Messages in this thread | | | Date | Fri, 16 Feb 2018 18:43:55 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 1/7] sched: Add static_key for asymmetric cpu capacity optimizations |
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On Fri, Feb 16, 2018 at 05:39:27PM +0000, Quentin Perret wrote: > AFAIU it should be safe, but without your check you'll have to go through > cpus_read_lock()/unlock() every time a CPU is hotplugged. There is probably > no good reason to re-do that again and again if the state of the key > never changes. I don't know how expensive those lock/unlock operations are, > but I bet they are more expensive than testing static_branch_unlikely() :)
This is not a performance critical path, more obvious code is more better.
Also cpus_read_lock() is dirt cheap most of the time.
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