Re: [PATCH] 2.4.9 Make thread group id visible in /proc/<pid>/status

[Dave McCracken <dmccr@us.ibm.com>]

--On Monday, August 20, 2001 19:09:16 +0000 Miquel van Smoorenburg 
<miquels@cistron-office.nl> wrote:

> Hmm, I've always been a bit curious about this .. I don't think getpid()
> should return tgid instead of pid. It looks broken to me. Thread groups
> are a good idea, but they should act more like process groups do.
> Switching pid and tgid is something that the LinuxThreads library
> should probably do, but not the kernel. IMHO.
>
> If one really wants CLONE_PID to work, fix CLONE_PID.

I wasn't on the list when getpid() was changed to return tgid.  I don't 
have a strong feeling about it, though it does make pthread semantics 
simpler.

CLONE_PID really isn't the semantic we want, though.  That would make all 
tasks in the process have the same pid, and no way to address a specific 
task.  We'd have to introduce something like a task id or a thread id. 
Having tgid and pid gives us the tools we need, and minimizes the 
compatibility issues.

Dave McCracken

======================================================================
Dave McCracken          IBM Linux Base Kernel Team      1-512-838-3059
dmccr@us.ibm.com                                        T/L   678-3059