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    SubjectRe: 2.6.14-rc4-rt7

    * Daniel Walker <> wrote:

    > I found this latency ~5 minutes after boot up, no load . It looks like
    > vgacon_scroll() has a memset like operation which can grow.

    do you have PRINTK_IGNORE_LOGLEVEL enabled? If yes then much of the
    printk code will run with interrupts disabled - hence non-preemptable.
    PRINTK_IGNORE_LOGLEVEL is a debugging feature for developers. I have
    added an extra explanation to the Kconfig, see below.


    Index: linux/lib/Kconfig.debug
    --- linux.orig/lib/Kconfig.debug
    +++ linux/lib/Kconfig.debug
    @@ -18,6 +18,11 @@ config PRINTK_IGNORE_LOGLEVEL
    distributions disable kernel log messages during
    certain phases of system startup.)

    + NOTE: this option also makes printk non-preemptible,
    + which might improve the output of debugging info or
    + crash info, but it might also cause latencies if your
    + kernel is printk-ing alot.
    Normally you dont need or want this option.

    config DEBUG_KERNEL
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      Last update: 2005-10-18 08:45    [W:0.021 / U:53.372 seconds]
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