[for-linus][PATCH 3/7] trace/timerlat: Add a header with PREEMPT_RT additional fields

Steven Rostedt
2021-08-12T01:14:07Z

Some extra flags are printed to the trace header when using the
PREEMPT_RT config. The extra flags are: need-resched-lazy,
preempt-lazy-depth, and migrate-disable.

Without printing these fields, the timerlat specific fields are
shifted by three positions, for example:

# tracer: timerlat
#
# _-----=> irqs-off
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# || /
# |||| ACTIVATION
# TASK-PID CPU# |||| TIMESTAMP ID CONTEXT LATENCY
# | | | |||| | | | |
<idle>-0 [000] d..h... 3279.798871: #1 context irq timer_latency 830 ns
<...>-807 [000] ....... 3279.798881: #1 context thread timer_latency 11301 ns

Add a new header for timerlat with the missing fields, to be used
when the PREEMPT_RT is enabled.

Link: https://lkml.kernel.org/r/babb83529a3211bd0805be0b8c21608230202c55.1626598844.git.bristot@kernel.org

Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
kernel/trace/trace_osnoise.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)

diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
index cbdda2fe4926..f9652278bd10 100644
--- a/kernel/trace/trace_osnoise.c
+++ b/kernel/trace/trace_osnoise.c
@@ -354,6 +354,24 @@ static void trace_osnoise_sample(struct osnoise_sample *sample)
/*
* Print the timerlat header info.
*/
+#ifdef CONFIG_PREEMPT_RT
+static void print_timerlat_headers(struct seq_file *s)
+{
+ seq_puts(s, "# _-------=> irqs-off\n");
+ seq_puts(s, "# / _------=> need-resched\n");
+ seq_puts(s, "# | / _-----=> need-resched-lazy\n");
+ seq_puts(s, "# || / _----=> hardirq/softirq\n");
+ seq_puts(s, "# ||| / _---=> preempt-depth\n");
+ seq_puts(s, "# |||| / _--=> preempt-lazy-depth\n");
+ seq_puts(s, "# ||||| / _-=> migrate-disable\n");
+ seq_puts(s, "# |||||| /\n");
+ seq_puts(s, "# ||||||| ACTIVATION\n");
+ seq_puts(s, "# TASK-PID CPU# ||||||| TIMESTAMP ID ");
+ seq_puts(s, " CONTEXT LATENCY\n");
+ seq_puts(s, "# | | | ||||||| | | ");
+ seq_puts(s, " | |\n");
+}
+#else /* CONFIG_PREEMPT_RT */
static void print_timerlat_headers(struct seq_file *s)
{
seq_puts(s, "# _-----=> irqs-off\n");
@@ -367,6 +385,7 @@ static void print_timerlat_headers(struct seq_file *s)
seq_puts(s, "# | | | |||| | | ");
seq_puts(s, " | |\n");
}
+#endif /* CONFIG_PREEMPT_RT */

/*
* Record an timerlat_sample into the tracer buffer.
--
2.30.2