Hi Richard,
I am sorry for frustrating you. I hear you louder for sure!! You have got me right - yes, the abiliy of 1588 should not stop with just offset correction. I want to understand what it takes for 1588 to match with SyncE. Yes, there are many roadblocks and what you have mentioned/admonished is already under our scrutiny. Thank you all for sharing your answers/opinions. Thanking you in anticipation, Regards, Chandra (c) : 0175508142 (O): 701.6412 "Knowledge speaks, Wisdom listens" -----Original Message----- From: Richard Cochran [mailto:[email protected]] Sent: Wednesday, March 18, 2015 4:29 PM To: Chandra Mallela Cc: Miroslav Lichvar; [email protected] Subject: Re: [Linuxptp-users] Expected throughput of the ptp4l On Wed, Mar 18, 2015 at 02:58:46AM +0000, Chandra Mallela wrote: > From my interactions with the customer as an architect, I could see the need > for 512 syncs per second, due to high-end frequency correction (think of a > 1588 application to replace/compete with SyncE applicationIn a pure telecom > application, high frequency Sync packets might encroach into datatraffic. > However, in back-hauling (be it telecom or networking), where high-throughput > is already a given parameter, high frequency Sync packets are desirable for > frequency corrections. ). On offset correction, I can take liberties on > DelayReq sets. If you have SyncE in place already, then you don't need the 512 rate. In fact, all you need is *one* offset measurement in order to correct the offset, once the clocks are locked. If you are trying to replace a SyncE system with a non-SyncE PTP system, then you can forget trying to match the SyncE synchronization performance. It just is not feasible, to my knowledge. > Do we have the performance metrics of the ptp4l in a standard Linux OS? At > what rates of the packets, does the stack break down? If we have any data, it > will be good for us to know. If you have any ideas as to how to arrive at the > numbers, please let me know - I can try it out with the system at my hand. The answer is, "it depends." I have seen good results with 1, 2, 4, and 8, packets per second on a low end embedded system. With 128, some time stamps are dropped due to hardware/driver constraints. Any performance metric is tied to the particular hardware used, and so even if I had such metrics, they would not help you too much. I already told you this more than once: If you really want to run 512 packets per second, then you are going to have to do some careful hardware selection and some serious system tuning. It won't be easy. Good luck, Richard ________________________________ Confidentiality Notice. This message may contain information that is confidential or otherwise protected from disclosure. If you are not the intended recipient, you are hereby notified that any use, disclosure, dissemination, distribution, or copying of this message, or any attachments, is strictly prohibited. If you have received this message in error, please advise the sender by reply e-mail, and delete the message and any attachments. Thank you. ------------------------------------------------------------------------------ Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ _______________________________________________ Linuxptp-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linuxptp-users
