Date: Wed, 2 Apr 1997 12:31:11 +0100 From: Josef Karthauser <joe@pavilion.net> To: Joerg Wunsch <joerg_wunsch@uriah.heep.sax.de> Cc: hackers@FreeBSD.ORG, gbeach@cybernet.com Subject: Re: Internal clock Message-ID: <19970402123111.58518@pavilion.net> In-Reply-To: <19970401203429.XR37988@uriah.heep.sax.de>; from J Wunsch on Tue, Apr 01, 1997 at 08:34:29PM %2B0200 References: <3340C326.6150@cybernet.com> <19970401151947.61221@pavilion.net> <19970401203429.XR37988@uriah.heep.sax.de>
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On Tue, Apr 01, 1997 at 08:34:29PM +0200, J Wunsch wrote:
> As Josef Karthauser wrote:
>
> > I'm using gettimeofday which returns:
> >
> > struct timeval {
> > long tv_sec; /* seconds since Jan. 1, 1970 */
> > long tv_usec; /* and microseconds */
> > };
> >
> > I've no idea of the actual system resolution, ...
>
> RTFM clocks(7).
I have read this, although I still wasn't too clear about the above.
The fact that a system clock ticks in useconds doesn't mean that there's
going to be an interrupt every usec. I didn't get a chance to look at
the source either, as it was a late night hacking midi code.
> > BTW a question to the hackers... does anyone have any plans for
> > adding a real-time scheduling class, aka threads under solaris?
>
> There's already a pseudo-realtime scheduling class available, see
> rtprio(1). This has, of course, nothing to do with threads at all,
> nor will it be true realtime, since there's still the problem that
> scheduling doesn't happen while running in kernel context (i.e., the
> kernel cannot be preempted -- Solaris seems to have gone great lengths
> to create some preemption points for long-time running kernel
> functions).
I found the solaris way a bit of a nightmare. I wanted to set up
a cyclic midi in buffer, but unfortunately the serial devices
seemed to run somewhere below the real time class :(
I'm now reviving the old solaris project and porting it to FreeBSD
(that now being my platform of choice ;) [and I can drive midi directly,
instead of out of a 19200k serial port into an Amiga which did the
baud rate translation.]
Joe
--
Josef Karthauser
Technical Manager Email: joe@pavilion.net
Pavilion Internet plc. [Tel: +44 1273 607072 Fax: +44 1273 607073]
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