From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762777Ab3IDPI7 (ORCPT ); Wed, 4 Sep 2013 11:08:59 -0400 Received: from cantor2.suse.de ([195.135.220.15]:60835 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752813Ab3IDPI5 (ORCPT ); Wed, 4 Sep 2013 11:08:57 -0400 Date: Wed, 4 Sep 2013 17:08:54 +0200 From: Jan Kara To: Andy Lutomirski Cc: linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org, Dave Chinner , "Theodore Ts'o" , Dave Hansen , xfs@oss.sgi.com, Jan Kara , Tim Chen , Christoph Hellwig Subject: Re: [PATCH v3 0/5] Rework mtime and ctime updates on mmaped writes Message-ID: <20130904150854.GF3996@quack.suse.cz> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 22-08-13 17:03:16, Andy Lutomirski wrote: > Writes via mmap currently update mtime and ctime in ->page_mkwrite. > This hurts both throughput and latency. In workloads that dirty a > large number of mmapped pages, ->page_mkwrite can be hot and > file_update_time is slow and scales poorly. Updating timestamps can > also sleep, which hurts latency for real-time workloads. It would help to make your case if you posted the latency comparison before & after the patchset in this introductory email. We can then see how significant is the reduction of latency... Honza -- Jan Kara SUSE Labs, CR