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Date: Thu, 23 Aug 2012 11:01:55 +0900
From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
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Subject: Re: [Qemu-devel] [PATCH 2/5] trace-cmd: Use tracing directory to
	count CPUs
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To: Steven Rostedt <rostedt@goodmis.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>, Arnd Bergmann <arnd@arndb.de>, qemu-devel@nongnu.org, Frederic Weisbecker <fweisbec@gmail.com>, Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>, Rusty Russell <rusty@rustcorp.com.au>, linux-kernel@vger.kernel.org, Borislav Petkov <bp@amd64.org>, virtualization@lists.linux-foundation.org, "Franch Ch. Eigler" <fche@redhat.com>, Ingo Molnar <mingo@redhat.com>, Mathieu Desnoyers <mathieu.desnoyers@efficios.com>, Anthony Liguori <anthony@codemonkey.ws>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Amit Shah <amit.shah@redhat.com>, yrl.pp-manager.tt@hitachi.com

(2012/08/22 22:41), Steven Rostedt wrote:
> On Wed, 2012-08-22 at 17:43 +0900, Yoshihiro YUNOMAE wrote:
>> From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
>>
>> Count debugfs/tracing/per_cpu/cpu* to determine the
>> number of CPUs.
> 
> I'm curious, do you find that sysconf doesn't return the # of CPUs the
> system has?

No, sysconf returns the number of hosts CPUs, not guests.

> I've had boxes where the per_cpu/cpu* had more cpus than the
> box actually holds. But this was a bug in the kernel, not the tool. This
> change log needs to have rational instead of just explaining what the
> patch does.

Ah, I see. Hmm, then this should be enabled by a command line
option or an environment variable.

Thank you,


-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com