Re: Accessing Pentium MSRs
Bernd Schmidt (crux@pool.informatik.rwth-aachen.de)
Wed, 10 Apr 1996 10:00:45 +0200 (MET DST)
> > Over the weekend, I crufted together a little kernel patch that adds two
> > syscalls to let processes access some of the Pentium MSR registers. Using these
> > event counters, you can analyze how your code behaves (e.g. how often the
> > second pipeline is in use, or how many branches are taken). If someone is
> > interested, I'll post the patch here.
>
> Sounds useful. I assume you are also saving/restoring the values over
> context switches ?. Would making the MSR access a ptrace extension be better
> than new syscalls ?
Yes, I modified the tss and the switch_to macro. Every task can count its own
events. I'll tidy the code up a little and post it (probably) on Friday. I
won't do it as a ptrace extension, though, since I have no idea about how to do
that :).