From: Masami Hiramatsu <mhiramat@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Mathieu Desnoyers <compudj@krystal.dyndns.org>,
LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>,
Thomas Gleixner <tglx@linutronix.de>,
Andrew Morton <akpm@linux-foundation.org>,
prasad@linux.vnet.ibm.com,
Linus Torvalds <torvalds@linux-foundation.org>,
"Frank Ch. Eigler" <fche@redhat.com>,
David Wilder <dwilder@us.ibm.com>,
hch@lst.de, Martin Bligh <mbligh@google.com>,
Christoph Hellwig <hch@infradead.org>,
Steven Rostedt <srostedt@redhat.com>
Subject: Re: [RFC PATCH v4] Unified trace buffer
Date: Fri, 26 Sep 2008 12:57:25 -0400 [thread overview]
Message-ID: <48DD1475.1090109@redhat.com> (raw)
In-Reply-To: <1222426855.16700.264.camel@lappy.programming.kicks-ass.net>
Peter Zijlstra wrote:
> On Fri, 2008-09-26 at 06:45 -0400, Steven Rostedt wrote:
>> On Fri, 26 Sep 2008, Peter Zijlstra wrote:
>>> On Thu, 2008-09-25 at 23:20 -0400, Mathieu Desnoyers wrote:
>>>> You could also fallback on a 2-level page array when buffer size is >
>>>> 64MB. The cost is mainly a supplementary pointer dereference, but one
>>>> more should not make sure a big difference overall.
>>> I'm still not sure why we don't just link the pages using the page
>>> frames, we don't need the random access, do we?
>> Yeah we can go back to that (as ftrace does).
>>
>> 1) It can be very error prone. I will need to encapsulate the logic more.
>
> Sure.
>
>> 2) I'm still not sure if crash can handle it.
>
> It ought to, and if it can't it should be fixed. Having easy access to
> the pageframes is vital to debugging VM issues. So I'd not bother about
> this issue too much.
>
>> I was going to reply to Masami with this answer, but it makes things more
>> complex. For v1 (non RFC v1) I wanted to start simple. v2 can have this
>> enhancement.
>
> Right - I just object to having anything vmalloc.
I just requested that the expansion of buffer size limitation too. :)
I don't stick with vmalloc. If that (page frame chain?) can
achieve better performance, I agree that trace buffer uses it.
Thank you,
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division
e-mail: mhiramat@redhat.com
next prev parent reply other threads:[~2008-09-26 17:09 UTC|newest]
Thread overview: 102+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-25 18:51 [RFC PATCH 0/2 v3] Unified trace buffer Steven Rostedt
2008-09-25 18:51 ` [RFC PATCH 1/2 " Steven Rostedt
2008-09-26 1:02 ` [RFC PATCH v4] " Steven Rostedt
2008-09-26 1:52 ` Masami Hiramatsu
2008-09-26 2:11 ` Steven Rostedt
2008-09-26 2:47 ` Masami Hiramatsu
2008-09-26 3:20 ` Mathieu Desnoyers
2008-09-26 7:18 ` Peter Zijlstra
2008-09-26 10:45 ` Steven Rostedt
2008-09-26 11:00 ` Peter Zijlstra
2008-09-26 16:57 ` Masami Hiramatsu [this message]
2008-09-26 17:14 ` Steven Rostedt
2008-09-26 10:47 ` Steven Rostedt
2008-09-26 16:04 ` Mathieu Desnoyers
2008-09-26 17:11 ` [PATCH v5] " Steven Rostedt
2008-09-26 17:31 ` Arnaldo Carvalho de Melo
2008-09-26 17:37 ` Linus Torvalds
2008-09-26 17:46 ` Steven Rostedt
2008-09-27 17:02 ` Ingo Molnar
2008-09-27 17:18 ` Steven Rostedt
2008-09-26 18:05 ` [PATCH v6] " Steven Rostedt
2008-09-26 18:30 ` Richard Holden
2008-09-26 18:39 ` Steven Rostedt
2008-09-26 18:59 ` Peter Zijlstra
2008-09-26 19:46 ` Martin Bligh
2008-09-26 19:52 ` Steven Rostedt
2008-09-26 21:37 ` Steven Rostedt
2008-09-26 19:14 ` Peter Zijlstra
2008-09-26 22:28 ` Mike Travis
2008-09-26 23:56 ` Steven Rostedt
2008-09-27 0:05 ` Mike Travis
2008-09-27 0:18 ` Steven Rostedt
2008-09-27 0:46 ` Mike Travis
2008-09-27 0:52 ` Steven Rostedt
2008-09-26 19:17 ` Peter Zijlstra
2008-09-26 23:16 ` Arjan van de Ven
2008-09-26 20:08 ` Peter Zijlstra
2008-09-26 21:14 ` Masami Hiramatsu
2008-09-26 21:26 ` Steven Rostedt
2008-09-26 21:13 ` [PATCH v7] " Steven Rostedt
2008-09-27 2:02 ` [PATCH v8] " Steven Rostedt
2008-09-27 6:06 ` [PATCH v9] " Steven Rostedt
2008-09-27 18:39 ` Ingo Molnar
2008-09-27 19:24 ` Steven Rostedt
2008-09-27 19:41 ` Ingo Molnar
2008-09-27 19:54 ` Steven Rostedt
2008-09-27 20:00 ` Ingo Molnar
2008-09-29 15:05 ` Steven Rostedt
2008-09-27 20:07 ` Martin Bligh
2008-09-27 20:34 ` Ingo Molnar
2008-09-29 16:10 ` [PATCH v10 Golden] " Steven Rostedt
2008-09-29 16:11 ` Steven Rostedt
2008-09-29 23:35 ` Mathieu Desnoyers
2008-09-30 0:01 ` Steven Rostedt
2008-09-30 0:03 ` Mathieu Desnoyers
2008-09-30 0:12 ` Steven Rostedt
2008-09-30 3:46 ` Mathieu Desnoyers
2008-09-30 4:00 ` Steven Rostedt
2008-09-30 15:20 ` Jonathan Corbet
2008-09-30 15:54 ` Peter Zijlstra
2008-09-30 16:38 ` Linus Torvalds
2008-09-30 16:48 ` Steven Rostedt
2008-09-30 17:00 ` Peter Zijlstra
2008-09-30 17:41 ` Steven Rostedt
2008-09-30 17:49 ` Peter Zijlstra
2008-09-30 17:56 ` Steven Rostedt
2008-09-30 18:02 ` Steven Rostedt
2008-09-30 17:01 ` Linus Torvalds
2008-10-01 15:14 ` [PATCH] ring_buffer: allocate buffer page pointer Steven Rostedt
2008-10-01 17:36 ` Mathieu Desnoyers
2008-10-01 17:49 ` Steven Rostedt
2008-10-01 18:21 ` Mathieu Desnoyers
2008-10-02 8:50 ` Ingo Molnar
2008-10-02 8:51 ` Ingo Molnar
2008-10-02 9:05 ` [PATCH] ring-buffer: fix build error Ingo Molnar
2008-10-02 9:38 ` [boot crash] " Ingo Molnar
2008-10-02 13:16 ` Steven Rostedt
2008-10-02 13:17 ` Steven Rostedt
2008-10-02 15:50 ` Ingo Molnar
2008-10-02 18:27 ` Steven Rostedt
2008-10-02 18:55 ` Ingo Molnar
2008-10-02 23:18 ` [PATCH] ring_buffer: map to cpu not page Steven Rostedt
2008-10-02 23:36 ` Steven Rostedt
2008-10-03 4:56 ` [PATCH] x86 Topology cpu_to_node parameter check Mathieu Desnoyers
2008-10-03 5:20 ` Steven Rostedt
2008-10-03 15:56 ` Mathieu Desnoyers
2008-10-03 16:26 ` Steven Rostedt
2008-10-03 17:21 ` Mathieu Desnoyers
2008-10-03 17:54 ` Steven Rostedt
2008-10-03 18:53 ` [PATCH] topology.h define mess fix Mathieu Desnoyers
2008-10-03 20:14 ` Luck, Tony
2008-10-03 22:47 ` [PATCH] topology.h define mess fix v2 Mathieu Desnoyers
2008-10-03 7:27 ` [PATCH] ring_buffer: map to cpu not page Ingo Molnar
2008-10-02 9:06 ` [PATCH] ring_buffer: allocate buffer page pointer Andrew Morton
2008-10-02 9:41 ` Ingo Molnar
2008-10-02 13:06 ` Steven Rostedt
2008-09-26 22:31 ` [PATCH v6] Unified trace buffer Arnaldo Carvalho de Melo
2008-09-26 23:58 ` Steven Rostedt
2008-09-27 0:13 ` Linus Torvalds
2008-09-27 0:23 ` Steven Rostedt
2008-09-27 0:28 ` Steven Rostedt
2008-09-25 18:51 ` [RFC PATCH 2/2 v3] ftrace: make work with new ring buffer Steven Rostedt
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