Amazon’s DAMON merged into Linux 5.15 for data access monitoring framework


The DAMON kernel feature developed by Amazon engineers has landed successfully in the Linux 5.15 tree.

As part of the 147 fixes bundled into the kernel today by Andrew Morton, the most notable addition is the merger of DAMON functionality.

Since early 2020, Amazon fixes have been released for DAMON as an addition to the Linux kernel for data access monitoring. DAMON is designed for a variety of use cases, from behavioral analysis to aid debugging to managing overloaded systems. One area that has recently gained attention and where DAMON is moving forward is proactive system memory reclamation.

After the DAMON code has undergone about three dozen overhaul cycles over the past year and a half, it has now been merged into the mainline today.

Today’s landing shouldn’t come as a surprise as a month ago Andrew Morton indicated he would take it through his patch collection for 5.15.

DAMON is a data access monitoring infrastructure subsystem for the Linux kernel. DAMON’s basic mechanisms called “region-based sampling” and “adaptive region adjustment” make it

– accurate (the monitored information is useful for DRAM level memory management. However, it may not be appropriate for cache level precision.),

– lightweight (the overhead for monitoring is low enough to be applied online while having no impact on the performance of target workloads.), and

– scalable (the upper limit of the instrumentation overload is controllable regardless of the size of the target workloads.).

By using this framework, therefore, kernel main memory management mechanisms such as retrieval and THP can be optimized for better memory management. The work of optimizing the management of the experimental memory which leads to a high instrumentation overload may be retried. In user space, meanwhile, users with special workloads will be able to write custom tools or applications for deeper understanding and specialized optimizations of their systems.

DAMON’s base code is just under four thousand lines of code so it will be very interesting in the future to see what new DAMON-based solutions might come to the kernel. More details on DAMON via the documentation.

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