From: "J. Bruce Fields" <bfields@fieldses.org>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: Zach Brown <zab@redhat.com>,
Anna Schumaker <schumaker.anna@gmail.com>,
Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux-Fsdevel <linux-fsdevel@vger.kernel.org>,
"linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
Trond Myklebust <Trond.Myklebust@netapp.com>,
Bryan Schumaker <bjschuma@netapp.com>,
"Martin K. Petersen" <mkp@mkp.net>, Jens Axboe <axboe@kernel.dk>,
Mark Fasheh <mfasheh@suse.com>, Joel Becker <jlbec@evilplan.org>,
Eric Wong <normalperson@yhbt.net>
Subject: Re: [RFC] extending splice for copy offloading
Date: Thu, 26 Sep 2013 11:34:00 -0400 [thread overview]
Message-ID: <20130926153359.GE704@fieldses.org> (raw)
In-Reply-To: <CAJfpegsQ0A3T+46o9nsPwaH83JCbgyhgRNGPgzTqs0EcsmDuiQ@mail.gmail.com>
On Thu, Sep 26, 2013 at 10:58:05AM +0200, Miklos Szeredi wrote:
> On Wed, Sep 25, 2013 at 11:07 PM, Zach Brown <zab@redhat.com> wrote:
> >> A client-side copy will be slower, but I guess it does have the
> >> advantage that the application can track progress to some degree, and
> >> abort it fairly quickly without leaving the file in a totally undefined
> >> state--and both might be useful if the copy's not a simple constant-time
> >> operation.
> >
> > I suppose, but can't the app achieve a nice middle ground by copying the
> > file in smaller syscalls? Avoid bulk data motion back to the client,
> > but still get notification every, I dunno, few hundred meg?
>
> Yes. And if "cp" could just be switched from a read+write syscall
> pair to a single splice syscall using the same buffer size.
Will the various magic fs-specific copy operations become inefficient
when the range copied is too small?
(Totally naive question, as I have no idea how they really work.)
--b.
> And then
> the user would only notice that things got faster in case of server
> side copy. No problems with long blocking times (at least not much
> worse than it was).
>
> However "cp" doesn't do reflinking by default, it has a switch for
> that. If we just want "cp" and the like to use splice without fearing
> side effects then by default we should try to be as close to
> read+write behavior as possible. No? That's what I'm really
> worrying about when you want to wire up splice to reflink by default.
> I do think there should be a flag for that. And if on the block level
> some magic happens, so be it. It's not the fs deverloper's worry any
> more ;)
>
> Thanks,
> Miklos
> --
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next prev parent reply other threads:[~2013-09-26 15:34 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-11 17:06 [RFC] extending splice for copy offloading Zach Brown
2013-09-11 17:06 ` [PATCH 1/3] splice: add DIRECT flag for splicing between files Zach Brown
2013-09-11 17:06 ` [PATCH 2/3] splice: add f_op->splice_direct Zach Brown
2013-09-11 17:06 ` [PATCH 3/3] btrfs: implement .splice_direct extent copying Zach Brown
2013-09-11 21:17 ` [RFC] extending splice for copy offloading Eric Wong
2013-09-16 19:44 ` Rob Landley
2013-09-19 12:59 ` Jeff Layton
2013-09-20 9:49 ` Szeredi Miklos
2013-09-25 18:38 ` Zach Brown
2013-09-25 19:02 ` Anna Schumaker
2013-09-25 19:06 ` Zach Brown
2013-09-25 19:55 ` J. Bruce Fields
2013-09-25 21:07 ` Zach Brown
2013-09-26 8:58 ` Miklos Szeredi
2013-09-26 15:34 ` J. Bruce Fields [this message]
2013-09-26 16:46 ` Ric Wheeler
2013-09-26 18:06 ` Miklos Szeredi
2013-09-26 19:06 ` Zach Brown
2013-09-26 19:53 ` Miklos Szeredi
2013-09-26 21:23 ` Ric Wheeler
2013-09-27 4:47 ` Miklos Szeredi
2013-09-27 14:00 ` Ric Wheeler
2013-09-27 14:39 ` Miklos Szeredi
2013-10-06 8:42 ` Rob Landley
2013-09-26 18:55 ` Zach Brown
2013-09-26 21:26 ` Ric Wheeler
2013-09-27 20:05 ` J. Bruce Fields
2013-09-27 20:50 ` Zach Brown
2013-09-28 5:49 ` Miklos Szeredi
2013-09-28 15:20 ` Myklebust, Trond
2013-09-28 21:20 ` Ric Wheeler
2013-09-30 12:20 ` Miklos Szeredi
2013-09-30 14:34 ` J. Bruce Fields
2013-09-30 14:48 ` Ric Wheeler
2013-09-30 14:51 ` Miklos Szeredi
2013-09-30 14:52 ` Ric Wheeler
2013-09-30 15:24 ` Miklos Szeredi
2013-09-30 14:28 ` Ric Wheeler
2013-09-30 15:33 ` Myklebust, Trond
2013-09-30 15:38 ` Miklos Szeredi
2013-09-30 14:41 ` Ric Wheeler
2013-09-30 15:46 ` Miklos Szeredi
2013-09-30 14:49 ` Ric Wheeler
2013-09-30 15:57 ` Miklos Szeredi
2013-09-30 16:31 ` Miklos Szeredi
2013-09-30 17:17 ` Bernd Schubert
2013-09-30 17:44 ` Myklebust, Trond
2013-09-30 17:48 ` Bernd Schubert
2013-09-30 18:02 ` Myklebust, Trond
2013-09-30 18:49 ` Bernd Schubert
2013-09-30 19:34 ` Myklebust, Trond
2013-09-30 20:00 ` Bernd Schubert
2013-09-30 20:08 ` Ric Wheeler
2013-09-30 20:27 ` Myklebust, Trond
2013-09-30 20:10 ` Myklebust, Trond
2013-10-01 18:42 ` J. Bruce Fields
2013-10-01 19:58 ` Zach Brown
2013-10-02 12:58 ` Jan Kara
2013-10-02 13:31 ` David Lang
2013-12-18 12:41 ` Christoph Hellwig
2013-12-18 17:10 ` Zach Brown
2013-12-18 17:26 ` Anna Schumaker
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