Re: spin lock contention: lru_list lock

From: Roger Larsson (roger.larsson@norran.net)
Date: Sat Feb 19 2000 - 08:59:31 EST

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    "David S. Miller" wrote:
    >
    > Date: Sat, 19 Feb 2000 13:53:14 +0100
    > From: Manfred Spraul <manfreds@colorfullife.com>
    >
    > I get extremely long hold times for the lru_list lock:
    >
    > sync_buffers(): up to 14 milliseconds, average 12 milliseconds. [called
    > 10 times per second.]
    > __invalidate_buffers(): up to 8 milliseconds, average 7 milliseconds.[
    > called ~4.5 times/sec]
    >
    > A lock can be held for 2 minutes at a time, this isn't what matters.
    >
    It does matter.
    Since all the time you are holding the lock you remain in kernel.
    All the time you remain in kernel prevents schedules, even if an
    interrupt
    awakes a process with higher priority.
    To get working multimedia (like audio) any code executing in kernel for
    more than a few microseconds may give you problems.

    Ingo Molnar has prepared some patches that helps. (Nothing released
    for 2.3 yet)

    For the more about this story check:
      http://www.gardena.net/benno/linux/audio

    /RogerL 

    --
Home page:
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