linux-kernel - Re: Unexpected splice "always copy" behavior observed

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Message-ID: <20100519155136.GA2039@Krystal>
Date:	Wed, 19 May 2010 11:51:36 -0400
From:	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Nick Piggin <npiggin@...e.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Pierre Tardy <tardyp@...il.com>, Ingo Molnar <mingo@...e.hu>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Tom Zanussi <tzanussi@...il.com>,
	Paul Mackerras <paulus@...ba.org>,
	linux-kernel@...r.kernel.org, arjan@...radead.org,
	ziga.mahkovec@...il.com, davem <davem@...emloft.net>,
	linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Christoph Lameter <cl@...ux-foundation.org>,
	Tejun Heo <tj@...nel.org>, Jens Axboe <jens.axboe@...cle.com>
Subject: Re: Unexpected splice "always copy" behavior observed

* Steven Rostedt (rostedt@...dmis.org) wrote:
> On Wed, 2010-05-19 at 07:59 -0700, Linus Torvalds wrote:
> > 
> 
> > 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.
> 
> My use case is just to move the data from the ring buffer into a file
> (or network) as fast as possible. It creates a new file and all
> additions are "append to a file".
> 
> I believe Mathieu does the same.
> 
> With me, you are correct.

Same here. My ring buffer only ever use splice() to append at the end of a file
or to the network, and always outputs data in multiples of the page size.

Thanks,

Mathieu

> 
> -- Steve
> 
> 

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
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