Messages in this thread | | | Date | Wed, 18 Sep 2002 10:36:53 -0700 | From | William Lee Irwin III <> | Subject | Re: [patch] lockless, scalable get_pid(), for_each_process() elimination, 2.5.35-BK |
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On Wed, 18 Sep 2002, William Lee Irwin III wrote: >> The lockups I see range from hours to "it spun over the weekend, time to >> pull the plug".
On Wed, Sep 18, 2002 at 07:36:00PM +0200, Ingo Molnar wrote: > this can happen if there's a genuine PID space squeeze wrt. nr_threads - > that is solved by adding Linus' suggestion to the PID allocator. I believe > you saw that problem, not any inherent get_pid() algorithmic inefficiency. > nevertheless we do lock up for 32 seconds if there are 32K PIDs allocated > in a row and last_pid hits that range - regardless of pid_max. (Depending > on the cache architecture it could take significantly more.)
There were only 10K tasks, with likely consecutively-allocated PID's, and some minor background fork()/exit() activity, but there are more offenders on the read side than get_pid() itself.
There is no question of PID space: the full 2^30 was configured in the tests done after the PID space expansion.
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