Re: [chrony-users] gpsd, pps and chrony

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I am afraid I have never gone into the Linux entrails to figure out how the HZ
variable works and how it interacts with chrony.


On Tue, 5 Apr 2011, Ed W wrote:


That is not a config error. It is a "hardware" error-- the clock is
irredemably broken. (Fortunately it was just your kernel config that
broke it
so you could recover, but chrony could not)


OK, so I have chrony built in a uclibc chroot with /usr/src/linux holding a
32bit kernel with HZ set to 1024 (I think).  The host is a 64bit kernel with
HZ set to 250 - however, I don't think this should be relevant?

This is then installed on my Alix (32bit only). If I set "linux_hz 1024" in
my conf file I get:

Apr  5 22:05:38 localhost user.info chronyd[3457]: chronyd version DEVELOPMENT starting
Apr  5 22:05:38 localhost user.info chronyd[3457]: Set system time, error in RTC = -9.552346
Apr  5 22:05:37 localhost user.info chronyd[3457]: set_config_hz=1 hz=1024 shift_hz=7 basic_freq_scale=0.12500000 nominal_tick=977 slew_delta_tick=81 max_tick_bias=97
Apr  5 22:05:37 localhost user.info chronyd[3457]: Linux kernel major=2 minor=6 patch=37
Apr  5 22:05:37 localhost user.info chronyd[3457]: Frequency -136.274 +- 0.078 ppm read from /var/lib/chrony/drift
Apr  5 22:05:37 localhost user.crit chronyd[3457]: Fatal error : adjtimex failed for set_frequency, freq_ppm=1.3627e+02 scaled_freq=1.3627e+02 required_tick=977



If I leave off all linux_hz config I get:

Apr  5 22:06:10 localhost user.info chronyd[3479]: chronyd version DEVELOPMENT starting
Apr  5 22:06:10 localhost user.info chronyd[3479]: Set system time, error in RTC = -9.553227
Apr  5 22:06:11 localhost user.info chronyd[3479]: set_config_hz=0 hz=100 shift_hz=7 basic_freq_scale=1.28000000 nominal_tick=10000 slew_delta_tick=833 max_tick_bias=1000
Apr  5 22:06:11 localhost user.info chronyd[3479]: Linux kernel major=2 minor=6 patch=37
Apr  5 22:06:11 localhost user.info chronyd[3479]: Frequency -136.274 +- 0.078 ppm read from /var/lib/chrony/drift
Apr  5 22:06:11 localhost user.alert kernel: [ 1704.211743] grsec: time set by /usr/sbin/chronyd[chronyd:3479] uid/euid:0/0 gid/egid:0/0, parent /bin/busybox[init:1] uid/euid:0/0 gid/egid:0/0
Apr  5 22:06:19 localhost user.info chronyd[3479]: System trim from RTC = -0.593289
Apr  5 22:06:20 localhost user.info chronyd[3479]: System's initial offset : 0.001843 seconds slow of true (slew)
...


My question is why I see "hz=100" and why the 1024 config causes the fatal error?

I'm fairly sure I was still getting hz=100 in the logs when built against a kernel source using 1000hz and 250hz. Also I only looked at the config code quickly, but I can't see where it's trying to read the kernel HZ value at compile time?

What am I missing?

Note, seems to be working fine without any config stanzas, I just thought it curious?

Ed W

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