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Date: Thu, 18 Nov 2010 18:10:01 +0100
From: Oleg Nesterov <oleg@redhat.com>
Subject: Re: [RFC][PATCH v2 5/7] taskstats: Improve cumulative CPU time
	accounting
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To: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Cc: Shailabh Nagar <nagar1234@in.ibm.com>, Andrew Morton <akpm@linux-foundation.org>, Venkatesh Pallipadi <venki@google.com>, Suresh Siddha <suresh.b.siddha@intel.com>, Peter Zijlstra <a.p.zijlstra@chello.nl>, Ingo Molnar <mingo@elte.hu>, John stultz <johnstul@us.ibm.com>, Thomas Gleixner <tglx@linutronix.de>, Balbir Singh <balbir@linux.vnet.ibm.com>, Martin Schwidefsky <schwidefsky@de.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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Sorry for delay.

On 11/16, Michael Holzheu wrote:
>
> On Sat, 2010-11-13 at 19:38 +0100, Oleg Nesterov wrote:
> > First of all, let me repeat, I am not going to discuss whether we need
> > these changes or not, I do not know even if I understand your motivation.
>
> Sorry, if I was not clear enough with my descriptions. Let me try to
> describe my motivation again:

Yes, more or less I see what this patch does (I hope ;).

> 2. Because of reparent to init, there are situations where it is
>    not clear to which tasks the CPU time of dead tasks between
>    two snapshots has been accounted. This is a problem for example 2.

Yes, I see.

But I must admit, _personally_ I am not sure this problem worth the
trouble. And, I already mentioned daemonize() case, IOW I am not sure
it is _always_ right to choose exiting_parent->parent for accounting.
To me, this can be equally confusing. A user sees the running deamon
with ppid = 1, then this daemon exits and top reports the "unrelated"
process as cpu consumer.


But once again. I am _not_ against this patch. I never know when it
comes to new features. Certainly you know better if this suits top.

What I actually meant is: dear CC list, please look at this change
and comment ;)

Oleg.