On Mon, 27 Jan 2025 22:50:18 +0100 Michal Clapinski <mclapinski@xxxxxxxxxx> wrote: > Our goal is to keep memory usage of a VM low on the host. For that > reason, we use free page reporting which by default reports free pages > of order 9 and larger to the host to be freed. The feature works well > only if the memory in the guest is not fragmented below pages of order > 9. Proactive compaction can be reused to achieve defragmentation after > some parameter tweaking. > > When the fragmentation score (lower is better) gets larger than the > high watermark, proactive compaction kicks in. Compaction stops when > the score goes below the low watermark (or no progress is made and > backoff kicks in). Let's define the difference between high and low > watermarks as leeway. Before these changes, the minimum possible value > for low watermark was 5 and the leeway was hardcoded to 10 (so minimum > possible value for high watermark was 15). > It would be helpful to let us know the benefits of this change for our users. Some reasonably detailed real-world before-and-after narrative would suit, please.
