Messages in this thread | | | Date | Tue, 4 Jul 2017 17:32:37 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [patch V2 2/2] mm/memory-hotplug: Switch locking to a percpu rwsem |
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On Tue, 4 Jul 2017, Davidlohr Bueso wrote: > On Tue, 04 Jul 2017, Davidlohr Bueso wrote: > > > As a side effect you end up optimizing get/put_online_mems() at the cost > > of more overhead for the actual hotplug operation, which is rare and of less > > performance importance. > > So nm this, the reader side actually gets _more_ expensive with pcpu-rwsems > due to at least two full barriers for each get/put operation.
Compared to a mutex_lock/unlock() pair on a global mutex ....
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