ftrace: tracing header should put '#' at the beginning of a line
In a recent discussion, Andrew Morton pointed out that tracing header
should put '#' at the beginning of a line.
Then, we can easily filtered the header by following grep usage:
cat trace | grep -v '^#'
Wakeup trace also has the same header problem.
Comparison of headers displayed:
before this patch:
# tracer: wakeup
#
wakeup latency trace v1.1.5 on 2.6.29-rc7-tip-tip
--------------------------------------------------------------------
latency: 19059 us, #21277/21277, CPU#1 | (M:desktop VP:0, KP:0, SP:0 HP:0 #P:4)
-----------------
| task: kondemand/1-1644 (uid:0 nice:-5 policy:0 rt_prio:0)
-----------------
# _------=> CPU#
# / _-----=> irqs-off
# | / _----=> need-resched
# || / _---=> hardirq/softirq
# ||| / _--=> preempt-depth
# |||| /
# ||||| delay
# cmd pid ||||| time | caller
# \ / ||||| \ | /
irqbalan-1887 1d.s. 0us : 1887:120:R + [001] 1644:115:S kondemand/1
irqbalan-1887 1d.s. 1us : default_wake_function <-autoremove_wake_function
irqbalan-1887 1d.s. 2us : check_preempt_wakeup <-try_to_wake_up
after this patch:
# tracer: wakeup
#
# wakeup latency trace v1.1.5 on 2.6.29-rc7-tip-tip
# --------------------------------------------------------------------
# latency: 529 us, #530/530, CPU#0 | (M:desktop VP:0, KP:0, SP:0 HP:0 #P:4)
# -----------------
# | task: kondemand/0-1641 (uid:0 nice:-5 policy:0 rt_prio:0)
# -----------------
#
# _------=> CPU#
# / _-----=> irqs-off
# | / _----=> need-resched
# || / _---=> hardirq/softirq
# ||| / _--=> preempt-depth
# |||| /
# ||||| delay
# cmd pid ||||| time | caller
# \ / ||||| \ | /
sshd-2496 0d.s. 0us : 2496:120:R + [000] 1641:115:S kondemand/0
sshd-2496 0d.s. 1us : default_wake_function <-autoremove_wake_function
sshd-2496 0d.s. 1us : check_preempt_wakeup <-try_to_wake_up
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <20090308124421.23C3.A69D9226@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index cc94f86..e5b5619 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1466,11 +1466,11 @@
total = entries +
ring_buffer_overruns(iter->tr->buffer);
- seq_printf(m, "%s latency trace v1.1.5 on %s\n",
+ seq_printf(m, "# %s latency trace v1.1.5 on %s\n",
name, UTS_RELEASE);
- seq_puts(m, "-----------------------------------"
+ seq_puts(m, "# -----------------------------------"
"---------------------------------\n");
- seq_printf(m, " latency: %lu us, #%lu/%lu, CPU#%d |"
+ seq_printf(m, "# latency: %lu us, #%lu/%lu, CPU#%d |"
" (M:%s VP:%d, KP:%d, SP:%d HP:%d",
nsecs_to_usecs(data->saved_latency),
entries,
@@ -1492,24 +1492,24 @@
#else
seq_puts(m, ")\n");
#endif
- seq_puts(m, " -----------------\n");
- seq_printf(m, " | task: %.16s-%d "
+ seq_puts(m, "# -----------------\n");
+ seq_printf(m, "# | task: %.16s-%d "
"(uid:%d nice:%ld policy:%ld rt_prio:%ld)\n",
data->comm, data->pid, data->uid, data->nice,
data->policy, data->rt_priority);
- seq_puts(m, " -----------------\n");
+ seq_puts(m, "# -----------------\n");
if (data->critical_start) {
- seq_puts(m, " => started at: ");
+ seq_puts(m, "# => started at: ");
seq_print_ip_sym(&iter->seq, data->critical_start, sym_flags);
trace_print_seq(m, &iter->seq);
- seq_puts(m, "\n => ended at: ");
+ seq_puts(m, "\n# => ended at: ");
seq_print_ip_sym(&iter->seq, data->critical_end, sym_flags);
trace_print_seq(m, &iter->seq);
- seq_puts(m, "\n");
+ seq_puts(m, "#\n");
}
- seq_puts(m, "\n");
+ seq_puts(m, "#\n");
}
static void test_cpu_buff_start(struct trace_iterator *iter)