From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
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>
Subject: Re: Perf and ftrace [was Re: PyTimechart]
Date: Wed, 12 May 2010 16:52:25 -0400 [thread overview]
Message-ID: <20100512205225.GA31848@Krystal> (raw)
In-Reply-To: <1273690878.1626.165.camel@laptop>
* Peter Zijlstra (peterz@infradead.org) wrote:
> On Wed, 2010-05-12 at 14:51 -0400, Mathieu Desnoyers wrote:
> >
> > It makes it hard to use splice() or read() if you don't specify the buffer size
> > at creation time. That alone seems like a pretty good argument for fixing the
> > size before the mmap() call.
>
> Our read() doesn't actually provide the same data splice()/mmap() would.
> But yeah, hence my proposal to create a separate syscall that creates
> buffer objects.
>
Well, it's a bit strange to have read() vs splice() outputting different data,
isn't it ?
I would think it's rather more natural to have read() and splice()
implementations outputting the exact same data, and mmap() just mmapping the
ring buffer in userspace. If you really want to export that information in text
format, then a different file descriptor could be used for that, with read()
and splice() support.
Thanks,
Mathieu
--
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
next prev parent reply other threads:[~2010-05-12 20:52 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-11 21:10 [RFC] PyTimechart Pierre Tardy
2010-05-11 21:36 ` Frederic Weisbecker
2010-05-12 13:37 ` Pierre Tardy
2010-05-12 14:48 ` Frederic Weisbecker
2010-05-12 15:36 ` Steven Rostedt
2010-05-12 16:46 ` Perf and ftrace [was Re: PyTimechart] Frederic Weisbecker
2010-05-12 17:00 ` Peter Zijlstra
2010-05-12 17:07 ` Mathieu Desnoyers
2010-05-12 17:47 ` Peter Zijlstra
2010-05-12 17:53 ` Mathieu Desnoyers
2010-05-12 18:00 ` Peter Zijlstra
2010-05-12 18:04 ` Mathieu Desnoyers
2010-05-12 18:08 ` Peter Zijlstra
2010-05-12 18:37 ` Mathieu Desnoyers
2010-05-12 18:46 ` Steven Rostedt
2010-05-12 20:27 ` Mathieu Desnoyers
2010-05-12 22:21 ` Steven Rostedt
2010-05-13 13:20 ` Mathieu Desnoyers
2010-05-13 15:42 ` Steven Rostedt
2010-05-13 16:31 ` Mathieu Desnoyers
2010-05-13 16:46 ` Steven Rostedt
2010-05-13 17:10 ` Mathieu Desnoyers
2010-05-13 18:33 ` Steven Rostedt
2010-05-14 7:53 ` Peter Zijlstra
2010-05-12 18:49 ` Peter Zijlstra
2010-05-12 18:51 ` Mathieu Desnoyers
2010-05-12 19:01 ` Peter Zijlstra
2010-05-12 20:52 ` Mathieu Desnoyers [this message]
2010-05-12 17:11 ` Ingo Molnar
2010-05-12 16:59 ` [RFC] PyTimechart Ingo Molnar
2010-05-12 17:15 ` Steven Rostedt
2010-05-12 18:23 ` Ingo Molnar
2010-05-12 17:13 ` Pierre Tardy
2010-05-13 15:02 ` Arnaldo Carvalho de Melo
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