On Mon, Dec 20, 2010 at 10:44:46AM -0500, Steven Rostedt wrote:
> On Mon, 2010-12-20 at 16:24 +0100, Frederic Weisbecker wrote:
> > The timer interrupt handles several things like preemption,
> > timekeeping, rcu, etc...
> >
> > However it appears that sometimes it is simply useless like
> > when a task runs alone and even more when it is in userspace
> > as RCU doesn't need it at all in such case.
> >
> > It appears that HPC workload would get some win of such timer
> > deactivation, and perhaps also the Real Time world as this
> > minimizes the critical sections due to way less interrupts to
> > handle.
> >
> > It works through the procfs interface:
> >
> > echo 1> /proc/self/nohz
>
> I wounder if we could just have this happen automatically.
But this would add some global overhead, especially in the syscall
path as we need to take the slow path to hook userspace resume/exit.