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Subject[RFC][PATCH v2 02/11] perf: core, add pmu register and lookup functions
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And add new api pmu::init_event

Changes log
v2: Use RCU for synchronization (Peter Zijlstra)
v1: add pmu register and lookup functions

Signed-off-by: Lin Ming <ming.m.lin@intel.com>
---
include/linux/perf_event.h | 11 ++++++
kernel/perf_event.c | 73 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 84 insertions(+), 0 deletions(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 6c01c5f..40809f5 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -549,10 +549,16 @@ struct perf_event;

#define PERF_EVENT_TXN_STARTED 1

+#define PMU_TYPE_CPU 0
+#define PMU_TYPE_NODE 1
+
/**
* struct pmu - generic performance monitoring unit
*/
struct pmu {
+ int id;
+ struct list_head entry;
+
int (*enable) (struct perf_event *event);
void (*disable) (struct perf_event *event);
int (*start) (struct perf_event *event);
@@ -569,6 +575,8 @@ struct pmu {
void (*start_txn) (struct pmu *pmu);
void (*cancel_txn) (struct pmu *pmu);
int (*commit_txn) (struct pmu *pmu);
+
+ int (*init_event) (struct perf_event *event);
};

/**
@@ -1013,6 +1021,9 @@ extern int perf_swevent_get_recursion_context(void);
extern void perf_swevent_put_recursion_context(int rctx);
extern void perf_event_enable(struct perf_event *event);
extern void perf_event_disable(struct perf_event *event);
+
+extern int perf_event_register_pmu(struct pmu *pmu);
+extern void perf_event_unregister_pmu(int id);
#else
static inline void
perf_event_task_sched_in(struct task_struct *task) { }
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index ba7a37a..31b032b 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -40,6 +40,12 @@
*/
static DEFINE_PER_CPU(struct perf_cpu_context, perf_cpu_context);

+/*
+ * The list of multiple hw pmus
+ */
+static struct list_head pmus;
+static DEFINE_SPINLOCK(pmus_lock);
+
int perf_max_events __read_mostly = 1;
static int perf_reserved_percpu __read_mostly;
static int perf_overcommit __read_mostly = 1;
@@ -4678,6 +4684,34 @@ static struct pmu *sw_perf_event_init(struct perf_event *event)
return pmu;
}

+static struct pmu *perf_event_lookup_pmu(struct perf_event *event)
+{
+ struct pmu *pmu = NULL;
+ int pmu_id = event->attr.type;
+
+ switch (event->attr.type) {
+ case PERF_TYPE_HARDWARE:
+ case PERF_TYPE_HW_CACHE:
+ case PERF_TYPE_RAW:
+ pmu_id = PMU_TYPE_CPU;
+ break;
+
+ /* TBD: will add other pmu type later */
+
+ default:
+ return NULL;
+ }
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(pmu, &pmus, entry) {
+ if (pmu->id == pmu_id)
+ break;
+ }
+ rcu_read_unlock();
+
+ return pmu;
+}
+
/*
* Allocate and initialize a event structure
*/
@@ -5635,6 +5669,8 @@ void __init perf_event_init(void)
perf_cpu_notify(&perf_cpu_nb, (unsigned long)CPU_ONLINE,
(void *)(long)smp_processor_id());
register_cpu_notifier(&perf_cpu_nb);
+
+ INIT_LIST_HEAD(&pmus);
}

static ssize_t perf_show_reserve_percpu(struct sysdev_class *class,
@@ -5734,3 +5770,40 @@ static int __init perf_event_sysfs_init(void)
&perfclass_attr_group);
}
device_initcall(perf_event_sysfs_init);
+
+int perf_event_register_pmu(struct pmu *pmu)
+{
+ struct pmu *tmp;
+ int ret = 1;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(tmp, &pmus, entry) {
+ if (tmp->id == pmu->id) {
+ ret = 0;
+ goto err;
+ }
+ }
+ rcu_read_unlock();
+
+ spin_lock(&pmus_lock);
+ list_add_tail_rcu(&pmu->entry, &pmus);
+ spin_unlock(&pmus_lock);
+
+err:
+ return ret;
+}
+
+void perf_event_unregister_pmu(int id)
+{
+ struct pmu *tmp = NULL;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(tmp, &pmus, entry) {
+ if (tmp->id == id)
+ break;
+ }
+ rcu_read_unlock();
+
+ if (tmp)
+ list_del_rcu(&tmp->entry);
+}





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