Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753259AbaATN7K (ORCPT ); Mon, 20 Jan 2014 08:59:10 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:40071 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752630AbaATN66 (ORCPT ); Mon, 20 Jan 2014 08:58:58 -0500 Date: Mon, 20 Jan 2014 05:58:55 -0800 From: Christoph Hellwig To: Dave Chinner Cc: Sergey Meirovich , Christoph Hellwig , xfs@oss.sgi.com, Jan Kara , linux-scsi , Linux Kernel Mailing List , Gluk Subject: Re: Terrible performance of sequential O_DIRECT 4k writes in SAN environment. ~3 times slower then Solars 10 with the same HBA/Storage. Message-ID: <20140120135855.GA26280@infradead.org> References: <20140106201032.GA13491@quack.suse.cz> <20140107155830.GA28395@infradead.org> <20140108140307.GA588@infradead.org> <20140115220721.GY3469@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140115220721.GY3469@dastard> 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 Thu, Jan 16, 2014 at 09:07:21AM +1100, Dave Chinner wrote: > Yes, I think it can be done relatively simply. We'd have to change > the code in xfs_file_aio_write_checks() to check whether EOF zeroing > was required rather than always taking an exclusive lock (for block > aligned IO at EOF sub-block zeroing isn't required), That's not even required for supporting aio appends, just a further optimization for it. > and then we'd > have to modify the direct IO code to set the is_async flag > appropriately. We'd probably need a new flag to say tell the DIO > code that AIO beyond EOF is OK, but that isn't hard to do.... Yep, need a flag to allow appending writes and then defer them. > Christoph, are you going to get any time to look at doing this in > the next few days? I'll probably need at least another week before I can get to it. If you wanna pick it up before than feel free. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/