Re: interrupt latency and driver locking

From: John Polstra (jdp_at_polstra.com)
Date: 09/20/03

  • Next message: Luigi Rizzo: "Re: interrupt latency and driver locking" 
    Date: Sat, 20 Sep 2003 13:00:54 -0700 (PDT)
To: Luigi Rizzo <rizzo@icir.org>

    On 20-Sep-2003 Luigi Rizzo wrote:

    > the main problem, as i see it, is that when there are PHY events you
    > still need to do some expensive work while holding a lock that
    > blocks interrupts, with very bad impact on the worst-case
    > response of the system.

    I agree that is a problem, but I don't think it is the main problem.
    In a running system, PHY events essentially never happen, so it
    doesn't matter much if they take a long time. In other words, the PHY
    really only needs attention when the link state changes, and for all
    practical purposes that never happens in a running system.

    What is killing us is the periodic polling of the PHY every second,
    only to find out that nothing has changed.

    John
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