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From: Anna Schumaker <schumaker.anna@gmail.com>
To: Zach Brown <zab@redhat.com>, Christoph Hellwig <hch@infradead.org>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@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: Wed, 18 Dec 2013 12:26:11 -0500	[thread overview]
Message-ID: <52B1DAB3.6060302@gmail.com> (raw)
In-Reply-To: <20131218171044.GK14533@lenny.home.zabbo.net>

On 12/18/2013 12:10 PM, Zach Brown wrote:
> On Wed, Dec 18, 2013 at 04:41:26AM -0800, Christoph Hellwig wrote:
>> On Wed, Sep 11, 2013 at 10:06:47AM -0700, Zach Brown wrote:
>>> When I first started on this stuff I followed the lead of previous
>>> work and added a new syscall for the copy operation:
>>>
>>> https://lkml.org/lkml/2013/5/14/618
>>>
>>> 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.
>>>
>>> Extending splice avoids all the noise of adding a new syscall and
>>> naturally falls back to buffered copying as that's what the direct
>>> splice path does for sendfile() today.
>> Given the convolute mess that the splice code already is I'd rather
>> prefer not overloading it even further.
> I agree after trying to weave the copy offloading API into the splice
> interface.  There are also weird cases that we haven't really discussed
> so far (preserving unwritten allocations between the copied files?) that
> would muddy the waters even further.
>
> The further the APIs drift from each other, the more I'm prefering
> giving copy offloading its own clean syscall.  Even if the argument
> types superficially match the splice() ABI.
>
>> We can still fall back to the splice code as a fallback if no option
>> is provided as a last resort, but I think making the splice code handle
>> even more totally different cases is the wrong direction.
> I'm with you.  I'll have another version out sometime after the US
> holiday break.. say in a few weeks?

That'll work for me, I'll update my NFS code once your new patches are out.

Anna

>
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  reply	other threads:[~2013-12-18 17:26 UTC|newest]

Thread overview: 111+ 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   ` Zach Brown
2013-09-11 17:06 ` [PATCH 2/3] splice: add f_op->splice_direct Zach Brown
2013-09-11 17:06   ` Zach Brown
2013-09-11 17:06 ` [PATCH 3/3] btrfs: implement .splice_direct extent copying Zach Brown
2013-09-11 17:06   ` Zach Brown
2013-09-11 21:17 ` [RFC] extending splice for copy offloading Eric Wong
2013-09-16 19:44   ` Rob Landley
2013-09-16 19:44     ` Rob Landley
2013-09-19 12:59   ` Jeff Layton
2013-09-20  9:49 ` Szeredi Miklos
2013-09-20  9:49   ` Szeredi Miklos
2013-09-25 18:38   ` Zach Brown
2013-09-25 18:38     ` Zach Brown
2013-09-25 19:02     ` Anna Schumaker
2013-09-25 19:06       ` Zach Brown
2013-09-25 19:06         ` Zach Brown
2013-09-25 19:55         ` J. Bruce Fields
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
2013-09-26 16:46                 ` Ric Wheeler
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
2013-09-26 21:23                         ` Ric Wheeler
2013-09-27  4:47                         ` Miklos Szeredi
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
2013-10-06  8:42                     ` Rob Landley
2013-09-26 18:55               ` Zach Brown
2013-09-26 21:26                 ` Ric Wheeler
2013-09-26 21:26                   ` Ric Wheeler
2013-09-27 20:05                   ` J. Bruce Fields
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 15:20                           ` Myklebust, Trond
2013-09-28 15:20                           ` Myklebust, Trond
2013-09-28 21:20                           ` Ric Wheeler
2013-09-30 12:20                             ` Miklos Szeredi
2013-09-30 12:20                               ` Miklos Szeredi
2013-09-30 14:34                               ` J. Bruce Fields
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 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 15:33                                           ` Myklebust, Trond
2013-09-30 15:33                                           ` Myklebust, Trond
2013-09-30 15:38                                         ` Miklos Szeredi
2013-09-30 15:38                                           ` Miklos Szeredi
2013-09-30 14:41                                           ` Ric Wheeler
2013-09-30 14:41                                             ` Ric Wheeler
2013-09-30 15:46                                             ` Miklos Szeredi
2013-09-30 15:46                                               ` Miklos Szeredi
2013-09-30 14:49                                               ` Ric Wheeler
2013-09-30 14:49                                                 ` Ric Wheeler
2013-09-30 15:57                                                 ` Miklos Szeredi
2013-09-30 15:57                                                   ` Miklos Szeredi
2013-09-30 16:31                                                   ` 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 17:44                                                         ` Myklebust, Trond
2013-09-30 17:44                                                         ` Myklebust, Trond
2013-09-30 17:48                                                         ` Bernd Schubert
2013-09-30 17:48                                                           ` Bernd Schubert
2013-09-30 18:02                                                           ` Myklebust, Trond
2013-09-30 18:02                                                             ` Myklebust, Trond
2013-09-30 18:02                                                             ` Myklebust, Trond
2013-09-30 18:49                                                             ` Bernd Schubert
2013-09-30 19:34                                                               ` Myklebust, Trond
2013-09-30 19:34                                                                 ` Myklebust, Trond
2013-09-30 19:34                                                                 ` Myklebust, Trond
2013-09-30 20:00                                                                 ` Bernd Schubert
2013-09-30 20:00                                                                   ` Bernd Schubert
2013-09-30 20:08                                                                   ` Ric Wheeler
2013-09-30 20:08                                                                     ` Ric Wheeler
2013-09-30 20:27                                                                     ` Myklebust, Trond
2013-09-30 20:27                                                                       ` Myklebust, Trond
2013-09-30 20:27                                                                       ` Myklebust, Trond
2013-09-30 20:10                                                                   ` Myklebust, Trond
2013-09-30 20:10                                                                     ` Myklebust, Trond
2013-09-30 20:10                                                                     ` Myklebust, Trond
2013-10-01 18:42                                               ` J. Bruce Fields
2013-10-01 18:42                                                 ` J. Bruce Fields
2013-10-01 19:58                                       ` Zach Brown
2013-10-01 19:58                                         ` Zach Brown
2013-10-02 12:58                                         ` Jan Kara
2013-10-02 12:58                                           ` Jan Kara
2013-10-02 13:31                                           ` David Lang
2013-12-18 12:41 ` Christoph Hellwig
2013-12-18 12:41   ` Christoph Hellwig
2013-12-18 17:10   ` Zach Brown
2013-12-18 17:26     ` Anna Schumaker [this message]
  -- strict thread matches above, loose matches on Subject: below --
2013-09-26 17:22 Steve French
     [not found] ` <CAH2r5muBuTK7ZZ+aKGC4q35gqaSWF4o07eoHypLKiNn5Y83RbQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-09-26 19:34   ` David Disseldorp
2013-10-10  2:18     ` Steve French
2013-10-01 21:05   ` J. Bruce Fields
     [not found]     ` <20131001210531.GA7093-uC3wQj2KruNg9hUCZPvPmw@public.gmane.org>
2013-10-02  1:19       ` Steve French

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