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Date: Tue, 29 Jan 2013 03:39:10 +0100
Message-ID: <CAFTL4hwbbLoPYwvyEUYyn2EuEj=2nw2NPehe8G4rykRTE3LziA@mail.gmail.com>
Subject: Re: [GIT PULL] cputime: Full dynticks task/cputime accounting v7
From: Frederic Weisbecker <fweisbec@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@kernel.org>, LKML <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Li Zhong <zhong@linux.vnet.ibm.com>,
        Namhyung Kim <namhyung.kim@lge.com>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Paul Gortmaker <paul.gortmaker@windriver.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Sedat Dilek <sedat.dilek@gmail.com>, Gleb Natapov <gleb@redhat.com>,
        Marcelo Tosatti <mtosatti@redhat.com>, Tony Luck <tony.luck@intel.com>,
        Fenghua Yu <fenghua.yu@intel.com>
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2013/1/29 Steven Rostedt <rostedt@goodmis.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@goodmis.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@bxtest ~]# 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@bxtest ~]# 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
>
>