linux-kernel - Re: [GIT PULL] cputime: Full dynticks task/cputime accounting v7

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Date:	Tue, 29 Jan 2013 03:39:10 +0100
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Li Zhong <zhong@...ux.vnet.ibm.com>,
	Namhyung Kim <namhyung.kim@....com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Sedat Dilek <sedat.dilek@...il.com>,
	Gleb Natapov <gleb@...hat.com>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	Tony Luck <tony.luck@...el.com>,
	Fenghua Yu <fenghua.yu@...el.com>
Subject: Re: [GIT PULL] cputime: Full dynticks task/cputime accounting v7

2013/1/29 Steven Rostedt <rostedt@...dmis.org>:
> On Mon, 2013-01-28 at 19:02 -0500, Steven Rostedt wrote:
>
>> I've ran these through some basic tests and I don't see any issues. But
>> why did you drop the 'comment' patch that you had in v6?
>>
>> Acked-by: Steven Rostedt <rostedt@...dmis.org>
>>
>
> I'm sorry but I need to un-Ack. Due to a test machine setup error, I've
> been testing the same config over and over and not other configs.
>
> Everything works great up until I enabled the dynamic tick and force
> context tracking.
>
> User time seems to be pretty much the same, but the kernel time is
> screwed:
>
> For all my other tests (I finally tested other configs and without your
> patches) I had my kernel time test report something like this:
>
> [root@...est ~]# time /work/c/kernelspin  10
>
> real    0m10.001s
> user    0m1.114s
> sys     0m8.886s
>
>
> But after enabling the force context_tracking I get this:
>
> [root@...est ~]# time /work/c/kernelspin  10
>
> real    0m10.001s
> user    0m3.769s
> sys     0m6.203s
>
>
> Consistently. All the other runs always had a 1.X 8.X ratio. This seems
> to give 3.7x 6.2x ratio consistently. Maybe it's more accurate then the
> others. Or something else is broken.
>
> I'll look deeper into it.

Please send me your kernelspin so I can test as well.

Thanks.

>
> -- Steve
>
>
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