From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wj0-f200.google.com (mail-wj0-f200.google.com [209.85.210.200]) by kanga.kvack.org (Postfix) with ESMTP id A25E96B0033 for ; Sun, 5 Feb 2017 05:13:20 -0500 (EST) Received: by mail-wj0-f200.google.com with SMTP id jz4so12399445wjb.5 for ; Sun, 05 Feb 2017 02:13:20 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id t84si3870659wmb.165.2017.02.05.02.13.19 for (version=TLS1 cipher=AES128-SHA bits=128/128); Sun, 05 Feb 2017 02:13:19 -0800 (PST) Date: Sun, 5 Feb 2017 11:13:16 +0100 From: Michal Hocko Subject: Re: [PATCH] mm, vmscan: Clear PGDAT_WRITEBACK when zone is balanced Message-ID: <20170205101316.GC22713@dhcp22.suse.cz> References: <20170203203222.gq7hk66yc36lpgtb@suse.de> <20170205101113.GB22713@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170205101113.GB22713@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: 'Andrew Morton' , Hillf Danton , 'Johannes Weiner' , 'Minchan Kim' , 'Rik van Riel' , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Sun 05-02-17 11:11:13, Michal Hocko wrote: > On Fri 03-02-17 20:32:22, Mel Gorman wrote: > > Hillf Danton pointed out that since commit 1d82de618dd ("mm, vmscan: > > make kswapd reclaim in terms of nodes") that PGDAT_WRITEBACK is no longer > > cleared. It was not noticed as triggering it requires pages under writeback > > to cycle twice through the LRU and before kswapd gets stalled. Historically, > > such issues tended to occur on small machines writing heavily to slow > > storage such as a USB stick. Once kswapd stalls, direct reclaim stalls may > > be higher but due to the fact that memory pressure is requires, it would not > > be very noticable. Michal Hocko suggested removing the flag entirely but > > the conservative fix is to restore the intended PGDAT_WRITEBACK behaviour > > and clear the flag when a suitable zone is balanced. > > > > Signed-off-by: Mel Gorman > > I agree this is a more conservative approach but I think removing > PGDAT_WRITEBACK should simplify things a bit. > > Acked-by: Michal Hocko Ohh, an please add Fixes: 1d82de618ddd ("mm, vmscan: make kswapd reclaim in terms of nodes") -- 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