itimers: Add tracepoints for itimer
Xiao Guangrong [Mon, 10 Aug 2009 02:52:30 +0000 (10:52 +0800)]
Add tracepoints for all itimer variants: ITIMER_REAL, ITIMER_VIRTUAL
and ITIMER_PROF.

[ tglx: Fixed comments and made the output more readable, parseable
   and consistent. Replaced pid_vnr by pid_nr because the hrtimer
   callback can happen in any namespace ]

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Anton Blanchard <anton@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Zhaolei <zhaolei@cn.fujitsu.com>
LKML-Reference: <4A7F8B6E.2010109@cn.fujitsu.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

include/trace/events/timer.h
kernel/itimer.c
kernel/posix-cpu-timers.c

index df3c07f..1844c48 100644 (file)
@@ -270,6 +270,72 @@ TRACE_EVENT(hrtimer_cancel,
        TP_printk("hrtimer %p", __entry->timer)
 );
 
+/**
+ * itimer_state - called when itimer is started or canceled
+ * @which:     name of the interval timer
+ * @value:     the itimers value, itimer is canceled if value->it_value is
+ *             zero, otherwise it is started
+ * @expires:   the itimers expiry time
+ */
+TRACE_EVENT(itimer_state,
+
+       TP_PROTO(int which, const struct itimerval *const value,
+                cputime_t expires),
+
+       TP_ARGS(which, value, expires),
+
+       TP_STRUCT__entry(
+               __field(        int,            which           )
+               __field(        cputime_t,      expires         )
+               __field(        long,           value_sec       )
+               __field(        long,           value_usec      )
+               __field(        long,           interval_sec    )
+               __field(        long,           interval_usec   )
+       ),
+
+       TP_fast_assign(
+               __entry->which          = which;
+               __entry->expires        = expires;
+               __entry->value_sec      = value->it_value.tv_sec;
+               __entry->value_usec     = value->it_value.tv_usec;
+               __entry->interval_sec   = value->it_interval.tv_sec;
+               __entry->interval_usec  = value->it_interval.tv_usec;
+       ),
+
+       TP_printk("which %d, expires %lu, it_value %lu.%lu, it_interval %lu.%lu",
+                 __entry->which, __entry->expires,
+                 __entry->value_sec, __entry->value_usec,
+                 __entry->interval_sec, __entry->interval_usec)
+);
+
+/**
+ * itimer_expire - called when itimer expires
+ * @which:     type of the interval timer
+ * @pid:       pid of the process which owns the timer
+ * @now:       current time, used to calculate the latency of itimer
+ */
+TRACE_EVENT(itimer_expire,
+
+       TP_PROTO(int which, struct pid *pid, cputime_t now),
+
+       TP_ARGS(which, pid, now),
+
+       TP_STRUCT__entry(
+               __field( int ,          which   )
+               __field( pid_t,         pid     )
+               __field( cputime_t,     now     )
+       ),
+
+       TP_fast_assign(
+               __entry->which  = which;
+               __entry->now    = now;
+               __entry->pid    = pid_nr(pid);
+       ),
+
+           TP_printk("which %d, pid %d, now %lu", __entry->which,
+                     (int) __entry->pid, __entry->now)
+);
+
 #endif /*  _TRACE_TIMER_H */
 
 /* This part must be outside protection */
index 8078a32..b03451e 100644 (file)
@@ -12,6 +12,7 @@
 #include <linux/time.h>
 #include <linux/posix-timers.h>
 #include <linux/hrtimer.h>
+#include <trace/events/timer.h>
 
 #include <asm/uaccess.h>
 
@@ -122,6 +123,7 @@ enum hrtimer_restart it_real_fn(struct hrtimer *timer)
        struct signal_struct *sig =
                container_of(timer, struct signal_struct, real_timer);
 
+       trace_itimer_expire(ITIMER_REAL, sig->leader_pid, 0);
        kill_pid_info(SIGALRM, SEND_SIG_PRIV, sig->leader_pid);
 
        return HRTIMER_NORESTART;
@@ -166,6 +168,8 @@ static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
        }
        it->expires = nval;
        it->incr = ninterval;
+       trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
+                          ITIMER_VIRTUAL : ITIMER_PROF, value, nval);
 
        spin_unlock_irq(&tsk->sighand->siglock);
 
@@ -217,6 +221,7 @@ again:
                } else
                        tsk->signal->it_real_incr.tv64 = 0;
 
+               trace_itimer_state(ITIMER_REAL, value, 0);
                spin_unlock_irq(&tsk->sighand->siglock);
                break;
        case ITIMER_VIRTUAL:
index 12161f7..5c9dc22 100644 (file)
@@ -8,6 +8,7 @@
 #include <linux/math64.h>
 #include <asm/uaccess.h>
 #include <linux/kernel_stat.h>
+#include <trace/events/timer.h>
 
 /*
  * Called after updating RLIMIT_CPU to set timer expiration if necessary.
@@ -1090,9 +1091,13 @@ static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it,
                                                          cputime_one_jiffy);
                                it->error -= onecputick;
                        }
-               } else
+               } else {
                        it->expires = cputime_zero;
+               }
 
+               trace_itimer_expire(signo == SIGPROF ?
+                                   ITIMER_PROF : ITIMER_VIRTUAL,
+                                   tsk->signal->leader_pid, cur_time);
                __group_send_sig_info(signo, SEND_SIG_PRIV, tsk);
        }