Return-Path: linux-nfs-owner@vger.kernel.org Received: from dcvr.yhbt.net ([64.71.152.64]:37397 "EHLO dcvr.yhbt.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757248Ab3IKVYM (ORCPT ); Wed, 11 Sep 2013 17:24:12 -0400 Date: Wed, 11 Sep 2013 21:17:23 +0000 From: Eric Wong To: Zach Brown Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org, Trond Myklebust , Bryan Schumaker , "Martin K. Petersen" , Jens Axboe , Mark Fasheh , Joel Becker Subject: Re: [RFC] extending splice for copy offloading Message-ID: <20130911211722.GA9725@dcvr.yhbt.net> References: <1378919210-10372-1-git-send-email-zab@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1378919210-10372-1-git-send-email-zab@redhat.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: Zach Brown wrote: > Towards the end of that thread Eric Wong asked why we didn't just > extend splice. I immediately replied with some dumb dismissive > answer. Once I sat down and looked at it, though, it does make a > lot of sense. So good job, Eric. +10 Dummie points for me. Thanks for revisiting that :> > Some things to talk about: > - I really don't care about the naming here. If you do, holler. Exposing "DIRECT" to userspace now might confuse users into expecting O_DIRECT behavior. I say this as an easily-confused user. In the future, perhaps O_DIRECT behavior can become per-splice (instead of just per-open) and can save SPLICE_F_DIRECT for that. > - We might want different flags for file-to-file splicing and acceleration > - We might want flags to require or forbid acceleration > - We might want to provide all these flags to sendfile, too Another syscall? I prefer not. Better to just maintain the sendfile API as-is for compatibility reasons and nudge users towards splice. > Thoughts? Objections? I'll try to test/comment more in a week or two (not much time for computing until then).