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    SubjectRe: [RFC] Arch option to touch newly allocated pages
    David Woodhouse writes:
    >
    > jdike@karaya.com said:
    > > Yeah, MADV_DONTNEED looks right. UML and Linux/s390 (assuming VM has
    > > the equivalent of MADV_DONTNEED) would need a hook in free_pages to
    > > make that happen.
    >
    > MADV_DONTNEED
    > Do not expect access in the near future. (For the
    > time being, the application is finished with the
    > given range, so the kernel can free resources asso­
    > ciated with it.)
    >
    > It's not clear from that that the host kernel is actually permitted to
    > discard the data.
    >
    > alan@lxorguk.ukuu.org.uk said:
    > > VM allows you to give it back a page and if you use it again you get
    > > a clean copy. What it seems to lack is the more ideal "here have this
    > > page and if I reuse it trap if you did throw it out" semantic.
    >
    > I've wittered on occasion about other situations where such
    > semantics might be useful -- essentially 'drop these pages if you
    > need to as if they were clean, and tell me when I next touch them so
    > I can recreate their data'.

    Indeed. I'd love such a feature. It's got applications in
    numerical/scientific code, not just UML.

    Regards,

    Richard....
    Permanent: rgooch@atnf.csiro.au
    Current: rgooch@ras.ucalgary.ca
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