From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f45.google.com (mail-wm0-f45.google.com [74.125.82.45]) by kanga.kvack.org (Postfix) with ESMTP id 366726B0258 for ; Tue, 24 Nov 2015 08:37:13 -0500 (EST) Received: by wmvv187 with SMTP id v187so209738310wmv.1 for ; Tue, 24 Nov 2015 05:37:12 -0800 (PST) Received: from mail-wm0-f42.google.com (mail-wm0-f42.google.com. [74.125.82.42]) by mx.google.com with ESMTPS id o125si19783892wma.42.2015.11.24.05.37.12 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 24 Nov 2015 05:37:12 -0800 (PST) Received: by wmww144 with SMTP id w144so138909493wmw.1 for ; Tue, 24 Nov 2015 05:37:11 -0800 (PST) Date: Tue, 24 Nov 2015 14:37:10 +0100 From: Michal Hocko Subject: Re: [PATCH 2/2] mm, vmscan: do not overestimate anonymous reclaimable pages Message-ID: <20151124133710.GJ29472@dhcp22.suse.cz> References: <1448366100-11023-1-git-send-email-mhocko@kernel.org> <1448366100-11023-3-git-send-email-mhocko@kernel.org> <20151124130740.GG29014@esperanza> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151124130740.GG29014@esperanza> Sender: owner-linux-mm@kvack.org List-ID: To: Vladimir Davydov Cc: Andrew Morton , Johannes Weiner , Vlastimil Babka , Mel Gorman , linux-mm@kvack.org, LKML On Tue 24-11-15 16:07:40, Vladimir Davydov wrote: > On Tue, Nov 24, 2015 at 12:55:00PM +0100, Michal Hocko wrote: > > zone_reclaimable_pages considers all anonymous pages on LRUs reclaimable > > if there is at least one entry on the swap storage left. This can be > > really misleading when the swap is short on space and skew reclaim > > decisions based on zone_reclaimable_pages. Fix this by clamping the > > number to the minimum of the available swap space and anon LRU pages. > > Suppose there's 100M of swap and 1G of anon pages. This patch makes > zone_reclaimable_pages return 100M instead of 1G in this case. If you > rotate 600M of oldest anon pages, which is quite possible, > zone_reclaimable will start returning false, which is wrong, because > there are still 400M pages that were not even scanned, besides those > 600M of rotated pages could have become reclaimable after their ref bits > got cleared. Uhm, OK, I guess you are right. Making zone_reclaimable less conservative can lead to hard to expect results. Scratch this patch please. > I think it is the name of zone_reclaimable_pages which is misleading. It > should be called something like "zone_scannable_pages" judging by how it > is used in zone_reclaimable. Thanks! -- Michal Hocko SUSE Labs -- 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