src/patches/suse-2.6.27.25/patches.trace/lttng-instrumentation-timer.patch

   1 From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
   2 Subject: LTTng instrumentation - timer
   3
   4 Original patch header:
   5   LTTng instrumentation - timer
   6
   7   Instrument timer activity (timer set, expired, current time updates) to keep
   8   information about the "real time" flow within the kernel. It can be used by a
   9   trace analysis tool to synchronize information coming from various sources, e.g.
  10   to merge traces with system logs.
  11
  12   Those tracepoints are used by LTTng.
  13
  14   About the performance impact of tracepoints (which is comparable to markers),
  15   even without immediate values optimizations, tests done by Hideo Aoki on ia64
  16   show no regression. His test case was using hackbench on a kernel where
  17   scheduler instrumentation (about 5 events in code scheduler code) was added.
  18   See the "Tracepoints" patch header for performance result detail.
  19
  20   Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
  21   CC: 'Ingo Molnar' <mingo@elte.hu>
  22   CC: "David S. Miller" <davem@davemloft.net>
  23   CC: Masami Hiramatsu <mhiramat@redhat.com>
  24   CC: 'Peter Zijlstra' <peterz@infradead.org>
  25   CC: "Frank Ch. Eigler" <fche@redhat.com>
  26   CC: 'Hideo AOKI' <haoki@redhat.com>
  27   CC: Takashi Nishiie <t-nishiie@np.css.fujitsu.com>
  28   CC: 'Steven Rostedt' <rostedt@goodmis.org>
  29   CC: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
  30
  31 Acked-by: Jan Blunck <jblunck@suse.de>
  32 ---
  33 ---
  34  include/trace/timer.h |   24 ++++++++++++++++++++++++
  35  kernel/itimer.c       |    5 +++++
  36  kernel/timer.c        |    8 +++++++-
  37  3 files changed, 36 insertions(+), 1 deletion(-)
  38
  39 --- /dev/null
  40 +++ b/include/trace/timer.h
  41 @@ -0,0 +1,24 @@
  42 +#ifndef _TRACE_TIMER_H
  43 +#define _TRACE_TIMER_H
  44 +
  45 +#include <linux/tracepoint.h>
  46 +
  47 +DEFINE_TRACE(timer_itimer_expired,
  48 +       TPPROTO(struct signal_struct *sig),
  49 +       TPARGS(sig));
  50 +DEFINE_TRACE(timer_itimer_set,
  51 +       TPPROTO(int which, struct itimerval *value),
  52 +       TPARGS(which, value));
  53 +DEFINE_TRACE(timer_set,
  54 +       TPPROTO(struct timer_list *timer),
  55 +       TPARGS(timer));
  56 +/*
  57 + * xtime_lock is taken when kernel_timer_update_time tracepoint is reached.
  58 + */
  59 +DEFINE_TRACE(timer_update_time,
  60 +       TPPROTO(struct timespec *_xtime, struct timespec *_wall_to_monotonic),
  61 +       TPARGS(_xtime, _wall_to_monotonic));
  62 +DEFINE_TRACE(timer_timeout,
  63 +       TPPROTO(struct task_struct *p),
  64 +       TPARGS(p));
  65 +#endif
  66 --- a/kernel/itimer.c
  67 +++ b/kernel/itimer.c
  68 @@ -12,6 +12,7 @@
  69  #include <linux/time.h>
  70  #include <linux/posix-timers.h>
  71  #include <linux/hrtimer.h>
  72 +#include <trace/timer.h>
  73
  74  #include <asm/uaccess.h>
  75
  76 @@ -132,6 +133,8 @@ enum hrtimer_restart it_real_fn(struct h
  77         struct signal_struct *sig =
  78                 container_of(timer, struct signal_struct, real_timer);
  79
  80 +       trace_timer_itimer_expired(sig);
  81 +
  82         kill_pid_info(SIGALRM, SEND_SIG_PRIV, sig->leader_pid);
  83
  84         return HRTIMER_NORESTART;
  85 @@ -157,6 +160,8 @@ int do_setitimer(int which, struct itime
  86             !timeval_valid(&value->it_interval))
  87                 return -EINVAL;
  88
  89 +       trace_timer_itimer_set(which, value);
  90 +
  91         switch (which) {
  92         case ITIMER_REAL:
  93  again:
  94 --- a/kernel/timer.c
  95 +++ b/kernel/timer.c
  96 @@ -37,12 +37,14 @@
  97  #include <linux/delay.h>
  98  #include <linux/tick.h>
  99  #include <linux/kallsyms.h>
 100 +#include <trace/timer.h>
 101
 102  #include <asm/uaccess.h>
 103  #include <asm/unistd.h>
 104  #include <asm/div64.h>
 105  #include <asm/timex.h>
 106  #include <asm/io.h>
 107 +#include <asm/irq_regs.h>
 108
 109  u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES;
 110
 111 @@ -357,6 +359,7 @@ static void internal_add_timer(struct tv
 112                 i = (expires >> (TVR_BITS + 3 * TVN_BITS)) & TVN_MASK;
 113                 vec = base->tv5.vec + i;
 114         }
 115 +       trace_timer_set(timer);
 116         /*
 117          * Timers are FIFO:
 118          */
 119 @@ -1135,6 +1138,7 @@ void do_timer(unsigned long ticks)
 120  {
 121         jiffies_64 += ticks;
 122         update_times(ticks);
 123 +       trace_timer_update_time(&xtime, &wall_to_monotonic);
 124  }
 125
 126  #ifdef __ARCH_WANT_SYS_ALARM
 127 @@ -1216,7 +1220,9 @@ SYSCALL_DEFINE0(getegid)
 128
 129  static void process_timeout(unsigned long __data)
 130  {
 131 -       wake_up_process((struct task_struct *)__data);
 132 +       struct task_struct *task = (struct task_struct *)__data;
 133 +       trace_timer_timeout(task);
 134 +       wake_up_process(task);
 135  }
 136
 137  /**