On Mon, 26 Nov 2007 22:36:17 -0600
Robert Hancock <[email protected]> wrote:
> [email protected] wrote:
> > Question: Why is ksoftirqd eating about 5 to 10 percent of my CPU
> > on an idle system? The problem occurs if I config the kernel with
> > tickless support (i.e. CONFIG_TICK_ONESHOT=y). (Thanks to
> > "oprofile" for putting me onto this.)
> >
> > I have noted this same problem on kernel versions: 2.6.23.1,
> > 2.6.23.8 and 2.6.23.9
> >
> > **************************************************************************
> > *** Output from "vmstat -n 1 10" -- Note very high context switch
> > rate *** *** This is on a idle
> > machine! ***
> > **************************************************************************
> >
> > procs -----------memory---------- ---swap-- -----io---- --system--
> > ----cpu----
> > r b swpd free buff cache si so bi bo in cs
> > us sy id wa
> > 0 0 0 1925556 4768 116104 0 0 124 2 6
> > 7538 1 2 96 1
> > 0 0 0 1925556 4768 116104 0 0 0 0 2
> > 147329 0 1 99 0
>
> What did oprofile show? It should be able to narrow down what
> function(s) are responsible for the CPU usage..
>
or better, what does powertop version 1.9 show?
that tends to show tickless wakeup artifacts quite nicely
--
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