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| author | Shaohua Li <shaohua.li@intel.com> | 2011-11-01 01:07:03 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-11-01 01:30:45 +0100 |
| commit | 3da367c3e5fca71d4e778fa565d9b098d5518f4a (patch) | |
| tree | 915dff1989bdffaed157b56f724631b5d8f2d328 /mm/page-writeback.c | |
| parent | radix_tree: clean away saw_unset_tag leftovers (diff) | |
| download | linux-3da367c3e5fca71d4e778fa565d9b098d5518f4a.tar.xz linux-3da367c3e5fca71d4e778fa565d9b098d5518f4a.zip | |
vmscan: add block plug for page reclaim
per-task block plug can reduce block queue lock contention and increase
request merge. Currently page reclaim doesn't support it. I originally
thought page reclaim doesn't need it, because kswapd thread count is
limited and file cache write is done at flusher mostly.
When I test a workload with heavy swap in a 4-node machine, each CPU is
doing direct page reclaim and swap. This causes block queue lock
contention. In my test, without below patch, the CPU utilization is about
2% ~ 7%. With the patch, the CPU utilization is about 1% ~ 3%. Disk
throughput isn't changed. This should improve normal kswapd write and
file cache write too (increase request merge for example), but might not
be so obvious as I explain above.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page-writeback.c')
0 files changed, 0 insertions, 0 deletions