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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: Peter 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: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2009-04-09 10:53:44 +02:00 committed by Ingo Molnar
parent b3828ebb39
commit 9ee318a782
1 changed files with 36 additions and 3 deletions
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39
kernel/perf_counter.c
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@ -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 @@ got_name:
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 @@ done:
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;
}