Re: [PATCH] Help Resource Counters Scale better (v4.1)

Balbir Singh
2009-08-13T03:33:48Z

* nishimura@mxp.nes.nec.co.jp <nishimura@mxp.nes.nec.co.jp> [2009-08-13 10:03:50]:

> > @@ -1855,9 +1883,14 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
> > break;
> > }
> >
> > - res_counter_uncharge(&mem->res, PAGE_SIZE, &soft_limit_excess);
> > - if (do_swap_account && (ctype != MEM_CGROUP_CHARGE_TYPE_SWAPOUT))
> > - res_counter_uncharge(&mem->memsw, PAGE_SIZE, NULL);
> > + if (!mem_cgroup_is_root(mem)) {
> > + res_counter_uncharge(&mem->res, PAGE_SIZE, &soft_limit_excess);
> > + if (do_swap_account &&
> > + (ctype != MEM_CGROUP_CHARGE_TYPE_SWAPOUT))
> > + res_counter_uncharge(&mem->memsw, PAGE_SIZE, NULL);
> > + }
> > + if (ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT && mem_cgroup_is_root(mem))
> > + mem_cgroup_swap_statistics(mem, true);
> I think mem_cgroup_is_root(mem) would be unnecessary here.
> Otherwise, MEM_CGROUP_STAT_SWAPOUT of groups except root memcgroup wouldn't
> be counted properly.
>

I think you have a valid point, but it will not impact us currently
since we use SWAPOUT only for root accounting.

>
> > @@ -2461,10 +2496,26 @@ static u64 mem_cgroup_read(struct cgroup *cont, struct cftype *cft)
> > name = MEMFILE_ATTR(cft->private);
> > switch (type) {
> > case _MEM:
> > - val = res_counter_read_u64(&mem->res, name);
> > + if (name == RES_USAGE && mem_cgroup_is_root(mem)) {
> > + val = mem_cgroup_read_stat(&mem->stat,
> > + MEM_CGROUP_STAT_CACHE);
> > + val += mem_cgroup_read_stat(&mem->stat,
> > + MEM_CGROUP_STAT_RSS);
> > + val <<= PAGE_SHIFT;
> > + } else
> > + val = res_counter_read_u64(&mem->res, name);
> > break;
> > case _MEMSWAP:
> > - val = res_counter_read_u64(&mem->memsw, name);
> > + if (name == RES_USAGE && mem_cgroup_is_root(mem)) {
> > + val = mem_cgroup_read_stat(&mem->stat,
> > + MEM_CGROUP_STAT_CACHE);
> > + val += mem_cgroup_read_stat(&mem->stat,
> > + MEM_CGROUP_STAT_RSS);
> > + val += mem_cgroup_read_stat(&mem->stat,
> > + MEM_CGROUP_STAT_SWAPOUT);
> > + val <<= PAGE_SHIFT;
> > + } else
> > + val = res_counter_read_u64(&mem->memsw, name);
> > break;
> > default:
> > BUG();
> Considering use_hierarchy==1 case in the root memcgroup, shouldn't we use
> mem_cgroup_walk_tree() here to sum up all the children's usage ?
> *.usage_in_bytes show sum of all the children's usage now if use_hierarchy==1.

If memory.use_hiearchy=1, we should use total_stats..right. Let me
send out a newer version for review.

--
Balbir