On Fri, 2014-05-02 at 08:36 +0200, Mike Galbraith wrote: > Reason why is that case was on a box where FAIR_SLEEPERS is disabled by > default, meaning there is no such thing as wakeup preemption. Guess > what happens when you don't have shared LLC for a fast/light wakee to > escape to when the waker is a pig. The worst thing possible in that > case is to wake affine. Leave the poor thing wherever it was, else it > will take a latency hit that need not have been.
Oh yeah, and you'll see similar issues playing with kvm. No escape routes are available, as no llc domain exists. Globally do a sync wakeup CPU affine, and for some loads that will induce massive wreckage where as If select_isle_sibling() had been there to save the day, all would have been peachy. Is it good, or is it evil... depends. -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/
