[tip:perf/urgent] perf: Optimize perf_disable

tip-bot for Peter Zijlstra
2010-03-10T13:10:56Z

Commit-ID: 32975a4f114be52286f9a5bf6c230dbb8c0e1903
Gitweb: http://git.kernel.org/tip/32975a4f114be52286f9a5bf6c230dbb8c0e1903
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Sat, 6 Mar 2010 19:49:19 +0100
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 10 Mar 2010 13:22:25 +0100

perf: Optimize perf_disable

Currently we always call hw_perf_disable(), even if its already disabled,
this seems superflous, esp. since it cannot be made NMI safe (see further
patches).

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: paulus@samba.org
Cc: eranian@google.com
Cc: robert.richter@amd.com
Cc: fweisbec@gmail.com
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
kernel/perf_event.c | 16 +++-------------
1 files changed, 3 insertions(+), 13 deletions(-)

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 73329de..d810846 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -93,25 +93,15 @@ void __weak perf_event_print_debug(void) { }

static DEFINE_PER_CPU(int, perf_disable_count);

-void __perf_disable(void)
-{
- __get_cpu_var(perf_disable_count)++;
-}
-
-bool __perf_enable(void)
-{
- return !--__get_cpu_var(perf_disable_count);
-}
-
void perf_disable(void)
{
- __perf_disable();
- hw_perf_disable();
+ if (!__get_cpu_var(perf_disable_count)++)
+ hw_perf_disable();
}

void perf_enable(void)
{
- if (__perf_enable())
+ if (!--__get_cpu_var(perf_disable_count))
hw_perf_enable();
}