Re: Bug: 2.6.15 Process accounting fails to account for small time slice loads (still)
From: Tom Burns
Date: Tue Jan 30 2007 - 13:57:08 EST
Hi Tim.
That would be great if you could find that patch - I can worry about
porting it to the current kernel. We're having an issue where our
device, while routing large amounts of network traffic, reports 0% CPU
utilisation when it cannot be the case, and I think this is the cause.
Cheers,
Tom Burns
On 1/30/07, Tim Schmielau <tim@xxxxxxxxxxxxxxxxxxxxxx> wrote:
On Tue, 30 Jan 2007, Tom Burns wrote:
> The bug described back in 2004 in the following message still seems to exist:
>
> http://linux.derkeiler.com/Mailing-Lists/Kernel/2004-05/4313.html
>
> Essentially, it appears that if a process sleeps before it uses up a
> complete jiffy then no charge is made to its process accounting table.
That's not a bug, it's a feature. ;-)
More seriously, it's a design decision. The benefit of exactly correct
micro bookkeeping does not seem to warrant the extra cost in terms of cpu
cycles spent in the accounting code.
IIRC there was a patch for that some years ago, if you are interested I
will try to find it. No idea how much work it would be to port it to
current kernels, though.
Tim
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