rootfs: configure chronyc service with makestep

[xs3c]

The current chrony service does not step the system clock,
so add the modification to do this if the adjustment is
larger than one second

Fixes: #316

Signed-off-by: Yang, Wei wei.yang1@linux.alibaba.com

[jodh-intel]

Thanks @xs3c.

lgtm

/cc @amshinde for her thoughts. @grahamwhaley may have a view on this too from the metrics perspective.

[jodh-intel]

Idea: this is fine, but now there are two changes to this file, you could instead do:

cat >>"${chrony_conf_file}"<<EOT
refclock PHC /dev/ptp0 poll 3 dpoll -2 offset 0

# Step the system clock instead of slewing it if the adjustment is larger than
# one second, at any time
echo "makestep 1 -1
EOT

[xs3c]

Done

[jodh-intel]

/test

[grahamwhaley]

I think the idea is fine/right. I'd be interested to know:

• will this time sync be guaranteed to happen before the container workload gets launched? That is, it is synchronous or async with the workload. Async could cause some interesting issues maybe for workloads in the future if their time suddenly jumps for instance.
• have we witnessed the time being out between the host and the guest, and by how much?

/cc @mcastelino who I think first toyed with syncing the clocks

[jodh-intel]

Thanks again @xs3c! 😄

[xs3c]

@jodh-intel you are welcome 😄

[amshinde]

lgtm, as it is generally a good practice to makestep esp if the host goes to sleep.
@xs3c During testing this a while back, we had not seen a large difference in the the host and the guest time, just when the guest had booted up.
Can you provide some values on what improvements you are seeing with this approach at bootup.

@grahamwhaley I have also being toying with the idea of adding a systemd ordering for the agent and chrony, to make sure we start the agent after chrony has fully started up(perhaps allowing it to sync the time before any workload is started by the agent).
I believe we can achieve this with adding an After=chronyd.service in the agent service file, allowing the agent to start after chrony. I think with After=, the agent would still start, even if chrony failed to start, need to confirm this though.

[jcvenegas]

/test

[jodh-intel]

Restarted ARM CI now that #265 has landed.

[amshinde]

@Pennyzct ARM CI still seems to be failing. Can you take a look?
Did #265 solve the chrony startup issue for you on ARM? Can you confirm? A quick glance at the failures dont show errors related to that.

[Pennyzct]

Hi~ @amshinde
osbuilder/ repo and runtime/ repo have different test cases, the error

Makefile:55: recipe for target '/tmp/osbuilder-test.4zzNcbN/rootfs-osbuilder/.clearlinux_rootfs.done' failed
make: *** [/tmp/osbuilder-test.4zzNcbN/rootfs-osbuilder/.clearlinux_rootfs.done] Error 1

should be fixed by #320. I will restart to see how it works now. ;)
and #265 did fix ARM CI failure on runtime/ repo. you may see one proof in one new PR runtime/#1823 in runtime/ repo, ARM CI got green. ;)

[Pennyzct]

we have all green here~~~~🎉🎊