From: Robert Richter robert.richter@linaro.org
Expose persistent events in the system to userland using sysfs. Perf tools are able to read existing pmu events from sysfs. Now we use a persistent pmu as an event container containing all registered persistent events of the system. This patch adds dynamically registration of persistent events to sysfs. E.g. something like this:
/sys/bus/event_source/devices/persistent/events/mce_record:persistent,config=106 /sys/bus/event_source/devices/persistent/format/persistent:attr5:23
Perf tools need to support the attr<num> syntax that is added in a separate patch set. With it we are able to run perf tool commands to read persistent events, e.g.:
# perf record -e persistent/mce_record/ sleep 10 # perf top -e persistent/mce_record/
[ Jiri: Document attr<index> syntax in sysfs ABI ] [ Namhyung: Fix sysfs registration with lockdep enabled ] Cc: Jiri Olsa jolsa@redhat.com Cc: Namhyung Kim namhyung@kernel.org Signed-off-by: Robert Richter robert.richter@linaro.org Signed-off-by: Robert Richter rric@kernel.org --- .../testing/sysfs-bus-event_source-devices-format | 43 ++++++++++++---- kernel/events/persistent.c | 60 ++++++++++++++++++++++ 2 files changed, 92 insertions(+), 11 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-bus-event_source-devices-format b/Documentation/ABI/testing/sysfs-bus-event_source-devices-format index 77f47ff..2dbb911 100644 --- a/Documentation/ABI/testing/sysfs-bus-event_source-devices-format +++ b/Documentation/ABI/testing/sysfs-bus-event_source-devices-format @@ -1,13 +1,14 @@ -Where: /sys/bus/event_source/devices/<dev>/format +Where: /sys/bus/event_source/devices/<pmu>/format/<name> Date: January 2012 -Kernel Version: 3.3 +Kernel Version: 3.3 + 3.xx (added attr<index>:<bits>) Contact: Jiri Olsa jolsa@redhat.com -Description: - Attribute group to describe the magic bits that go into - perf_event_attr::config[012] for a particular pmu. - Each attribute of this group defines the 'hardware' bitmask - we want to export, so that userspace can deal with sane - name/value pairs. + +Description: Define formats for bit ranges in perf_event_attr + + Attribute group to describe the magic bits that go + into struct perf_event_attr for a particular pmu. Bit + range may be any bit mask of an u64 (bits 0 to 63).
Userspace must be prepared for the possibility that attributes define overlapping bit ranges. For example: @@ -15,6 +16,26 @@ Contact: Jiri Olsa jolsa@redhat.com attr2 = 'config:0-7' attr3 = 'config:12-35'
- Example: 'config1:1,6-10,44' - Defines contents of attribute that occupies bits 1,6-10,44 of - perf_event_attr::config1. + Syntax Description + + config[012]*:<bits> Each attribute of this group + defines the 'hardware' bitmask + we want to export, so that + userspace can deal with sane + name/value pairs. + + attr<index>:<bits> Set any field of the event + attribute. The index is a + decimal number that specifies + the u64 value to be set within + struct perf_event_attr. + + Examples: + + 'config1:1,6-10,44' Defines contents of attribute + that occupies bits 1,6-10,44 + of perf_event_attr::config1. + + 'attr5:23' Define the persistent event + flag (bit 23 of the attribute + flags) diff --git a/kernel/events/persistent.c b/kernel/events/persistent.c index ede95ab..aca1e98 100644 --- a/kernel/events/persistent.c +++ b/kernel/events/persistent.c @@ -8,6 +8,7 @@ #define CPU_BUFFER_NR_PAGES ((512 * 1024) / PAGE_SIZE)
struct pevent { + struct perf_pmu_events_attr sysfs; char *name; int id; }; @@ -119,6 +120,8 @@ static void persistent_event_close(int cpu, struct pevent *pevent) persistent_event_release(event); }
+static int pevent_sysfs_register(struct pevent *event); + static int __maybe_unused persistent_open(char *name, struct perf_event_attr *attr, int nr_pages) { @@ -144,12 +147,18 @@ persistent_open(char *name, struct perf_event_attr *attr, int nr_pages) goto fail; }
+ pevent->sysfs.id = pevent->id; + for_each_possible_cpu(cpu) { ret = persistent_event_open(cpu, pevent, attr, nr_pages); if (ret) goto fail; }
+ ret = pevent_sysfs_register(pevent); + if (ret) + goto fail; + return 0; fail: for_each_possible_cpu(cpu) @@ -223,10 +232,61 @@ static struct attribute_group persistent_format_group = { .attrs = persistent_format_attrs, };
+#define MAX_EVENTS 16 + +static struct attribute *pevents_attr[MAX_EVENTS + 1] = { }; + +static struct attribute_group pevents_group = { + .name = "events", + .attrs = pevents_attr, +}; + static const struct attribute_group *persistent_attr_groups[] = { &persistent_format_group, + NULL, /* placeholder: &pevents_group */ NULL, }; +#define EVENTS_GROUP_PTR (&persistent_attr_groups[1]) + +static ssize_t pevent_sysfs_show(struct device *dev, + struct device_attribute *__attr, char *page) +{ + struct perf_pmu_events_attr *attr = + container_of(__attr, struct perf_pmu_events_attr, attr); + return sprintf(page, "persistent,config=%lld", + (unsigned long long)attr->id); +} + +static int pevent_sysfs_register(struct pevent *pevent) +{ + struct perf_pmu_events_attr *sysfs = &pevent->sysfs; + struct attribute *attr = &sysfs->attr.attr; + struct device *dev = persistent_pmu.dev; + const struct attribute_group **group = EVENTS_GROUP_PTR; + int idx; + + sysfs->id = pevent->id; + sysfs->attr = (struct device_attribute) + __ATTR(, 0444, pevent_sysfs_show, NULL); + attr->name = pevent->name; + sysfs_attr_init(attr); + + /* add sysfs attr to events: */ + for (idx = 0; idx < MAX_EVENTS; idx++) { + if (!cmpxchg(pevents_attr + idx, NULL, attr)) + break; + } + + if (idx >= MAX_EVENTS) + return -ENOSPC; + if (!idx) + *group = &pevents_group; + if (!dev) + return 0; /* sysfs not yet initialized */ + if (idx) + return sysfs_add_file_to_group(&dev->kobj, attr, (*group)->name); + return sysfs_create_group(&persistent_pmu.dev->kobj, *group); +}
static int persistent_pmu_init(struct perf_event *event) {