perf_counter: x86: Disallow interval of 1
authorIngo Molnar <mingo@elte.hu>
Fri, 15 May 2009 06:25:22 +0000 (08:25 +0200)
committerIngo Molnar <mingo@elte.hu>
Fri, 15 May 2009 07:47:05 +0000 (09:47 +0200)
commit1c80f4b598d9b075a2a0be694e28be93a6702bcc
treeb48d59fecd365342d6c2c8aab7912de9cd7aa030
parenta4016a79fcbd139e7378944c0d86a39fdbc70ecc
perf_counter: x86: Disallow interval of 1

On certain CPUs i have observed a stuck PMU if interval was set to
1 and NMIs were used. The PMU had PMC0 set in MSR_CORE_PERF_GLOBAL_STATUS,
but it was not possible to ack it via MSR_CORE_PERF_GLOBAL_OVF_CTRL,
and the NMI loop got stuck infinitely.

[ Impact: fix rare hangs during high perfcounter load ]

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: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
arch/x86/kernel/cpu/perf_counter.c