From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754084Ab1DRJ0L (ORCPT ); Mon, 18 Apr 2011 05:26:11 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:45440 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752101Ab1DRJ0J (ORCPT ); Mon, 18 Apr 2011 05:26:09 -0400 Date: Mon, 18 Apr 2011 05:26:07 -0400 From: Christoph Hellwig To: Jens Axboe Cc: Shaohua Li , lkml , Tejun Heo , "Shi, Alex" , "Chen, Tim C" Subject: Re: [RFC]block: add flush request at head Message-ID: <20110418092607.GA3837@infradead.org> References: <1303112174.3981.187.camel@sli10-conroe> <4DABF194.4010603@fusionio.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4DABF194.4010603@fusionio.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 18, 2011 at 10:08:52AM +0200, Jens Axboe wrote: > Might be worth adding something for this special case, seems like the > NCQ restrictions will continue to be around forever (or a long time, at > least). I heared people are working on adding a queued FLUSH to the standard, but it's going to take a long time for it to get into real life systems. What would help now is allowing libata to actually use the FUA bit, given that every common disk and controller supports it these days. Shaohua, does adding a libata.fua = 1 to the kernel command line help your benchmark in any way? It should if you flushes are mostly from journal writes, but not from fsync that didn't change any metadata.