From: Shaohua Li Date: Tue, 1 Nov 2011 00:07:03 +0000 (-0700) Subject: vmscan: add block plug for page reclaim X-Git-Tag: v3.2-rc1~108^2~115 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3da367c3e5fca71d4e778fa565d9b098d5518f4a;p=pandora-kernel.git 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 Cc: Jens Axboe Cc: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed