Madhavan Venkataraman wrote: > Bill Holler wrote: >> How often will callouts cause a cross-call to another cpu? >> Will this be eliminated with the new per-cpu callout infrastructure? >> >> > Callouts, by themselves, don't use X-calls. However, normal callouts are > handled via taskq threads. So, waking up a taskq thread will involve > the customary preemption actions which will involve X-calls. > Also, realtime callouts are typically used to wake up threads. > This wake up can involve the same kind of X-calls. > There isn't a whole lot we can do about it.
Thinking out loud: Callouts will often cause threads to be dispatched on cpus other then the one the callout/cyclic occurred on. We do not currently know how to account for this in idle cpu sleep time prediction.... Sounds like a job for the Power Aware Dispatcher. :-b Bill > > I haven't yet had a chance to study how the new design reduces > X-calls although the per-CPU nature of things suggests there may > be less X-calling. However, I have no data on that. >> Eric noticed callouts causing cross-calls make it more difficult >> for the idle thread to predict how long it will be idle. >> >> Bill >> _______________________________________________ >> tesla-dev mailing list >> tesla-dev at opensolaris.org >> http://mail.opensolaris.org/mailman/listinfo/tesla-dev >> >
