src/patches/suse-2.6.27.31/patches.arch/x86-mce-make-polling-timer-interval-per-cpu

   1 From: Andi Kleen <andi@firstfloor.org>
   2 Date: Thu, 9 Apr 2009 10:28:22 +0000 (+0200)
   3 Subject: x86, mce: make polling timer interval per CPU
   4 Patch-mainline: v2.6.30-rc5~52^2~1
   5 Git-commit: 6298c512bc1007c3ff5c9ce20e6996781651cc45
   6 References: bnc#507557
   7
   8 x86, mce: make polling timer interval per CPU
   9
  10 The polling timer while running per CPU still uses a global next_interval
  11 variable, which lead to some CPUs either polling too fast or too slow.
  12 This was not a serious problem because all errors get picked up eventually,
  13 but it's still better to avoid it. Turn next_interval into a per cpu variable.
  14
  15 v2: Fix check_interval == 0 case (Hidetoshi Seto)
  16
  17 [ Impact: minor bug fix ]
  18
  19 Signed-off-by: Andi Kleen <ak@linux.intel.com>
  20 Reviewed-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
  21 Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
  22 Acked-by: Jeff Mahoney <jeffm@suse.com>
  23 ---
  24  arch/x86/kernel/cpu/mcheck/mce_64.c |   24 ++++++++++++------------
  25  1 file changed, 12 insertions(+), 12 deletions(-)
  26
  27 --- a/arch/x86/kernel/cpu/mcheck/mce_64.c
  28 +++ b/arch/x86/kernel/cpu/mcheck/mce_64.c
  29 @@ -352,13 +352,14 @@ void mce_log_therm_throt_event(unsigned
  30   */
  31
  32  static int check_interval = 5 * 60; /* 5 minutes */
  33 -static int next_interval; /* in jiffies */
  34 +static DEFINE_PER_CPU(int, next_interval); /* in jiffies */
  35  static void mcheck_timer(unsigned long);
  36  static DEFINE_PER_CPU(struct timer_list, mce_timer);
  37
  38  static void mcheck_timer(unsigned long data)
  39  {
  40         struct timer_list *t = &per_cpu(mce_timer, data);
  41 +       int *n;
  42
  43         WARN_ON(smp_processor_id() != data);
  44
  45 @@ -369,14 +370,14 @@ static void mcheck_timer(unsigned long d
  46          * Alert userspace if needed.  If we logged an MCE, reduce the
  47          * polling interval, otherwise increase the polling interval.
  48          */
  49 +       n = &__get_cpu_var(next_interval);
  50         if (mce_notify_user()) {
  51 -               next_interval = max(next_interval/2, HZ/100);
  52 +               *n = max(*n/2, HZ/100);
  53         } else {
  54 -               next_interval = min(next_interval * 2,
  55 -                               (int)round_jiffies_relative(check_interval*HZ));
  56 +               *n = min(*n*2, (int)round_jiffies_relative(check_interval*HZ));
  57         }
  58
  59 -       t->expires = jiffies + next_interval;
  60 +       t->expires = jiffies + *n;
  61         add_timer(t);
  62  }
  63
  64 @@ -502,14 +503,13 @@ static void __cpuinit mce_cpu_features(s
  65  static void mce_init_timer(void)
  66  {
  67         struct timer_list *t = &__get_cpu_var(mce_timer);
  68 +       int *n = &__get_cpu_var(next_interval);
  69
  70 -       /* data race harmless because everyone sets to the same value */
  71 -       if (!next_interval)
  72 -               next_interval = check_interval * HZ;
  73 -       if (!next_interval)
  74 +       *n = check_interval * HZ;
  75 +       if (!*n)
  76                 return;
  77         setup_timer(t, mcheck_timer, smp_processor_id());
  78 -       t->expires = round_jiffies(jiffies + next_interval);
  79 +       t->expires = round_jiffies(jiffies + *n);
  80         add_timer(t);
  81  }
  82
  83 @@ -761,7 +761,6 @@ static void mce_cpu_restart(void *data)
  84  /* Reinit MCEs after user configuration changes */
  85  static void mce_restart(void)
  86  {
  87 -       next_interval = check_interval * HZ;
  88         on_each_cpu(mce_cpu_restart, NULL, 1);
  89  }
  90
  91 @@ -912,7 +911,8 @@ static int __cpuinit mce_cpu_callback(st
  92                 break;
  93         case CPU_DOWN_FAILED:
  94         case CPU_DOWN_FAILED_FROZEN:
  95 -               t->expires = round_jiffies(jiffies + next_interval);
  96 +               t->expires = round_jiffies(jiffies +
  97 +                                               __get_cpu_var(next_interval));
  98                 add_timer_on(t, cpu);
  99                 break;
 100         }