Re: [PATCH 12/32] nohz: Try not to give the timekeeping duty to a cpuset nohz cpu

Dimitri Sivanich
2011-08-30T15:30:46Z

On Tue, Aug 30, 2011 at 05:17:06PM +0200, Frederic Weisbecker wrote:
> On Mon, Aug 29, 2011 at 04:55:45PM +0200, Peter Zijlstra wrote:
> > On Mon, 2011-08-15 at 17:52 +0200, Frederic Weisbecker wrote:
> > > Try to give the timekeeing duty to a CPU that doesn't belong
> > > to any nohz cpuset when possible, so that we increase the chance
> > > for these nohz cpusets to run their CPUs out of periodic tick
> > > mode.
> >
> > You and Dmitiri might want to get together:
> >
> > lkml.kernel.org/r/20110823195628.GB4533@sgi.com
>
> Right!
>
> There is another missing piece in my patchset. If every non adaptive-nohz
> CPUs are sleeping, then none is handling the do_timer duty and adaptive nohz
> CPUs run with a stale jiffies and walltime.
>
> I need to handle that.

Frederic,

Please note that the patch that Peter references (lkml.kernel.org/r/20110823195628.GB4533@sgi.com) supports only the nohz=off case.