Re: [patch] lockless, scalable get_pid(), for_each_process()

[Linus Torvalds]

On Wed, 18 Sep 2002, Rik van Riel wrote:
>
> On second thought ... yes there's a reason.  Suppose you have
> 100000 threads on your box already, how long is it going to
> take to walk them all to figure out the pid distribution ?
> 
> And are you willing to walk 100000 threads for every 16 pids allocated ?

Give me a real-life case where that happens, and I might care. I dare you.

The pid space is not a uniform distribution, which your made-up-example
depends on. So you usually walk the 100000 threads _once_, and then you
don't have to walk them again for quite a long time.

And guys, if this is a performance problem for some extreme site, the fix
is truly trivial:

	echo $((0x7fffffff)) > /proc/sys/max_pid

and you're done.

You're completely making up a problem that is not a problem in real life.  
Come back to me when the above doesn't work _in_practice_ and somebody is
actually bitten, and maybe I'll care.

Until then, all you're doing is mental masturbation. 

		Linus