Linux 5.4 Scheduler Changes Bring Better AMD EPYC Load Balancing, Other Optimizations

The Linux 5.4 scheduler changes are fairly exciting on multiple fronts.

One of the Linux 5.4 scheduler changes we have been looking forward to is improved EPYC load balancing and that work is indeed part of today's pull request. The better EPYC load balancing is a scheduler topology improvement to better deal with load balancing across NUMA nodes on EPYC 2P servers. I'll be running some benchmarks of this EPYC-specific scheduler change in the days ahead.

Beyond that, there are a number of other EPYC improvements coming for Linux 5.4:

- Improved balancing when SCHED_IDLE tasks are present.

- More patches bringing the real-time PREEMPT_RT tree closer to the mainline code, but a few hundred patches are still out-of-tree.

- The CPU cgroup controller now supports min and max tunables for better CPU bandwidth usage handling.

- Improvements of high CPU core counts with high thread count applications being limited by cpu.cfs_quota_us.

- Various other improvements.

More details via the scheduler pull request for Linux 5.4.