ftrace: add tracing of context switches
This patch adds context switch tracing, of the format of:
_------=> CPU#
/ _-----=> irqs-off
| / _----=> need-resched
|| / _---=> hardirq/softirq
||| / _--=> preempt-depth
|||| /
||||| delay
cmd pid ||||| time | pid:prio:state
\ / ||||| \ | /
swapper-0 1d..3 137us+: 0:140:R --> 2912:120
sshd-2912 1d..3 216us+: 2912:120:S --> 0:140
swapper-0 1d..3 261us+: 0:140:R --> 2912:120
bash-2920 0d..3 267us+: 2920:120:S --> 0:140
sshd-2912 1d..3 330us!: 2912:120:S --> 0:140
swapper-0 1d..3 2389us+: 0:140:R --> 2847:120
yum-upda-2847 1d..3 2411us!: 2847:120:S --> 0:140
swapper-0 0d..3 11089us+: 0:140:R --> 3139:120
gdm-bina-3139 0d..3 11113us!: 3139:120:S --> 0:140
swapper-0 1d..3 102328us+: 0:140:R --> 2847:120
yum-upda-2847 1d..3 102348us!: 2847:120:S --> 0:140
"sched_switch" is added to /debugfs/tracing/available_tracers
[ Eugene Teo <eugeneteo@kernel.sg: remove unused tracing_sched_switch_enabled ]
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 6bb5e50..6b54ceb 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -1,6 +1,7 @@
obj-$(CONFIG_FTRACE) += libftrace.o
obj-$(CONFIG_TRACING) += trace.o
+obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o
obj-$(CONFIG_FTRACE) += trace_functions.o
libftrace-y := ftrace.o