Messages in this thread | | | Date | Tue, 1 Oct 2013 17:34:52 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH] hotplug: Optimize {get,put}_online_cpus() |
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On 10/01, Paul E. McKenney wrote: > > On Tue, Oct 01, 2013 at 04:48:20PM +0200, Peter Zijlstra wrote: > > On Tue, Oct 01, 2013 at 07:45:37AM -0700, Paul E. McKenney wrote: > > > If you don't have cpuhp_seq, you need some other way to avoid > > > counter overflow. Which might be provided by limited number of > > > tasks, or, on 64-bit systems, 64-bit counters. > > > > How so? PID space is basically limited to 30 bits, so how could we > > overflow a 32bit reference counter? > > Nesting.
Still it seems that UINT_MAX / PID_MAX_LIMIT has enough room.
But again, OK lets make it ulong. The question is, how cpuhp_seq can help and why we can't kill it.
Oleg.
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