On Tue, Aug 01, 2017 at 06:23:09AM -0700, Paul E. McKenney wrote: > On Tue, Aug 01, 2017 at 12:22:03PM +0200, Peter Zijlstra wrote: > > [ . . . ] > > > As to scheduler IPIs, those are limited to the CPUs the user is limited > > to and are rate limited by the wakeup-latency of the tasks. After all, > > all the time a task is runnable but not running, wakeups are no-ops. > > Can't that wakeup-latency limitation be overcome by a normal user simply > by having lots of tasks to wake up, which then go back to sleep almost > immediately? Coupled with very a low-priority CPU-bound task on each CPU?
Let me put it like this; there is no way to cause more interference using IPIs then there is simply running while(1) loops ;-)
