From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f70.google.com (mail-lf0-f70.google.com [209.85.215.70]) by kanga.kvack.org (Postfix) with ESMTP id A32CB6B0005 for ; Tue, 31 May 2016 08:29:27 -0400 (EDT) Received: by mail-lf0-f70.google.com with SMTP id h68so63867963lfh.2 for ; Tue, 31 May 2016 05:29:27 -0700 (PDT) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id n1si50433800wjz.36.2016.05.31.05.29.26 for (version=TLS1 cipher=AES128-SHA bits=128/128); Tue, 31 May 2016 05:29:26 -0700 (PDT) Subject: Re: [RFC 12/13] mm, compaction: more reliably increase direct compaction priority References: <1462865763-22084-1-git-send-email-vbabka@suse.cz> <1462865763-22084-13-git-send-email-vbabka@suse.cz> <20160531063740.GC30967@js1304-P5Q-DELUXE> <276c5490-c5e3-2ba5-68d8-df02922f6122@suse.cz> From: Vlastimil Babka Message-ID: <8c3efbf0-6c05-273d-5d35-bd0b386a20ec@suse.cz> Date: Tue, 31 May 2016 14:29:24 +0200 MIME-Version: 1.0 In-Reply-To: <276c5490-c5e3-2ba5-68d8-df02922f6122@suse.cz> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Joonsoo Kim Cc: Michal Hocko , linux-mm@kvack.org, Andrew Morton , Rik van Riel , David Rientjes , Mel Gorman , Johannes Weiner , Tetsuo Handa , linux-kernel@vger.kernel.org, Linus Torvalds On 05/31/2016 02:07 PM, Vlastimil Babka wrote: > On 05/31/2016 08:37 AM, Joonsoo Kim wrote: >>> @@ -3695,22 +3695,22 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, >>> else >>> no_progress_loops++; >>> >>> - if (should_reclaim_retry(gfp_mask, order, ac, alloc_flags, >>> - did_some_progress > 0, no_progress_loops)) >>> - goto retry; >>> - >>> + should_retry = should_reclaim_retry(gfp_mask, order, ac, alloc_flags, >>> + did_some_progress > 0, no_progress_loops); >>> /* >>> * It doesn't make any sense to retry for the compaction if the order-0 >>> * reclaim is not able to make any progress because the current >>> * implementation of the compaction depends on the sufficient amount >>> * of free memory (see __compaction_suitable) >>> */ >>> - if (did_some_progress > 0 && >>> - should_compact_retry(ac, order, alloc_flags, >>> + if (did_some_progress > 0) >>> + should_retry |= should_compact_retry(ac, order, alloc_flags, >>> compact_result, &compact_priority, >>> - compaction_retries)) >>> + compaction_retries); >>> + if (should_retry) >>> goto retry; >> >> Hmm... it looks odd that we check should_compact_retry() when >> did_some_progress > 0. If system is full of anonymous memory and we >> don't have swap, we can't reclaim anything but we can compact. > > Right, thanks. Hmm on the other hand, should_compact_retry will assume (in compaction_zonelist_suitable()) that reclaimable memory is actually reclaimable. If there's nothing to tell us that it actually isn't, if we drop the reclaim progress requirement. That's risking an infinite loop? -- 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