Subject: Re: [patch] dubious process system time.
From: Martin Schwidefsky <schwidefsky@de.ibm.com>
Reply-To: schwidefsky@de.ibm.com
To: Andi Kleen <ak@suse.de>
Cc: linux-kernel@vger.kernel.org
In-Reply-To: <200608241718.29406.ak@suse.de>
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Organization: IBM Corporation
Date: Thu, 24 Aug 2006 18:02:43 +0200
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On Thu, 2006-08-24 at 17:18 +0200, Andi Kleen wrote:
> > At the moment hardirq+softirq is just added to a random process, in
> > general this is completely wrong. 
> 
> It's better than not accounting it at all.

I think it is worse than not accounting it. You are "charging" a process
of some user for something that the user has nothing to do with.

> > You just need a system with a cpu hog 
> > and an i/o bound process and you get queer results.
> 
> Yes, but system load that is invisible to standard monitoring
> tools is even worse.

But it isn't invisible. cpustat->hardirq and cpustate->softirq will be
increased. /proc/stat will show the system time spent in these two
contexts.

> If you stop accounting it to random processes you have to 
> account it somewhere else. Preferably somewhere that standard tools
> automatically pick up.

Again, why do I have to account non-process related time to a process?
Ihmo that is completly wrong.

-- 
blue skies,
  Martin.

Martin Schwidefsky
Linux for zSeries Development & Services
IBM Deutschland Entwicklung GmbH

"Reality continues to ruin my life." - Calvin.


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