Messages in this thread | | | Date | Mon, 28 Jan 2019 16:31:18 -0500 | From | Johannes Weiner <> | Subject | Re: [PATCH] mm,slab,vmscan: accumulate gradual pressure on small slabs |
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On Mon, Jan 28, 2019 at 02:35:35PM -0500, Rik van Riel wrote: > There are a few issues with the way the number of slab objects to > scan is calculated in do_shrink_slab. First, for zero-seek slabs, > we could leave the last object around forever. That could result > in pinning a dying cgroup into memory, instead of reclaiming it. > The fix for that is trivial. > > Secondly, small slabs receive much more pressure, relative to their > size, than larger slabs, due to "rounding up" the minimum number of > scanned objects to batch_size. > > We can keep the pressure on all slabs equal relative to their size > by accumulating the scan pressure on small slabs over time, resulting > in sometimes scanning an object, instead of always scanning several. > > This results in lower system CPU use, and a lower major fault rate, > as actively used entries from smaller caches get reclaimed less > aggressively, and need to be reloaded/recreated less often. > > Fixes: 4b85afbdacd2 ("mm: zero-seek shrinkers") > Fixes: 172b06c32b94 ("mm: slowly shrink slabs with a relatively small number of objects") > Cc: Johannes Weiner <hannes@cmpxchg.org> > Cc: Chris Mason <clm@fb.com> > Cc: Roman Gushchin <guro@fb.com> > Cc: kernel-team@fb.com > Tested-by: Chris Mason <clm@fb.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
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