From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rob Landley Subject: Re: [RFC] extending splice for copy offloading Date: Mon, 16 Sep 2013 14:44:53 -0500 Message-ID: <1379360693.1974.29@driftwood> References: <1378919210-10372-1-git-send-email-zab@redhat.com> <20130911211722.GA9725@dcvr.yhbt.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; DelSp=Yes; Format=Flowed Content-Transfer-Encoding: 8BIT Cc: Zach Brown , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Trond Myklebust , Bryan Schumaker , "Martin K. Petersen" , Jens Axboe , Mark Fasheh , Joel Becker To: Eric Wong Return-path: In-Reply-To: <20130911211722.GA9725-yBiyF41qdooeIZ0/mPfg9Q@public.gmane.org> (from normalperson-rMlxZR9MS24@public.gmane.org on Wed Sep 11 16:17:23 2013) Content-Disposition: inline Sender: linux-nfs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-fsdevel.vger.kernel.org On 09/11/2013 04:17:23 PM, Eric Wong wrote: > 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). Just a vague note that I've wanted to use splice implementing cp and patch and cat and so on in toybox, but couldn't because it needs a pipe. So I'm quite interested in moves to lift this restriction... Rob-- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html