From: Tomas Glozar <tglozar@xxxxxxxxxx>
When using rtla timerlat with userspace threads (-u or -U), rtla
disables the OSNOISE_WORKLOAD option in
/sys/kernel/tracing/osnoise/options. This option is not re-enabled in a
subsequent run with kernel-space threads, leading to rtla collecting no
results if the previous run exited abnormally:
$ rtla timerlat top -u
^\Quit (core dumped)
$ rtla timerlat top -k -d 1s
Timer Latency
0 00:00:01 | IRQ Timer Latency (us) | Thread Timer Latency (us)
CPU COUNT | cur min avg max | cur min avg max
The issue persists until OSNOISE_WORKLOAD is set manually by running:
$ echo OSNOISE_WORKLOAD > /sys/kernel/tracing/osnoise/options
Set OSNOISE_WORKLOAD when running rtla with kernel-space threads if
available to fix the issue.
Cc: stable@xxxxxxxxxxxxxxx
Cc: John Kacur <jkacur@xxxxxxxxxx>
Cc: Luis Goncalves <lgoncalv@xxxxxxxxxx>
Link: https://lore.kernel.org/20250107144823.239782-4-tglozar@xxxxxxxxxx
Fixes: cdca4f4e5e8e ("rtla/timerlat_top: Add timerlat user-space support")
Signed-off-by: Tomas Glozar <tglozar@xxxxxxxxxx>
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
---
tools/tracing/rtla/src/timerlat_top.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/tools/tracing/rtla/src/timerlat_top.c b/tools/tracing/rtla/src/timerlat_top.c
index d358cd39f360..f387597d3ac2 100644
--- a/tools/tracing/rtla/src/timerlat_top.c
+++ b/tools/tracing/rtla/src/timerlat_top.c
@@ -851,12 +851,15 @@ timerlat_top_apply_config(struct osnoise_tool *top, struct timerlat_top_params *
}
}
- if (params->user_top) {
- retval = osnoise_set_workload(top->context, 0);
- if (retval) {
- err_msg("Failed to set OSNOISE_WORKLOAD option\n");
- goto out_err;
- }
+ /*
+ * Set workload according to type of thread if the kernel supports it.
+ * On kernels without support, user threads will have already failed
+ * on missing timerlat_fd, and kernel threads do not need it.
+ */
+ retval = osnoise_set_workload(top->context, params->kernel_workload);
+ if (retval < -1) {
+ err_msg("Failed to set OSNOISE_WORKLOAD option\n");
+ goto out_err;
}
if (isatty(STDOUT_FILENO) && !params->quiet)
--
2.45.2
