Re: [patch 0/7] sched: change nohz idle load balancing logic topush model

From: Dominik Brodowski
Date: Thu May 20 2010 - 07:18:04 EST


On Thu, May 20, 2010 at 09:07:42PM +1000, Nigel Cunningham wrote:
> "Load balancing tick" is still number one in my powertop list of top
> causes of wakeups (sitting at ~60 to 80 per second as I type this, with
> ~170 wakeups per second total). Comparing this to the numbers I posted
> earlier, we seem to have a win.
> I do wonder, though, whether further work could still be done. If I take
> one core offline, for example, I'm still getting load balancing ticks.
> Intuitively, I'd expect there to be no need for them with only one core
> available. But maybe I'm just ignorant of what's going on.

Are you using HZ=1000, and is the CPU active ~ 6-8 % ? If so, is it just the
regular timer tick while the CPU is active, and so not a real "wakeup"? (Or
possibly double the number if both CPUs are active)

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