Messages in this thread | | | Date | Tue, 27 Jan 2015 16:04:46 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 2/5] sched/deadline: Remove cpu_active_mask from cpudl_find() |
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On Mon, Jan 19, 2015 at 04:49:37AM +0000, Xunlei Pang wrote: > cpu_active_mask is rarely changeable, so remove this operation > to gain a little performance. > > If there is a change in cpu_active_mask, rq_online_dl() and > rq_offline_dl() should take care of it normally, so cpudl:: > free_cpus carries enough information for us. > > For the rare case(causing a task put onto a dying cpu) which > rq_offline_dl() can't handle timely, then it can be handled > through _cpu_down()->...->multi_cpu_stop()->migration_call() > ->migrate_tasks(), preventing the task from hanging on the > dead cpu.
Maybe; I'll need to go crawl through the long and twisted history of active_mask here :/
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