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>

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 73329de..d810846 100644 (file)
--- 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();
 }