From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wj0-f199.google.com (mail-wj0-f199.google.com [209.85.210.199]) by kanga.kvack.org (Postfix) with ESMTP id 48C866B0033 for ; Fri, 3 Feb 2017 16:24:29 -0500 (EST) Received: by mail-wj0-f199.google.com with SMTP id an2so7944025wjc.3 for ; Fri, 03 Feb 2017 13:24:29 -0800 (PST) Received: from gum.cmpxchg.org (gum.cmpxchg.org. [85.214.110.215]) by mx.google.com with ESMTPS id b203si3354258wme.154.2017.02.03.13.24.27 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 03 Feb 2017 13:24:28 -0800 (PST) Date: Fri, 3 Feb 2017 16:24:11 -0500 From: Johannes Weiner Subject: Re: [PATCH] mm, vmscan: Clear PGDAT_WRITEBACK when zone is balanced Message-ID: <20170203212411.GA12133@cmpxchg.org> References: <20170203203222.gq7hk66yc36lpgtb@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170203203222.gq7hk66yc36lpgtb@suse.de> Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: 'Andrew Morton' , Hillf Danton , 'Michal Hocko' , 'Minchan Kim' , 'Rik van Riel' , linux-mm@kvack.org, linux-kernel@vger.kernel.org On Fri, Feb 03, 2017 at 08:32:22PM +0000, 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 Acked-by: Johannes Weiner -- 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