Messages in this thread | | | Date | Sat, 11 Aug 2012 01:49:25 +0900 | From | Kamezawa Hiroyuki <> | Subject | Re: [PATCH v2 02/11] memcg: Reclaim when more than one page needed. |
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(2012/08/11 0:42), Michal Hocko wrote: > On Thu 09-08-12 17:01:10, Glauber Costa wrote: > [...] >> @@ -2317,18 +2318,18 @@ static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, >> } else >> mem_over_limit = mem_cgroup_from_res_counter(fail_res, res); >> /* >> - * nr_pages can be either a huge page (HPAGE_PMD_NR), a batch >> - * of regular pages (CHARGE_BATCH), or a single regular page (1). >> - * >> * Never reclaim on behalf of optional batching, retry with a >> * single page instead. >> */ >> - if (nr_pages == CHARGE_BATCH) >> + if (nr_pages > min_pages) >> return CHARGE_RETRY; > > This is dangerous because THP charges will be retried now while they > previously failed with CHARGE_NOMEM which means that we will keep > attempting potentially endlessly.
with THP, I thought nr_pages == min_pages, and no retry.
> Why cannot we simply do if (nr_pages < CHARGE_BATCH) and get rid of the > min_pages altogether?
Hm, I think a slab can be larger than CHARGE_BATCH.
> Also the comment doesn't seem to be valid anymore. > I agree it's not clean. Because our assumption on nr_pages are changed, I think this behavior should not depend on nr_pages value.. Shouldn't we have a flag to indicate "trial-for-batched charge" ?
Thanks, -Kame
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