Messages in this thread | | | Date | Fri, 22 Mar 2019 22:49:46 +0000 | From | Chris Down <> | Subject | Re: [PATCH REBASED] mm, memcg: Make scan aggression always exclude protection |
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Roman Gushchin writes: >I've noticed that the old version is just wrong: if cgroup_size is way smaller >than max(min, low), scan will be set to -lruvec_size. >Given that it's unsigned long, we'll end up with scanning the whole list >(due to clamp() below).
Are you certain? If so, I don't see what you mean. This is how the code looks in Linus' tree after the fixups:
unsigned long cgroup_size = mem_cgroup_size(memcg); unsigned long baseline = 0;
if (!sc->memcg_low_reclaim) baseline = lruvec_size; scan = lruvec_size * cgroup_size / protection - baseline;
This works correctly as far as I can tell:
low reclaim case:
In [1]: cgroup_size=50; lruvec_size=10; protection=2000; baseline=0; lruvec_size * cgroup_size // protection - baseline Out[1]: 0
normal case:
In [2]: cgroup_size=3000; lruvec_size=10; protection=2000; baseline=lruvec_size; lruvec_size * cgroup_size // protection - baseline Out[2]: 5
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