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| author | Joonsoo Kim <iamjoonsoo.kim@lge.com> | 2015-09-09 00:03:59 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-09-09 00:35:28 +0200 |
| commit | 1a16718cf7f4f48ee2aa2cfd9a961c6b433a7b5b (patch) | |
| tree | 0a1aeebba5fb2f8ebd1d4ba20d515be44ab078ce /mm/internal.h | |
| parent | mm: use numa_mem_id() in alloc_pages_node() (diff) | |
| download | linux-1a16718cf7f4f48ee2aa2cfd9a961c6b433a7b5b.tar.xz linux-1a16718cf7f4f48ee2aa2cfd9a961c6b433a7b5b.zip | |
mm/compaction: correct to flush migrated pages if pageblock skip happens
We cache isolate_start_pfn before entering isolate_migratepages(). If
pageblock is skipped in isolate_migratepages() due to whatever reason,
cc->migrate_pfn can be far from isolate_start_pfn hence we flush pages
that were freed. For example, the following scenario can be possible:
- assume order-9 compaction, pageblock order is 9
- start_isolate_pfn is 0x200
- isolate_migratepages()
- skip a number of pageblocks
- start to isolate from pfn 0x600
- cc->migrate_pfn = 0x620
- return
- last_migrated_pfn is set to 0x200
- check flushing condition
- current_block_start is set to 0x600
- last_migrated_pfn < current_block_start then do useless flush
This wrong flush would not help the performance and success rate so this
patch tries to fix it. One simple way to know the exact position where
we start to isolate migratable pages is that we cache it in
isolate_migratepages() before entering actual isolation. This patch
implements that and fixes the problem.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to '')
| -rw-r--r-- | mm/internal.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/mm/internal.h b/mm/internal.h index 1195dd2d6a2b..bc0fa9a69e46 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -182,6 +182,7 @@ struct compact_control { unsigned long nr_migratepages; /* Number of pages to migrate */ unsigned long free_pfn; /* isolate_freepages search base */ unsigned long migrate_pfn; /* isolate_migratepages search base */ + unsigned long last_migrated_pfn;/* Not yet flushed page being freed */ enum migrate_mode mode; /* Async or sync migration mode */ bool ignore_skip_hint; /* Scan blocks even if marked skip */ int order; /* order a direct compactor needs */ |