From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta7.messagelabs.com (mail6.bemta7.messagelabs.com [216.82.255.55]) by kanga.kvack.org (Postfix) with ESMTP id 7D2699000C8 for ; Fri, 30 Sep 2011 03:35:27 -0400 (EDT) Received: by iaen33 with SMTP id n33so2526993iae.14 for ; Fri, 30 Sep 2011 00:35:25 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1317367044-475-4-git-send-email-jweiner@redhat.com> References: <1317367044-475-1-git-send-email-jweiner@redhat.com> <1317367044-475-4-git-send-email-jweiner@redhat.com> Date: Fri, 30 Sep 2011 10:35:25 +0300 Message-ID: Subject: Re: [patch 3/5] mm: try to distribute dirty pages fairly across zones From: Pekka Enberg Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: Johannes Weiner Cc: Andrew Morton , Mel Gorman , Christoph Hellwig , Dave Chinner , Wu Fengguang , Jan Kara , Rik van Riel , Minchan Kim , Chris Mason , Theodore Ts'o , Andreas Dilger , Shaohua Li , xfs@oss.sgi.com, linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Hi Johannes! On Fri, Sep 30, 2011 at 10:17 AM, Johannes Weiner wrot= e: > But there is a flaw in that we have a zoned page allocator which does > not care about the global state but rather the state of individual > memory zones. =A0And right now there is nothing that prevents one zone > from filling up with dirty pages while other zones are spared, which > frequently leads to situations where kswapd, in order to restore the > watermark of free pages, does indeed have to write pages from that > zone's LRU list. =A0This can interfere so badly with IO from the flusher > threads that major filesystems (btrfs, xfs, ext4) mostly ignore write > requests from reclaim already, taking away the VM's only possibility > to keep such a zone balanced, aside from hoping the flushers will soon > clean pages from that zone. The obvious question is: how did you test this? Can you share the results? Pekka -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org