MAX_PID changes in 2.5.31

From: Ingo Molnar (
Date: Mon Aug 19 2002 - 14:55:02 EST


afaics, you did the PID_MAX changes in v2.5.31? This is a change i had for
(surprise) threading purposes already, but done a bit differently.

The main problem is that there's the old-style SysV IPC interface that
uses 16-bit PIDs still. All recent SysV applications (linked against glibc
2.2 or newer) use IPC_64, but any application linked against pre-2.2
glibcs will fail. glibc 2.2 was released 2 years ago, is this enough of a
timeout to obsolete the non-IPC_64 interfaces?

if that is the case then can i rip all the non-IPC_64 parts out of ipc/*,
and let non-IPC_64 calls fail? Right now it's silent breakage that

or, in my threading tree, i introduced a /proc/sys/kernel/pid_max tunable,
which has the safe conservative value of 32K PIDs, but which can be
changed by the admin to have higher PIDs.

[anything more complex than this i think should be ignored - we do not
want to complicate PID allocations just for the sake of a single old
16-bit interface.]


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