6.6-stable review patch. If anyone has any objections, please let me know.
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From: Tomas Glozar tglozar@redhat.com
commit 217f0b1e990e30a1f06f6d531fdb4530f4788d48 upstream.
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 [ params->kernel_workload does not exist in 6.6, use !params->user_top ] Signed-off-by: Tomas Glozar tglozar@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- tools/tracing/rtla/src/timerlat_top.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-)
--- a/tools/tracing/rtla/src/timerlat_top.c +++ b/tools/tracing/rtla/src/timerlat_top.c @@ -679,12 +679,15 @@ timerlat_top_apply_config(struct osnoise auto_house_keeping(¶ms->monitored_cpus); }
- 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->user_top); + if (retval < -1) { + err_msg("Failed to set OSNOISE_WORKLOAD option\n"); + goto out_err; }
return 0;