[tip:perfcounters/core] perf_counter: Add unique counter id

tip-bot for Peter Zijlstra
2009-06-02T20:16:53Z

Commit-ID: 8e5799b1ad2a0567fdfaaf0e91b40efee010f2c1
Gitweb: http://git.kernel.org/tip/8e5799b1ad2a0567fdfaaf0e91b40efee010f2c1
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Tue, 2 Jun 2009 15:08:15 +0200
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Tue, 2 Jun 2009 21:45:29 +0200

perf_counter: Add unique counter id

Stephan raised the issue that we currently cannot distinguish between
similar counters within a group (PERF_RECORD_GROUP uses the config
value as identifier).

Therefore, generate a new ID for each counter using a global u64
sequence counter.

Reported-by: Stephane Eranian <eranian@googlemail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

---
include/linux/perf_counter.h | 8 +++++---
kernel/perf_counter.c | 9 +++++++--
2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 9ec20fc..4845a21 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -114,8 +114,9 @@ enum perf_counter_record_format {
* in increasing order of bit value, after the counter value.
*/
enum perf_counter_read_format {
- PERF_FORMAT_TOTAL_TIME_ENABLED = 1,
- PERF_FORMAT_TOTAL_TIME_RUNNING = 2,
+ PERF_FORMAT_TOTAL_TIME_ENABLED = 1U << 0,
+ PERF_FORMAT_TOTAL_TIME_RUNNING = 1U << 1,
+ PERF_FORMAT_ID = 1U << 2,
};

/*
@@ -290,7 +291,7 @@ enum perf_event_type {
* { u32 cpu, res; } && PERF_RECORD_CPU
*
* { u64 nr;
- * { u64 event, val; } cnt[nr]; } && PERF_RECORD_GROUP
+ * { u64 id, val; } cnt[nr]; } && PERF_RECORD_GROUP
*
* { u16 nr,
* hv,
@@ -503,6 +504,7 @@ struct perf_counter {
struct rcu_head rcu_head;

struct pid_namespace *ns;
+ u64 id;
#endif
};

diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index caa012c..978ecfc 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -1510,6 +1510,8 @@ perf_read_hw(struct perf_counter *counter, char __user *buf, size_t count)
if (counter->hw_event.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
values[n++] = counter->total_time_running +
atomic64_read(&counter->child_total_time_running);
+ if (counter->hw_event.read_format & PERF_FORMAT_ID)
+ values[n++] = counter->id;
mutex_unlock(&counter->child_mutex);

if (count < n * sizeof(u64))
@@ -2303,7 +2305,7 @@ static void perf_counter_output(struct perf_counter *counter,
u32 pid, tid;
} tid_entry;
struct {
- u64 event;
+ u64 id;
u64 counter;
} group_entry;
struct perf_callchain_entry *callchain = NULL;
@@ -2416,7 +2418,7 @@ static void perf_counter_output(struct perf_counter *counter,
if (sub != counter)
sub->pmu->read(sub);

- group_entry.event = sub->hw_event.config;
+ group_entry.id = sub->id;
group_entry.counter = atomic64_read(&sub->count);

perf_output_put(&handle, group_entry);
@@ -3375,6 +3377,8 @@ done:
return counter;
}

+static atomic64_t perf_counter_id;
+
/**
* sys_perf_counter_open - open a performance counter, associate it to a task/cpu
*
@@ -3470,6 +3474,7 @@ SYSCALL_DEFINE5(perf_counter_open,
mutex_unlock(&current->perf_counter_mutex);

counter->ns = get_pid_ns(current->nsproxy->pid_ns);
+ counter->id = atomic64_inc_return(&perf_counter_id);

fput_light(counter_file, fput_needed2);