On 2/2/2021 11:39 AM, PATRICK KEROULAS wrote:
>
>
> On Tue, Feb 2, 2021 at 2:31 PM Jacob Keller <jacob.e.kel...@intel.com
> <mailto:jacob.e.kel...@intel.com>> wrote:
>>
>> >> When the app is running, the whole traffic is redirected to DPDK,
>> >> depriving ptpl4 from PTP messages. Given a very stable source of
>> >> packets, I can notice a small drift of the packet timestamps (few
>> >> 10usec/s). Sure a drift is to be expected but here is what's surprised
>> >> me. When shutting down ptpl4 before the capture app is started, no
> drift
>> >> can be noticed.
>> >>
>>
>>
>> So in the "failure" case, ptp4l is running but not receiving any packet
>> data?
>>
>> Where as in the "success" case, you've stopped ptp4l and thus are sure
>> that nothing is tuning the clock at all?
>>
>
> That is correct Jacob.
>
I wonder if when ptp4l is running, its last adjustment is skewed, so it
causes clock drift over time.
You might want to get some logging of what the clock frequency
adjustment is. I believe you can gather this information via the test
program for PHC access to read frequency adjustment data to see what the
adjustment is in both cases.
Thanks,
Jake
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