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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>