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    SubjectTimer queues: Which one should I use...
    Hi, thanks for your effort to support Zip drive, 

    campbell@tirian.che.curtin.edu.au writes:
    > I've only just joined this mailing list but I've heard that there has
    > been some discussion on timer queues. I have been working on a driver
    > (Iomega parallel port ZIP drive) and found that tq_scheduler stops
    > polling/processing when the system loads up (gcc -O2 does it quiet
    > nicely when compiling the gcc source).
    >
    > I've since switched to using tq_timer with more stable results but
    > apparently there has been a performance drop. Any suggestions?

    While the tasks of tq_timer are executed by timer ticks, tq_immediate
    runs (somewhat) immediately. You can queue some tasks on the queue of
    tq_immediate, and the tasks are executed when bottom_half is called.
    For example, you can queue a task in the interrupt handler, and the
    task is executed when the control exits interrupt handler and
    bottom_half is called. Another example is, you can queue a task in
    normal kernel mode (not interrupt), and when the control goes back to
    userland, bottom_half is called and the task is executed.

    Usage:
    queue_task(&task, &tq_immediate);
    mark_bh(IMMEDIATE_BH);

    Although I don't know much about ZIP drive, here is a idea:
    For slow command (seek/write/...): use tq_timer
    For fast command (read/status/..): use tq_immediate

    Hope this helps,
    --
    NIIBE Yutaka

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