linux-kernel - [for-next][PATCH 08/11] rtla/hwnoise: Reduce runtime to 75%

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Date:   Tue, 13 Jun 2023 18:07:58 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org
Cc:     Daniel Bristot de Oliveira <bristot@...nel.org>,
        William White <chwhite@...hat.com>,
        Jonathan Corbet <corbet@....net>,
        Juri Lelli <juri.lelli@...hat.com>
Subject: [for-next][PATCH 08/11] rtla/hwnoise: Reduce runtime to 75%

From: Daniel Bristot de Oliveira <bristot@...nel.org>

osnoise runs 100% of time by default. It makes sense because osnoise
is preemptive. hwnoise checks preemption once a second, so it
reduces system progress.

Reduce runtime to 75% to avoid problems by default. I added a Fixes
as it might avoid problems for first time users as it lands on distros.

Link: https://lkml.kernel.org/r/af0b7113ffc00031b9af4bb40ef5889a27dadf8c.1686066600.git.bristot@kernel.org

Cc: William White <chwhite@...hat.com>
Cc: Jonathan Corbet <corbet@....net>
Tested-by: Juri Lelli <juri.lelli@...hat.com>
Fixes: 1f428356c38d ("rtla: Add hwnoise tool")
Signed-off-by: Daniel Bristot de Oliveira <bristot@...nel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
 tools/tracing/rtla/src/osnoise_top.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/tools/tracing/rtla/src/osnoise_top.c b/tools/tracing/rtla/src/osnoise_top.c
index 85abba568faf..f7c959be8677 100644
--- a/tools/tracing/rtla/src/osnoise_top.c
+++ b/tools/tracing/rtla/src/osnoise_top.c
@@ -348,8 +348,14 @@ struct osnoise_top_params *osnoise_top_parse_args(int argc, char **argv)
 	if (!params)
 		exit(1);
 
-	if (strcmp(argv[0], "hwnoise") == 0)
+	if (strcmp(argv[0], "hwnoise") == 0) {
 		params->mode = MODE_HWNOISE;
+		/*
+		 * Reduce CPU usage for 75% to avoid killing the system.
+		 */
+		params->runtime = 750000;
+		params->period = 1000000;
+	}
 
 	while (1) {
 		static struct option long_options[] = {
-- 
2.39.2