From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752099AbaIITxW (ORCPT ); Tue, 9 Sep 2014 15:53:22 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:45829 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751712AbaIITxU (ORCPT ); Tue, 9 Sep 2014 15:53:20 -0400 Date: Tue, 9 Sep 2014 12:53:18 -0700 From: Andrew Morton To: Mel Gorman Cc: Leon Romanovsky , Vlastimil Babka , Johannes Weiner , Linux Kernel , Linux-MM , Linux-FSDevel Subject: Re: [PATCH] mm: page_alloc: Fix setting of ZONE_FAIR_DEPLETED on UP v2 Message-Id: <20140909125318.b07aee9f77b5a15d6b3041f1@linux-foundation.org> In-Reply-To: <20140908115718.GL17501@suse.de> References: <1404893588-21371-1-git-send-email-mgorman@suse.de> <1404893588-21371-7-git-send-email-mgorman@suse.de> <53E4EC53.1050904@suse.cz> <20140811121241.GD7970@suse.de> <53E8B83D.1070004@suse.cz> <20140902140116.GD29501@cmpxchg.org> <20140905101451.GF17501@suse.de> <20140908115718.GL17501@suse.de> X-Mailer: Sylpheed 3.2.0beta5 (GTK+ 2.24.10; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 8 Sep 2014 12:57:18 +0100 Mel Gorman wrote: > zone_page_state is an API hazard because of the difference in behaviour > between SMP and UP is very surprising. There is a good reason to allow > NR_ALLOC_BATCH to go negative -- when the counter is reset the negative > value takes recent activity into account. This patch makes zone_page_state > behave the same on SMP and UP as saving one branch on UP is not likely to > make a measurable performance difference. > > ... > > --- a/include/linux/vmstat.h > +++ b/include/linux/vmstat.h > @@ -131,10 +131,8 @@ static inline unsigned long zone_page_state(struct zone *zone, > enum zone_stat_item item) > { > long x = atomic_long_read(&zone->vm_stat[item]); > -#ifdef CONFIG_SMP > if (x < 0) > x = 0; > -#endif > return x; > } We now have three fixes for the same thing. I'm presently holding on to hannes's mm-page_alloc-fix-zone-allocation-fairness-on-up.patch. Regularizing zone_page_state() in this fashion seems a good idea and is presumably safe because callers have been tested with SMP. So unless shouted at I think I'll queue this one for 3.18? From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [PATCH] mm: page_alloc: Fix setting of ZONE_FAIR_DEPLETED on UP v2 Date: Tue, 9 Sep 2014 12:53:18 -0700 Message-ID: <20140909125318.b07aee9f77b5a15d6b3041f1@linux-foundation.org> References: <1404893588-21371-1-git-send-email-mgorman@suse.de> <1404893588-21371-7-git-send-email-mgorman@suse.de> <53E4EC53.1050904@suse.cz> <20140811121241.GD7970@suse.de> <53E8B83D.1070004@suse.cz> <20140902140116.GD29501@cmpxchg.org> <20140905101451.GF17501@suse.de> <20140908115718.GL17501@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Leon Romanovsky , Vlastimil Babka , Johannes Weiner , Linux Kernel , Linux-MM , Linux-FSDevel To: Mel Gorman Return-path: In-Reply-To: <20140908115718.GL17501@suse.de> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Mon, 8 Sep 2014 12:57:18 +0100 Mel Gorman wrote: > zone_page_state is an API hazard because of the difference in behaviour > between SMP and UP is very surprising. There is a good reason to allow > NR_ALLOC_BATCH to go negative -- when the counter is reset the negative > value takes recent activity into account. This patch makes zone_page_state > behave the same on SMP and UP as saving one branch on UP is not likely to > make a measurable performance difference. > > ... > > --- a/include/linux/vmstat.h > +++ b/include/linux/vmstat.h > @@ -131,10 +131,8 @@ static inline unsigned long zone_page_state(struct zone *zone, > enum zone_stat_item item) > { > long x = atomic_long_read(&zone->vm_stat[item]); > -#ifdef CONFIG_SMP > if (x < 0) > x = 0; > -#endif > return x; > } We now have three fixes for the same thing. I'm presently holding on to hannes's mm-page_alloc-fix-zone-allocation-fairness-on-up.patch. Regularizing zone_page_state() in this fashion seems a good idea and is presumably safe because callers have been tested with SMP. So unless shouted at I think I'll queue this one for 3.18? -- 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