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Date: Thu, 10 Dec 2009 09:06:08 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>,
       Steven Rostedt <rostedt@goodmis.org>,
       Frederic Weisbecker <fweisbec@gmail.com>,
       LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] softirq,tracing: enable to trace softirq raise latency
Message-ID: <20091210080608.GA944@elte.hu>
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* Lai Jiangshan <laijs@cn.fujitsu.com> wrote:

> Rebase it for the newly codes
> Collect Acks(Acked-by Mathieu Desnoyers and Frederic Weisbecker)
> 
> 
> From: Lai Jiangshan <laijs@cn.fujitsu.com>
> 
> Add a tracepoint for tracing when softirq action is raised.
> 
> It and the existed tracepoints complete softirq's tracepoints:
> softirq_raise, softirq_entry and softirq_exit.
> 
> And when this tracepoint is used in combination with
> the softirq_entry tracepoint we can determine
> the softirq raise latency.
> 
> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
> Acked-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
> Acked-by: Frederic Weisbecker <fweisbec@gmail.com>

ok, it would be nice to expose this functionality via some sort of 'perf 
trace --irqlatency' (or perhaps a separate 'perf irq record' 'perf irq 
trace' tool) so that users/developers can make use of this new event and 
that we can check that it works and latencies are correct, etc.

	Ingo