perf_counter: add some comments

Add a few comments because I was forgetting what field what for what
functionality.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090408130409.036984214@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2009-04-08 15:01:29 +02:00 • committed by Ingo Molnar
commit 8740f9418c