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Working Set Size Estimation (2018)

The Working Set Size (WSS) is how much memory an application needs to keep working. Your application may have 100 Gbytes of main memory allocated and page mapped, but it is only touching 50 Mbytes each second to do its job.

Without a swap device, the Linux out-of-memory (OOM) killer can kill sacrificial processes to free space, which doesn't tell us a great deal about WSS. There are a lot of PMCs: for caches, the MMU and TLB, and memory events, so I think it's possible that we could model a CPU, plug in all these numbers, and have it estimate not just the WSS but also the access pattern. This tool sets and reads system and process page flags, which can take over one second of CPU time, during which application may experience slightly higher latency (eg, 5%).

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