mm: clarify why we want kmalloc before falling backto vmallock
While converting drm_[cm]alloc* helpers to kvmalloc* variants Chris Wilson has wondered why we want to try kmalloc before vmalloc fallback even for larger allocations requests. Let's clarify that one larger physically contiguous block is less likely to fragment memory than many scattered pages which can prevent more large blocks from being created. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/20170517080932.21423-1-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Suggested-by: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/util.c')
| -rw-r--r-- | mm/util.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/mm/util.c b/mm/util.c index 464df3489903..26be6407abd7 100644 --- a/mm/util.c +++ b/mm/util.c @@ -357,8 +357,11 @@ void *kvmalloc_node(size_t size, gfp_t flags, int node) WARN_ON_ONCE((flags & GFP_KERNEL) != GFP_KERNEL); /* - * Make sure that larger requests are not too disruptive - no OOM - * killer and no allocation failure warnings as we have a fallback + * We want to attempt a large physically contiguous block first because + * it is less likely to fragment multiple larger blocks and therefore + * contribute to a long term fragmentation less than vmalloc fallback. + * However make sure that larger requests are not too disruptive - no + * OOM killer and no allocation failure warnings as we have a fallback. */ if (size > PAGE_SIZE) { kmalloc_flags |= __GFP_NOWARN; |