RE: [Lse-tech] Re: CPUSET Proposal

Luck, Tony
2003-09-25T18:49:52Z

> You could also do a big chunk of this by allowing normal
> privledge users
> to sched_setaffinity() a *subset* of their current allowed
> CPU set, but
> not expand it. sched_setaffinity() isn't *that* old of an
> interface, so
> I'm not sure why you can't just change the application at
> this point.

Because you need virtual cpu numbers. Suppose I have a 16-way
system, and *two* applications that know nothing about each other,
but each happens to want 5 cpus to run.

With cpusets each application can ask the kernel for 5 cpus
(or a wrapper that invokes the application can do so), and then
the application can happily divide its work between virtual cpus
0, 1, 2, 3, 4 (using sched_setaffinity()). The kernel can be smart
and provide different physical cpus for each of the cpusets.

-Tony