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Commit 9ee318a7 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf_counter: optimize mmap/comm tracking 



Impact: performance optimization

The mmap/comm tracking code does quite a lot of work before it discovers
there's no interest in it, avoid that by keeping a counter.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090409085524.427173196@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent b3828ebb

kernel/perf_counter.c

+36 −3
Original line number Diff line number Diff line
@@ -38,6 +38,10 @@ int perf_max_counters __read_mostly = 1; 
static int perf_reserved_percpu __read_mostly;

static int perf_overcommit __read_mostly = 1;



static atomic_t nr_mmap_tracking __read_mostly;

static atomic_t nr_munmap_tracking __read_mostly;

static atomic_t nr_comm_tracking __read_mostly;



/*

 * Mutex for (sysadmin-configurable) counter reservations:

 */
@@ -1186,6 +1190,13 @@ static void free_counter(struct perf_counter *counter) 
{

	perf_pending_sync(counter);



	if (counter->hw_event.mmap)

		atomic_dec(&nr_mmap_tracking);

	if (counter->hw_event.munmap)

		atomic_dec(&nr_munmap_tracking);

	if (counter->hw_event.comm)

		atomic_dec(&nr_comm_tracking);



	if (counter->destroy)

		counter->destroy(counter);
@@ -2005,7 +2016,12 @@ static void perf_counter_comm_event(struct perf_comm_event *comm_event) 


void perf_counter_comm(struct task_struct *task)

{

	struct perf_comm_event comm_event = {

	struct perf_comm_event comm_event;



	if (!atomic_read(&nr_comm_tracking))

		return;

       

	comm_event = (struct perf_comm_event){

		.task	= task,

		.event  = {

			.header = { .type = PERF_EVENT_COMM, },
@@ -2128,7 +2144,12 @@ static void perf_counter_mmap_event(struct perf_mmap_event *mmap_event) 
void perf_counter_mmap(unsigned long addr, unsigned long len,

		       unsigned long pgoff, struct file *file)

{

	struct perf_mmap_event mmap_event = {

	struct perf_mmap_event mmap_event;



	if (!atomic_read(&nr_mmap_tracking))

		return;



	mmap_event = (struct perf_mmap_event){

		.file   = file,

		.event  = {

			.header = { .type = PERF_EVENT_MMAP, },
@@ -2146,7 +2167,12 @@ void perf_counter_mmap(unsigned long addr, unsigned long len, 
void perf_counter_munmap(unsigned long addr, unsigned long len,

			 unsigned long pgoff, struct file *file)

{

	struct perf_mmap_event mmap_event = {

	struct perf_mmap_event mmap_event;



	if (!atomic_read(&nr_munmap_tracking))

		return;



	mmap_event = (struct perf_mmap_event){

		.file   = file,

		.event  = {

			.header = { .type = PERF_EVENT_MUNMAP, },
@@ -2725,6 +2751,13 @@ perf_counter_alloc(struct perf_counter_hw_event *hw_event, 


	counter->hw_ops = hw_ops;



	if (counter->hw_event.mmap)

		atomic_inc(&nr_mmap_tracking);

	if (counter->hw_event.munmap)

		atomic_inc(&nr_munmap_tracking);

	if (counter->hw_event.comm)

		atomic_inc(&nr_comm_tracking);



	return counter;

}