Re: clocksource_watchdog causing scheduling of timers every second (was [v13] support "task_isolation" mode)

On Fri, Aug 12, 2016 at 09:19:19AM -0700, Paul E. McKenney wrote:

On Fri, Aug 12, 2016 at 04:26:13PM +0200, Frederic Weisbecker wrote:

quoted

On Fri, Aug 12, 2016 at 09:23:13AM -0500, Christoph Lameter wrote:

quoted

On Thu, 11 Aug 2016, Paul E. McKenney wrote:

quoted

Heh!  The only really good idea is for clocks to be reliably in sync.

But if they go out of sync, what do you want to do instead?

For a NOHZ task? Write a message to the syslog and reenable tick.

Fair enough!  Kicking off a low-priority task would achieve the latter
but not necessarily the former.  And of course assumes that the worker
thread is at real-time priority with various scheduler anti-starvation
features disabled.

quoted

Indeed, a strong clocksource is a requirement for a full tickless machine.

No disagrement here!  ;-)

I have a bot in my mind that randomly posts obvious statements about nohz_full
here and then :-)