Messages in this thread |  | | | Date | Tue, 18 Aug 2009 10:26:09 +0800 | | From | Wu Fengguang <> | | Subject | Re: [RFC] respect the referenced bit of KVM guest pages? |
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On Tue, Aug 18, 2009 at 02:04:46AM +0800, Dike, Jeffrey G wrote: > > Jeff, can you confirm if the mem cgroup's inactive list is small? > > Nope. I have plenty on the inactive anon list, between 13K and 16K pages (i.e. 52M to 64M). > > The inactive mapped list is much smaller - 0 to ~700 pages. > > The active lists are comparable in size, but larger - 16K - 19K pages for anon and 60 - 450 pages for mapped.
The anon inactive list is "over scanned". Take 16k pages for example, with DEF_PRIORITY=12, (16k >> 12) = 4. So when shrink_zone() expects to scan 4 pages in the active/inactive list, it will be scanned SWAP_CLUSTER_MAX=32 pages in effect.
This triggers the background aging of active anon list because inactive_anon_is_low() is found to be true, which keeps the active:inactive ratio in balance.
So anon inactive list over scanned => anon active list over scanned => anon lists over scanned relative to file lists. (The inactive file list may or may not be over scanned depending on its size <> (1<<prio) pages.)
Anyway this is not the expected way vmscan should work, and batching up the cgroup vmscan could get rid of the mess.
Thanks, Fengguang
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