Revert "perf/x86/intel, watchdog: Switch NMI watchdog to ref cycles on x86" (44530d58) · Commits · 戴 / test

This reverts commit . Stephane reported the following regression: > Since Andi added: > > commit > 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>

arch/x86/kernel/apic/hw_nmi.c

+0 −8

Original line number	Diff line number	Diff line
		@@ -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;

include/linux/nmi.h

+0 −1

Original line number	Diff line number	Diff line
		@@ -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;

kernel/watchdog.c

+0 −7

Original line number	Diff line number	Diff line
		@@ -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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