On Wed, Aug 19, 2020 at 03:41:48PM +0000, David Laight wrote: > Does linux have an O(1) (or do I mean o(1)) pid allocator? > Or does it have to do a linear scan to find a gap?? O(log(n)). It uses the IDR allocator, so 'n' in this case is the number of PIDs currently allocated, and it's log_64 rather than log_2 (which makes no difference to O() but does make a bit of a difference to performance)
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