linux-kernel - Re: Perf and ftrace [was Re: PyTimechart]

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Message-ID: <20100512180438.GE15953@Krystal>
Date:	Wed, 12 May 2010 14:04:38 -0400
From:	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Frederic Weisbecker <fweisbec@...il.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	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>
Subject: Re: Perf and ftrace [was Re: PyTimechart]

* Peter Zijlstra (peterz@...radead.org) wrote:
> On Wed, 2010-05-12 at 13:53 -0400, Mathieu Desnoyers wrote:
> > 
> > Would you be fine with an alternative implementation and API that support both
> > mmap() and splice(), without any need to swap pages ? 
> 
> Sure, what did you have in mind?
> 
> You basically give you page to splice, never to see it again, you'd need
> to fill that hole in your buffer again.
> 

Can't we keep multiple references to each page ? (shared page) so it's still in
the buffer, also accessed by mmap(), and in addition accessed by splice.

Mathieu


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