diff options
| author | Ingo Molnar <mingo@elte.hu> | 2008-12-08 14:20:16 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-12-08 15:56:42 +0100 |
| commit | 87b9cf4623ad4e5fc009e48c020593dffd5d3793 (patch) | |
| tree | bd49f47b3fee4f4dc956e7db303fb1c20d53eee3 | |
| parent | 241771ef016b5c0c83cd7a4372a74321c973c1e6 (diff) | |
x86, perfcounters: read out MSR_CORE_PERF_GLOBAL_STATUS with counters disabled
Impact: make perfcounter NMI and IRQ sequence more robust
Make __smp_perf_counter_interrupt() a bit more conservative: first disable
all counters, then read out the status. Most invocations are because there
are real events, so there's no performance impact.
Code flow gets a bit simpler as well this way.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
| -rw-r--r-- | arch/x86/kernel/cpu/perf_counter.c | 12 |
1 files changed, 5 insertions, 7 deletions
diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c index 82440cbed0e..615e953208e 100644 --- a/arch/x86/kernel/cpu/perf_counter.c +++ b/arch/x86/kernel/cpu/perf_counter.c @@ -383,18 +383,16 @@ static void __smp_perf_counter_interrupt(struct pt_regs *regs, int nmi) struct cpu_hw_counters *cpuc; u64 ack, status; - rdmsrl(MSR_CORE_PERF_GLOBAL_STATUS, status); - if (!status) { - ack_APIC_irq(); - return; - } - /* Disable counters globally */ wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, 0, 0); ack_APIC_irq(); cpuc = &per_cpu(cpu_hw_counters, cpu); + rdmsrl(MSR_CORE_PERF_GLOBAL_STATUS, status); + if (!status) + goto out; + again: ack = status; for_each_bit(bit, (unsigned long *) &status, nr_hw_counters) { @@ -440,7 +438,7 @@ again: rdmsrl(MSR_CORE_PERF_GLOBAL_STATUS, status); if (status) goto again; - +out: /* * Do not reenable when global enable is off: */ |