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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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bc078e4eab
Oprofile is currently broken on systems running with NOHZ enabled. A maximum of 1 tick is accounted via the timer_hook if a cpu sleeps for a longer period of time. This does bad things to the percentages in the profiler output. To solve this problem convert oprofile to use a restarting hrtimer instead of the timer_hook. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Robert Richter <robert.richter@amd.com>
107 lines
2.2 KiB
C
107 lines
2.2 KiB
C
/**
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* @file timer_int.c
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*
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* @remark Copyright 2002 OProfile authors
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* @remark Read the file COPYING
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*
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* @author John Levon <levon@movementarian.org>
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*/
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#include <linux/kernel.h>
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#include <linux/notifier.h>
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#include <linux/smp.h>
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#include <linux/oprofile.h>
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#include <linux/profile.h>
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#include <linux/init.h>
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#include <linux/cpu.h>
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#include <linux/hrtimer.h>
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#include <asm/irq_regs.h>
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#include <asm/ptrace.h>
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#include "oprof.h"
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static DEFINE_PER_CPU(struct hrtimer, oprofile_hrtimer);
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static enum hrtimer_restart oprofile_hrtimer_notify(struct hrtimer *hrtimer)
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{
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oprofile_add_sample(get_irq_regs(), 0);
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hrtimer_forward_now(hrtimer, ns_to_ktime(TICK_NSEC));
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return HRTIMER_RESTART;
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}
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static void __oprofile_hrtimer_start(void *unused)
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{
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struct hrtimer *hrtimer = &__get_cpu_var(oprofile_hrtimer);
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hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
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hrtimer->function = oprofile_hrtimer_notify;
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hrtimer_start(hrtimer, ns_to_ktime(TICK_NSEC),
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HRTIMER_MODE_REL_PINNED);
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}
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static int oprofile_hrtimer_start(void)
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{
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on_each_cpu(__oprofile_hrtimer_start, NULL, 1);
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return 0;
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}
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static void __oprofile_hrtimer_stop(int cpu)
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{
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struct hrtimer *hrtimer = &per_cpu(oprofile_hrtimer, cpu);
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hrtimer_cancel(hrtimer);
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}
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static void oprofile_hrtimer_stop(void)
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{
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int cpu;
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for_each_online_cpu(cpu)
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__oprofile_hrtimer_stop(cpu);
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}
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static int __cpuinit oprofile_cpu_notify(struct notifier_block *self,
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unsigned long action, void *hcpu)
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{
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long cpu = (long) hcpu;
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switch (action) {
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case CPU_ONLINE:
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case CPU_ONLINE_FROZEN:
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smp_call_function_single(cpu, __oprofile_hrtimer_start,
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NULL, 1);
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break;
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case CPU_DEAD:
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case CPU_DEAD_FROZEN:
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__oprofile_hrtimer_stop(cpu);
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break;
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}
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return NOTIFY_OK;
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}
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static struct notifier_block __refdata oprofile_cpu_notifier = {
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.notifier_call = oprofile_cpu_notify,
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};
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int __init oprofile_timer_init(struct oprofile_operations *ops)
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{
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int rc;
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rc = register_hotcpu_notifier(&oprofile_cpu_notifier);
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if (rc)
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return rc;
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ops->create_files = NULL;
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ops->setup = NULL;
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ops->shutdown = NULL;
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ops->start = oprofile_hrtimer_start;
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ops->stop = oprofile_hrtimer_stop;
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ops->cpu_type = "timer";
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return 0;
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}
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void __exit oprofile_timer_exit(void)
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{
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unregister_hotcpu_notifier(&oprofile_cpu_notifier);
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}
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