Hal Murray wrote: >> No. Even the hardware of ten to fifteen years ago has sufficient >> capacity to run ntpd. I run ntpd on Sun Ultra 10 machines with 440 MHz >> CPU's (late 1990's vintage). > > Are you using PPS? Does your kernel have hardpps? > > My question was not whether ntpd would run on old machines, but > why the hardpps code was needed in the kernel. > > I was guessing that old machines had performance issues. > That seems like the best explaination even if it doesn't > fit today's data.
Even not-so-old machines have performance issues. Someone here once wrote that if you have good hardware, it's best to let ntpd take care of the PPS because ntpd has superior algorithms to the NTP-style algorithms in the kernel. However, my PC has either a clock or voltage regulation that's absolute garbage, and hardpps would be nice. My current viable options are these: 1) Use my current Linux 2.6.18.1 + LinuxPPS and sit and watch as ntpd darts +/- 120 us over the course of a few hours, even when idle. 2) Reboot to FreeBSD and let the kernel, hardpps, and the NTP kernel code make more radical short-term adjustments, and ntpd will dart +/- 10 us over a few hours. 3) Recompile glibc with support with older kernels without breaking my system, then fetch Linux 2.6.17.8, fetch Ulrich's last PPSkit alpha, and hope it all works. 4) Run ntpd on an ancient Pentium 75, where the clock on it is good but the hardware is noisy, have the added network delay, have my choice of FreeBSD or Linux 2.4 + PPSkit, and have everything working as designed. There's a certain amount of frustration on my part. There are actually two issues here, it seems, and it goes to Ulrich's point: a) hardpps support, and b) what to do with it, in the way of more NTP algorithms in the kernel. But when I Google for Linux PPS support and hit an archive from a kernel mailing list or something, it's usually of someone wanting to do something with PPS, followed by two or three answers on why it can't be done. Is there just a resistance about it all? It's a testament to look in the PPSkit archive, to see all of those file dates on all of the various verions, and seeing it all stop a few months ago. If you think of what Linux has gone through in that time, one can't help but admire the author's dedication. I'm sure that there would be more PPSkit versions if the conditions were right. Michael _______________________________________________ questions mailing list [EMAIL PROTECTED] https://lists.ntp.isc.org/mailman/listinfo/questions
