Messages in this thread | | | Subject | Re: rcu: performance regression | From | Peter Zijlstra <> | Date | Tue, 14 Jun 2011 15:14:58 +0200 |
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On Tue, 2011-06-14 at 06:02 -0700, Paul E. McKenney wrote: > > This commit also cause hackbench process mode performance dropping, and > > Shaohua's patch do recovered this. But in hackbench testing, the vmstat > > show context switch have some reduce. And perf tool show > > root_domain->cpupri->prio_to_cpu[]->lock has contention with the commit. > > Steven, Peter, would any of the recent fixes address this lock contention?
No. People occasionally run into that thing, but given the constraints on SCHED_FIFO SMP (run the n highest priority tasks on m cpus; n<=m) there isn't really much we can do.
IIRC Chris Mason once proposed a lockless version, but that opened up race windows, Steve might know the details better.
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