From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f53.google.com (mail-pa0-f53.google.com [209.85.220.53]) by kanga.kvack.org (Postfix) with ESMTP id BD29D82F64 for ; Fri, 30 Oct 2015 00:10:24 -0400 (EDT) Received: by padhy1 with SMTP id hy1so55010486pad.0 for ; Thu, 29 Oct 2015 21:10:24 -0700 (PDT) Received: from out4133-146.mail.aliyun.com (out4133-146.mail.aliyun.com. [42.120.133.146]) by mx.google.com with ESMTP id vs7si7656278pab.78.2015.10.29.21.10.23 for ; Thu, 29 Oct 2015 21:10:23 -0700 (PDT) Reply-To: "Hillf Danton" From: "Hillf Danton" References: <1446131835-3263-1-git-send-email-mhocko@kernel.org> <1446131835-3263-2-git-send-email-mhocko@kernel.org> In-Reply-To: <1446131835-3263-2-git-send-email-mhocko@kernel.org> Subject: Re: [RFC 1/3] mm, oom: refactor oom detection Date: Fri, 30 Oct 2015 12:10:15 +0800 Message-ID: <00f201d112c8$e2377720$a6a66560$@alibaba-inc.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Content-Language: zh-cn Sender: owner-linux-mm@kvack.org List-ID: To: mhocko@kernel.org, linux-mm@kvack.org Cc: 'Andrew Morton' , 'Linus Torvalds' , 'Mel Gorman' , 'Johannes Weiner' , 'Rik van Riel' , 'David Rientjes' , 'Tetsuo Handa' , 'LKML' , 'Michal Hocko' > +/* > + * Number of backoff steps for potentially reclaimable pages if the direct reclaim > + * cannot make any progress. Each step will reduce 1/MAX_STALL_BACKOFF of the > + * reclaimable memory. > + */ > +#define MAX_STALL_BACKOFF 16 > + > static inline struct page * > __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, > struct alloc_context *ac) > @@ -2984,6 +2991,9 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, > enum migrate_mode migration_mode = MIGRATE_ASYNC; > bool deferred_compaction = false; > int contended_compaction = COMPACT_CONTENDED_NONE; > + struct zone *zone; > + struct zoneref *z; > + int stall_backoff = 0; > > /* > * In the slowpath, we sanity check order to avoid ever trying to > @@ -3135,13 +3145,56 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, > if (gfp_mask & __GFP_NORETRY) > goto noretry; > > - /* Keep reclaiming pages as long as there is reasonable progress */ > + /* > + * Do not retry high order allocations unless they are __GFP_REPEAT > + * and even then do not retry endlessly. > + */ > pages_reclaimed += did_some_progress; > - if ((did_some_progress && order <= PAGE_ALLOC_COSTLY_ORDER) || > - ((gfp_mask & __GFP_REPEAT) && pages_reclaimed < (1 << order))) { > - /* Wait for some write requests to complete then retry */ > - wait_iff_congested(ac->preferred_zone, BLK_RW_ASYNC, HZ/50); > - goto retry; > + if (order > PAGE_ALLOC_COSTLY_ORDER) { > + if (!(gfp_mask & __GFP_REPEAT) || pages_reclaimed >= (1< + goto noretry; > + > + if (did_some_progress) > + goto retry; > + } > + > + /* > + * Be optimistic and consider all pages on reclaimable LRUs as usable > + * but make sure we converge to OOM if we cannot make any progress after > + * multiple consecutive failed attempts. > + */ > + if (did_some_progress) > + stall_backoff = 0; > + else > + stall_backoff = min(stall_backoff+1, MAX_STALL_BACKOFF); > + > + /* > + * Keep reclaiming pages while there is a chance this will lead somewhere. > + * If none of the target zones can satisfy our allocation request even > + * if all reclaimable pages are considered then we are screwed and have > + * to go OOM. > + */ > + for_each_zone_zonelist_nodemask(zone, z, ac->zonelist, ac->high_zoneidx, ac->nodemask) { > + unsigned long free = zone_page_state(zone, NR_FREE_PAGES); > + unsigned long reclaimable; > + unsigned long target; > + > + reclaimable = zone_reclaimable_pages(zone) + > + zone_page_state(zone, NR_ISOLATED_FILE) + > + zone_page_state(zone, NR_ISOLATED_ANON); > + target = reclaimable; > + target -= stall_backoff * (1 + target/MAX_STALL_BACKOFF); target = reclaimable - stall_backoff * (1 + target/MAX_STALL_BACKOFF); = reclaimable - stall_backoff - stall_backoff * (target/MAX_STALL_BACKOFF); then the first stall_backoff looks unreasonable. I guess you mean target = reclaimable - target * (stall_backoff/MAX_STALL_BACKOFF); = reclaimable - stall_back * (target/MAX_STALL_BACKOFF); > + target += free; > + > + /* > + * Would the allocation succeed if we reclaimed the whole target? > + */ > + if (__zone_watermark_ok(zone, order, min_wmark_pages(zone), > + ac->high_zoneidx, alloc_flags, target)) { > + /* Wait for some write requests to complete then retry */ > + wait_iff_congested(zone, BLK_RW_ASYNC, HZ/50); > + goto retry; > + } > } > [...] /* > @@ -2734,10 +2730,6 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, > goto retry; > } > > - /* Any of the zones still reclaimable? Don't OOM. */ > - if (zones_reclaimable) > - return 1; > - Looks cleanup of zones_reclaimable left. > return 0; > } > > -- > 2.6.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org