Re: [accounting regression since rc1] scheduler updates

Ingo Molnar
2007-08-20T19:05:29Z

* Martin Schwidefsky <schwidefsky@de.ibm.com> wrote:

> On Mon, 2007-08-20 at 20:08 +0200, Ingo Molnar wrote:
> > For sched_clock()'s behavior while the virtual CPU is idle: my current
> > idea for that is the patch below (a loosely analoguous problem exists
> > with nohz/dynticks): it makes sched_clock() valid across idle periods
> > too and uses wall-clock time for that.
>
> Ok, that would mean that sched_clock can just return the virtual cpu
> time and the two hooks starts and stops the idle periods as far as the
> scheduler is concerned. In this case we can use the patch from Jan
> with the new implementation for sched_clock and add the two hooks to
> the places where the cpu-idle notifiers are done (do_monitor_call and
> default_idle). In fact this could be an idle-notifier. Hmm, I take a
> closer look tomorrow when I'm back at the office.

ok. Just to make it sure wrt. release-management: you said s390
sched_clock() is currently at least as precise as stime/utime - so this
would suggest that there is no regression over v2.6.22? Regardless of
whether it's a live regression or not, i think we want the nohz
improvement (and the s390 patch if the callbacks are OK to you) in .23,
and we want to migrate all users of "raw" sched_clock() [blktrace,
softlockup-detector, print-timestamps, etc.] over to the better
cpu_clock() interface.

Ingo