linux-kernel - Re: [PATCH 00/12] perf lock: New subcommand "perf lock", for analyzing lock statistics

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Date:	Sun, 31 Jan 2010 21:44:08 +0100
From:	Jens Axboe <jens.axboe@...cle.com>
To:	Hitoshi Mitake <mitake@....info.waseda.ac.jp>
Cc:	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Tom Zanussi <tzanussi@...il.com>,
	Steven Rostedt <srostedt@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Greg Kroah-Hartman <gregkh@...e.de>
Subject: Re: [PATCH 00/12] perf lock: New subcommand "perf lock", for
	analyzing  lock statistics

On Sat, Jan 30 2010, Hitoshi Mitake wrote:
> (2010???01???29??? 23:34), Jens Axboe wrote:
>> On Fri, Jan 22 2010, Hitoshi Mitake wrote:
>>    
>>> Adding new subcommand "perf lock" to perf.
>>>
>>> I made this patch series on
>>> latest perf/core of tip (ef12a141306c90336a3a10d40213ecd98624d274),
>>> so please apply this series to perf/core.
>>>      
>> [snip]
>>
>> I wanted to give this a go today, since I think it's pretty nifty and a
>> lot better than using /proc/lock_stat. But it basically spirals the
>> system into death [1]. How big a system did you test this on?
>>
>> [1] Got this: [  117.097918] hrtimer: interrupt took 35093901 ns
>>
>>    
>
> I tested this on Core i7 965 + 3GB DRAM machine.
> Test program is mainly "perf bench sched messaging".
>
> Could you tell me the detail of your test situation?

I tried to run it on a 64 thread box, on a fio job that was driving 80
disks. It was just a quick test, but after ~20 seconds it had not even
gotten started yet, it was still stuck in setting up the jobs and
traversing sysfs for finding disk stats, etc. I can try something
lighter to see if it's the cpu count or the tough job that was making it
spiral into (near) death.

-- 
Jens Axboe

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