Why would you need multiple phc2sys processes? Shouldn't you only need one? Shouldn't the command phc2sys -s /dev/ptp0 -c /dev/ptp1 -w sync the two clocks? And would this still go through the system clock?
Thank you Kyle -----Original Message----- From: Luke Bigum [mailto:luke.bi...@lmax.com] Sent: Tuesday, April 25, 2017 8:40 AM To: linuxptp-users Subject: Re: [Linuxptp-users] ptp inducing as many hops as possible Kyle, I think you've misunderstood what Richard was talking about. You can't just arbitrarily set any network interface to use any PHC - the oscillator under the PHC device is physically attached to the NIC. Unless you have a multi-port network card that shares one oscillator (eg: SolarFlare 7x22), most NICs will probably have their own PHC. That's why you're getting the device mismatch error. I've used multiple phc2sys processes in the past to sync different NICs, but this is not a true Boundary Clock. You'll be copying time up and down the Linux stack and through the system clock, so you are subject to all sorts of kernel scheduling jitter and PCI bus latency. If you just want some sort of PTP signal and don't care so much about accuracy though, you can do this. Also regarding your question earlier about Gain Peaking, Richard was warning you about cumulative error. So if you are proposing to go: grandmaster -> BC 1 port 1 -> BC 1 port 2 -> BC 2 port 1 -> BC 2 port 2 -> BC 3 port 1 -> BC 3 port 3 And it costs, say, +/- 10us of jitter to go between ports, by the time you get to BC3 port 3 you'll be at +/- 60us. -- Luke Bigum Lead Engineer Information Systems ----- Original Message ----- From: "Mace, Kyle P." <kyle.m...@gd-ms.com> To: "Richard Cochran" <richardcoch...@gmail.com> Cc: "linuxptp-users" <linuxptp-users@lists.sourceforge.net> Sent: Tuesday, 25 April, 2017 14:19:47 Subject: Re: [Linuxptp-users] ptp inducing as many hops as possible Alright I am having troubles forcing the ports to use the same PHC. When I specify which PHC to use I get an error about PHC device mismatch. Is there a way to unattach the hardware clock from a specific port? Output of error sudo ptp4l -i eno1 -p /dev/ptp1 -m -s ptp4l[61532.475]: selected /dev/ptp1 as PTP clock ptp4l[61532.475]: port 1: PHC device mismatch ptp4l[61532.476]: port 1: /dev/ptp1 requested, but /dev/ptp0 attached ptp4l[61532.476]: failed to open port eno1 Or would I be able to enable the boundary_clock_jbod option in a config file and then sync the clocks off the system clock using phc2sys? -----Original Message----- From: Richard Cochran [mailto:richardcoch...@gmail.com] Sent: Thursday, April 20, 2017 4:27 PM To: Mace, Kyle P. Cc: linuxptp-users@lists.sourceforge.net Subject: Re: [Linuxptp-users] ptp inducing as many hops as possible On Thu, Apr 20, 2017 at 07:08:52PM +0000, Mace, Kyle P. wrote: > I am in need to test ptp with as many 'hops' as possible. I have > multiple systems with dual Ethernet ports. I would like to have a > setup something like this: grandmaster -> BC 1 port 1 -> BC 1 port 2 > -> BC 2 port 1 -> BC 2 port 2 -> BC 3 port 1 -> BC 3 port 3 -> > etc.. Anyone have any ideas if this is possible? The linuxptp stack supports this. Remember that all the ports of the BC must share the same clock (that is, the same PHC). Also, long chains of BC are prone to "gain peaking". HTH, Richard ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Linuxptp-users mailing list Linuxptp-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxptp-users --- LMAX Exchange, Yellow Building, 1A Nicholas Road, London W11 4AN http://www.LMAX.com/ Recognised by the most prestigious technology and business awards Financial technology awards 2017 Best FX trading venue, Fund Technology & WSL Awards 2016 Best trading & execution venue, HFM US Technology Awards FX industry awards 2016, 2015, 2014, 2013 Winner, Profit & Loss Readers' Choice Awards 2016, 2015, 2014, 2013 Winner, WSL Institutional Trading Awards Business growth awards 2016, 2015 Winner, Deloitte UK Technology Fast 50 2015, 2014, 2013, Winner, The Sunday Times Tech Track 100 2016, 2015 Winner, Deloitte EMEA Technology Fast 500 2015 Winner, Tech City UK Future 50 --- FX and CFDs are leveraged products that can result in losses exceeding your deposit. 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