Random high CPU utilization issue encountered with database benchmark program

A random high CPU utilization issue has been encountered with the database benchmark program running on a 192-CPU virtual machine in Azure. This issue was initially discovered in Oracle Linux 8.4 and Ubuntu 20.04 (5.11.0-1022-azure); however, a complete fix for the issue isn't yet available in the upstream kernels.

This issue typically manifests itself with a >90% CPU utilization spike occurring every 1 to 2 minutes and lasting approximately 5 to 20 seconds, which degrades the system's performance significantly. When the CPU utilization spike is occurring, each of the 192 CPUs' %sys increases up to 60+%, and the %si increases up to 30%. In certain cases, the >90% CPU utilization spike has been observed 100% of the time.

To avoid encountering this issue, set the dm_mod.dm_mq_queue_depth=256 kernel parameter.

(Bug ID 33665982)