Amazon's DAMON Landing For Linux 5.15
Amazon has been posting DAMON patches for over a year and has gone through nearly three dozen revisions for this kernel module to monitor data accesses for specific user-space processes. DAMON is designed to be lightweight and accurate for performance-centric domains. The core infrastructure of DAMON is now ready for mainline while building off DAMON are more features coming down the pipe. One worth noting is DAMON-based proactive memory reclamation for providing sizable memory savings. There are also various open-source user-space utilities built by Amazon around DAMON.
DAMON is a data access monitoring framework subsystem for the Linux kernel. The core mechanisms of DAMON called 'region based sampling' and 'adaptive regions adjustment' make it
- accurate (The monitored information is useful for DRAM level memory management. It might not appropriate for Cache-level accuracy, though.),
- light-weight (The monitoring overhead is low enough to be applied online while making no impact on the performance of the target workloads.), and
- scalable (the upper-bound of the instrumentation overhead is controllable regardless of the size of target workloads.).
Using this framework, therefore, the kernel's core memory management mechanisms such as reclamation and THP can be optimized for better memory management. The experimental memory management optimization works that incurring high instrumentation overhead will be able to have another try. In user space, meanwhile, users who have some special workloads will be able to write personalized tools or applications for deeper understanding and specialized optimizations of their systems.
The news today is Andrew Morton reporting in that he has merged the key DAMON patches into the memory management code he oversees for the Linux kernel.
With Andrew picking up the DAMON patches now into his tree, this makes it part of the material that will be sent to Linus Torvalds in a few weeks for mainlining once the Linux 5.15 merge window opens.