Commit-ID: 9ee318a7825929bc3734110b83ae8e20e53d9de3
Gitweb: http://git.kernel.org/tip/9ee318a7825929bc3734110b83ae8e20e53d9de3
Author: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
AuthorDate: Thu, 9 Apr 2009 10:53:44 +0200
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Thu, 9 Apr 2009 11:50:43 +0200
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@xxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Corey Ashford <cjashfor@xxxxxxxxxxxxxxxxxx>
LKML-Reference: <20090409085524.427173196@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
kernel/perf_counter.c | 39 ++++++++++++++++++++++++++++++++++++---
1 files changed, 36 insertions(+), 3 deletions(-)
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index b07195b..76376ec 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -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;
}
--
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