Re: [patch 0/2] sched, timers: simplify calc_load and avoid cpuiteration loop

From: Dimitri Sivanich
Date: Thu May 14 2009 - 13:23:40 EST


I ran this patchset on a 64p ia64 machine and latency-wise it looks good. I can't really speak for the loadavg calculation.

On Thu, May 14, 2009 at 11:21:14AM -0000, Thomas Gleixner wrote:
> Dimitri Sivanich pointed out that calc_load iterates over all online
> CPUs under xtime lock which can cause long latencies on large SMP
> systems.
>
> The following patch series removes the iteration loop and lets
> scheduler_tick() on each CPU update the number of active tasks. The
> calc_load() function just uses this variable and updates avenrun from
> do_timer().
>
> Dimitri, can you please test run this on one of your large machines ?
>
> Thanks,
>
> tglx
>
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