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oprofile: convert oprofile from timer_hook to hrtimer

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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>
This commit is contained in:
Martin Schwidefsky 2010-03-02 16:01:10 +01:00 committed by Robert Richter
parent cfc9c0b450
commit bc078e4eab
3 changed files with 81 additions and 16 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

12
drivers/oprofile/oprof.c
View file

@ -253,22 +253,26 @@ static int __init oprofile_init(void)
int err;
err = oprofile_arch_init(&oprofile_ops);
if (err < 0 || timer) {
printk(KERN_INFO "oprofile: using timer interrupt.\n");
oprofile_timer_init(&oprofile_ops);
err = oprofile_timer_init(&oprofile_ops);
if (err)
goto out_arch;
}
err = oprofilefs_register();
if (err)
oprofile_arch_exit();
goto out_arch;
return 0;
out_arch:
oprofile_arch_exit();
return err;
}
static void __exit oprofile_exit(void)
{
oprofile_timer_exit();
oprofilefs_unregister();
oprofile_arch_exit();
}

3
drivers/oprofile/oprof.h
View file

@ -34,7 +34,8 @@ struct super_block;
struct dentry;
void oprofile_create_files(struct super_block *sb, struct dentry *root);
void oprofile_timer_init(struct oprofile_operations *ops);
int oprofile_timer_init(struct oprofile_operations *ops);
void oprofile_timer_exit(void);
int oprofile_set_backtrace(unsigned long depth);
int oprofile_set_timeout(unsigned long time);

82
drivers/oprofile/timer_int.c
View file

@ -13,34 +13,94 @@
#include <linux/oprofile.h>
#include <linux/profile.h>
#include <linux/init.h>
#include <linux/cpu.h>
#include <linux/hrtimer.h>
#include <asm/irq_regs.h>
#include <asm/ptrace.h>
#include "oprof.h"
static int timer_notify(struct pt_regs *regs)
static DEFINE_PER_CPU(struct hrtimer, oprofile_hrtimer);
static enum hrtimer_restart oprofile_hrtimer_notify(struct hrtimer *hrtimer)
{
oprofile_add_sample(regs, 0);
oprofile_add_sample(get_irq_regs(), 0);
hrtimer_forward_now(hrtimer, ns_to_ktime(TICK_NSEC));
return HRTIMER_RESTART;
}
static void __oprofile_hrtimer_start(void *unused)
{
struct hrtimer *hrtimer = &__get_cpu_var(oprofile_hrtimer);
hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
hrtimer->function = oprofile_hrtimer_notify;
hrtimer_start(hrtimer, ns_to_ktime(TICK_NSEC),
HRTIMER_MODE_REL_PINNED);
}
static int oprofile_hrtimer_start(void)
{
on_each_cpu(__oprofile_hrtimer_start, NULL, 1);
return 0;
}
static int timer_start(void)
static void __oprofile_hrtimer_stop(int cpu)
{
return register_timer_hook(timer_notify);
struct hrtimer *hrtimer = &per_cpu(oprofile_hrtimer, cpu);
hrtimer_cancel(hrtimer);
}
static void timer_stop(void)
static void oprofile_hrtimer_stop(void)
{
unregister_timer_hook(timer_notify);
int cpu;
for_each_online_cpu(cpu)
__oprofile_hrtimer_stop(cpu);
}
void __init oprofile_timer_init(struct oprofile_operations *ops)
static int __cpuinit oprofile_cpu_notify(struct notifier_block *self,
unsigned long action, void *hcpu)
{
long cpu = (long) hcpu;
switch (action) {
case CPU_ONLINE:
case CPU_ONLINE_FROZEN:
smp_call_function_single(cpu, __oprofile_hrtimer_start,
NULL, 1);
break;
case CPU_DEAD:
case CPU_DEAD_FROZEN:
__oprofile_hrtimer_stop(cpu);
break;
}
return NOTIFY_OK;
}
static struct notifier_block __refdata oprofile_cpu_notifier = {
.notifier_call = oprofile_cpu_notify,
};
int __init oprofile_timer_init(struct oprofile_operations *ops)
{
int rc;
rc = register_hotcpu_notifier(&oprofile_cpu_notifier);
if (rc)
return rc;
ops->create_files = NULL;
ops->setup = NULL;
ops->shutdown = NULL;
ops->start = timer_start;
ops->stop = timer_stop;
ops->start = oprofile_hrtimer_start;
ops->stop = oprofile_hrtimer_stop;
ops->cpu_type = "timer";
return 0;
}
void __exit oprofile_timer_exit(void)
{
unregister_hotcpu_notifier(&oprofile_cpu_notifier);
}