> -----Original Message----- > From: Miroslav Lichvar [mailto:[email protected]] > Sent: Wednesday, May 09, 2018 7:56 AM > To: [email protected] > Subject: [Linuxptp-devel] Delay requests causing ptp4l to miss sync TX > timestamp? > > I'm trying to measure the maximum throughput of ptp4l handling unicast > delay requests and I'm seeing some unexpected (at least for me) > behavior. When the rate of requests reaches a threshold, ptp4l > switches to the fault state after missing the TX timestamp of its own > sync message, which is sent just once per second. From tcpdump output > it doesn't look like the sync message was dropped due to a full queue. > > Delay responses don't generate TX timestamps (unlike NSM responses). > How can a high rate of RX timestamps cause a TX timestamp to be > missed? Is this a common HW limitation? I see this happening with > three different drivers (tg3, igb, ixgbe). >
I'm not aware of such a limitation... Is it possible that it's fast enough that the general latency in the system exceeds the polling timeout? What about if you increase the timeout window when waiting for the timestamp response? For the Intel parts, they should share a common tx_hwtstamp_skipped or tx_hwtstamp_missed counters in ethtool -S which should indicate if the driver thinks timestamps are being missed. Thanks, Jake > -- > Miroslav Lichvar > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Linuxptp-devel mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/linuxptp-devel ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Linuxptp-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linuxptp-devel
