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    SubjectRe: [take19 1/4] kevent: Core files.
    On Tue, Oct 17, 2006 at 12:59:47AM -0500, Chase Venters ( wrote:
    > On Tuesday 17 October 2006 00:09, Johann Borck wrote:
    > > Regarding mukevent I'm thinking of a event-type specific struct, that is
    > > filled by the originating code, and placed into a per-event-type ring
    > > buffer (which requires modification of kevent_wait).
    > I'd personally worry about an implementation that used a per-event-type ring
    > buffer, because you're still left having to hack around starvation issues in
    > user-space. It is of course possible under the current model for anyone who
    > wants per-event-type ring buffers to have them - just make separate kevent
    > sets.
    > I haven't thought this through all the way yet, but why not have variable
    > length event structures and have the kernel fill in a "next" pointer in each
    > one? This could even be used to keep backwards binary compatibility while

    Why do we want variable size structures in mmap ring buffer?

    > adding additional fields to the structures over time, though no space would
    > be wasted on modern programs. You still end up with a question of what to do
    > in case of overflow, but I'm thinking the thing to do in that case might be
    > to start pushing overflow events onto a linked list which can be written back
    > into the ring buffer when space becomes available. The appropriate behavior
    > would be to throw new events on the linked list if the linked list had any
    > events, so that things are delivered in order, but write to the mapped buffer
    > directly otherwise.

    I think in a similar way.
    Kevent actually do not require such list, since it has already queue of
    the ready events.

    Evgeniy Polyakov
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