Annotation of wikisrc/projects/project/policy_plugins.mdwn, revision 1.3

1.1       jmmv        1: [[!template id=project
                      2: 
1.3     ! dholland    3: title="Kernel plugins for FS policy logic (research)"
1.1       jmmv        4: 
                      5: contact="""
                      6: [tech-kern](mailto:tech-kern@NetBSD.org)
                      7: """
                      8: 
1.2       dholland    9: category="filesystems"
1.1       jmmv       10: difficulty="medium"
                     11: 
                     12: description="""
                     13: The policy code in the kernel that controls file caching and readahead behavior
                     14: is necessarily one-size-fits-all, and the knobs available to applications to
                     15: tune it, like madvise() and posix_fadvise(), are fairly blunt
                     16: hammers. Furthermore, it has been shown that the overhead from user<->kernel
                     17: domain crossings makes syscall-driven fine-grained policy control ineffective.
1.3     ! dholland   18: (Though, that was shown in the past when processors were much slower
        !            19: relative to disks and it may not be true any more.)
1.1       jmmv       20: 
1.3     ! dholland   21: Is it possible to use BPF, or create a different BPF-like tool (that
        !            22: is, a small code generator with
1.1       jmmv       23: very simple and very clear safety properties) to allow safe in-kernel
                     24: fine-grained policy control?
                     25: 
                     26: Caution: this is a research project.
                     27: """
                     28: ]]

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