Date: Tue, 17 Nov 2009 07:01:30 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Roland McGrath <roland@redhat.com>, lkml <linux-kernel@vger.kernel.org>,
       systemtap <systemtap@sources.redhat.com>,
       DLE <dle-develop@lists.sourceforge.net>
Subject: Re: [PATCH -tip 3/3] Add get_signal tracepoint
Message-ID: <20091117060130.GB30852@elte.hu>
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* Masami Hiramatsu <mhiramat@redhat.com> wrote:

> >  - signal IPI/wakeup events
> 
> All signals might be used for IPI, isn't it? :-)

I mean, to analyze the various dynamic delivery details of how a signal 
send affects a target task:

 1) which task/PID was selected to be woken

 2) if the task got woken (from sleep) due to the signal sending

 3) if it was already woken, whether it needed an IPI via kick_process()

What proportion of signals were wakeups and what proportion hit an 
already running task is a relevant question to ask when analyzing the 
performance characteristics of signals.

	Ingo
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