Messages in this thread | | | Subject | Re: [RFC patch 1/2] sched: dynamically adapt granularity with nr_running | From | Steven Rostedt <> | Date | Mon, 13 Sep 2010 11:39:28 -0400 |
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On Mon, 2010-09-13 at 11:25 -0400, Mathieu Desnoyers wrote:
> > > The more divs we put it, the more expensive it all becomes. > > > > > > > What about: > > > > if (delta_exec < sysctl_sched_min_granularity || > > delta_exec < __sched_gran(cfs_rq->nr_running)) > > > > This way we avoid the div when delta_exec is less than the > > min_granularity, and then we can do the div to perhaps avoid a needless > > resched? > > Please note that my patch does not even take the 32-bit div when there are less > than 4 threads running on the system. > > So I'm not at all sure we're trying to optimize an important case here.
If we have 5 threads running and hit this where delta_exec is < sched_min_granularity, then we do have that div, right? Question is, how often do we hit this condition where delta_exec is less while running more that 4 threads?
-- Steve
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