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SubjectRe: PID Wrap <strangeness>
On Wed, 23 Feb 2000, Mathijs Mohlmann wrote:

>
> On Tue, Feb 22, 2000 at 05:31:51PM -0500, Richard B. Johnson wrote:
> > On Linux 2.3.41 (haven't checked others) when the PID wraps past
> > 32,767 the next PID is 300. It is not the next-available low one.
> >
> > Does anybody know why?
>
> For speed, since a lot of pids lower than 300 are used by daemons,
> there's no need to check them. This will speedup the get_pid
> function after a wrap.
>
> me
>

The lowest numbered pid, not currently in use, can be readily obtained
when a task exits. The task exit is currently the slowest thing to do
because of the wait-for-status requirement. Adding a variable and
a comparison at process exit would get the number for free.

A hard-coded number of 300 is an eye-opener.

Cheers,
Dick Johnson

Penguin : Linux version 2.3.41 on an i686 machine (800.63 BogoMips).


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