From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757453AbcFAN0s (ORCPT ); Wed, 1 Jun 2016 09:26:48 -0400 Received: from mail-wm0-f67.google.com ([74.125.82.67]:33132 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752732AbcFAN0q (ORCPT ); Wed, 1 Jun 2016 09:26:46 -0400 Date: Wed, 1 Jun 2016 15:26:43 +0200 From: Michal Hocko To: Vlastimil Babka Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mel Gorman , Joonsoo Kim , David Rientjes , Rik van Riel Subject: Re: [PATCH v2 03/18] mm, page_alloc: don't retry initial attempt in slowpath Message-ID: <20160601132643.GP26601@dhcp22.suse.cz> References: <20160531130818.28724-1-vbabka@suse.cz> <20160531130818.28724-4-vbabka@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160531130818.28724-4-vbabka@suse.cz> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 31-05-16 15:08:03, Vlastimil Babka wrote: [...] > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index da3a62a94b4a..9f83259a18a8 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -3367,10 +3367,9 @@ __alloc_pages_direct_reclaim(gfp_t gfp_mask, unsigned int order, > bool drained = false; > > *did_some_progress = __perform_reclaim(gfp_mask, order, ac); > - if (unlikely(!(*did_some_progress))) > - return NULL; > > retry: > + /* We attempt even when no progress, as kswapd might have done some */ > page = get_page_from_freelist(gfp_mask, order, alloc_flags, ac); Is this really likely to happen, though? Sure we might have last few reclaimable pages on the LRU lists but I am not sure this would make a large difference then. That being said, I do not think this is harmful but I find it a bit weird to invoke a reclaim and then ignore the feedback... Will leave the decision up to you but the original patch seemed neater. > > /* > @@ -3378,7 +3377,7 @@ __alloc_pages_direct_reclaim(gfp_t gfp_mask, unsigned int order, > * pages are pinned on the per-cpu lists or in high alloc reserves. > * Shrink them them and try again > */ > - if (!page && !drained) { > + if (!page && *did_some_progress && !drained) { > unreserve_highatomic_pageblock(ac); > drain_all_pages(NULL); > drained = true; I do not remember this in the previous version. Why shouldn't we unreserve highatomic reserves when there was no progress? -- Michal Hocko SUSE Labs