Although reduced, I’m still seeing spikes with the patch below.

Denny



> On Nov 16, 2016, at 00:53, Miroslav Lichvar <mlich...@redhat.com> wrote:
> 
> On Tue, Nov 15, 2016 at 08:24:37PM -0800, Denny Page wrote:
>> With the latest drop in the repo, I’m still seeing the wild spikes in the 
>> standard deviation with hardware time stamping against the fast responding 
>> hardare units. I'm also still seeing a better base deviation using software 
>> timestamps against them as well.
>> 
>> I do see better results with hardware time stamping when doing chrony to 
>> chrony, but I believe that this is a result of the general purpose computers 
>> being a bit slower to respond than the dedicated hardware units.
> 
> Hm, the fix helped with the spikes I was seeking. Did we rule out the
> possibility that in your case the spikes are due to the other issue with
> out-of-order HW timestamps? Could you try it with this patch to make
> sure only measurements with HW timestamps are used?
> 
> --- a/ntp_core.c
> +++ b/ntp_core.c
> @@ -1434,6 +1434,9 @@ receive_packet(NCR_Instance inst, NTP_Local_Address 
> *local_addr,
>        prevent a synchronisation loop */
>     testD = message->stratum <= 1 || REF_GetMode() != REF_ModeNormal ||
>             pkt_refid != UTI_IPToRefid(&local_addr->ip_addr);
> +
> +    if (inst->local_tx.source != NTP_TS_HARDWARE || rx_ts->source != 
> NTP_TS_HARDWARE)
> +      testB = 0;
>   } else {
>     offset = delay = dispersion = 0.0;
>     sample_time = rx_ts->ts;


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