From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f177.google.com (mail-wi0-f177.google.com [209.85.212.177]) by kanga.kvack.org (Postfix) with ESMTP id 248286B0035 for ; Fri, 8 Aug 2014 11:27:21 -0400 (EDT) Received: by mail-wi0-f177.google.com with SMTP id ho1so1201594wib.10 for ; Fri, 08 Aug 2014 08:27:20 -0700 (PDT) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id lj18si3669366wic.98.2014.08.08.08.27.17 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 08 Aug 2014 08:27:17 -0700 (PDT) Message-ID: <53E4EC53.1050904@suse.cz> Date: Fri, 08 Aug 2014 17:27:15 +0200 From: Vlastimil Babka MIME-Version: 1.0 Subject: Re: [PATCH 6/6] mm: page_alloc: Reduce cost of the fair zone allocation policy References: <1404893588-21371-1-git-send-email-mgorman@suse.de> <1404893588-21371-7-git-send-email-mgorman@suse.de> In-Reply-To: <1404893588-21371-7-git-send-email-mgorman@suse.de> Content-Type: text/plain; charset=ISO-8859-2 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman , Andrew Morton Cc: Linux Kernel , Linux-MM , Linux-FSDevel , Johannes Weiner On 07/09/2014 10:13 AM, Mel Gorman wrote: > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1604,6 +1604,9 @@ again: > } > > __mod_zone_page_state(zone, NR_ALLOC_BATCH, -(1 << order)); This can underflow zero, right? > + if (zone_page_state(zone, NR_ALLOC_BATCH) == 0 && AFAICS, zone_page_state will correct negative values to zero only for CONFIG_SMP. Won't this check be broken on !CONFIG_SMP? I just stumbled upon this when trying to optimize the function. I didn't check how rest of the design copes with negative NR_ALLOC_BATCH values. > + !zone_is_fair_depleted(zone)) > + zone_set_flag(zone, ZONE_FAIR_DEPLETED); > > __count_zone_vm_events(PGALLOC, zone, 1 << order); > zone_statistics(preferred_zone, zone, gfp_flags); > @@ -1915,6 +1918,18 @@ static bool zone_allows_reclaim(struct zone *local_zone, struct zone *zone) > > #endif /* CONFIG_NUMA */ > -- 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