Re: Stolen and degraded time and schedulers

Dan Hecht
2007-03-14T20:26:15Z

>>> How is cpustat->steal used? How does it get out to usermode?
>>>
>> Via /proc/stat, used by modern 'top', maybe other utilities. It is
>> useful to users who want to see where the time is really going from
>> inside a guest when running on a (para)virtual machine.
>>
>> I believe previous set of xen paravirt-ops patches already handled
>> cases #2 and #3 (but no longer do since switching to clockevents), and
>> the old vmitime code did also. Obviously, we need revamp this stuff
>> to make it fit in with the new clockevents/hrtimer way of doing things.
>
> I added stolen time accounting to xen-pv_ops last night. For Xen, at
> least, it wasn't hard to fit into the clockevent infrastructure. I just
> update the stolen time accounting for each cpu when it gets a timer
> tick; they seem to get a tick every couple of seconds even when idle.
>

Sounds good. I don't see this in your patchset you sent yesterday
though; did you add it after sending out those patches? if so, could
you forward the new patch? does it explicitly prevent stolen time from
getting accounted as user/system time or does it just rely on NO_HZ
mode sort of happening to work that way (since the one shot timer is
skipped ahead for missed ticks)?

thanks,
Dan