Subject: Re: [RFC][PATCH v2 5/7] taskstats: Improve cumulative CPU time
 accounting
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>,
        Michael Holzheu <holzheu@linux.vnet.ibm.com>,
        Shailabh Nagar <nagar1234@in.ibm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Venkatesh Pallipadi <venki@google.com>,
        Suresh Siddha <suresh.b.siddha@intel.com>, Ingo Molnar <mingo@elte.hu>,
        John stultz <johnstul@us.ibm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Balbir Singh <balbir@linux.vnet.ibm.com>,
        Heiko Carstens <heiko.carstens@de.ibm.com>,
        Roland McGrath <roland@redhat.com>, linux-kernel@vger.kernel.org,
        linux-s390@vger.kernel.org
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Date: Mon, 15 Nov 2010 19:10:06 +0100
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On Mon, 2010-11-15 at 19:00 +0100, Martin Schwidefsky wrote:
> On Mon, 15 Nov 2010 18:51:57 +0100
> Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
> 
> > On Mon, 2010-11-15 at 18:49 +0100, Martin Schwidefsky wrote:
> > > > To what purpose? 
> > >  
> > > Is that a trick question? Why do we have tools like "top"? Or process
> > > accounting? The point is that the quality of the numbers we get right
> > > now is rather bad, the overhead of scanning /proc is horrendous and
> > > the 10ms granularity is rather coarse. 
> > 
> > But you're not just replacing top, you're adding all kinds of new
> > accounting crap all over the place.
> 
> We DO replace top. Patch #7 of 7.

You _also_ replace top, but its not by far the only thing you do. If you
simply replaced top you wouldn't need to add tons of extra accounting,
would you?
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