Messages in this thread | | | Date | Sat, 11 Aug 2012 02:56:20 +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 2:28), Michal Hocko wrote: > On Sat 11-08-12 01:49:25, KAMEZAWA Hiroyuki wrote: >> (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. > > right you are. > >>> 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" ? > > dunno, it would require a new parameter anyway (because abusing gfp > doesn't seem great idea). > ok, agreed.
-Kame
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