1. Release Notes for Unbreakable Enterprise Kernel Release 6
  2. Known Issues
  3. (aarch64) Perf tool can result in application slowdown when profiling some virtualized Arm platforms

(aarch64) Perf tool can result in application slowdown when profiling some virtualized Arm platforms

Note:

The following issue does not affect bare metal installations.

On virtual machines (VMs) that are running on a multi-socket aarch64 platform, if the perf top or perf record command is invoked, it is possible that application slowdowns may occur. In certain cases, the following message is emitted in a terminal window: 

kernel:watchdog: BUG: soft lockup

You can mitigate this problem as follows:

  • To avoid lockup situations and reduce probe effect, you can specify a sample period by using the -c flag with the perf record command, rather than a frequency by using the -F flag. For example, you would use the perf record -c command instead of the perf record -F 100 command.

  • Do not use the perf command with the --all-cpus flag. Instead, specify a minimal number of CPUs by using the perf -C command.

(Bug ID 32834324)