[ntp:questions] Time server question

Gabs Ricalde gsricalde at gmail.com
Fri Jul 19 20:58:46 UTC 2019


On Sat, Jul 20, 2019 at 2:26 AM Gabs Ricalde <gsricalde at gmail.com> wrote:
>
> On Wed, Jul 17, 2019 at 7:59 PM William Unruh <unruh at invalid.ca> wrote:
> > I suspect it will be a bad outcome. The rpoblem is that you get
> > interrupt contention, and the two interrups will put in time delays into
> > the second one processed.
> >
>
> That was my observation when I did some tests years ago with a single core Atom.
>
> With a dual core CPU, the interrupts can be simultaneously handled by
> both cores. In the attached plot, the parallel port timestamps are
> ahead by around 3 us, probably due to the RS232 line driver/receiver.
>
> When only one core is enabled, the serial port is handled first
> followed by the parallel port which causes a delay of around 10 us.
> The delay disappears when the serial port source is disconnected.

It seems the attachments were too large, trying again.


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