RE: [Linux-hls-devel] HLS errors appearing with cpu reservations

[John R. <re...@cs...>]

> > The 10s trace looks as I expected apart from a 500ms portion near the
> > start. Task 1 gets the CPU for its first period and then nothing until
> > 550ms; thereafter it gets 10ms every 50ms.
> I think this can be due to the fact that the reservation period and the
> task period are not synchronized (if I understand well, hourglass has no
> way to ensure the fact that the two periods are in phase... Or am I
> wrong? John, please correct me...).

It's true that without help from the scheduler, Hourglass cannot ensure
that a thread period is synched up with its reservation.

However, this 550 ms anomaly sounds like it's too large to be explained by
a phase difference, so I have no idea what's happening.

I changed offices this summer and my HLS test box is still sitting in a
corner turned off.  I'll get it running in the near future and try to
reproduce this.

Paul, is the HLS code in the Hourglass pre-release working for you?  If
so, I should roll out Hourglass 0.6.  There were a few other issues I was
trying to iron out relating to CPU speed detection on laptops and other
difficult machines but now that was so long ago I've forgotten the
issues...

> Integrating HLS with high-resolution-timers is on my todo list, but it
> requires some important changes to the code... It will take some time
> (although I know how to integrate the two things, because I already did
> something similar for another project).

Cool.  Was this the CBS scheduler you guys put into Linux?

John