Re: [RFC v2] perf: Rewrite core context handling

Peter Zijlstra
2022-08-24T15:06:16Z

On Wed, Aug 24, 2022 at 02:15:13PM +0200, Peter Zijlstra wrote:
> On Mon, Jun 13, 2022 at 04:35:11PM +0200, Peter Zijlstra wrote:
> > void x86_pmu_update_cpu_context(struct pmu *pmu, int cpu)
> > {
> > - struct perf_cpu_context *cpuctx;
> > + /* XXX: Don't need this quirk anymore */
> > + /*struct perf_cpu_context *cpuctx;
> >
> > if (!pmu->pmu_cpu_context)
> > return;
> >
> > cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
> > - cpuctx->ctx.pmu = pmu;
> > + cpuctx->ctx.pmu = pmu;*/
> > }
>
> Confirmed; my ADL seems to work fine without all that.

Additionally; this doesn't insta crash.

---
diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
index cb69ff1e6138..016072a89f8f 100644
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -1019,10 +1019,10 @@ static int armv8pmu_set_event_filter(struct hw_perf_event *event,
return 0;
}

-static int armv8pmu_filter_match(struct perf_event *event)
+static bool armv8pmu_filter(struct pmu *pmu, int cpu)
{
- unsigned long evtype = event->hw.config_base & ARMV8_PMU_EVTYPE_EVENT;
- return evtype != ARMV8_PMUV3_PERFCTR_CHAIN;
+ struct arm_pmu *armpmu = to_arm_pmu(pmu);
+ return !cpumask_test_cpu(smp_processor_id(), &armpmu->supported_cpus);
}

static void armv8pmu_reset(void *info)
@@ -1253,7 +1253,7 @@ static int armv8_pmu_init(struct arm_pmu *cpu_pmu, char *name,
cpu_pmu->stop = armv8pmu_stop;
cpu_pmu->reset = armv8pmu_reset;
cpu_pmu->set_event_filter = armv8pmu_set_event_filter;
- cpu_pmu->filter_match = armv8pmu_filter_match;
+ cpu_pmu->filter = armv8pmu_filter;

cpu_pmu->pmu.event_idx = armv8pmu_user_event_idx;

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 7a2d12ad6d1f..a8f1e38c66a7 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -86,6 +86,8 @@ DEFINE_STATIC_CALL_NULL(x86_pmu_swap_task_ctx, *x86_pmu.swap_task_ctx);
DEFINE_STATIC_CALL_NULL(x86_pmu_drain_pebs, *x86_pmu.drain_pebs);
DEFINE_STATIC_CALL_NULL(x86_pmu_pebs_aliases, *x86_pmu.pebs_aliases);

+DEFINE_STATIC_CALL_NULL(x86_pmu_filter, *x86_pmu.filter);
+
/*
* This one is magic, it will get called even when PMU init fails (because
* there is no PMU), in which case it should simply return NULL.
@@ -2038,6 +2040,7 @@ static void x86_pmu_static_call_update(void)
static_call_update(x86_pmu_pebs_aliases, x86_pmu.pebs_aliases);

static_call_update(x86_pmu_guest_get_msrs, x86_pmu.guest_get_msrs);
+ static_call_update(x86_pmu_filter, x86_pmu.filter);
}

static void _x86_pmu_read(struct perf_event *event)
@@ -2668,12 +2671,13 @@ static int x86_pmu_aux_output_match(struct perf_event *event)
return 0;
}

-static int x86_pmu_filter_match(struct perf_event *event)
+static bool x86_pmu_filter(struct pmu *pmu, int cpu)
{
- if (x86_pmu.filter_match)
- return x86_pmu.filter_match(event);
+ bool ret = false;

- return 1;
+ static_call_cond(x86_pmu_filter)(pmu, cpu, &ret);
+
+ return ret;
}

static struct pmu pmu = {
@@ -2704,7 +2708,7 @@ static struct pmu pmu = {

.aux_output_match = x86_pmu_aux_output_match,

- .filter_match = x86_pmu_filter_match,
+ .filter = x86_pmu_filter,
};

void arch_perf_update_userpage(struct perf_event *event,
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 768771e5e4e9..40cebd9b90a1 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -4675,12 +4675,11 @@ static int intel_pmu_aux_output_match(struct perf_event *event)
return is_intel_pt_event(event);
}

-static int intel_pmu_filter_match(struct perf_event *event)
+static void intel_pmu_filter(struct pmu *pmu, int cpu, bool *ret)
{
- struct x86_hybrid_pmu *pmu = hybrid_pmu(event->pmu);
- unsigned int cpu = smp_processor_id();
+ struct x86_hybrid_pmu *hpmu = hybrid_pmu(pmu);

- return cpumask_test_cpu(cpu, &pmu->supported_cpus);
+ *ret = !cpumask_test_cpu(cpu, &hpmu->supported_cpus);
}

PMU_FORMAT_ATTR(offcore_rsp, "config1:0-63");
@@ -6348,7 +6347,7 @@ __init int intel_pmu_init(void)
x86_pmu.update_topdown_event = adl_update_topdown_event;
x86_pmu.set_topdown_event_period = adl_set_topdown_event_period;

- x86_pmu.filter_match = intel_pmu_filter_match;
+ x86_pmu.filter = intel_pmu_filter;
x86_pmu.get_event_constraints = adl_get_event_constraints;
x86_pmu.hw_config = adl_hw_config;
x86_pmu.limit_period = spr_limit_period;
diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
index 9c835ecb232e..b3ff55fc5794 100644
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -924,7 +924,7 @@ struct x86_pmu {

int (*aux_output_match) (struct perf_event *event);

- int (*filter_match)(struct perf_event *event);
+ void (*filter)(struct pmu *pmu, int cpu, bool *ret);
/*
* Hybrid support
*
diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h
index 0407a38b470a..0f9519874fde 100644
--- a/include/linux/perf/arm_pmu.h
+++ b/include/linux/perf/arm_pmu.h
@@ -99,7 +99,7 @@ struct arm_pmu {
void (*stop)(struct arm_pmu *);
void (*reset)(void *);
int (*map_event)(struct perf_event *event);
- int (*filter_match)(struct perf_event *event);
+ bool (*filter)(struct pmu *pmu, int cpu);
int num_events;
bool secure_access; /* 32-bit ARM only */
#define ARMV8_PMUV3_MAX_COMMON_EVENTS 0x40
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 7847818e5397..4be3aaae89be 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -519,9 +519,10 @@ struct pmu {
/* optional */

/*
- * Filter events for PMU-specific reasons.
+ * Skip programming this PMU on the given CPU. Typically needed for
+ * big.LITTLE things.
*/
- int (*filter_match) (struct perf_event *event); /* optional */
+ bool (*filter) (struct pmu *pmu, int cpu); /* optional */

/*
* Check period value for PERF_EVENT_IOC_PERIOD ioctl.
diff --git a/kernel/events/core.c b/kernel/events/core.c
index c6b64a48dea6..180842ba8473 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2181,38 +2181,11 @@ static bool is_orphaned_event(struct perf_event *event)
return event->state == PERF_EVENT_STATE_DEAD;
}

-static inline int __pmu_filter_match(struct perf_event *event)
-{
- struct pmu *pmu = event->pmu;
- return pmu->filter_match ? pmu->filter_match(event) : 1;
-}
-
-/*
- * Check whether we should attempt to schedule an event group based on
- * PMU-specific filtering. An event group can consist of HW and SW events,
- * potentially with a SW leader, so we must check all the filters, to
- * determine whether a group is schedulable:
- */
-static inline int pmu_filter_match(struct perf_event *event)
-{
- struct perf_event *sibling;
-
- if (!__pmu_filter_match(event))
- return 0;
-
- for_each_sibling_event(sibling, event) {
- if (!__pmu_filter_match(sibling))
- return 0;
- }
-
- return 1;
-}
-
static inline int
event_filter_match(struct perf_event *event)
{
return (event->cpu == -1 || event->cpu == smp_processor_id()) &&
- perf_cgroup_match(event) && pmu_filter_match(event);
+ perf_cgroup_match(event);
}

static void
@@ -3661,6 +3634,9 @@ static noinline int visit_groups_merge(struct perf_event_context *ctx,
struct perf_event **evt;
int ret;

+ if (pmu->filter && pmu->filter(pmu, cpu))
+ return 0;
+
if (!ctx->task) {
cpuctx = this_cpu_ptr(&cpu_context);
event_heap = (struct min_heap){