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DescriptionMiroslav Lichvar
2018-10-29 16:43:31 UTC
Description of problem:
A new ioctl is needed to enable a more accurate synchronization of the system clock with HW timestamping (bug #1643974). When available, the ioctl needs to be supported by chrony.
Version-Release number of selected component (if applicable):
chrony-3.2-2.el7.x86_64
How reproducible:
always
Steps to Reproduce:
1. run chronyd as an NTP client with HW timestamping and look for hwclock messages in the debug output:
chronyd -d -d "server $LOCAL_NTPSERVER minpoll 2 maxpoll 2" \
'hwtimestamp *' |& grep 'hwclock.*err='
Actual results:
2018-10-20T19:19:44Z hwclock.c:191:(HCL_AccumulateSample) HW clock samples=16 offset=-1.859570e-08 freq=2.936241e-05 raw_freq=3.643518e-05 err=1.193500e-06 ref_diff=7.251244e+03
It depends on the NIC, PCIe slot, and other things, but usually the reported error is about 0.7-2.5 microseconds.
Expected results:
Reported error smaller than 0.5 microsecond at least for some supported NICs.