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Subject[PATCH v3 07/12] perf, persistent: Implementing a persistent pmu
Date
From: Robert Richter <robert.richter@linaro.org>

We want to use the kernel's pmu design to later expose persistent
events via sysfs to userland. Initially implement a persistent pmu.

The format syntax is introduced allowing to set bits anywhere in
struct perf_event_attr. This is used in this case to set the
persistent flag (attr5:23). The syntax is attr<num> where num is the
index of the u64 array in struct perf_event_attr. Otherwise syntax is
same as for config<num>.

Patches that implement this functionality for perf tools are sent in a
separate patchset.

Signed-off-by: Robert Richter <robert.richter@linaro.org>
Signed-off-by: Robert Richter <rric@kernel.org>
---
kernel/events/persistent.c | 34 ++++++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)

diff --git a/kernel/events/persistent.c b/kernel/events/persistent.c
index 926654f..ede95ab 100644
--- a/kernel/events/persistent.c
+++ b/kernel/events/persistent.c
@@ -12,6 +12,7 @@ struct pevent {
int id;
};

+static struct pmu persistent_pmu;
static DEFINE_PER_CPU(struct list_head, pevents);
static DEFINE_PER_CPU(struct mutex, pevents_lock);

@@ -210,10 +211,43 @@ int perf_get_persistent_event_fd(int cpu, int id)
return event_fd;
}

+PMU_FORMAT_ATTR(persistent, "attr5:23");
+
+static struct attribute *persistent_format_attrs[] = {
+ &format_attr_persistent.attr,
+ NULL,
+};
+
+static struct attribute_group persistent_format_group = {
+ .name = "format",
+ .attrs = persistent_format_attrs,
+};
+
+static const struct attribute_group *persistent_attr_groups[] = {
+ &persistent_format_group,
+ NULL,
+};
+
+static int persistent_pmu_init(struct perf_event *event)
+{
+ if (persistent_pmu.type != event->attr.type)
+ return -ENOENT;
+
+ /* Not a persistent event. */
+ return -EFAULT;
+}
+
+static struct pmu persistent_pmu = {
+ .event_init = persistent_pmu_init,
+ .attr_groups = persistent_attr_groups,
+};
+
void __init perf_register_persistent(void)
{
int cpu;

+ perf_pmu_register(&persistent_pmu, "persistent", PERF_TYPE_PERSISTENT);
+
for_each_possible_cpu(cpu) {
INIT_LIST_HEAD(&per_cpu(pevents, cpu));
mutex_init(&per_cpu(pevents_lock, cpu));
--
1.8.3.2


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