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 <ak@linux.intel.com>
> 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 <eranian@google.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/arch/x86/kernel/apic/hw_nmi.c b/arch/x86/kernel/apic/hw_nmi.c
index 016f426..7788ce6 100644
--- a/arch/x86/kernel/apic/hw_nmi.c
+++ b/arch/x86/kernel/apic/hw_nmi.c
@@ -18,16 +18,8 @@
#include <linux/nmi.h>
#include <linux/module.h>
#include <linux/delay.h>
-#include <linux/perf_event.h>
#ifdef CONFIG_HARDLOCKUP_DETECTOR
-int hw_nmi_get_event(void)
-{
- if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
- return PERF_COUNT_HW_REF_CPU_CYCLES;
- return PERF_COUNT_HW_CPU_CYCLES;
-}
-
u64 hw_nmi_get_sample_period(int watchdog_thresh)
{
return (u64)(cpu_khz) * 1000 * watchdog_thresh;
diff --git a/include/linux/nmi.h b/include/linux/nmi.h
index 79858af..4630eea 100644
--- a/include/linux/nmi.h
+++ b/include/linux/nmi.h
@@ -66,7 +66,6 @@
#ifdef CONFIG_LOCKUP_DETECTOR
u64 hw_nmi_get_sample_period(int watchdog_thresh);
-int hw_nmi_get_event(void);
extern int nmi_watchdog_enabled;
extern int soft_watchdog_enabled;
extern int watchdog_user_enabled;
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 8dd30fcd..9acb29f 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -315,12 +315,6 @@
#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 @@
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);