diff options
| author | Ingo Molnar <mingo@elte.hu> | 2009-05-15 08:25:22 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-05-15 09:47:05 +0200 |
| commit | 1c80f4b598d9b075a2a0be694e28be93a6702bcc (patch) | |
| tree | b48d59fecd365342d6c2c8aab7912de9cd7aa030 /arch | |
| parent | a4016a79fcbd139e7378944c0d86a39fdbc70ecc (diff) | |
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>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/cpu/perf_counter.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c index 1dcf67057f1..46a82d1e4cb 100644 --- a/arch/x86/kernel/cpu/perf_counter.c +++ b/arch/x86/kernel/cpu/perf_counter.c @@ -473,6 +473,11 @@ x86_perf_counter_set_period(struct perf_counter *counter, left += period; atomic64_set(&hwc->period_left, left); } + /* + * Quirk: certain CPUs dont like it if just 1 event is left: + */ + if (unlikely(left < 2)) + left = 2; per_cpu(prev_left[idx], smp_processor_id()) = left; |