perf_counter: x86: Emulate longer sample periods
commite4abb5d4f7ddabc1fc7c392cf0a10d8e5868c9ca
authorPeter Zijlstra <a.p.zijlstra@chello.nl>
Tue, 2 Jun 2009 14:08:20 +0000 (2 16:08 +0200)
committerIngo Molnar <mingo@elte.hu>
Tue, 2 Jun 2009 19:45:31 +0000 (2 21:45 +0200)
tree9d9c71a70afd922d4b371b0243ab149456d634ca
parent8a016db386195b193e2a8aeddff9fe937dcb7a40
perf_counter: x86: Emulate longer sample periods

Do as Power already does, emulate sample periods up to 2^63-1 by
composing them of smaller values limited by hardware capabilities.
Only once we wrap the software period do we generate an overflow
event.

Just 10 lines of new code.

Reported-by: Stephane Eranian <eranian@googlemail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
arch/x86/kernel/cpu/perf_counter.c