USB making time drift [was Re: dynamic-hz]

Pavel Machek
2004-12-14T22:11:04Z

Hi!

> On Tue, Dec 14, 2004 at 10:59:39AM +0100, Pavel Machek wrote:
> > Are you using CONFIG_HPET_TIMER by chance? It seems to be missing some
> > strategic -1, TSC (etc) get it right.
>
> I'm not using hpet because it's an old hardware, this is with timer_tsc.
> It must be reproducible in any machine out there, especially with
> machines with usb it should be reproducible even without any userspace
> testcase doing iopl/cli/sti. Time will go silenty in the future at every
> usb irq (they often last 3/4msec).

How much drift do you see?

I have machine with UHCI here, and am using usb most of the time
(bluetooth for gprs connection), and did not notice too bad
drift. ntpdate does some adjustment each time I connect to the
network, but it

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