Intel Delivers A Significant Memory Hotplugging Performance Optimization For Linux

Adding to the features expected to land for Linux 7.4 is a significant performance optimization for the memory hotplugging speed for adding additional RAM. In particular, the memory hotplugging being most applicable for cases like expanding the amount of memory for VMs or in today's CXL world for adding additional system memory.

Yuan Liu of Intel has been leading the work to optimize zone contiguous checks for improving memory hotplugging performance by avoiding page block by page block scans across an entire zone.

The patches have been queued into mm/core.git's "for-next" Git branch and thus expected to be submitted for the Linux 7.4 merge window in October. That cover letter goes over the technical details of this memory hotplugging optimization.

The exciting part are the results with memory hotplugging for a virtual machine seeing up to an 81% time reduction and also up to a 75% time reduction for memory hot unplugging:

Tests by Samsung also found sizable improvements for hot plugging memory via CXL:

Some nice speed-ups for those dealing with memory hot (un)plugging come Linux 7.4.