The hwlatd tracer will end up starting multiple per-cpu threads with the following script: #!/bin/sh cd /sys/kernel/debug/tracing echo 0 > tracing_on echo hwlat > current_tracer echo per-cpu > hwlat_detector/mode echo 100000 > hwlat_detector/width echo 200000 > hwlat_detector/window echo 1 > tracing_on To fix the issue, check if the hwlatd thread for the cpu is already running, before starting a new one. Along with the previous patch, this avoids running multiple instances of the same CPU thread on the system. Link: https://lore.kernel.org/all/20230302113654.2984709-1-tero.kristo@linux.intel.com/ Link: https://lkml.kernel.org/r/20230310100451.3948583-3-tero.kristo@linux.intel.com
Unified · Split
| @@ -492,6 +492,10 @@ static int start_cpu_kthread(unsigned int cpu) · 491 unmodified lines | |||
| 492 | { | 492 | { |
| 493 | struct task_struct *kthread; | 493 | struct task_struct *kthread; |
| 494 | 494 | ||
| 495 | /* Do not start a new hwlatd thread if it is already running */ | ||
| 496 | if (per_cpu(hwlat_per_cpu_data, cpu).kthread) | ||
| 497 | return 0; | ||
| 498 | |||
| 495 | kthread = kthread_run_on_cpu(kthread_fn, NULL, cpu, "hwlatd/%u"); | 499 | kthread = kthread_run_on_cpu(kthread_fn, NULL, cpu, "hwlatd/%u"); |
| 496 | if (IS_ERR(kthread)) { | 500 | if (IS_ERR(kthread)) { |
| 497 | pr_err(BANNER "could not start sampling thread\n"); | 501 | pr_err(BANNER "could not start sampling thread\n"); |