From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756041AbaISLV5 (ORCPT ); Fri, 19 Sep 2014 07:21:57 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:59023 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755831AbaISLVv (ORCPT ); Fri, 19 Sep 2014 07:21:51 -0400 Date: Fri, 19 Sep 2014 04:21:47 -0700 From: Christoph Hellwig To: "Elliott, Robert (Server Storage)" Cc: Andreas Dilger , Milosz Tanski , "linux-kernel@vger.kernel.org" , Christoph Hellwig , "linux-fsdevel@vger.kernel.org" , "linux-aio@kvack.org" , Mel Gorman , Volker Lendecke , Tejun Heo , Jeff Moyer Subject: Re: [RFC PATCH 0/7] Non-blockling buffered fs read (page cache only) Message-ID: <20140919112147.GA4639@infradead.org> References: <8EC2A7F3-0E25-4054-9863-4488B8ED5C8D@dilger.ca> <94D0CD8314A33A4D9D801C0FE68B402958C81D56@G9W0745.americas.hpqcorp.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <94D0CD8314A33A4D9D801C0FE68B402958C81D56@G9W0745.americas.hpqcorp.net> User-Agent: Mutt/1.5.23 (2014-03-12) 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, Sep 15, 2014 at 10:36:46PM +0000, Elliott, Robert (Server Storage) wrote: > That sounds like the proposed WRITE SCATTERED/READ GATHERED > commands for SCSI (where are related to, but not necessarily > tied to, atomic writes). We discussed them a bit at > LSF-MM 2013 - see http://lwn.net/Articles/548116/. In the same way a preadx/pwritex could use but would not require an O_ATOMIC. What's the status of those in t10? Last I heard READ GATHERED was out and they were only looking into WRITE SCATTERED? Without the atomic WRITE SCATTERED use case adding the syscalls seems rather pointless, and I'd really avoid blocking nice software only features like the per-I/O nonblock flag (and the similarly trivial per-I/O sync option I have a prototype for) on it. Speaking of easy flags: while a nonblock flags for writes wouldn't be anywhere near as easy as the one for reads would there be sufficient interested in it to bother implementing it?