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    SubjectRe: Synchronous signal delivery..
    Davide Libenzi wrote:
    > > And when that's done you have some nice bonuses:
    > >
    > > - All event types are reported equally fast, and in a single
    > > system call (read()).
    > >
    > > - The order in which events occurred is preserved.
    > > (This is lost when you have to scan multiple queues).
    > >
    > > - Hierarchies of event sets of any kind are possible.
    > > (epoll has solved the logical problems of this already).
    > >
    > > - Less code duplicated.
    > >
    > > - Adding new kinds of kernel events becomes _very_ simple.
    > Hmm ... using read() you'll lose the timeout capability, that IMHO is
    > pretty nice.

    Very good point.

    Timeouts could be events too - probably a good idea as they can then
    be absolute, relative, attached to different system clocks (monotonic
    vs. timeofday). I think the POSIX timer work is like that.

    It seems like a good idea to be able to attach one timeout event in
    the same system call as the event_read call itself - because it is
    _so_ common to vary the expiry time every time.

    Then again, it is also extremely common to write this:

    // calculate time until next application timer expires.
    // Note also race condition here, if we're preempted.
    read_events(..., next_app_time - timeofday)
    // we need to know the current time.

    So perhaps the current select/poll/epoll timeout method is not
    particularly optimal as it is?

    -- Jamie
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