[for-linus][PATCH 2/2] tracing: Print lazy preemption model

From: Steven Rostedt
Date: Tue Jan 14 2025 - 09:54:01 EST


From: Shrikanth Hegde <sshegde@xxxxxxxxxxxxx>

Print lazy preemption model in ftrace header when latency-format=1.

# cat /sys/kernel/debug/sched/preempt
none voluntary full (lazy)

Without patch:
latency: 0 us, #232946/232946, CPU#40 | (M:unknown VP:0, KP:0, SP:0 HP:0 #P:80)
^^^^^^^

With Patch:
latency: 0 us, #1897938/25566788, CPU#16 | (M:lazy VP:0, KP:0, SP:0 HP:0 #P:80)
^^^^

Now that lazy preemption is part of the kernel, make sure the tracing
infrastructure reflects that.

Link: https://lore.kernel.org/20250103093647.575919-1-sshegde@xxxxxxxxxxxxx
Signed-off-by: Shrikanth Hegde <sshegde@xxxxxxxxxxxxx>
Acked-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
---
kernel/trace/trace.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index f8aebcb01e62..b6e40e8791fa 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4122,6 +4122,7 @@ print_trace_header(struct seq_file *m, struct trace_iterator *iter)
preempt_model_none() ? "server" :
preempt_model_voluntary() ? "desktop" :
preempt_model_full() ? "preempt" :
+ preempt_model_lazy() ? "lazy" :
preempt_model_rt() ? "preempt_rt" :
"unknown",
/* These are reserved for later use */
--
2.45.2