Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751951AbbHTMpb (ORCPT ); Thu, 20 Aug 2015 08:45:31 -0400 Received: from mail-wi0-f169.google.com ([209.85.212.169]:33275 "EHLO mail-wi0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751249AbbHTMpa (ORCPT ); Thu, 20 Aug 2015 08:45:30 -0400 Date: Thu, 20 Aug 2015 14:45:27 +0200 From: Michal Hocko To: Mel Gorman Cc: Linux-MM , Johannes Weiner , Rik van Riel , Vlastimil Babka , David Rientjes , Joonsoo Kim , LKML Subject: Re: [PATCH 03/10] mm, page_alloc: Remove unnecessary recalculations for dirty zone balancing Message-ID: <20150820124526.GE20110@dhcp22.suse.cz> References: <1439376335-17895-1-git-send-email-mgorman@techsingularity.net> <1439376335-17895-4-git-send-email-mgorman@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1439376335-17895-4-git-send-email-mgorman@techsingularity.net> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3735 Lines: 103 On Wed 12-08-15 11:45:28, Mel Gorman wrote: > File-backed pages that will be immediately are balanced between zones but ^written to... > it's unnecessarily expensive. to do WHAT? I guess you meant checking gfp_mask resp. alloc_mask? I doubt it would make a noticeable difference as this is a slow path already but I agree it doesn't make sense to check it again. > Move consider_zone_balanced into the alloc_context > instead of checking bitmaps multiple times. The patch also gives the parameter > a more meaningful name. > > Signed-off-by: Mel Gorman > Acked-by: David Rientjes > Acked-by: Vlastimil Babka Acked-by: Michal Hocko > --- > mm/internal.h | 1 + > mm/page_alloc.c | 11 +++++++---- > 2 files changed, 8 insertions(+), 4 deletions(-) > > diff --git a/mm/internal.h b/mm/internal.h > index 36b23f1e2ca6..9331f802a067 100644 > --- a/mm/internal.h > +++ b/mm/internal.h > @@ -129,6 +129,7 @@ struct alloc_context { > int classzone_idx; > int migratetype; > enum zone_type high_zoneidx; > + bool spread_dirty_pages; > }; > > /* > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 5e1f6f4370bc..94f2f6bdd6d5 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2297,8 +2297,6 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags, > struct zoneref *z; > struct page *page = NULL; > struct zone *zone; > - bool consider_zone_dirty = (alloc_flags & ALLOC_WMARK_LOW) && > - (gfp_mask & __GFP_WRITE); > int nr_fair_skipped = 0; > bool zonelist_rescan; > > @@ -2350,14 +2348,14 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags, > * > * XXX: For now, allow allocations to potentially > * exceed the per-zone dirty limit in the slowpath > - * (ALLOC_WMARK_LOW unset) before going into reclaim, > + * (spread_dirty_pages unset) before going into reclaim, > * which is important when on a NUMA setup the allowed > * zones are together not big enough to reach the > * global limit. The proper fix for these situations > * will require awareness of zones in the > * dirty-throttling and the flusher threads. > */ > - if (consider_zone_dirty && !zone_dirty_ok(zone)) > + if (ac->spread_dirty_pages && !zone_dirty_ok(zone)) > continue; > > mark = zone->watermark[alloc_flags & ALLOC_WMARK_MASK]; > @@ -2997,6 +2995,10 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, > > /* We set it here, as __alloc_pages_slowpath might have changed it */ > ac.zonelist = zonelist; > + > + /* Dirty zone balancing only done in the fast path */ > + ac.spread_dirty_pages = (gfp_mask & __GFP_WRITE); > + > /* The preferred zone is used for statistics later */ > preferred_zoneref = first_zones_zonelist(ac.zonelist, ac.high_zoneidx, > ac.nodemask, &ac.preferred_zone); > @@ -3014,6 +3016,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, > * complete. > */ > alloc_mask = memalloc_noio_flags(gfp_mask); > + ac.spread_dirty_pages = false; > > page = __alloc_pages_slowpath(alloc_mask, order, &ac); > } > -- > 2.4.6 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/