Messages in this thread | | | Date | Fri, 24 Dec 2010 13:29:14 +0100 | From | Frederic Weisbecker <> | Subject | Re: [RFC PATCH 01/15] nohz_task: New mask for cpus having nohz task |
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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.
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