diff options
| author | Minchan Kim <minchan@kernel.org> | 2016-07-28 15:47:08 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-07-28 16:07:41 -0700 |
| commit | 9cb937e2195bc46aa3f21c50f78ee994bbf6e04a (patch) | |
| tree | 2803019792d87c99a1ef2b0f3ea81f626d9e85c1 | |
| parent | bca6759258dbef378bcf5b872177bcd2259ceb68 (diff) | |
| download | lwn-9cb937e2195bc46aa3f21c50f78ee994bbf6e04a.tar.gz lwn-9cb937e2195bc46aa3f21c50f78ee994bbf6e04a.zip | |
mm, page_alloc: fix dirtyable highmem calculation
When I tested vmscale in mmtest in 32bit, I found the benchmark was slow
down 0.5 times.
base node
1 global-1
User 12.98 16.04
System 147.61 166.42
Elapsed 26.48 38.08
With vmstat, I found IO wait avg is much increased compared to base.
The reason was highmem_dirtyable_memory accumulates free pages and
highmem_file_pages from HIGHMEM to MOVABLE zones which was wrong. With
that, dirth_thresh in throtlle_vm_write is always 0 so that it calls
congestion_wait frequently if writeback starts.
With this patch, it is much recovered.
base node fi
1 global-1 fix
User 12.98 16.04 13.78
System 147.61 166.42 143.92
Elapsed 26.48 38.08 29.64
Link: http://lkml.kernel.org/r/1468404004-5085-4-git-send-email-mgorman@techsingularity.net
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
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>
| -rw-r--r-- | mm/page-writeback.c | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 0bca2376bd42..573d138fa7a5 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -307,27 +307,31 @@ static unsigned long highmem_dirtyable_memory(unsigned long total) { #ifdef CONFIG_HIGHMEM int node; - unsigned long x = 0; + unsigned long x; int i; - unsigned long dirtyable = atomic_read(&highmem_file_pages); + unsigned long dirtyable = 0; for_each_node_state(node, N_HIGH_MEMORY) { for (i = ZONE_NORMAL + 1; i < MAX_NR_ZONES; i++) { struct zone *z; + unsigned long nr_pages; if (!is_highmem_idx(i)) continue; z = &NODE_DATA(node)->node_zones[i]; - dirtyable += zone_page_state(z, NR_FREE_PAGES); + if (!populated_zone(z)) + continue; + nr_pages = zone_page_state(z, NR_FREE_PAGES); /* watch for underflows */ - dirtyable -= min(dirtyable, high_wmark_pages(z)); - - x += dirtyable; + nr_pages -= min(nr_pages, high_wmark_pages(z)); + dirtyable += nr_pages; } } + x = dirtyable + atomic_read(&highmem_file_pages); + /* * Unreclaimable memory (kernel memory or anonymous memory * without swap) can bring down the dirtyable pages below |