| Date | Sun, 24 Mar 2013 20:00:07 +0100 | From | Jiri Slaby <> | Subject | Re: [RFC PATCH 0/8] Reduce system disruption due to kswapd |
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On 03/17/2013 02:04 PM, Mel Gorman wrote: > Kswapd and page reclaim behaviour has been screwy in one way or the other > for a long time. Very broadly speaking it worked in the far past because > machines were limited in memory so it did not have that many pages to scan > and it stalled congestion_wait() frequently to prevent it going completely > nuts. In recent times it has behaved very unsatisfactorily with some of > the problems compounded by the removal of stall logic and the introduction > of transparent hugepage support with high-order reclaims. > > There are many variations of bugs that are rooted in this area. One example > is reports of a large copy operations or backup causing the machine to > grind to a halt or applications pushed to swap. Sometimes in low memory > situations a large percentage of memory suddenly gets reclaimed. In other > cases an application starts and kswapd hits 100% CPU usage for prolonged > periods of time and so on. There is now talk of introducing features like > an extra free kbytes tunable to work around aspects of the problem instead > of trying to deal with it. It's compounded by the problem that it can be > very workload and machine specific. > > This RFC is aimed at investigating if kswapd can be address these various > problems in a relatively straight-forward fashion without a fundamental > rewrite. > > Patches 1-2 limits the number of pages kswapd reclaims while still obeying > the anon/file proportion of the LRUs it should be scanning.
Hi,
patch 1 does not apply (on the top of -next), so I can't test this :(.
thanks, -- js suse labs
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