Re: [chrony-users] makestep in Chrony

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On Wed, 9 May 2018, Miroslav Lichvar wrote:

On Sun, May 06, 2018 at 10:30:48AM +0000, Hei Chan wrote:
I am reading this:
It mentions, "Normally chronyd will cause the system to gradually correct any time offset, by slowing down or speeding up the clock as required".  Most of the Linux machines are using TSC as the source:$ cat /sys/devices/system/clocksource/clocksource0/current_clocksourcetsc
Given a machine using TSC as the clock source and new Intel CPUs have invariant TSC, how can chrony slow down or speed up the clock?  I am sure I misunderstand the doc.

The clocksources don't change their frequency. It's the software
system clock maintained by the kernel, whose frequency is adjusted by
the adjtimex(2) system call.

To expand, there is counter that counts the pulses in TSC, but those pulses
need to be converted into seconds. That conversion factor can get changed by
the adjtimex.

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