Revert "perf/x86/intel, watchdog: Switch NMI watchdog to ref cycles on x86"

This reverts commit 2c95afc1e83d93fac3be6923465e1753c2c53b0a.

Stephane reported the following regression:

 > Since Andi added:
 >
 > commit 2c95afc1e83d93fac3be6923465e1753c2c53b0a
 > Author: Andi Kleen <[email protected]>
 > Date:   Thu Jun 9 06:14:38 2016 -0700
 >
 >    perf/x86/intel, watchdog: Switch NMI watchdog to ref cycles on x86
 >
 > $ perf stat -e ref-cycles ls
 >   <not counted> ....
 >
 > fails systematically because the ref-cycles is now used by the
 > watchdog and given this is a system-wide pinned event, it monopolizes
 > the fixed counter 2 which is the only counter able to measure this event.

Since the next merge window is near, fix the regression for now
by reverting the commit.

Reported-by: Stephane Eranian <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Vince Weaver <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Signed-off-by: Ingo Molnar <[email protected]>

1 files changed, 0 insertions, 7 deletions

diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 8dd30fcd91be..9acb29f280ec 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -315,12 +315,6 @@ static int is_softlockup(unsigned long touch_ts)
 
 #ifdef CONFIG_HARDLOCKUP_DETECTOR
 
-/* Can be overriden by architecture */
-__weak int hw_nmi_get_event(void)
-{
-	return PERF_COUNT_HW_CPU_CYCLES;
-}
-
 static struct perf_event_attr wd_hw_attr = {
 	.type		= PERF_TYPE_HARDWARE,
 	.config		= PERF_COUNT_HW_CPU_CYCLES,
@@ -610,7 +604,6 @@ static int watchdog_nmi_enable(unsigned int cpu)
 
 	wd_attr = &wd_hw_attr;
 	wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh);
-	wd_attr->config = hw_nmi_get_event();
 
 	/* Try to register using hardware perf events */
 	event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL);