The policy code in the kernel that controls file caching and readahead behavior is necessarily one-size-fits-all, and the knobs available to applications to tune it, like madvise() and posix_fadvise(), are fairly blunt hammers. Furthermore, it has been shown that the overhead from user<->kernel domain crossings makes syscall-driven fine-grained policy control ineffective.

Is it possible to create a BPF-like tool (that is, a small code generator with very simple and very clear safety properties) to allow safe in-kernel fine-grained policy control?

Caution: this is a research project.

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