Eric Lee / linux-smarc-t335x-v3.2

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Commit bc078e4eab65f11bbaeed380593ab8151b30d703

Authored by Martin Schwidefsky
Committed by Robert Richter
1 parent cfc9c0b450
Exists in master and in 4 other branches v3.2_AM335xPSP_04.06.00.11, v3.2_NEWT335xPSP_04.06.00.11, v3.2_SBC_SMARTMEN, v3.2_SMARCT335xPSP_04.06.00.11

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>

Showing 3 changed files with 79 additions and 14 deletions Side-by-side Diff

drivers/oprofile/oprof.c
Diff comments   View file @ bc078e4
... ... @@ -253,22 +253,26 @@
253 253 int err;
254 254  
255 255 err = oprofile_arch_init(&oprofile_ops);
256   -
257 256 if (err < 0 || timer) {
258 257 printk(KERN_INFO "oprofile: using timer interrupt.\n");
259   - oprofile_timer_init(&oprofile_ops);
  258 + err = oprofile_timer_init(&oprofile_ops);
  259 + if (err)
  260 + goto out_arch;
260 261 }
261   -
262 262 err = oprofilefs_register();
263 263 if (err)
264   - oprofile_arch_exit();
  264 + goto out_arch;
  265 + return 0;
265 266  
  267 +out_arch:
  268 + oprofile_arch_exit();
266 269 return err;
267 270 }
268 271  
269 272  
270 273 static void __exit oprofile_exit(void)
271 274 {
  275 + oprofile_timer_exit();
272 276 oprofilefs_unregister();
273 277 oprofile_arch_exit();
274 278 }
drivers/oprofile/oprof.h
Diff comments   View file @ bc078e4
... ... @@ -34,7 +34,8 @@
34 34 struct dentry;
35 35  
36 36 void oprofile_create_files(struct super_block *sb, struct dentry *root);
37   -void oprofile_timer_init(struct oprofile_operations *ops);
  37 +int oprofile_timer_init(struct oprofile_operations *ops);
  38 +void oprofile_timer_exit(void);
38 39  
39 40 int oprofile_set_backtrace(unsigned long depth);
40 41 int oprofile_set_timeout(unsigned long time);
drivers/oprofile/timer_int.c
Diff comments   View file @ bc078e4
... ... @@ -13,35 +13,95 @@
13 13 #include <linux/oprofile.h>
14 14 #include <linux/profile.h>
15 15 #include <linux/init.h>
  16 +#include <linux/cpu.h>
  17 +#include <linux/hrtimer.h>
  18 +#include <asm/irq_regs.h>
16 19 #include <asm/ptrace.h>
17 20  
18 21 #include "oprof.h"
19 22  
20   -static int timer_notify(struct pt_regs *regs)
  23 +static DEFINE_PER_CPU(struct hrtimer, oprofile_hrtimer);
  24 +
  25 +static enum hrtimer_restart oprofile_hrtimer_notify(struct hrtimer *hrtimer)
21 26 {
22   - oprofile_add_sample(regs, 0);
  27 + oprofile_add_sample(get_irq_regs(), 0);
  28 + hrtimer_forward_now(hrtimer, ns_to_ktime(TICK_NSEC));
  29 + return HRTIMER_RESTART;
  30 +}
  31 +
  32 +static void __oprofile_hrtimer_start(void *unused)
  33 +{
  34 + struct hrtimer *hrtimer = &__get_cpu_var(oprofile_hrtimer);
  35 +
  36 + hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
  37 + hrtimer->function = oprofile_hrtimer_notify;
  38 +
  39 + hrtimer_start(hrtimer, ns_to_ktime(TICK_NSEC),
  40 + HRTIMER_MODE_REL_PINNED);
  41 +}
  42 +
  43 +static int oprofile_hrtimer_start(void)
  44 +{
  45 + on_each_cpu(__oprofile_hrtimer_start, NULL, 1);
23 46 return 0;
24 47 }
25 48  
26   -static int timer_start(void)
  49 +static void __oprofile_hrtimer_stop(int cpu)
27 50 {
28   - return register_timer_hook(timer_notify);
  51 + struct hrtimer *hrtimer = &per_cpu(oprofile_hrtimer, cpu);
  52 +
  53 + hrtimer_cancel(hrtimer);
29 54 }
30 55  
  56 +static void oprofile_hrtimer_stop(void)
  57 +{
  58 + int cpu;
31 59  
32   -static void timer_stop(void)
  60 + for_each_online_cpu(cpu)
  61 + __oprofile_hrtimer_stop(cpu);
  62 +}
  63 +
  64 +static int __cpuinit oprofile_cpu_notify(struct notifier_block *self,
  65 + unsigned long action, void *hcpu)
33 66 {
34   - unregister_timer_hook(timer_notify);
  67 + long cpu = (long) hcpu;
  68 +
  69 + switch (action) {
  70 + case CPU_ONLINE:
  71 + case CPU_ONLINE_FROZEN:
  72 + smp_call_function_single(cpu, __oprofile_hrtimer_start,
  73 + NULL, 1);
  74 + break;
  75 + case CPU_DEAD:
  76 + case CPU_DEAD_FROZEN:
  77 + __oprofile_hrtimer_stop(cpu);
  78 + break;
  79 + }
  80 + return NOTIFY_OK;
35 81 }
36 82  
  83 +static struct notifier_block __refdata oprofile_cpu_notifier = {
  84 + .notifier_call = oprofile_cpu_notify,
  85 +};
37 86  
38   -void __init oprofile_timer_init(struct oprofile_operations *ops)
  87 +int __init oprofile_timer_init(struct oprofile_operations *ops)
39 88 {
  89 + int rc;
  90 +
  91 + rc = register_hotcpu_notifier(&oprofile_cpu_notifier);
  92 + if (rc)
  93 + return rc;
40 94 ops->create_files = NULL;
41 95 ops->setup = NULL;
42 96 ops->shutdown = NULL;
43   - ops->start = timer_start;
44   - ops->stop = timer_stop;
  97 + ops->start = oprofile_hrtimer_start;
  98 + ops->stop = oprofile_hrtimer_stop;
45 99 ops->cpu_type = "timer";
  100 + return 0;
  101 +}
  102 +
  103 +void __exit oprofile_timer_exit(void)
  104 +{
  105 + unregister_hotcpu_notifier(&oprofile_cpu_notifier);
46 106 }