Re: Stolen and degraded time and schedulers

Jeremy Fitzhardinge
2007-03-14T21:16:48Z

Daniel Walker wrote:
> For interactive tasks (basic scheduling) the execution time, and sleep
> time need to be measured.

Sleep time is interesting. It doesn't make much sense to talk about
time that was stolen while a process was sleeping (it was either stolen
from another running process, or the VCPU was just plain idle). Also,
the definition of sched_clock I'm talking about is inherently per-cpu,
and sleeping has nothing to do with any cpu by definition.

So something other than sched_clock should be used to measure sleep
time, but it needs to produce interval measurements which are in the
same units as sched_clock.

> It's also used for some posix cpu timers
> (sched_ns) , and it used for migration thread initialization.

sched_ns doesn't use it directly except for the case where the process
is currently running. Anyway, it's compatible with what I'm talking about.

> I'm sure
> it's used for a variety of out-of-tree random timing as well..
>

Yeah, well...

J