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Date: Wed, 11 Mar 2015 18:37:09 +0530
From: Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>
To: mpe@...erman.id.au, benh@...nel.crashing.org, paulus@...ba.org
Cc: linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
linuxppc-dev@...abs.org, eranian@...gle.com, ak@...ux.intel.com,
srivatsa@....edu, Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>
Subject: [RFC PATCH 3/7] powerpc/powernv: uncore cpumask and CPU hotplug
Patch to add cpumask attribute for the Nest pmu to
control per-chip counter values to be read by cpus.
Also adds support of cpu hotplug.
Signed-off-by: Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>
---
arch/powerpc/perf/uncore_pmu.c | 152 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 152 insertions(+)
diff --git a/arch/powerpc/perf/uncore_pmu.c b/arch/powerpc/perf/uncore_pmu.c
index cc544d3..67ab6c0 100644
--- a/arch/powerpc/perf/uncore_pmu.c
+++ b/arch/powerpc/perf/uncore_pmu.c
@@ -19,6 +19,32 @@
struct ppc64_uncore_type *empty_uncore[] = { NULL, };
struct ppc64_uncore_type **ppc64_uncore = empty_uncore;
+/* mask of cpus that collect uncore events */
+static cpumask_t uncore_cpu_mask;
+
+static ssize_t uncore_get_attr_cpumask(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return cpumap_print_to_pagebuf(true, buf, &uncore_cpu_mask);
+}
+
+/*
+ * cpumask attr used by perf userspace to pick the cpus to execute
+ * in case of -a option. User can still specify -C option to override.
+ * Since these Nest Counters are per-chip, make only one cpu from chip
+ * to read.
+ */
+static DEVICE_ATTR(cpumask, S_IRUGO, uncore_get_attr_cpumask, NULL);
+
+static struct attribute *uncore_pmu_attrs[] = {
+ &dev_attr_cpumask.attr,
+ NULL,
+};
+
+static struct attribute_group uncore_pmu_attr_group = {
+ .attrs = uncore_pmu_attrs,
+};
+
struct ppc64_uncore_pmu *uncore_event_to_pmu(struct perf_event *event)
{
return container_of(event->pmu, struct ppc64_uncore_pmu, pmu);
@@ -43,6 +69,7 @@ int __init uncore_type_init(struct ppc64_uncore_type *type)
type->name, (int)i);
}
+ type->pmu_group = &uncore_pmu_attr_group;
return 0;
}
@@ -82,6 +109,130 @@ static int __init uncore_pmus_register(void)
return 0;
}
+static void
+uncore_change_context(struct ppc64_uncore_type **uncores,
+ int old_cpu, int new_cpu)
+{
+ struct ppc64_uncore_type *type;
+ struct ppc64_uncore_pmu *pmu;
+ int i, j;
+
+ for (i = 0; uncores[i]; i++) {
+ type = uncores[i];
+ for (j = 0; j < type->num_boxes; j++) {
+ pmu = &type->pmus[j];
+ if (old_cpu < 0)
+ continue;
+ if (new_cpu >= 0) {
+ perf_pmu_migrate_context(&pmu->pmu,
+ old_cpu, new_cpu);
+ }
+ }
+ }
+}
+
+static void uncore_event_init_cpu(int cpu)
+{
+ int i, phys_id;
+
+ phys_id = topology_physical_package_id(cpu);
+ for_each_cpu(i, &uncore_cpu_mask) {
+ if (phys_id == topology_physical_package_id(i))
+ return;
+ }
+
+ cpumask_set_cpu(cpu, &uncore_cpu_mask);
+
+ uncore_change_context(ppc64_uncore, -1, cpu);
+}
+
+static void uncore_event_exit_cpu(int cpu)
+{
+ int i, phys_id, target;
+
+ /* if exiting cpu is used for collecting uncore events */
+ if (!cpumask_test_and_clear_cpu(cpu, &uncore_cpu_mask))
+ return;
+
+ /* find a new cpu to collect uncore events */
+ phys_id = topology_physical_package_id(cpu);
+ target = -1;
+ for_each_online_cpu(i) {
+ if (i == cpu)
+ continue;
+ if (phys_id == topology_physical_package_id(i)) {
+ target = i;
+ break;
+ }
+ }
+
+ /* migrate uncore events to the new cpu */
+ if (target >= 0)
+ cpumask_set_cpu(target, &uncore_cpu_mask);
+
+ uncore_change_context(ppc64_uncore, cpu, target);
+}
+
+static int uncore_cpu_notifier(struct notifier_block *self,
+ unsigned long action, void *hcpu)
+{
+ unsigned int cpu = (long)hcpu;
+
+ /* select the cpu that collects uncore events */
+ switch (action & ~CPU_TASKS_FROZEN) {
+ case CPU_DOWN_FAILED:
+ case CPU_STARTING:
+ uncore_event_init_cpu(cpu);
+ break;
+ case CPU_DOWN_PREPARE:
+ uncore_event_exit_cpu(cpu);
+ break;
+ default:
+ break;
+ }
+
+ return NOTIFY_OK;
+}
+
+static struct notifier_block uncore_cpu_nb = {
+ .notifier_call = uncore_cpu_notifier,
+ /*
+ * to migrate uncore events, our notifier should be executed
+ * before perf core's notifier.
+ */
+ .priority = CPU_PRI_PERF + 1,
+};
+
+static void __init cpumask_per_chip_init(void)
+{
+ int cpu;
+
+ if (!cpumask_empty(&uncore_cpu_mask))
+ return;
+
+ cpu_notifier_register_begin();
+
+ for_each_online_cpu(cpu) {
+ int i, phys_id = topology_physical_package_id(cpu);
+
+ for_each_cpu(i, &uncore_cpu_mask) {
+ if (phys_id == topology_physical_package_id(i)) {
+ phys_id = -1;
+ break;
+ }
+ }
+ if (phys_id < 0)
+ continue;
+
+ uncore_event_init_cpu(cpu);
+ }
+
+ __register_cpu_notifier(&uncore_cpu_nb);
+
+ cpu_notifier_register_done();
+}
+
+
static int __init uncore_init(void)
{
int ret = 0;
@@ -95,6 +246,7 @@ static int __init uncore_init(void)
if (ret)
return ret;
+ cpumask_per_chip_init();
uncore_pmus_register();
return ret;
--
1.9.1
--
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