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

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Message-ID: <1359426979.17639.10.camel@gandalf.local.home>
Date:	Mon, 28 Jan 2013 21:36:19 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Frederic Weisbecker <fweisbec@...il.com>
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

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.

-- Steve

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