Commit 8e5799b1 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

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: default avatarStephane Eranian <eranian@googlemail.com>
Signed-off-by: default avatarPeter 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: default avatarIngo Molnar <mingo@elte.hu>
parent 53e111a7

include/linux/perf_counter.h

+5 −3
Original line number Diff line number Diff line
@@ -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

};

kernel/perf_counter.c

+7 −2
Original line number Diff line number Diff line
@@ -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);

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