Re: quadratic behaviour

From: William Lee Irwin III (
Date: Sat Sep 21 2002 - 12:46:06 EST

On Sat, 21 Sep 2002, Linus Torvalds wrote:
>> But the quadratic behaviour wrt processes clearly isn't fixed.
>> Suggestions welcome (and we'll need to avoid the same quadratic
>> behaviour wrt the threads when we expose them).

On Sat, Sep 21, 2002 at 07:49:49PM +0200, Ingo Molnar wrote:
> in the case of threads my plan is to use the pid alloction bitmap for
> this. It slightly overestimates the pids because orphan sessions and pgrps
> are included as well, but this should not be a problem because procfs also
> does a pid lookup when the specific directory is accessed. This method is
> inherently restartable, the pid bitmap pages are never freed, and it's the
> most cache-compact representation of the sorted pidlist. And it can be
> accessed lockless ...

This sounds more attractive still. I'll forego the strategy of my prior
post and try to squeeze some more benchmark numbers out of things over
the weekend.

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