Messages in this thread | | | Date | Thu, 31 Mar 2016 12:47:05 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 1/2] sched/fair: move cpufreq hook to update_cfs_rq_load_avg() |
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On Thu, Mar 31, 2016 at 11:50:40AM +0200, Vincent Guittot wrote: > > In what case? Assuming you talk about a remove wakeup, no. Only if that > > wakeup results in a preemption, which isn't a given. > > yes, i was speaking about a remote wakeup. > In the ttwu_queue_remote, there is a call to smp_send_reschedule. Is > there another way to add a remote task in the wake list ?
Right, but at that point we don't yet know how much util will change.
And doing that IPI unconditionally is expensive; see:
518cd6234178 ("sched: Only queue remote wakeups when crossing cache boundaries")
13% regression on TCP_RR.
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