Commit-ID: 44530d588e142a96cf0cd345a7cb8911c4f88720
Gitweb: http://git.kernel.org/tip/44530d588e142a96cf0cd345a7cb8911c4f88720
Author: Ingo Molnar <mingo@xxxxxxxxxx>
AuthorDate: Sun, 10 Jul 2016 20:58:36 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Sun, 10 Jul 2016 20:58:36 +0200
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@xxxxxxxxxxxxxxx>
> 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@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Vince Weaver <vincent.weaver@xxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/kernel/apic/hw_nmi.c | 8 --------
include/linux/nmi.h | 1 -
kernel/watchdog.c | 7 -------
3 files changed, 16 deletions(-)
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 @@ static inline bool trigger_allbutself_cpu_backtrace(void)
#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 @@ 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);
--
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