On Wed 27-02-13 18:57:32, Roman Gushchin wrote:
[...]
> >> + *
> >> + */
> >> +unsigned int mem_cgroup_low_limit_scale(struct lruvec *lruvec)
> >> +{
> >> + struct mem_cgroup_per_zone *mz;
> >> + struct mem_cgroup *memcg;
> >> + unsigned long long low_limit;
> >> + unsigned long long usage;
> >> + unsigned int i;
> >> +
> >> + mz = container_of(lruvec, struct mem_cgroup_per_zone, lruvec);
> >> + memcg = mz->memcg;
> >> + if (!memcg)
> >> + return 0;
> >> +
> >> + low_limit = res_counter_read_u64(&memcg->res, RES_LOW_LIMIT);
> >> + if (!low_limit)
> >> + return 0;
> >> +
> >> + usage = res_counter_read_u64(&memcg->res, RES_USAGE);
> >> +
> >> + if (usage < low_limit)
> >> + return DEF_PRIORITY - 2;
> >> +
> >> + for (i = 0; i < DEF_PRIORITY - 2; i++)
> >> + if (usage - low_limit > (usage >> (i + 3)))
> >> + break;
> >
> > why this doesn't depend in the current reclaim priority?
>
> How do you want to use reclaim priority here?
But then you can get up to 2*DEF_PRIORITY-2 priority (in
get_scan_count) in the end and we are back to my original and more
fundamental objection that the low_limit depends on the group size
because small groups basically do not get scanned when under/close_to
limit while big groups do get scanned and reclaimed.
> I don't like an idea to start ignoring low limit on some priorities.
Well, but you are doing that already. If you are reclaiming for prio 0 then
you add up just DEF_PRIORITY-2 which means you reclaim for all groups with
more than 1024 pages on the LRUs.
[...]
--
Michal Hocko
SUSE Labs
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