* [Intel-wired-lan] bad iperf3 tcp performance of Intel 10G NIC when MTU is 9000 @ 2020-02-04 15:34 Yi Yang =?unknown-8bit?b?5p2o77+9RC3kupHmnI3liqHpm4blm6I=?= 2020-02-06 18:18 ` Alexander Duyck 0 siblings, 1 reply; 4+ messages in thread From: Yi Yang =?unknown-8bit?b?5p2o77+9RC3kupHmnI3liqHpm4blm6I=?= @ 2020-02-04 15:34 UTC (permalink / raw) To: intel-wired-lan Hi, all We find a very weird issue on Intel 10G NIC, iperf3 tcp performance is good when MTU is 1500, but it is about one third of the former when MTU is 9000, anybody knows why it is so, is any solution to it available? The below is our kernel and ixgbe deriver information: Ubuntu 16.04 and kernel is updated to 4.15.0-36-generic x86_64 Ixgbe driver version: 5.1.0-k Firmware version: 0x61c10001 BTW, tso is on. -------------- next part -------------- A non-text attachment was scrubbed... Name: smime.p7s Type: application/pkcs7-signature Size: 3600 bytes Desc: not available URL: <http://lists.osuosl.org/pipermail/intel-wired-lan/attachments/20200204/9d1b4744/attachment.p7s> ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Intel-wired-lan] bad iperf3 tcp performance of Intel 10G NIC when MTU is 9000 2020-02-04 15:34 [Intel-wired-lan] bad iperf3 tcp performance of Intel 10G NIC when MTU is 9000 Yi Yang =?unknown-8bit?b?5p2o77+9RC3kupHmnI3liqHpm4blm6I=?= @ 2020-02-06 18:18 ` Alexander Duyck 2020-02-07 0:13 ` [Intel-wired-lan] 答复: " Yi Yang =?unknown-8bit?b?5p2o54eaLeS6keacjeWKoembhuWbog==?= 0 siblings, 1 reply; 4+ messages in thread From: Alexander Duyck @ 2020-02-06 18:18 UTC (permalink / raw) To: intel-wired-lan On Tue, Feb 4, 2020 at 7:34 AM Yi Yang (??)-????? <yangyi01@inspur.com> wrote: > > Hi, all > > We find a very weird issue on Intel 10G NIC, iperf3 tcp performance is good > when MTU is 1500, but it is about one third of the former when MTU is 9000, > anybody knows why it is so, is any solution to it available? > > The below is our kernel and ixgbe deriver information: > > Ubuntu 16.04 and kernel is updated to 4.15.0-36-generic x86_64 > Ixgbe driver version: 5.1.0-k > Firmware version: 0x61c10001 > > BTW, tso is on. There could be quite a few things going on, but it is hard to say without more information. What is the test you are running and what are the numbers you are seeing at 1500 MTU versus 9000 MTU? Have you taken a look at the "netstat -s" info on both ends to see if anything might be going on there? One possibility is if you have a congested network moving the 9K MTU frames can be slower as any 9K frames dropped will have to be retransmitted and since the frames are larger you may encounter the need for retransmit more often and they would be slower. Also have you checked the network path to make certain that you are able to send 9K frames between the two systems? If there are any switches in between not configured for 9K MTU that could cause performance issues. One debugging step you might try would be to incrementally increase the MTU size and run several tests to see if there is a certain packet size that the performance drops at. If we find the regression starts at a certain size it could point to a specific issue either in the network stack, driver, or the network itself. Thanks. - Alex ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Intel-wired-lan] 答复: bad iperf3 tcp performance of Intel 10G NIC when MTU is 9000 2020-02-06 18:18 ` Alexander Duyck @ 2020-02-07 0:13 ` Yi Yang =?unknown-8bit?b?5p2o54eaLeS6keacjeWKoembhuWbog==?= 2020-02-07 1:05 ` [Intel-wired-lan] " Alexander Duyck 0 siblings, 1 reply; 4+ messages in thread From: Yi Yang =?unknown-8bit?b?5p2o54eaLeS6keacjeWKoembhuWbog==?= @ 2020-02-07 0:13 UTC (permalink / raw) To: intel-wired-lan Alex, thank you so much for your great suggestion. We have double checked switches, they have set jumbo frame support, we ran iperf3 to check performance, iperf3 udp is ok even if MTU is set to 9000, so we can believe no other traffic resulted in network congestion. Iperf3 tcp performance is about 8.9Gbps if MTU is set to 1500, but it is just about 3 Gbps if MTU is set to 9000. Iperf3 udp performance is about 8.9Gbps if MTU is set to 9000. I also checked the same thing in another environment, which used i40e but not ixgbe, all the cases are ok, that is why I doubt it is a kernel or driver or firmware issue, did you receive similar issue report? -----????----- ???: Alexander Duyck [mailto:alexander.duyck at gmail.com] ????: 2020?2?7? 2:19 ???: Yi Yang (??)-????? <yangyi01@inspur.com> ??: jeffrey.t.kirsher at intel.com; yang_y_yi at 163.com; intel-wired-lan at lists.osuosl.org ??: Re: [Intel-wired-lan] bad iperf3 tcp performance of Intel 10G NIC when MTU is 9000 On Tue, Feb 4, 2020 at 7:34 AM Yi Yang (??)-????? <yangyi01@inspur.com> wrote: > > Hi, all > > We find a very weird issue on Intel 10G NIC, iperf3 tcp performance is > good when MTU is 1500, but it is about one third of the former when > MTU is 9000, anybody knows why it is so, is any solution to it available? > > The below is our kernel and ixgbe deriver information: > > Ubuntu 16.04 and kernel is updated to 4.15.0-36-generic x86_64 Ixgbe > driver version: 5.1.0-k Firmware version: 0x61c10001 > > BTW, tso is on. There could be quite a few things going on, but it is hard to say without more information. What is the test you are running and what are the numbers you are seeing at 1500 MTU versus 9000 MTU? Have you taken a look at the "netstat -s" info on both ends to see if anything might be going on there? One possibility is if you have a congested network moving the 9K MTU frames can be slower as any 9K frames dropped will have to be retransmitted and since the frames are larger you may encounter the need for retransmit more often and they would be slower. Also have you checked the network path to make certain that you are able to send 9K frames between the two systems? If there are any switches in between not configured for 9K MTU that could cause performance issues. One debugging step you might try would be to incrementally increase the MTU size and run several tests to see if there is a certain packet size that the performance drops at. If we find the regression starts at a certain size it could point to a specific issue either in the network stack, driver, or the network itself. Thanks. - Alex -------------- next part -------------- A non-text attachment was scrubbed... Name: smime.p7s Type: application/pkcs7-signature Size: 3600 bytes Desc: not available URL: <http://lists.osuosl.org/pipermail/intel-wired-lan/attachments/20200207/b856f719/attachment.p7s> ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Intel-wired-lan] bad iperf3 tcp performance of Intel 10G NIC when MTU is 9000 2020-02-07 0:13 ` [Intel-wired-lan] 答复: " Yi Yang =?unknown-8bit?b?5p2o54eaLeS6keacjeWKoembhuWbog==?= @ 2020-02-07 1:05 ` Alexander Duyck 0 siblings, 0 replies; 4+ messages in thread From: Alexander Duyck @ 2020-02-07 1:05 UTC (permalink / raw) To: intel-wired-lan I haven't heard of any similar issues. The fact that it impacts TCP only has me wondering if LRO/RSC might be enabled on the NIC and is possibly causing issues. You might try disabling LRO via "ethtool -k/-K" if it is enabled to see if that resolves the issue. Beyond that the only other feature I can think of that we might want to eliminate would be GRO. It probably wouldn't hurt to try disabling those features on both ends and seeing if one of them resolves the issue. Thanks. - Alex On Thu, Feb 6, 2020 at 4:16 PM Yi Yang (??)-????? <yangyi01@inspur.com> wrote: > > Alex, thank you so much for your great suggestion. We have double checked switches, they have set jumbo frame support, we ran iperf3 to check performance, iperf3 udp is ok even if MTU is set to 9000, so we can believe no other traffic resulted in network congestion. Iperf3 tcp performance is about 8.9Gbps if MTU is set to 1500, but it is just about 3 Gbps if MTU is set to 9000. Iperf3 udp performance is about 8.9Gbps if MTU is set to 9000. > > I also checked the same thing in another environment, which used i40e but not ixgbe, all the cases are ok, that is why I doubt it is a kernel or driver or firmware issue, did you receive similar issue report? > > -----????----- > ???: Alexander Duyck [mailto:alexander.duyck at gmail.com] > ????: 2020?2?7? 2:19 > ???: Yi Yang (??)-????? <yangyi01@inspur.com> > ??: jeffrey.t.kirsher at intel.com; yang_y_yi at 163.com; intel-wired-lan at lists.osuosl.org > ??: Re: [Intel-wired-lan] bad iperf3 tcp performance of Intel 10G NIC when MTU is 9000 > > On Tue, Feb 4, 2020 at 7:34 AM Yi Yang (??)-????? <yangyi01@inspur.com> wrote: > > > > Hi, all > > > > We find a very weird issue on Intel 10G NIC, iperf3 tcp performance is > > good when MTU is 1500, but it is about one third of the former when > > MTU is 9000, anybody knows why it is so, is any solution to it available? > > > > The below is our kernel and ixgbe deriver information: > > > > Ubuntu 16.04 and kernel is updated to 4.15.0-36-generic x86_64 Ixgbe > > driver version: 5.1.0-k Firmware version: 0x61c10001 > > > > BTW, tso is on. > > There could be quite a few things going on, but it is hard to say without more information. > > What is the test you are running and what are the numbers you are seeing at 1500 MTU versus 9000 MTU? Have you taken a look at the "netstat -s" info on both ends to see if anything might be going on there? One possibility is if you have a congested network moving the 9K MTU frames can be slower as any 9K frames dropped will have to be retransmitted and since the frames are larger you may encounter the need for retransmit more often and they would be slower. > > Also have you checked the network path to make certain that you are able to send 9K frames between the two systems? If there are any switches in between not configured for 9K MTU that could cause performance issues. > > One debugging step you might try would be to incrementally increase the MTU size and run several tests to see if there is a certain packet size that the performance drops at. If we find the regression starts at a certain size it could point to a specific issue either in the network stack, driver, or the network itself. > > Thanks. > > - Alex ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2020-02-07 1:05 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2020-02-04 15:34 [Intel-wired-lan] bad iperf3 tcp performance of Intel 10G NIC when MTU is 9000 Yi Yang =?unknown-8bit?b?5p2o77+9RC3kupHmnI3liqHpm4blm6I=?= 2020-02-06 18:18 ` Alexander Duyck 2020-02-07 0:13 ` [Intel-wired-lan] 答复: " Yi Yang =?unknown-8bit?b?5p2o54eaLeS6keacjeWKoembhuWbog==?= 2020-02-07 1:05 ` [Intel-wired-lan] " Alexander Duyck
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