In response (albeit a week plus late) to the recent hubbub about the cpu
affinity patches, 
I'd like to throw a third contender in the ring.

Attatched is a patch (against 2.4.16) which implements a /proc and a prctl()
interface to 
the cpus_allowed flag.  The truly exciting (at least for me) part of this patch
is the 
launch_policy flag that it also introduces.  The launch_policy flag is used
similarly to 
the cpus_allowed flag, but it controls the cpus_allowed flags of any subsequent
children 
of the process, instead of the cpus_allowed of the process itself.  Via this
flag, there 
are no worries about processes being able to fork children before a 'chaff' or
'echo' or 
anything else for that matter can be executed.  The child process is assigned
the desired 
cpus_allowed at fork/exec time.  All this without having to bounce the current
process to 
different cpus to (hopefully) acheive the same results.

The launch_policy flag can acually be quite powerful.  It allows for children
to be 
instantiated on the correct cpu/node with a minimum of memory footprint on the
wrong 
cpu/node.  This can be taken advantage of via the /proc interface (for smp/numa
unaware 
programs) or through prctl() for more clueful programs.

You must have CAP_SYS_NICE or be the owner of the process to change *either*
cpus_allowed 
or launch_policy.

I will momentarily be posting this patch in its own thread for greater
exposure.

Feedback of any kind will be greatly appreciated!

Enjoy!

-matt