On Fri, 2013-02-15 at 13:21 +0100, Peter Zijlstra wrote: > On Fri, 2013-02-15 at 08:26 +0100, Mike Galbraith wrote: > > > > (the throttle is supposed to keep idle_balance() from doing severe > > damage, that may want a peek/tweak) > > Right, as it stands idle_balance() can do a lot of work and if the avg > idle time is less than the time we spend looking for a suitable task we > loose. > > I've wanted to make this smarter by having the cpufreq/cpuidle avg idle > time guestimator in the scheduler core so we actually know how log we > expect to be idle and couple that with a cache refresh cost per sched > domain (something we used to have pre 2.6.21 or so) so we can auto-limit > the domain traversal for idle_balance. > > So far that's all fantasy though.. > > Related, I wanted to use the idle time guestimate to 'optimize' the idle > loop, currently that stuff is stupid expensive and pokes at timer > hardware etc.. if we know we won't be idle longer than it takes to poke > at timer hardware, don't go into nohz mode etc.
Yup. My trees have nohz throttled too, it's too expensive for fast switchers scheduling cross core. -Mike -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
