From: Tomas Glozar tglozar@redhat.com
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@vger.kernel.org Cc: John Kacur jkacur@redhat.com Cc: Luis Goncalves lgoncalv@redhat.com Link: https://lore.kernel.org/20250107144823.239782-4-tglozar@redhat.com Fixes: cdca4f4e5e8e ("rtla/timerlat_top: Add timerlat user-space support") Signed-off-by: Tomas Glozar tglozar@redhat.com Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org --- 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)