mm, compaction: persistently skip hugetlbfs pageblocks

It is pointless to migrate hugetlb memory as part of memory compaction
if the hugetlb size is equal to the pageblock order.  No defragmentation
is occurring in this condition.

It is also pointless to for the freeing scanner to scan a pageblock
where a hugetlb page is pinned.  Unconditionally skip these pageblocks,
and do so peristently so that they are not rescanned until it is
observed that these hugepages are no longer pinned.

It would also be possible to do this by involving the hugetlb subsystem
in marking pageblocks to no longer be skipped when they hugetlb pages
are freed.  This is a simple solution that doesn't involve any
additional subsystems in pageblock skip manipulation.

[rientjes@google.com: fix build]
  Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1708201734390.117182@chino.kir.corp.google.com
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1708151639130.106658@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Tested-by: Michal Hocko <mhocko@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Rientjes 2017-11-17 15:26:30 -08:00 committed by Linus Torvalds
parent a0647dc920
commit 21dc7e0236
2 changed files with 54 additions and 11 deletions

View file

@ -96,6 +96,17 @@ void set_pfnblock_flags_mask(struct page *page,
#define set_pageblock_skip(page) \
set_pageblock_flags_group(page, 1, PB_migrate_skip, \
PB_migrate_skip)
#else
static inline bool get_pageblock_skip(struct page *page)
{
return false;
}
static inline void clear_pageblock_skip(struct page *page)
{
}
static inline void set_pageblock_skip(struct page *page)
{
}
#endif /* CONFIG_COMPACTION */
#endif /* PAGEBLOCK_FLAGS_H */