Re: [PATCH -v3] perf, x86: try to handle unknown nmis with running perfctrs

Peter Zijlstra
2010-08-19T14:27:29Z

On Thu, 2010-08-19 at 10:12 -0400, Don Zickus wrote:
> On Thu, Aug 19, 2010 at 12:45:53PM +0200, Peter Zijlstra wrote:
> >
> > I queued it with that part changed to:
>
> I realized the other day this change doesn't cover the nehalem, core and p4
> cases which use
>
> intel_pmu_handle_irq
> p4_pmu_handle_irq
>
> as their handlers. Though that patch can go on top of Robert's.

Something like this?

---
Index: linux-2.6/arch/x86/kernel/cpu/perf_event_intel.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/cpu/perf_event_intel.c
+++ linux-2.6/arch/x86/kernel/cpu/perf_event_intel.c
@@ -713,6 +713,7 @@ static int intel_pmu_handle_irq(struct p
struct cpu_hw_events *cpuc;
int bit, loops;
u64 ack, status;
+ int handled = 0;

perf_sample_data_init(&data, 0);

@@ -743,12 +744,16 @@ again:
/*
* PEBS overflow sets bit 62 in the global status register
*/
- if (__test_and_clear_bit(62, (unsigned long *)&status))
+ if (__test_and_clear_bit(62, (unsigned long *)&status)) {
+ handled++;
x86_pmu.drain_pebs(regs);
+ }

for_each_set_bit(bit, (unsigned long *)&status, X86_PMC_IDX_MAX) {
struct perf_event *event = cpuc->events[bit];

+ handled++;
+
if (!test_bit(bit, cpuc->active_mask))
continue;

@@ -772,7 +777,7 @@ again:

done:
intel_pmu_enable_all(0);
- return 1;
+ return handled;
}

static struct event_constraint *
Index: linux-2.6/arch/x86/kernel/cpu/perf_event_p4.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/cpu/perf_event_p4.c
+++ linux-2.6/arch/x86/kernel/cpu/perf_event_p4.c
@@ -673,7 +673,7 @@ static int p4_pmu_handle_irq(struct pt_r
if (!overflow && (val & (1ULL << (x86_pmu.cntval_bits - 1))))
continue;

- handled += overflow;
+ handled += !!overflow;

/* event overflow for sure */
data.period = event->hw.last_period;
@@ -690,7 +690,7 @@ static int p4_pmu_handle_irq(struct pt_r
inc_irq_stat(apic_perf_irqs);
}

- return handled > 0;
+ return handled;
}

/*