On Fri, Aug 21, 2015 at 12:30 AM, Clemens Gruber <clemens.gru...@pqgruber.com> wrote: > Hi, > > I am experiencing massive RX packet loss on my i.MX6Q (Chip rev 1.3) on Linux > 4.2-rc7 with a Marvell 88E1510 Gigabit Ethernet PHY connected over RGMII. > I noticed it when doing an UDP benchmark with iperf3. When sending UDP packets > from a Debian PC to the i.MX6 with a rate of 100 Mbit/s, 99% of the packets > are > lost. With a rate of 10 Mbit/s, we are still losing 93% of all packets. TCP RX > does suffer from packet loss too, but still achieves about 211 Mbit/s. > TX is not affected. > > Steps to reproduce: > On the i.MX6: iperf3 -s > On a desktop PC: iperf3 -b 10M -u -c MX6IP > > The iperf3 results: > [ ID] Interval Transfer Bandwidth Jitter Lost/Total > [ 4] 0.00-10.00 sec 11.8 MBytes 9.90 Mbits/sec 0.687 ms 1397/1497 > (93%) > > During the 10 Mbit UDP test, the IEEE_rx_macerr counter increased to 5371. > ifconfig eth0 shows: > RX packets:9216 errors:5248 dropped:170 overruns:5248 frame:5248 > TX packets:83 errors:0 dropped:0 overruns:0 carrier:0 > collisions:0 > > Here are the TCP results with iperf3 -c MX6IP: > [ ID] Interval Transfer Bandwidth Retr > [ 4] 0.00-10.00 sec 252 MBytes 211 Mbits/sec 4343 sender > [ 4] 0.00-10.00 sec 251 MBytes 211 Mbits/sec receiver > > During the TCP test, IEEE_rx_macerr increased to 4059. > ifconfig eth0 shows: > RX packets:186368 errors:4206 dropped:50 overruns:4206 frame:4206 > TX packets:41861 errors:0 dropped:0 overruns:0 carrier:0 > collisions:0 > > Freescale errata entry ERR004512 did mention a RX FIFO overrun. Is this > related? > > Forcing pause frames via ethtool -A eth0 rx on tx on, does not improve it: > Same amount of UDP packet loss with reduced TCP throughput of 190 Mbit/s. > IEEE_rx_macerr increased up to 5232 during UDP 10Mbit and up to 4270 for TCP. > > I am already using the MX6QDL_PAD_GPIO_6__ENET_IRQ workaround, which solved > the > ping latency issues from ERR006687 but not the packet loss problem. > > I read through the mailing list archives and found a discussion between > Russell > King, Marek Vasut, Eric Nelson, Fugang Duan and others about a similar > problem. > I therefore added you and contributors to fec_main.c to the CC. > > One suggestion I found, was adding udelay(210); to fec_enet_rx(): > https://lkml.org/lkml/2014/8/22/88 > But this also did not reduce the packet loss. (I added it to the fec_enet_rx > function just before return pkt_received; but I still got 93% packet loss) > > Does anyone have the equipment/setup to trace an i.MX6Q during UDP RX traffic > from iperf3 to find the root cause of this packet loss problem? > > What else could we do to fix this? >
This is a bug in iperf3's UDP tests. Do the same test with iperf2 and you will see expected performance. I believe there is a bug open in github about it. -Jon -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
