On 07/11/2011 01:20 PM, Johannes Weiner wrote:
I CC'd Rik for reclaim-wizardry. But if I am not completly off with this there is a chance that the change that let the active list grow unscanned may actually have contributed to this single-page writing problem becoming worse?
Yes, the patch probably contributed. However, the patch does help protect the working set in the page cache from streaming IO, so on balance I believe we need to keep this change. What it changes is that the size of the inactive file list can no longer grow unbounded, keeping it a little smaller than it could have grown in the past.
commit 56e49d218890f49b0057710a4b6fef31f5ffbfec Author: Rik van Riel<riel@xxxxxxxxxx> Date: Tue Jun 16 15:32:28 2009 -0700 vmscan: evict use-once pages first When the file LRU lists are dominated by streaming IO pages, evict those pages first, before considering evicting other pages. This should be safe from deadlocks or performance problems because only three things can happen to an inactive file page: 1) referenced twice and promoted to the active list 2) evicted by the pageout code 3) under IO, after which it will get evicted or promoted The pages freed in this way can either be reused for streaming IO, or allocated for something else. If the pages are used for streaming IO, this pageout pattern continues. Otherwise, we will fall back to the normal pageout pattern. Signed-off-by: Rik van Riel<riel@xxxxxxxxxx> Reported-by: Elladan<elladan@xxxxxxxxxx> Cc: KOSAKI Motohiro<kosaki.motohiro@xxxxxxxxxxxxxx> Cc: Peter Zijlstra<peterz@xxxxxxxxxxxxx> Cc: Lee Schermerhorn<lee.schermerhorn@xxxxxx> Acked-by: Johannes Weiner<hannes@xxxxxxxxxxx> Signed-off-by: Andrew Morton<akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds<torvalds@xxxxxxxxxxxxxxxxxxxx>
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