From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id 6EDB76B0087 for ; Tue, 7 Dec 2010 12:35:08 -0500 (EST) Message-ID: <4CFE7015.3070000@redhat.com> Date: Tue, 07 Dec 2010 12:34:13 -0500 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [PATCH] writeback: safety margin for bdi stat errors References: <20101205064430.GA15027@localhost> <4CFB9BE1.3030902@redhat.com> <20101207131136.GA20366@localhost> In-Reply-To: <20101207131136.GA20366@localhost> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Wu Fengguang Cc: Peter Zijlstra , Andrew Morton , Theodore Ts'o , Chris Mason , Dave Chinner , Jan Kara , Jens Axboe , Mel Gorman , KOSAKI Motohiro , Christoph Hellwig , linux-mm , "linux-fsdevel@vger.kernel.org" , LKML List-ID: On 12/07/2010 08:11 AM, Wu Fengguang wrote: > So the root cause is, the bdi_dirty is well under nr_dirty due to > accounting errors. They should be very close because there is only one > heavy dirtied bdi in the system. This can be fixed by using > bdi_stat_sum(), however that's costly on large NUMA machines. So do a > less costly fix of lowering the bdi limit, so that the accounting > errors won't lead to the absurd situation "global limit exceeded but > bdi limit not exceeded". > > CC: Rik van Riel > CC: Peter Zijlstra > Signed-off-by: Wu Fengguang I like this simple approach. Acked-by: Rik van Riel -- All rights reversed -- 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 policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org