To: Ingo Molnar <mingo@elte.hu>
Cc: Steven Rostedt <rostedt@goodmis.org>,
       Frederic Weisbecker <fweisbec@gmail.com>,
       Tim Bird <tim.bird@am.sony.com>,
       Andrew Morton <akpm@linux-foundation.org>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>,
       Arnaldo Carvalho de Melo <acme@redhat.com>,
       Li Zefan <lizf@cn.fujitsu.com>, Thomas Gleixner <tglx@linutronix.de>,
       linux kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/4] ftrace - add function_duration tracer
References: <4B202778.4030801@am.sony.com> <20091210070800.GB16874@elte.hu>
	<20091210120332.GA5042@nowhere> <20091210141121.GB1436@elte.hu>
	<1260456803.2146.167.camel@gandalf.stny.rr.com>
	<20091210153845.GA28230@elte.hu>
From: fche@redhat.com (Frank Ch. Eigler)
Date: Thu, 10 Dec 2009 12:28:46 -0500
In-Reply-To: <20091210153845.GA28230@elte.hu> (Ingo Molnar's message of "Thu, 10 Dec 2009 16:38:45 +0100")
Message-ID: <y0md42magc1.fsf@fche.csb>
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Ingo Molnar <mingo@elte.hu> writes:

> [...]
> Just off the top of my head we want to be able to trace:
>
>  - max irq service latencies for a given IRQ
>  - max block IO completion latencies for a app
>  - max TLB flush latencies in the system
>  - max sys_open() latencies in a task
>  - max fork()/exit() latencies in a workload
>  - max scheduling latencies on a given CPU
>  - max page fault latencies
>  - max wakeup latencies for a given task
>  - max memory allocation latencies
>
>  - ... and dozens and dozens of other things where there's a "start"
>    and a "stop" event and where we want to measure the time between
>    them.
> [...]

FWIW, those who want to collect such measurements today can do so with
a few lines of systemtap script for each of the above.


- FChE
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