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    SubjectRe: [RFC][PATCH 0/2] PF_flags cleaups
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    On Mon, 2010-09-20 at 08:40 -0700, Linus Torvalds wrote:
    > On Mon, Sep 20, 2010 at 8:13 AM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
    > > Because we recently ran out of PF_flags, try and clean up.
    > >
    > > Patches are on top of -tip, which already includes the PF_ALIGNWARN
    > > removal.
    >
    > Looks ok by me conceptually, but I _really_ hate the naming of that
    > second patch and the pointless churn.
    >

    > and look how much straightforward it would have been had you just kept
    > the same simple semantics with just a new field:
    >
    > - new_flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER);
    > + new_type &= ~(TT_SUPERPRIV | TT_WQ_WORKER);
    >
    > and nobody could possibly have any objections to a straightforward
    > "move the task type flags into a separate field" patch.

    Sure, can do. Like said, my initial approach was to compress these type
    bits into fewer bits by converting all these individual bits (PF_KSWAPD,
    PF_WQ_WORKER, etc) into a linear range which spans less bits.

    But indeed, if we're OK with adding a new field (which is I think the
    biggest question, and your reply seems imply you don't mind at all),
    then keeping the old structure and moving them over to a new field will
    generate a much saner patch.

    (I only left the helper functions in in case people would object to
    adding another field and we'd need to really compress bits again).

    One point though, I noticed we actually expose p->flags to userspace,
    which basically makes PF_flags an ABI, do we care?


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