>
> On Wed, 17 Mar 1999, Ulrich Windl wrote:
>
> > Question
> > Every once in a while my system looses 30 msec. How comes?
> >
> > Answer
> > You are running Linux; you are using automatic module loading using
> > /sbin/kerneld. During module loading the kernel does not take good
> > care of the time. If you can spare the memory, please load the
> > modules at boot time.
> >
> > Remark to the editor
> > This once occured to me. The sound system was demand loaded. A small
> > application told the time every 15 minutes (saytime running in cron).
> > The ntp logging showed me that something strange happened every 15
> > minutes. I found out it was the loading of the sound module every
> > 15 minutes.
>
> module loading does not disable interrupts. There might be modules which
> disable interrupts during initialization (sound drivers), thus causing
> lost ticks. But otherwise, the majority of modules and the generic module
> code is just fine.
Agreed; it's not my wording, but a quote. Historically much code
assumed it'll be executed during bootup when you can be not nice to
multitasking issues. Then loadable modules and kerneld came, and some
code still disables interrupts for too long during autodetection or
initialization.
Ulrich
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