Messages in this thread | | | Date | Wed, 12 Apr 2017 18:21:57 +0200 | From | Peter Zijlstra <> | Subject | Re: [RFC][PATCH] sched: Have do_idle() call __schedule() without enabling preemption |
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On Wed, Apr 12, 2017 at 10:41:24AM -0400, Steven Rostedt wrote: > [ tl;dr; version ] > > Peter, In order to have synchronize_rcu_tasks() work, the idle task can > never be preempted. There's a very small window in > schedule_preempt_disable() that enables preemption, and when this > happens, it breaks synchronize_rcu_tasks() (see above email for > details). > > Is there any reason to enable preemption, or can we simply have idle > call into schedule without ever allowing it to be preempted, as in my > patch?
Dunno,.. this changelog should convince me, not make me do the work :-)
> Note, it is almost good enough to just change > schedule_preempt_disable() to do the exact same thing, but there's one > instance in kernel/locking/mutex.c that calls it in a non running state.
The point being that that must not happen because of sched_submit_work(), which, for idle, should not matter.
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