Re: Context switch times

Andrea Arcangeli
2001-10-05T00:45:38Z

On Thu, Oct 04, 2001 at 04:41:02PM -0700, Mike Kravetz wrote:
> I know that running LMbench with 2 active tasks on an 8 CPU system
> results in those 2 tasks being 'round-robined' among all 8 CPUs.
> Prior analysis leads me to believe the reason for this is due to
> IPI latency. reschedule_idle() chooses the 'best/correct' CPU for
> a task to run on, but before schedule() runs on that CPU another
> CPU runs schedule() and the result is that the task runs on a
> ?less desirable? CPU. The nature of the LMbench scheduler benchmark

doesn't lmbench wakeup only via pipes? Linux uses the sync-wakeup that
avoids reschedule_idle in such case, to serialize the pipe load in the
same cpu.

Andrea