From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [PATCH v7 0/5] vfs: Non-blockling buffered fs read (page cache only) Date: Fri, 27 Mar 2015 01:35:16 -0700 Message-ID: <20150327013516.8c6788be.akpm@linux-foundation.org> References: <20150326202824.65d03787.akpm@linux-foundation.org> <20150327081822.GA28669@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20150327081822.GA28669-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Christoph Hellwig Cc: Milosz Tanski , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-aio-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Mel Gorman , Volker Lendecke , Tejun Heo , Jeff Moyer , Theodore Ts'o , Al Viro , linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Michael Kerrisk , linux-arch-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Dave Chinner List-Id: linux-arch.vger.kernel.org On Fri, 27 Mar 2015 01:18:22 -0700 Christoph Hellwig wrote: > On Thu, Mar 26, 2015 at 08:28:24PM -0700, Andrew Morton wrote: > > I still don't understand why pwritev() exists. We discussed this last > > time but it seems nothing has changed. I'm not seeing here an adequate > > description of why it exists nor a justification for its addition. > > pwritev2? I have patches to support per-I/O O_DSYNC with it, lots of > folks including Samba and SCSI targets want this because their protocols > support it. The patches were posted with earlier versions of Miklos > series. > > It's cleaner to add the two system calls in go when we plan using them > anyway and have symmetric infrastructure, and I did not hear any > disagreement with that on LSF. Did you skip this session? Put it in the changelogs. All of it. A conference discussion is no use to people who weren't there. > > And (again) we've discussed this before, but the patchset gets resent > > as if nothing had happened. > > We had long discussiosn about it both here and at LSF. We had everyone > agree and nod there, and only your repeated argument here, so maybe it's > not Miklos who is disonnected but you? I don't find conferences to be a good place to conduct code and design review. > Also that whole fincore argument is rather hypothetic - it's only been > pushed in to ugly to live multiplexers that also expose things like > pfns, while with preadv2 we have a trivial and easy to use API read to > merge, and various consumerms just waiting for it. fincore() doesn't have to be ugly. Please address the design issues I raised. How is pread2() useful to the class of applications which cannot proceed until all data is available? From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:35300 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752865AbbC0IeI (ORCPT ); Fri, 27 Mar 2015 04:34:08 -0400 Date: Fri, 27 Mar 2015 01:35:16 -0700 From: Andrew Morton Subject: Re: [PATCH v7 0/5] vfs: Non-blockling buffered fs read (page cache only) Message-ID: <20150327013516.8c6788be.akpm@linux-foundation.org> In-Reply-To: <20150327081822.GA28669@infradead.org> References: <20150326202824.65d03787.akpm@linux-foundation.org> <20150327081822.GA28669@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Christoph Hellwig Cc: Milosz Tanski , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, Mel Gorman , Volker Lendecke , Tejun Heo , Jeff Moyer , Theodore Ts'o , Al Viro , linux-api@vger.kernel.org, Michael Kerrisk , linux-arch@vger.kernel.org, Dave Chinner Message-ID: <20150327083516.sdWZqu3AtpWGIpdMMgiUBTNMP5CYZ5SfiJHQwrdl9Xo@z> On Fri, 27 Mar 2015 01:18:22 -0700 Christoph Hellwig wrote: > On Thu, Mar 26, 2015 at 08:28:24PM -0700, Andrew Morton wrote: > > I still don't understand why pwritev() exists. We discussed this last > > time but it seems nothing has changed. I'm not seeing here an adequate > > description of why it exists nor a justification for its addition. > > pwritev2? I have patches to support per-I/O O_DSYNC with it, lots of > folks including Samba and SCSI targets want this because their protocols > support it. The patches were posted with earlier versions of Miklos > series. > > It's cleaner to add the two system calls in go when we plan using them > anyway and have symmetric infrastructure, and I did not hear any > disagreement with that on LSF. Did you skip this session? Put it in the changelogs. All of it. A conference discussion is no use to people who weren't there. > > And (again) we've discussed this before, but the patchset gets resent > > as if nothing had happened. > > We had long discussiosn about it both here and at LSF. We had everyone > agree and nod there, and only your repeated argument here, so maybe it's > not Miklos who is disonnected but you? I don't find conferences to be a good place to conduct code and design review. > Also that whole fincore argument is rather hypothetic - it's only been > pushed in to ugly to live multiplexers that also expose things like > pfns, while with preadv2 we have a trivial and easy to use API read to > merge, and various consumerms just waiting for it. fincore() doesn't have to be ugly. Please address the design issues I raised. How is pread2() useful to the class of applications which cannot proceed until all data is available?