From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f42.google.com (mail-wg0-f42.google.com [74.125.82.42]) by kanga.kvack.org (Postfix) with ESMTP id 5C3DD6B006E for ; Wed, 25 Feb 2015 09:13:40 -0500 (EST) Received: by wggx12 with SMTP id x12so3895391wgg.6 for ; Wed, 25 Feb 2015 06:13:39 -0800 (PST) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id t12si29240553wib.91.2015.02.25.06.13.38 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 25 Feb 2015 06:13:38 -0800 (PST) Date: Wed, 25 Feb 2015 15:13:37 +0100 From: Michal Hocko Subject: Re: [PATCH RFC 1/4] mm: throttle MADV_FREE Message-ID: <20150225141337.GE26680@dhcp22.suse.cz> References: <1424765897-27377-1-git-send-email-minchan@kernel.org> <20150224154318.GA14939@dhcp22.suse.cz> <20150224225401.GA2506@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150224225401.GA2506@kernel.org> Sender: owner-linux-mm@kvack.org List-ID: To: Shaohua Li Cc: Minchan Kim , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Rik van Riel , Johannes Weiner , Mel Gorman , Yalin.Wang@sonymobile.com On Tue 24-02-15 14:54:01, Shaohua Li wrote: > On Tue, Feb 24, 2015 at 04:43:18PM +0100, Michal Hocko wrote: > > On Tue 24-02-15 17:18:14, Minchan Kim wrote: > > > Recently, Shaohua reported that MADV_FREE is much slower than > > > MADV_DONTNEED in his MADV_FREE bomb test. The reason is many of > > > applications went to stall with direct reclaim since kswapd's > > > reclaim speed isn't fast than applications's allocation speed > > > so that it causes lots of stall and lock contention. > > > > I am not sure I understand this correctly. So the issue is that there is > > huge number of MADV_FREE on the LRU and they are not close to the tail > > of the list so the reclaim has to do a lot of work before it starts > > dropping them? > > I thought the main reason is current reclaim stragety. Anonymous pages are > considered to be hard to be reclaimed with current policy, VM bias to reclaim > file pages (anon pages are in active list first, referenced pte will reactivate > anon pages and increase rotate count) Makes sense. We are really biasing to page cache reclaim most of the time. -- 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