rtla/hwnoise: Reduce runtime to 75%

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@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Fixes: 1f428356c38d ("rtla: Add hwnoise tool")
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/tools/tracing/rtla/src/osnoise_top.c b/tools/tracing/rtla/src/osnoise_top.c
index 85abba5..f7c959b 100644 (file)
--- 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[] = {