Linux Patches Improve KVM Guest Performance For Hosts Under Memory Pressure

Google engineer Yu Zhao known for his work on MGLRU has published a new patch series today that "significantly improves" the KVM guest performance when the host system is under heavy memory pressure.

The new patch series is "mm/kvm: lockless accessed bit harvest" that Yu Zhao sums up as:

"This patchset RCU-protects KVM page tables and compare-and-exchanges KVM PTEs with the accessed bit set by hardware. It significantly improves the performance of guests when the host is under heavy memory pressure.

ChromeOS has been using a similar approach since mid 2021 and it was proven successful on tens of millions devices."

These Linux KVM patches deal with optimizing the guest performance when the host memory is over-committed. More comprehensive benchmarks to showcase the performance improvements of these five patches are said to be coming soon.

This new patch series is coming too late to see it for v6.3 but hopefully everything pans out and we'll be able to see this Linux KVM optimization tuning for a kernel release later in 2023.