RE: random PIDs

[alad@hss.hns.com]

"Heusden, Folkert van" <f.v.heusden@ftr.nl> on 04/05/2001 03:45:13 PM

To:   manfred@colorfullife.com
cc:   linux-kernel@vger.kernel.org (bcc: Amol Lad/HSS)

Subject:  RE: random PIDs




>  Finished & tested my random PID kernel/fork.c:get_pid() replacement.
> > This one keeps track of the last N (default is 64) pids who have exited.

> > These are then not used. So, one cannot have more then 32767 - (64 + 1
> > (init) + 1 (idle)) = 32761 processes :o)
> DW> Huh, should be 32701, right?!
> You're absolutely right. It must've been the victory trance :o)
M> Have you actually tried to create lots of threads?

No

M> IIRC get_pid will loop forever if it doesn't find a free pid, and in the
M> worst case you can trigger that with ~11000 running threads.

Ah, ok. But why would you have 11.000 running threads?

M> And the current code can create multiple threads with the same pid (I
M> never tried to trigger that bug, but it seems to be possible)

mine will do that too:

        if (flags & CLONE_PID)
                return current->pid;

As far as my knowledge reaches, threads are cloned which triggers the
code I quoted above.

>>>> cloning of threads never means that all the clome flags are set.. AFAIK
CLONE_PID flag is used only by swpapper
process (pid- 0) during boot-up and then never used again....
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