Re: [chrony-dev] SW/HW timestamping on Linux

[Denny Page <dennypage@xxxxxx>]

Miroslav,

The kernel is 4.4.26. The problem appears to be hardware timestamping and multiple interfaces.

Here is the test setup: 3 identical hardware NTP units. Two accessible via switch on igb0. One accessible vi igb3 as a directly connected IP point to point. Here are test results:

test 1
- hw stamps off for all interfaces
- all ntp servers enabled
- result: K K for all servers (as expected)

test 2
- hw stamps on for igb0
- all ntp servers enabled
- result: H H for servers attached via igb0, D K for server attached via igb3

test 3
- hw stamps on for igb3
- all ntp servers enabled
- result: D K for servers attached via igb0, mixed D H and H H for server attached via igb3

test 4
- hw stamps on for both igb0 and igb3
- all ntp servers enabled
- result: H H for one server attached via igb0, mixed H H and D H for other server attached via igb0, mixed H H and D H for server attached via igb3


test 5
- hw stamps on for igb0
- ntp servers attached via igb0 enabled, server attached via igb3 disabled
- result: H H for both servers (as expected)

test 6
- hw stamps on for igb3
- ntp servers attached via igb0 enabled, server attached via igb3 disabled
- result: D K for both servers


test 7
- hw stamps on for igb0
- ntp servers attached via igb0 disabled, server attached via igb3 enabled
- result: D K

test 8
- hw stamps on for igb3
- ntp servers attached via igb0 disabled, server attached via igb3 enabled
- result: mixed D H and H H


Denny



> On Nov 10, 2016, at 11:45, Miroslav Lichvar <mlichvar@xxxxxxxxxx> wrote:
> 
> On Thu, Nov 10, 2016 at 11:25:31AM -0800, Denny Page wrote:
>> Miroslav,
>> 
>> And D H?
> 
> D means daemon, i.e. no SW or HW timestamp. The first one is for
> transmit timestampt, the other one for receive timestamp. If only the
> first entry in the log is like that, then it's ok. If not, something
> is wrong. What kernel version do you have? It might help if we could
> see the debug output from chronyd -d -d when compiled with the
> --enable-debug option.
> 
> -- 
> Miroslav Lichvar
> 
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