From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: Olof Johansson <olof@lixom.net>,
linuxppc-dev@ozlabs.org, paulus@samba.org
Subject: Re: New time code miscalculates cpu usage
Date: Thu, 25 Oct 2007 07:56:09 +1000 [thread overview]
Message-ID: <1193262969.6653.32.camel@pasglop> (raw)
In-Reply-To: <471FA875.6080602@ru.mvista.com>
On Thu, 2007-10-25 at 00:17 +0400, Sergei Shtylyov wrote:
> Hello.
>
> Olof Johansson wrote:
>
> > Not sure when this started happening, but I wanted to report it. I'll
> > start bisecting in a day or two if noone else has gotten around to
> > looking at it:
>
> > $ echo "int main(void) { while(1); }" > test.c ; gcc test.c
> > $ time ./a.out & sleep 2 ; killall a.out
> > real 0m2.008s
> > user 0m4.014s
> > sys 0m0.002s
> >
> > Seen on POWER5 and PA6T, haven't tried anything else yet.
>
> I'm not surprised -- the kernel accounts twice for each tick.
Your input would be much more valuable if you actually pointed out where
that happens and why since you seem to know it.
Ben.
next prev parent reply other threads:[~2007-10-24 21:56 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-16 20:25 New time code miscalculates cpu usage Olof Johansson
2007-10-17 6:07 ` Tony Breeds
2007-10-24 20:19 ` Olof Johansson
2007-10-24 20:17 ` Sergei Shtylyov
2007-10-24 21:56 ` Benjamin Herrenschmidt [this message]
2007-10-25 0:19 ` Paul Mackerras
2007-10-25 0:53 ` Benjamin Herrenschmidt
2007-10-25 12:46 ` Sergei Shtylyov
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