DAMON-Powered Proactive Reclamation Revised For Linux Memory Savings

Written by Michael Larabel in Linux Kernel on 21 July 2021 at 05:00 AM EDT. 1 Comment
Amazon's DAMON is looking like it might be near for mainlining into the Linux kernel for this "Data Access Monitor". One of the follow-up patches that builds off DAMON that is also being pursued by Amazon engineers for proactive reclamation of memory pages.

Sent out on Tuesday was the third take on this DAMON-based proactive reclamation in a lightweight manner that is suitable for use within production environments. DAMON is used for efficiently figuring out cold pages on the system to reclaim.

With this newest set of 15 patches, the DAMON-based proactive reclamation support has been re-based against the latest upstream memory management kernel tree, there is now support for a time quota to limit the amount of time trying to reclaim cold pages, and improved handling around reclamation restarts.

As for the overall performance impact and benefit from using this proactive reclamation technique, the patches note, "In short, DAMON_RECLAIM on v5.13 Linux kernel with ZRAM swap device and 50ms/s time quota achieves 40.34% memory saving with only 3.38% runtime overhead. For this, DAMON_RECLAIM consumes only 5.16% of single CPU time. Among the CPU consumption, only up to about 1.448% of single CPU time is expected to be used for the access pattern monitoring."

More details on this latest work around the "DAMON_RECLAIM" functionality via the kernel mailing list.
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