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

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Message-ID: <20250114145328.130372281@goodmis.org>
Date: Tue, 14 Jan 2025 09:53:15 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: linux-kernel@...r.kernel.org
Cc: Masami Hiramatsu <mhiramat@...nel.org>,
 Mark Rutland <mark.rutland@....com>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 Shrikanth Hegde <sshegde@...ux.ibm.com>
Subject: [for-linus][PATCH 2/2] tracing: Print lazy preemption model

From: Shrikanth Hegde <sshegde@...ux.ibm.com>

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@linux.ibm.com
Signed-off-by: Shrikanth Hegde <sshegde@...ux.ibm.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
 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