From owner-freebsd-smp Tue Jun 30 11:55:25 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id LAA12917 for freebsd-smp-outgoing; Tue, 30 Jun 1998 11:55:25 -0700 (PDT) (envelope-from owner-freebsd-smp@FreeBSD.ORG) Received: from zibbi.mikom.csir.co.za (zibbi.mikom.csir.co.za [146.64.24.58]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id LAA12895 for ; Tue, 30 Jun 1998 11:55:19 -0700 (PDT) (envelope-from jhay@zibbi.mikom.csir.co.za) Received: (from jhay@localhost) by zibbi.mikom.csir.co.za (8.9.0/8.9.0) id UAA19830; Tue, 30 Jun 1998 20:47:42 +0200 (SAT) From: John Hay Message-Id: <199806301847.UAA19830@zibbi.mikom.csir.co.za> Subject: Re: time problem? In-Reply-To: <15031.899230982@critter.freebsd.dk> from Poul-Henning Kamp at "Jun 30, 98 08:23:02 pm" To: phk@critter.freebsd.dk (Poul-Henning Kamp) Date: Tue, 30 Jun 1998 20:47:42 +0200 (SAT) Cc: freebsd-smp@FreeBSD.ORG X-Mailer: ELM [version 2.4ME+ PL32 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-smp@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org > > >I followed Tony Li's advice and started ntpd again on the machine with > >no local reference clocks and the machine has now been up for more than > >24 hours with no jumps at all, so it looks like it is calling nanotime() > >from within the sio interrupt that causes the problems. :-( > > yes, that may not be entirely safe to do according to Bruce. > > >So what are my options then? Can I somehow run the sio interrupts at > >a lower priority? I would really prefer to have the pps signal on the > >serial port, because the port is already used to read the serial stream > >from the GPS. > > I don't know :-) Hmmm, so it seems that I'll have to get the soldering out and get the pps signal hooked up to the printer port to see if that works better. :-) > > You're entering territory here where I have not yet managed to venture... > > I pressume you havn't used the PPS_SYNC stuff in the kernel (if not: don't!) Well I have and on the old 486 it works pretty ok, so I guess I shouldn't upgrade it until I have resolved this. :-) What I do know is the way you calculate the second pararameter for hardpps() in your printer port pps driver and the way I did it in my patch, seems to make it very unstable. :-) Here is how it looks on the 486: ------------- # /usr/local/sbin/ntpdc shark ntpdc> kerni pll offset: 0 us pll frequency: -14.932 ppm maximum error: 15266 us estimated error: 1 us status: 0107 pll time constant: 2 precision: 1 us frequency tolerance: 512 ppm pps frequency: -55.983 ppm pps stability: 0.010 ppm pps jitter: 2 us calibration interval: 256 s calibration cycles: 6790 jitter exceeded: 450 stability exceeded: 4 calibration errors: 37 ntpdc> peer remote local st poll reach delay offset disp ======================================================================= =GPS_NMEA(0) 0.0.0.0 0 64 377 0.00000 -0.000049 0.00092 *PPS(0) 0.0.0.0 0 64 377 0.00000 0.000001 0.00092 +orca.cids.org.z 0.0.0.0 1 64 0 0.00000 0.000000 16.0000 ---------------- > And it doesn't happen if you run !SMP with the TSC timecounter, right ? I'll have a look at it again. John -- John Hay -- John.Hay@mikom.csir.co.za To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message