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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Nick Piggin <npiggin@suse.de>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Pierre Tardy <tardyp@gmail.com>, Ingo Molnar <mingo@elte.hu>,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	Tom Zanussi <tzanussi@gmail.com>,
	Paul Mackerras <paulus@samba.org>,
	linux-kernel@vger.kernel.org, arjan@infradead.org,
	ziga.mahkovec@gmail.com, davem <davem@davemloft.net>,
	linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
	KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
	Christoph Lameter <cl@linux-foundation.org>,
	Tejun Heo <tj@kernel.org>, Jens Axboe <jens.axboe@oracle.com>
Subject: Re: Unexpected splice "always copy" behavior observed
Date: Wed, 19 May 2010 07:59:48 -0700 (PDT)	[thread overview]
Message-ID: <alpine.LFD.2.00.1005190758070.23538@i5.linux-foundation.org> (raw)
In-Reply-To: <1274280968.26328.774.camel@gandalf.stny.rr.com>



On Wed, 19 May 2010, Steven Rostedt wrote:

> On Wed, 2010-05-19 at 07:39 -0700, Linus Torvalds wrote:
> 
> > The real limitation is likely always going to be the fact that it has to 
> > be page-aligned and a full page. For a lot of splice inputs, that simply 
> > won't be the case, and you'll end up copying for alignment reasons anyway.
> 
> That's understandable. For the use cases of splice I use, I work to make
> it page aligned and full pages. Anyone else using splice for
> optimizations, should do the same. It only makes sense.
> 
> The end of buffer may not be a full page, but then it's the end anyway,
> and I'm not as interested in the speed.

Btw, since you apparently have a real case - is the "splice to file" 
always just an append? IOW, if I'm not right in assuming that the only 
sane thing people would reasonable care about is "append to a file", then 
holler now.

		Linus

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  reply	other threads:[~2010-05-19 15:02 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-05-18 15:34 Mathieu Desnoyers
2010-05-18 15:51 ` Nick Piggin
2010-05-18 15:56   ` Christoph Lameter
2010-05-18 16:00     ` Nick Piggin
2010-05-18 16:13       ` Nick Piggin
2010-05-18 15:53 ` Steven Rostedt
2010-05-18 16:10   ` Steven Rostedt
2010-05-18 16:25     ` Linus Torvalds
2010-05-19  6:31       ` Nick Piggin
2010-05-19 14:39         ` Linus Torvalds
2010-05-19 14:56           ` Steven Rostedt
2010-05-19 14:59             ` Linus Torvalds [this message]
2010-05-19 15:12               ` Steven Rostedt
2010-05-19 15:51                 ` Mathieu Desnoyers
2010-05-19 15:33               ` Miklos Szeredi
2010-05-19 15:45                 ` Steven Rostedt
2010-05-19 15:55                   ` Nick Piggin
2010-05-19 16:01                     ` Mathieu Desnoyers
2010-05-19 16:36                     ` Steven Rostedt
2010-05-19 15:57                   ` Mathieu Desnoyers
2010-05-19 16:27                     ` Nick Piggin
2010-05-19 19:14                       ` Mathieu Desnoyers
2010-05-19 19:31                         ` Linus Torvalds
2010-05-19 21:49                           ` Mathieu Desnoyers
2010-05-20  0:04                             ` Linus Torvalds
2010-05-20  1:56                               ` Mathieu Desnoyers
2010-05-20 14:18                                 ` Linus Torvalds
2010-05-19 20:59               ` Rick Sherm
2010-05-19 15:17           ` Nick Piggin
2010-05-19 15:30             ` Linus Torvalds
2010-05-19 15:44               ` Nick Piggin
2010-05-19 15:28           ` Miklos Szeredi
2010-05-19 15:32             ` Linus Torvalds
2010-05-19 15:56               ` Miklos Szeredi
2010-05-19 16:01                 ` Linus Torvalds

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