Re: [Lse-tech] Re: CPUSET Proposal

Dave Hansen
2003-09-25T16:50:53Z

On Thu, 2003-09-25 at 06:26, Simon Derr wrote:
> On Wed, 24 Sep 2003, David Mosberger wrote:
>
> > BTW: What do cpusets provide that couldn't be done with user-level
> > tools on top of the existing sched_setaffinity() system call?
> This is a question we had a long in-house debate about.
>
> The main reason of the inclusion of cpusets *inside* the kernel, is that
> we have to deal with applications that may call sched_setaffinity() to
> bind their processes to CPUs. Therefore we have to intercept these calls.
> We could try to do some LD_PRELOAD userland trick or modify the libc, but
> that would not work for statically linked programs.

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.

--
Dave Hansen
haveblue@us.ibm.com