Re: [RFC PATCH 01/15] nohz_task: New mask for cpus having nohz task

[Frederic Weisbecker]

On Fri, Dec 24, 2010 at 09:19:56AM +0100, Dario Faggioli wrote:
> On Fri, 2010-12-24 at 16:00 +0800, Lai Jiangshan wrote: 
> > On 12/20/2010 11:24 PM, Frederic Weisbecker wrote:
> > >  
> > > +config NO_HZ_TASK
> > > +       bool "Tickless task"
> > > +       depends on HAVE_NO_HZ_TASK && NO_HZ && SMP && HIGH_RES_TIMERS
> > > +       help
> > > +         When a task runs alone on a CPU and switches into this mode,
> > > +         the timer interrupt will only trigger when it is strictly
> > > +         needed.
> > 
> > Why it depends on SMP?
> > 
> I guess that's because you need at least a ticking CPU for timekeeping
> and stuff... Right?
> 
> Regards,
> Dario


Exactly.

In the next version I'll probably drop that requirement. On UP a single task
must still be able to be in nohz mode when it is in userspace, as timekeeping
doesn't matter there until we reenter the kernel.

Dunno, I'll see what I can do.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/