Message-ID: <47918792.2080201@linux.intel.com>
Date: Fri, 18 Jan 2008 21:16:02 -0800
From: Arjan van de Ven <arjan@linux.intel.com>
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To: Andi Kleen <andi@firstfloor.org>
CC: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Linus Torvalds <torvalds@linux-foundation.org>,
       Ingo Molnar <mingo@elte.hu>, Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [Announce] Development release 0.1 of the LatencyTOP tool
References: <4790E3A6.7060807@linux.intel.com> <p73lk6m9ze7.fsf@bingen.suse.de>
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Andi Kleen wrote:
> Arjan van de Ven <arjan@linux.intel.com> writes:
> 
>> The Intel Open Source Technology Center is pleased to announce the
>> release of version 0.1 of LatencyTOP, a tool for developers to visualize
>> system latencies.
> 
> Just for completeness -- Linux already had a way to profile latencies
> since quite some time. It's little known unfortunately and doesn't
> work for modules since it's a special mode in the old non modular kernel
> profiler. 
> 
> You enable CONFIG_SCHEDSTATS and boot with profile=sleep and then you can
> use the readprofile command to read the data. Information can be reset with 
> echo > /proc/profile
> 
> There's also a profile=sched to profile the scheduler which works even
> without CONFIG_SCHEDSTATS

yes indeed; I sort of use the same infrastructure inside the scheduler; the biggest
reason I felt I had to do something different was that I wanted to do per process
data collection, so that you can see for a specific process what was going on.
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