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Date: Tue, 26 Jun 2012 11:12:22 +0400 From: Glauber Costa <glommer@...allels.com> To: David Rientjes <rientjes@...gle.com> CC: <cgroups@...r.kernel.org>, <linux-mm@...ck.org>, Andrew Morton <akpm@...ux-foundation.org>, <linux-kernel@...r.kernel.org>, Frederic Weisbecker <fweisbec@...il.com>, Pekka Enberg <penberg@...nel.org>, Michal Hocko <mhocko@...e.cz>, Johannes Weiner <hannes@...xchg.org>, Christoph Lameter <cl@...ux.com>, <devel@...nvz.org>, <kamezawa.hiroyu@...fujitsu.com>, Tejun Heo <tj@...nel.org>, Suleiman Souhlal <suleiman@...gle.com> Subject: Re: [PATCH 02/11] memcg: Reclaim when more than one page needed. > >> + * retries >> + */ >> +#define NR_PAGES_TO_RETRY 2 >> + > > Should be 1 << PAGE_ALLOC_COSTLY_ORDER? Where does this number come from? > The changelog doesn't specify. Hocko complained about that, and I changed. Where the number comes from, is stated in the comments: it is a number small enough to have high changes of had been freed by the previous reclaim, and yet around the number of pages of a kernel allocation. Of course there are allocations for nr_pages > 2. But 2 will already service the stack most of the time, and most of the slab caches. >> static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, >> - unsigned int nr_pages, bool oom_check) >> + unsigned int nr_pages, unsigned int min_pages, >> + bool oom_check) >> { >> unsigned long csize = nr_pages * PAGE_SIZE; >> struct mem_cgroup *mem_over_limit; >> @@ -2182,18 +2190,18 @@ 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; >> >> if (!(gfp_mask & __GFP_WAIT)) >> return CHARGE_WOULDBLOCK; >> >> + if (gfp_mask & __GFP_NORETRY) >> + return CHARGE_NOMEM; >> + >> ret = mem_cgroup_reclaim(mem_over_limit, gfp_mask, flags); >> if (mem_cgroup_margin(mem_over_limit) >= nr_pages) >> return CHARGE_RETRY; >> @@ -2206,7 +2214,7 @@ static int mem_cgroup_do_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, >> * unlikely to succeed so close to the limit, and we fall back >> * to regular pages anyway in case of failure. >> */ >> - if (nr_pages == 1 && ret) >> + if (nr_pages <= NR_PAGES_TO_RETRY && ret) >> return CHARGE_RETRY; >> >> /* >> @@ -2341,7 +2349,8 @@ again: >> nr_oom_retries = MEM_CGROUP_RECLAIM_RETRIES; >> } >> >> - ret = mem_cgroup_do_charge(memcg, gfp_mask, batch, oom_check); >> + ret = mem_cgroup_do_charge(memcg, gfp_mask, batch, nr_pages, >> + oom_check); >> switch (ret) { >> case CHARGE_OK: >> break; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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