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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2010-03-02 16:01:10 +0100
committerRobert Richter <robert.richter@amd.com>2010-03-02 17:03:20 +0100
commitbc078e4eab65f11bbaeed380593ab8151b30d703 (patch)
tree8d61457355fad4e5b5938cd7c01a1dd379778789
parentcfc9c0b450176a077205ef39092f0dc1a04e020a (diff)
downloadop-kernel-dev-bc078e4eab65f11bbaeed380593ab8151b30d703.zip
op-kernel-dev-bc078e4eab65f11bbaeed380593ab8151b30d703.tar.gz
oprofile: convert oprofile from timer_hook to hrtimer
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>
-rw-r--r--drivers/oprofile/oprof.c12
-rw-r--r--drivers/oprofile/oprof.h3
-rw-r--r--drivers/oprofile/timer_int.c78
3 files changed, 79 insertions, 14 deletions
diff --git a/drivers/oprofile/oprof.c b/drivers/oprofile/oprof.c
index dc8a042..b336cd9 100644
--- a/drivers/oprofile/oprof.c
+++ b/drivers/oprofile/oprof.c
@@ -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();
}
diff --git a/drivers/oprofile/oprof.h b/drivers/oprofile/oprof.h
index cb92f5c..47e12cb 100644
--- a/drivers/oprofile/oprof.h
+++ b/drivers/oprofile/oprof.h
@@ -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);
diff --git a/drivers/oprofile/timer_int.c b/drivers/oprofile/timer_int.c
index 333f915..dc0ae4d 100644
--- a/drivers/oprofile/timer_int.c
+++ b/drivers/oprofile/timer_int.c
@@ -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(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)
{
- oprofile_add_sample(regs, 0);
+ 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 oprofile_hrtimer_stop(void)
+{
+ int cpu;
+
+ for_each_online_cpu(cpu)
+ __oprofile_hrtimer_stop(cpu);
+}
-static void timer_stop(void)
+static int __cpuinit oprofile_cpu_notify(struct notifier_block *self,
+ unsigned long action, void *hcpu)
{
- unregister_timer_hook(timer_notify);
+ 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,
+};
-void __init oprofile_timer_init(struct oprofile_operations *ops)
+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);
}
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