Hi Miroslav, Sync is already sent using a constant interval as required by Standard even if it is lower than the nominal frequency for the actual implementation (stop and rearm). In other hands, you already have the depicted problems on your HW, if any, but on a different resonance frequency. The sync is forged by master as a one-to-many message that does not saturate the link, the randomization is required for the messages from Clients to Master (Delay-Req) in order to avoid congestion on Master. General messages are randomized also. Speaking about messages collision in TX path, this is not an issue here because your HW timestamp will (should) set the correct TS value at the end of TX queue. On the RX side, the TS is applied just before the RX queue.
As reported by Richard, the conformance is not impacted by the proposed fix. ciao luigi Il giorno mer 26 apr 2023 alle ore 10:17 Miroslav Lichvar < mlich...@redhat.com> ha scritto: > On Thu, Mar 30, 2023 at 08:08:12AM +0200, Luigi Mantellini wrote: > > The actual ptp4l implementation rearms timers after the expiration. This > approach doesn't permit to have a precise TX SYNC message scheduling. > > During my test the TX SYNC frequency is slightly lower the expectation > (eg 15.99Hz vs 16Hz). > > Can you please explain advantages of using a constant interval? > > Generally, sending timing sensitive messages over network in a > constant interval sounds like a bad idea to me. If there are multiple > hosts doing that (e.g. PTP servers in different domains) and they > happen to collide in their transmissions times (which requires > queueing and potentially impacts timestamp accuracy), this is more > likely to repeat frequently. If anything, I'd expect more randomness > to be added to the interval. > > -- > Miroslav Lichvar > > -- *Luigi 'Comio' Mantellini* My Professional Profile <http://www.linkedin.com/in/comio> *"UNIX is very simple, it just needs a genius to understand its simplicity." [cit.]*
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