On Thu, 13 Dec 2018 01:20:48 +0200
Risto Pajula <[email protected]> wrote:
> Hello.
>
> I'm not able reproduce the actual problem anymore which was the high
> ping latency from the internal network.
>
> This starts to sound like some sort of voodoo, but...
>
> I tested replacing the switch to another brand where internal network
> trtl8169 is connected. This did not have any effect on the behavior, the
> latency remained high.
>
> Then I disconnected every device and all the network cables from the
> internal network. The I connected everything again. After that
> reproducing the problem seems very difficult. Likelihood for this to
> happen dramatically decreased.
>
> Looking at pings 30min I once got this.
>
> Reply from 192.168.0.1: bytes=32 time<1ms TTL=64
> Reply from 192.168.0.1: bytes=32 time<1ms TTL=64
> Reply from 192.168.0.1: bytes=32 time<1ms TTL=64
> Reply from 192.168.0.1: bytes=32 time=18ms TTL=64
> Reply from 192.168.0.1: bytes=32 time=24ms TTL=64
> Reply from 192.168.0.1: bytes=32 time<1ms TTL=64
> Reply from 192.168.0.1: bytes=32 time<1ms TTL=64
>
> I did also look at the kernel traces, it seems the rtl8169 send FIFO
> still stalls, but it does not happen as often and in practice is hard to
> notice for the user.
>
> For example I did find this kind sequence:
>
> t0: rtl8169_start_xmit first 1506 byte frame is written
> ...9 more frames is transmitted
> t0+350us: 2 frames is still not sent. (transmission should have taken
> 120us + interframe time)
>
> BR.
> Risto
>
> On 12.12.2018 8:23, Heiner Kallweit wrote:
> > According to your description of the issue it doesn't need a very exotic
> > scenario to trigger it.
> > And due to the fact that Realtek network chips are used on a lot of
> > consumer mainboards, I would
> > assume quite some people are using such a mainboard for a use case like
> > yours.
> > This makes it somewhat suspicious that at least I'm not aware of more such
> > reports.
> > Therefore I think it's a good idea to check the other components of the
> > internal network.
> >
> > On 12.12.2018 02:28, Risto Pajula wrote:
> >> Hello.
> >>
> >> I added some debug prints to diagnose the bug properly. I can send the
> >> patches if you are willing to debug/try... for example this output is
> >> produced:
> >>
> >> 96096: <idle>-0 [000] ..s. 232.466703: rtl8169_start_xmit:
> >> RTLDBG221 eth1 rtl8169_start_xmit len: 1506 opts1: B0000000 txpol: 0
> >> entry: 24 cur_tx: 5656 frags: 0 dirty_tx: 5648 tx_left: 8
> >> 96097: <idle>-0 [000] ..s. 232.466704: rtl8169_start_xmit:
> >> RTLDBG111 eth1 rtl_tx_slots_avail
> >> 96099: <idle>-0 [000] d.h. 232.468827: rtl8169_interrupt:
> >> RTLDBG111 eth1 rtl8169_interrupt
> >> 96103: <idle>-0 [000] ..s. 232.468833: rtl8169_poll:
> >> RTLDBG111 eth1 rtl8169_poll
> >> 96104: <idle>-0 [000] ..s. 232.468834: rtl8169_poll:
> >> RTLDBG111 eth1 rtl_rx
> >> 96105: <idle>-0 [000] ..s. 232.468835: rtl8169_poll:
> >> RTLDBG111 eth1 rtl8169_try_rx_copy
> >> 96184: <idle>-0 [000] ..s. 232.468914: rtl_tx: RTLDBG222
> >> eth1 rtl_tx len: 1506 opts1: B00005E2 txpol: 0 entry: 16 cur_tx: 5657
> >> frags: 0 dirty_tx: 5648 tx_left: 9
> >> 96185: <idle>-0 [000] ..s. 232.468924: rtl_tx: RTLDBG223
> >> eth1 rtl_tx entry opts1: 16, B00005E2 17, B00005E2 18, B00005E2 19,
> >> B00005E2 20, B00005E2 21, B00005E2 22, B00005E2 23, B00005E2 24, B00005E2
> >> 96189: <idle>-0 [000] d.h. 232.469006: rtl8169_interrupt:
> >> RTLDBG111 eth1 rtl8169_interrupt
> >> 96193: <idle>-0 [000] ..s. 232.469012: rtl8169_poll:
> >> RTLDBG111 eth1 rtl8169_poll
> >> 96194: <idle>-0 [000] ..s. 232.469014: rtl8169_poll:
> >> RTLDBG111 eth1 rtl_rx
> >> 96196: <idle>-0 [000] ..s. 232.469020: rtl_tx: RTLDBG222
> >> eth1 rtl_tx len: 1506 opts1: 30000000 txpol: 0 entry: 16 cur_tx: 5657
> >> frags: 0 dirty_tx: 5648 tx_left: 9
> >> 96204: <idle>-0 [000] ..s. 232.469032: rtl_tx: RTLDBG222
> >> eth1 rtl_tx len: 1506 opts1: 30000000 txpol: 0 entry: 17 cur_tx: 5657
> >> frags: 0 dirty_tx: 5649 tx_left: 8
> >> 96212: <idle>-0 [000] ..s. 232.469041: rtl_tx: RTLDBG222
> >> eth1 rtl_tx len: 1506 opts1: B00005E2 txpol: 0 entry: 18 cur_tx: 5657
> >> frags: 0 dirty_tx: 5650 tx_left: 7
> >> 96213: <idle>-0 [000] ..s. 232.469050: rtl_tx: RTLDBG223
> >> eth1 rtl_tx entry opts1: 18, B00005E2 19, B00005E2 20, B00005E2 21,
> >> B00005E2 22, B00005E2 23, B00005E2 24, B00005E2
> >> 96235: <idle>-0 [000] d.h. 232.471253: rtl8169_interrupt:
> >> RTLDBG111 eth1 rtl8169_interrupt
> >>
> >> Here we can clearly see that TX Fifo descriptors are properly setup and
> >> send is initiated, but then the rtl8169 stops sending after few frames. I
> >> think the bug is in the HW side (or in the rtl8169 firmware). Some PCI
> >> settings might affect this, but then again shouldn't the rtl8169 then
> >> report PCI error interrupt...
> >>
> >> Also this TX Fifo stalling happens with any traffic and no
> >> netflix/netgem/large tcp windows are required to trigger it. What the
> >> netgem/netflix does is that it causes this bug to be visible by probably
> >> due to timing of the traffic pattern, and thus causes also upper layers of
> >> the network stack to take actions..
> >>
> >> RTL8168evl indeed is a onboard Ethernet on a reasonable new mothorboard
> >> and the RTL8169sb is and old PCI card. But, the same issue happens with
> >> both ethernet adapters (I switched the interfaces).
> >>
> >> But then again - this got me thinking... If the issue (send fifo stalling)
> >> does not happen in the internet facing interface even with heavy upload
> >> traffic, then the problem must be in the internal network itself. Tomorrow
> >> I will change the Ethernet switch. There could be some sort of
> >> compatibility problem?
> >>
> >> BR.
> >> Risto
> >>
> >>
> >> On 11.12.2018 21:51, Heiner Kallweit wrote:
> >>> OK, then another idea .. At the very beginning of the mail thread it
> >>> was stated that the router has to network ports:
> >>> linux router: Linux computer with Dualcore Intel Celeron G1840, running
> >>> currently Linux kernel 4.20.0-rc2, and openSUSE Leap 15.0
> >>> eth1: Linux Routers internal (NAT) interface, 192.168.0.1/24 network, mtu
> >>> set to 1500, RTL8169sb/8110sb
> >>> eth0: Linux Routers internet facing interface, public ip address, mtu set
> >>> to 1500, RTL8168evl/8111evl
> >>>
> >>> r8169 supports about 50 members of the RTL8169/RTL8168/RTL8101 family
> >>> and more or less every single member needs its own quirks.
> >>> RTL8168evl (PCIe) is somewhat recent, RTL8169sb (PCI) is ancient.
> >>> To rule out you triggered some hardware issue: Could you switch both
> >>> interfaces and check whether you see a change in system behavior?
> >>>
> >>> On 11.12.2018 18:01, Risto Pajula wrote:
> >>>> Hello.
> >>>>
> >>>> A freshly built 4.20.0-rc6-next-20181210-lp150.12.25-default waited me
> >>>> when I got back from work, but unfortunately it did not help at all, it
> >>>> behaved exactly in same manner.
> >>>>
> >>>> Reply from 192.168.0.1: bytes=32 time<1ms TTL=64
> >>>> Reply from 192.168.0.1: bytes=32 time<1ms TTL=64
> >>>> Reply from 192.168.0.1: bytes=32 time<1ms TTL=64
> >>>> Reply from 192.168.0.1: bytes=32 time<1ms TTL=64
> >>>> Reply from 192.168.0.1: bytes=32 time<1ms TTL=64
> >>>> Reply from 192.168.0.1: bytes=32 time=73ms TTL=64
> >>>> Reply from 192.168.0.1: bytes=32 time<1ms TTL=64
> >>>> Reply from 192.168.0.1: bytes=32 time=83ms TTL=64
> >>>> Reply from 192.168.0.1: bytes=32 time=307ms TTL=64
> >>>> Reply from 192.168.0.1: bytes=32 time=115ms TTL=64
> >>>> Reply from 192.168.0.1: bytes=32 time<1ms TTL=64
> >>>> Reply from 192.168.0.1: bytes=32 time<1ms TTL=64
> >>>>
> >>>> BR.
> >>>> Risto
> >>>>
> >>>>
> >>>> On 11.12.2018 0:20, Risto Pajula wrote:
> >>>>> Hello.
> >>>>>
> >>>>> I have not yet tested with linux-next but I will, thanks for pointing
> >>>>> that out.
> >>>>>
> >>>>> ...But I have studied the problem a bit more, indeed it seems that the
> >>>>> rtl8169 transmission queue gets stuck.
> >>>>>
> >>>>> Below is some trace log. Starting from 802026 a burst of frames is
> >>>>> forwarded from eth0 to eth1 and when we get to the rtl_tx only two
> >>>>> frames have been transmitted.. (Should have had 1,25 ms to transmit
> >>>>> them).. Also then the sequence seems to repeat for very long time that
> >>>>> only two massages get transmitted.
> >>>>>
> >>>>> 800541: <idle>-0 [001] ..s. 7237.698143:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 34
> >>>>> cur_tx: 4406946 frags: 0 dirty_tx: 4406946 tx_left: 0
> >>>>> 800671: <idle>-0 [001] ..s. 7237.698189:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 35
> >>>>> cur_tx: 4406947 frags: 0 dirty_tx: 4406946 tx_left: 1
> >>>>> 800835: <idle>-0 [001] ..s. 7237.698235:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 36
> >>>>> cur_tx: 4406948 frags: 0 dirty_tx: 4406946 tx_left: 2
> >>>>> 800905: <idle>-0 [000] ..s. 7237.698255: rtl8169_poll:
> >>>>> ORP33 eth1 rtl_tx len: 1506 entry: 37 cur_tx: 4406949 frags: 0
> >>>>> dirty_tx: 4406946 tx_left: 3
> >>>>> 800932: <idle>-0 [000] ..s. 7237.698263: rtl8169_poll:
> >>>>> ORP33 eth1 rtl_tx len: 1506 entry: 37 cur_tx: 4406949 frags: 0
> >>>>> dirty_tx: 4406947 tx_left: 2
> >>>>> 800960: <idle>-0 [000] ..s. 7237.698270: rtl8169_poll:
> >>>>> ORP33 eth1 rtl_tx len: 1506 entry: 37 cur_tx: 4406949 frags: 0
> >>>>> dirty_tx: 4406948 tx_left: 1
> >>>>> 800998: <idle>-0 [001] ..s. 7237.698282:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 37
> >>>>> cur_tx: 4406949 frags: 0 dirty_tx: 4406949 tx_left: 0
> >>>>> 801085: <idle>-0 [000] ..s. 7237.698312: rtl8169_poll:
> >>>>> ORP33 eth1 rtl_tx len: 1506 entry: 38 cur_tx: 4406950 frags: 0
> >>>>> dirty_tx: 4406949 tx_left: 1
> >>>>> 801137: <idle>-0 [001] ..s. 7237.698329:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 38
> >>>>> cur_tx: 4406950 frags: 0 dirty_tx: 4406950 tx_left: 0
> >>>>> 801229: <idle>-0 [000] ..s. 7237.698363: rtl8169_poll:
> >>>>> ORP33 eth1 rtl_tx len: 1506 entry: 39 cur_tx: 4406951 frags: 0
> >>>>> dirty_tx: 4406950 tx_left: 1
> >>>>> 801264: <idle>-0 [001] ..s. 7237.698375:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 39
> >>>>> cur_tx: 4406951 frags: 0 dirty_tx: 4406951 tx_left: 0
> >>>>> 801356: <idle>-0 [000] ..s. 7237.698409: rtl8169_poll:
> >>>>> ORP33 eth1 rtl_tx len: 1506 entry: 40 cur_tx: 4406952 frags: 0
> >>>>> dirty_tx: 4406951 tx_left: 1
> >>>>> 801391: <idle>-0 [001] ..s. 7237.698421:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 40
> >>>>> cur_tx: 4406952 frags: 0 dirty_tx: 4406952 tx_left: 0
> >>>>> 801482: <idle>-0 [000] ..s. 7237.698455: rtl8169_poll:
> >>>>> ORP33 eth1 rtl_tx len: 1506 entry: 41 cur_tx: 4406953 frags: 0
> >>>>> dirty_tx: 4406952 tx_left: 1
> >>>>> 801518: <idle>-0 [001] ..s. 7237.698468:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 41
> >>>>> cur_tx: 4406953 frags: 0 dirty_tx: 4406953 tx_left: 0
> >>>>> 801610: <idle>-0 [000] ..s. 7237.698502: rtl8169_poll:
> >>>>> ORP33 eth1 rtl_tx len: 1506 entry: 42 cur_tx: 4406954 frags: 0
> >>>>> dirty_tx: 4406953 tx_left: 1
> >>>>> 801645: <idle>-0 [001] ..s. 7237.698514:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 42
> >>>>> cur_tx: 4406954 frags: 0 dirty_tx: 4406954 tx_left: 0
> >>>>> 801737: <idle>-0 [000] ..s. 7237.698548: rtl8169_poll:
> >>>>> ORP33 eth1 rtl_tx len: 1506 entry: 43 cur_tx: 4406955 frags: 0
> >>>>> dirty_tx: 4406954 tx_left: 1
> >>>>> 801772: <idle>-0 [001] ..s. 7237.698560:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 43
> >>>>> cur_tx: 4406955 frags: 0 dirty_tx: 4406955 tx_left: 0
> >>>>> 801864: <idle>-0 [000] ..s. 7237.698594: rtl8169_poll:
> >>>>> ORP33 eth1 rtl_tx len: 1506 entry: 44 cur_tx: 4406956 frags: 0
> >>>>> dirty_tx: 4406955 tx_left: 1
> >>>>> 801899: <idle>-0 [001] ..s. 7237.698607:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 44
> >>>>> cur_tx: 4406956 frags: 0 dirty_tx: 4406956 tx_left: 0
> >>>>> 801984: <idle>-0 [000] ..s. 7237.698640: rtl8169_poll:
> >>>>> ORP33 eth1 rtl_tx len: 1506 entry: 45 cur_tx: 4406957 frags: 0
> >>>>> dirty_tx: 4406956 tx_left: 1
> >>>>> 802026: <idle>-0 [001] ..s. 7237.698655:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 45
> >>>>> cur_tx: 4406957 frags: 0 dirty_tx: 4406957 tx_left: 0
> >>>>> 802129: <idle>-0 [001] ..s. 7237.698701:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 46
> >>>>> cur_tx: 4406958 frags: 0 dirty_tx: 4406957 tx_left: 1
> >>>>> 802232: <idle>-0 [001] ..s. 7237.698747:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 47
> >>>>> cur_tx: 4406959 frags: 0 dirty_tx: 4406957 tx_left: 2
> >>>>> 802335: <idle>-0 [001] ..s. 7237.698793:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 48
> >>>>> cur_tx: 4406960 frags: 0 dirty_tx: 4406957 tx_left: 3
> >>>>> 802438: <idle>-0 [001] ..s. 7237.698840:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 49
> >>>>> cur_tx: 4406961 frags: 0 dirty_tx: 4406957 tx_left: 4
> >>>>> 802541: <idle>-0 [001] ..s. 7237.698885:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 50
> >>>>> cur_tx: 4406962 frags: 0 dirty_tx: 4406957 tx_left: 5
> >>>>> 802644: <idle>-0 [001] ..s. 7237.698932:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 51
> >>>>> cur_tx: 4406963 frags: 0 dirty_tx: 4406957 tx_left: 6
> >>>>> 802747: <idle>-0 [001] ..s. 7237.698978:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 52
> >>>>> cur_tx: 4406964 frags: 0 dirty_tx: 4406957 tx_left: 7
> >>>>> 802851: <idle>-0 [001] ..s. 7237.699025:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 53
> >>>>> cur_tx: 4406965 frags: 0 dirty_tx: 4406957 tx_left: 8
> >>>>> 805094: <idle>-0 [000] ..s. 7237.699871: rtl8169_poll:
> >>>>> ORP33 eth1 rtl_tx len: 1506 entry: 54 cur_tx: 4406966 frags: 0
> >>>>> dirty_tx: 4406957 tx_left: 9
> >>>>> 805126: <idle>-0 [000] ..s. 7237.699878: rtl8169_poll:
> >>>>> ORP33 eth1 rtl_tx len: 1506 entry: 54 cur_tx: 4406966 frags: 0
> >>>>> dirty_tx: 4406958 tx_left: 8
> >>>>> 805197: <idle>-0 [001] ..s. 7237.699905:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 54
> >>>>> cur_tx: 4406966 frags: 0 dirty_tx: 4406959 tx_left: 7
> >>>>> 805234: <idle>-0 [001] ..s. 7237.699925:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 55
> >>>>> cur_tx: 4406967 frags: 0 dirty_tx: 4406959 tx_left: 8
> >>>>> 811446: <idle>-0 [000] ..s. 7237.702344: rtl8169_poll:
> >>>>> ORP33 eth1 rtl_tx len: 1506 entry: 56 cur_tx: 4406968 frags: 0
> >>>>> dirty_tx: 4406959 tx_left: 9
> >>>>> 811479: <idle>-0 [000] ..s. 7237.702354: rtl8169_poll:
> >>>>> ORP33 eth1 rtl_tx len: 1506 entry: 56 cur_tx: 4406968 frags: 0
> >>>>> dirty_tx: 4406960 tx_left: 8
> >>>>> 811641: <idle>-0 [000] ..s. 7237.702395:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 56
> >>>>> cur_tx: 4406968 frags: 0 dirty_tx: 4406961 tx_left: 7
> >>>>> 811733: <idle>-0 [000] ..s. 7237.702416:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 57
> >>>>> cur_tx: 4406969 frags: 0 dirty_tx: 4406961 tx_left: 8
> >>>>> 812050: hping3-2871 [000] ..s. 7237.704770: rtl8169_poll:
> >>>>> ORP33 eth1 rtl_tx len: 1506 entry: 58 cur_tx: 4406970 frags: 0
> >>>>> dirty_tx: 4406961 tx_left: 9
> >>>>> 812061: hping3-2871 [000] ..s. 7237.704777: rtl8169_poll:
> >>>>> ORP33 eth1 rtl_tx len: 1506 entry: 58 cur_tx: 4406970 frags: 0
> >>>>> dirty_tx: 4406962 tx_left: 8
> >>>>> 812124: hping3-2871 [000] ..s. 7237.704811:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 58
> >>>>> cur_tx: 4406970 frags: 0 dirty_tx: 4406963 tx_left: 7
> >>>>> 812176: hping3-2871 [000] ..s. 7237.704831:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 59
> >>>>> cur_tx: 4406971 frags: 0 dirty_tx: 4406963 tx_left: 8
> >>>>> 812300: <idle>-0 [000] ..s. 7237.707247: rtl8169_poll:
> >>>>> ORP33 eth1 rtl_tx len: 1506 entry: 60 cur_tx: 4406972 frags: 0
> >>>>> dirty_tx: 4406963 tx_left: 9
> >>>>> 812312: <idle>-0 [000] ..s. 7237.707257: rtl8169_poll:
> >>>>> ORP33 eth1 rtl_tx len: 1506 entry: 60 cur_tx: 4406972 frags: 0
> >>>>> dirty_tx: 4406964 tx_left: 8
> >>>>> 812389: <idle>-0 [000] ..s. 7237.707297:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 60
> >>>>> cur_tx: 4406972 frags: 0 dirty_tx: 4406965 tx_left: 7
> >>>>> 812426: <idle>-0 [000] ..s. 7237.707318:
> >>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 1506 entry: 61
> >>>>> cur_tx: 4406973 frags: 0 dirty_tx: 4406965 tx_left: 8
> >>>>> 812827: <idle>-0 [000] ..s. 7237.709690: rtl8169_poll:
> >>>>> ORP33 eth1 rtl_tx len: 1506 entry: 62 cur_tx: 4406974 frags: 0
> >>>>> dirty_tx: 4406965 tx_left: 9
> >>>>> 812838: <idle>-0 [000] ..s. 7237.709700: rtl8169_poll:
> >>>>> ORP33 eth1 rtl_tx len: 1506 entry: 62 cur_tx: 4406974 frags: 0
> >>>>> dirty_tx: 4406966 tx_left: 8
> >>>>> .....
> >>>>>
> >>>>>
> >>>>> BR.
> >>>>> Risto
> >>>>>
> >>>>> On 10.12.2018 23:26, Heiner Kallweit wrote:
> >>>>>> Did you test also with the latest linux-next kernel? Some recent
> >>>>>> changes like 2e6eedb4813e
> >>>>>> "r8169: make use of xmit_more and __netdev_sent_queue" may have a
> >>>>>> positive impact.
> >>>>>>
> >>>>>> On 10.12.2018 00:28, Risto Pajula wrote:
> >>>>>>> Hello.
> >>>>>>>
> >>>>>>> Old subject: "Re: IP fragmentation performance and don't fragment bug
> >>>>>>> when forwarding
> >>>>>>>
> >>>>>>>
> >>>>>>> I have now been tracing the kernel and finding the bug seems
> >>>>>>> difficult. I think the bug is combination of several things, likely
> >>>>>>> cause is that it only occurs with rtl8169 and how it is using the
> >>>>>>> netdevapi/DQL api.
> >>>>>>>
> >>>>>>> From my investigations seems that following happens:
> >>>>>>>
> >>>>>>> *Burst of frames is received from internet. (eth0)
> >>>>>>> *These are accepted and forwarded to the (eth1)
> >>>>>>> *DQL hits the limit, this causes the scheduling for the device to be
> >>>>>>> stopped (__QUEUE_STATE_STACK_XOFF)
> >>>>>>> *This and combination of some timing causes the performance
> >>>>>>> degradation, messages are only scheduled for transmission in soft Irq
> >>>>>>> context.
> >>>>>>>
> >>>>>>> I still do now know, why the DQL hits the limits.. I think it should
> >>>>>>> not, maybe something undesirable first happens with rtl8169.
> >>>>>>>
> >>>>>>> I inserted following trace printk functions to the code..
> >>>>>>>
> >>>>>>> rtl8169_start_xmit:
> >>>>>>> trace_printk("ORP33 %s rtl8169_start_xmit len: %d entry: %u cur_tx:
> >>>>>>> %u frags: %d dirty_tx: %u tx_left: %u\n" , tp->dev->name, skb->len,
> >>>>>>> entry, tp->cur_tx, frags, tp->dirty_tx, (tp->cur_tx - tp->dirty_tx) );
> >>>>>>>
> >>>>>>>
> >>>>>>> rtl_tx:
> >>>>>>> trace_printk("ORP33 %s rtl_tx len: %d entry: %u cur_tx: %u frags: %d
> >>>>>>> dirty_tx: %u tx_left: %u\n" , tp->dev->name, tx_skb->skb->len,
> >>>>>>> tp->cur_tx % NUM_TX_DESC, tp->cur_tx, 0, dirty_tx, tx_left );
> >>>>>>>
> >>>>>>>
> >>>>>>> Here is some grepped output only filtering the ping packet in two
> >>>>>>> different situations:
> >>>>>>>
> >>>>>>> //trace when downloading ubuntu (~20MB/s), only 3 secs fit to buffer.
> >>>>>>> ping is all the time normal....
> >>>>>>> //orig tracing.out3754
> >>>>>>> 117493: <idle>-0 [000] ..s. 5235.407116: rtl8169_poll:
> >>>>>>> ORP33 eth1 rtl_tx len: 54 entry: 57 cur_tx: 3747641 frags: 0
> >>>>>>> dirty_tx: 3747640 tx_left: 1
> >>>>>>> 118704: <idle>-0 [000] ..s. 5235.416057: rtl8169_poll:
> >>>>>>> ORP33 eth1 rtl_tx len: 54 entry: 20 cur_tx: 3747668 frags: 0
> >>>>>>> dirty_tx: 3747667 tx_left: 1
> >>>>>>> 346319: hping3-2871 [000] .... 5236.002456:
> >>>>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 54 entry: 8
> >>>>>>> cur_tx: 3754312 frags: 0 dirty_tx: 3754312 tx_left: 0
> >>>>>>> 346337: hping3-2871 [000] ..s. 5236.002475: rtl8169_poll:
> >>>>>>> ORP33 eth1 rtl_tx len: 54 entry: 9 cur_tx: 3754313 frags: 0 dirty_tx:
> >>>>>>> 3754312 tx_left: 1
> >>>>>>> 1277155: hping3-2871 [001] .... 5237.002627:
> >>>>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 54 entry: 38
> >>>>>>> cur_tx: 3766502 frags: 0 dirty_tx: 3766502 tx_left: 0
> >>>>>>> 1277173: <idle>-0 [000] ..s. 5237.002646: rtl8169_poll:
> >>>>>>> ORP33 eth1 rtl_tx len: 54 entry: 39 cur_tx: 3766503 frags: 0
> >>>>>>> dirty_tx: 3766502 tx_left: 1
> >>>>>>>
> >>>>>>>
> >>>>>>> //imcp messages from route to intenal network when TCP stream is on.
> >>>>>>> tracing.out3236/eth1_ring.txt is the original
> >>>>>>> //no idea why the first frame is tripled...
> >>>>>>> 200792: hping3-2871 [001] .... 3239.593384:
> >>>>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 54 entry: 34
> >>>>>>> cur_tx: 2132770 frags: 0 dirty_tx: 2132770 tx_left: 0
> >>>>>>> 201578: hping3-2871 [001] .... 3240.593625:
> >>>>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 54 entry: 40
> >>>>>>> cur_tx: 2132776 frags: 0 dirty_tx: 2132776 tx_left: 0
> >>>>>>> 341061: <idle>-0 [000] ..s. 3241.738011:
> >>>>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 54 entry: 52
> >>>>>>> cur_tx: 2133684 frags: 0 dirty_tx: 2133680 tx_left: 4
> >>>>>>> 342112: <idle>-0 [000] ..s. 3241.745297: rtl8169_poll:
> >>>>>>> ORP33 eth1 rtl_tx len: 54 entry: 59 cur_tx: 2133691 frags: 0
> >>>>>>> dirty_tx: 2133684 tx_left: 7
> >>>>>>> 500126: <idle>-0 [000] ..s. 3242.739500:
> >>>>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 54 entry: 49
> >>>>>>> cur_tx: 2134513 frags: 0 dirty_tx: 2134505 tx_left: 8
> >>>>>>> 501739: <idle>-0 [000] ..s. 3242.751654: rtl8169_poll:
> >>>>>>> ORP33 eth1 rtl_tx len: 54 entry: 58 cur_tx: 2134522 frags: 0
> >>>>>>> dirty_tx: 2134513 tx_left: 9
> >>>>>>> 646220: <idle>-0 [000] ..s. 3243.745761:
> >>>>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 54 entry: 41
> >>>>>>> cur_tx: 2135273 frags: 0 dirty_tx: 2135267 tx_left: 6
> >>>>>>> 647633: <idle>-0 [000] ..s. 3243.755486: rtl8169_poll:
> >>>>>>> ORP33 eth1 rtl_tx len: 54 entry: 49 cur_tx: 2135281 frags: 0
> >>>>>>> dirty_tx: 2135273 tx_left: 8
> >>>>>>> 802878: <idle>-0 [000] ..s. 3244.739947:
> >>>>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 54 entry: 23
> >>>>>>> cur_tx: 2136087 frags: 0 dirty_tx: 2136081 tx_left: 6
> >>>>>>> 804298: <idle>-0 [000] ..s. 3244.749677: rtl8169_poll:
> >>>>>>> ORP33 eth1 rtl_tx len: 54 entry: 31 cur_tx: 2136095 frags: 0
> >>>>>>> dirty_tx: 2136087 tx_left: 8
> >>>>>>> 961190: <idle>-0 [000] ..s. 3245.746217:
> >>>>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 54 entry: 16
> >>>>>>> cur_tx: 2136912 frags: 0 dirty_tx: 2136906 tx_left: 6
> >>>>>>> 962610: <idle>-0 [000] ..s. 3245.755946: rtl8169_poll:
> >>>>>>> ORP33 eth1 rtl_tx len: 54 entry: 24 cur_tx: 2136920 frags: 0
> >>>>>>> dirty_tx: 2136912 tx_left: 8
> >>>>>>> 1118044: <idle>-0 [000] ..s. 3246.740336:
> >>>>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 54 entry: 62
> >>>>>>> cur_tx: 2137726 frags: 0 dirty_tx: 2137720 tx_left: 6
> >>>>>>> 1119443: <idle>-0 [000] ..s. 3246.750047: rtl8169_poll:
> >>>>>>> ORP33 eth1 rtl_tx len: 54 entry: 5 cur_tx: 2137733 frags: 0 dirty_tx:
> >>>>>>> 2137726 tx_left: 7
> >>>>>>> 1264047: <idle>-0 [000] ..s. 3247.709202:
> >>>>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 54 entry: 29
> >>>>>>> cur_tx: 2138525 frags: 0 dirty_tx: 2138518 tx_left: 7
> >>>>>>> 1264740: <idle>-0 [000] ..s. 3247.718918: rtl8169_poll:
> >>>>>>> ORP33 eth1 rtl_tx len: 54 entry: 33 cur_tx: 2138529 frags: 0
> >>>>>>> dirty_tx: 2138525 tx_left: 4
> >>>>>>> 1419958: <idle>-0 [000] ..s. 3248.736436:
> >>>>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 54 entry: 48
> >>>>>>> cur_tx: 2139312 frags: 0 dirty_tx: 2139305 tx_left: 7
> >>>>>>> 1421551: <idle>-0 [000] ..s. 3248.746189: rtl8169_poll:
> >>>>>>> ORP33 eth1 rtl_tx len: 54 entry: 56 cur_tx: 2139320 frags: 0
> >>>>>>> dirty_tx: 2139312 tx_left: 8
> >>>>>>> 1578746: <idle>-0 [000] ..s. 3249.742702:
> >>>>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 54 entry: 46
> >>>>>>> cur_tx: 2140142 frags: 0 dirty_tx: 2140135 tx_left: 7
> >>>>>>> 1580194: <idle>-0 [000] ..s. 3249.752457: rtl8169_poll:
> >>>>>>> ORP33 eth1 rtl_tx len: 54 entry: 54 cur_tx: 2140150 frags: 0
> >>>>>>> dirty_tx: 2140142 tx_left: 8
> >>>>>>> 1729597: <idle>-0 [000] ..s. 3250.746839:
> >>>>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 54 entry: 36
> >>>>>>> cur_tx: 2140964 frags: 0 dirty_tx: 2140957 tx_left: 7
> >>>>>>> 1731015: <idle>-0 [000] ..s. 3250.756594: rtl8169_poll:
> >>>>>>> ORP33 eth1 rtl_tx len: 54 entry: 43 cur_tx: 2140971 frags: 0
> >>>>>>> dirty_tx: 2140964 tx_left: 7
> >>>>>>> 1881028: <idle>-0 [000] ..s. 3251.740991:
> >>>>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 54 entry: 19
> >>>>>>> cur_tx: 2141779 frags: 0 dirty_tx: 2141772 tx_left: 7
> >>>>>>> 1881381: <idle>-0 [000] ..s. 3251.750718: rtl8169_poll:
> >>>>>>> ORP33 eth1 rtl_tx len: 54 entry: 26 cur_tx: 2141786 frags: 0
> >>>>>>> dirty_tx: 2141779 tx_left: 7
> >>>>>>> //something happens, the output queue empties.. now it is fast, and
> >>>>>>> rtl8169_start_xmit is not called from soft_irq
> >>>>>>> 1896178: hping3-2871 [001] .... 3252.595994:
> >>>>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 54 entry: 23
> >>>>>>> cur_tx: 2141911 frags: 0 dirty_tx: 2141911 tx_left: 0
> >>>>>>> 1896196: <idle>-0 [000] ..s. 3252.596055: rtl8169_poll:
> >>>>>>> ORP33 eth1 rtl_tx len: 54 entry: 24 cur_tx: 2141912 frags: 0
> >>>>>>> dirty_tx: 2141911 tx_left: 1
> >>>>>>> 1923136: hping3-2871 [001] .... 3253.596227:
> >>>>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 54 entry: 50
> >>>>>>> cur_tx: 2142066 frags: 0 dirty_tx: 2142066 tx_left: 0
> >>>>>>> 1923154: <idle>-0 [000] ..s. 3253.596289: rtl8169_poll:
> >>>>>>> ORP33 eth1 rtl_tx len: 54 entry: 51 cur_tx: 2142067 frags: 0
> >>>>>>> dirty_tx: 2142066 tx_left: 1
> >>>>>>> 1951633: hping3-2871 [001] .... 3254.596459:
> >>>>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 54 entry: 5
> >>>>>>> cur_tx: 2142213 frags: 0 dirty_tx: 2142213 tx_left: 0
> >>>>>>> 1951651: <idle>-0 [000] ..s. 3254.596521: rtl8169_poll:
> >>>>>>> ORP33 eth1 rtl_tx len: 54 entry: 6 cur_tx: 2142214 frags: 0 dirty_tx:
> >>>>>>> 2142213 tx_left: 1
> >>>>>>> 1954472: hping3-2871 [001] .... 3255.596700:
> >>>>>>> rtl8169_start_xmit: ORP33 eth1 rtl8169_start_xmit len: 54 entry: 15
> >>>>>>> cur_tx: 2142223 frags: 0 dirty_tx: 2142223 tx_left: 0
> >>>>>>> 1954490: <idle>-0 [000] ..s. 3255.596763: rtl8169_poll:
> >>>>>>> ORP33 eth1 rtl_tx len: 54 entry: 16 cur_tx: 2142224 frags: 0
> >>>>>>> dirty_tx: 2142223 tx_left: 1
> >>>>>>> //until it soon, again is slow..
> >>>>>>>
> >>>>>>>
> >>>>>>> BR.
> >>>>>>> Risto
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>> On 7.12.2018 16:46, Risto Pajula wrote:
> >>>>>>>> Hello.
> >>>>>>>>
> >>>>>>>> I have been to track the poor forwarding latency to the TCP Window
> >>>>>>>> scale options. The Netgem device uses rather large windows scale
> >>>>>>>> options (x256) and I have been able to reproduce the routers poor
> >>>>>>>> forwarding latency also with linux box running in the internal
> >>>>>>>> network and changing the net.ipv4.tcp_rmem to a large value and thus
> >>>>>>>> changing the TCP window scaling options to larger ones. I still do
> >>>>>>>> not have clue why this causes the forwarfing in the linux kernel to
> >>>>>>>> block? Maybe something in the connection tracking....?
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> With the ICMP timestamp messages I have been able to also pinpoint
> >>>>>>>> that the latency is caused in the eth1 sending side (the following
> >>>>>>>> hping3 example is run in the router toward the internal network...
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> xxx:/usr/src/linux-4.20-rc2 # hping3 192.168.0.112 --icmp --icmp-ts
> >>>>>>>> -V
> >>>>>>>> using eth1, addr: 192.168.0.1, MTU: 1500
> >>>>>>>> HPING 192.168.0.112 (eth1 192.168.0.112): icmp mode set, 28 headers
> >>>>>>>> + 0 data bytes
> >>>>>>>> len=46 ip=192.168.0.112 ttl=64 id=49464 tos=0 iplen=40
> >>>>>>>> icmp_seq=0 rtt=7.9 ms
> >>>>>>>> ICMP timestamp: Originate=52294891 Receive=52294895 Transmit=52294895
> >>>>>>>> ICMP timestamp RTT tsrtt=7
> >>>>>>>>
> >>>>>>>> len=46 ip=192.168.0.112 ttl=64 id=49795 tos=0 iplen=40
> >>>>>>>> icmp_seq=1 rtt=235.9 ms
> >>>>>>>> ICMP timestamp: Originate=52295891 Receive=52296128 Transmit=52296128
> >>>>>>>> ICMP timestamp RTT tsrtt=235
> >>>>>>>>
> >>>>>>>> len=46 ip=192.168.0.112 ttl=64 id=49941 tos=0 iplen=40
> >>>>>>>> icmp_seq=2 rtt=3.8 ms
> >>>>>>>> ICMP timestamp: Originate=52296891 Receive=52296895 Transmit=52296895
> >>>>>>>> ICMP timestamp RTT tsrtt=3
> >>>>>>>>
> >>>>>>>> len=46 ip=192.168.0.112 ttl=64 id=50685 tos=0 iplen=40
> >>>>>>>> icmp_seq=3 rtt=47.8 ms
> >>>>>>>> ICMP timestamp: Originate=52297891 Receive=52297940 Transmit=52297940
> >>>>>>>> ICMP timestamp RTT tsrtt=47
> >>>>>>>>
> >>>>>>>> len=46 ip=192.168.0.112 ttl=64 id=51266 tos=0 iplen=40
> >>>>>>>> icmp_seq=4 rtt=7.7 ms
> >>>>>>>> ICMP timestamp: Originate=52298891 Receive=52298895 Transmit=52298895
> >>>>>>>> ICMP timestamp RTT tsrtt=7
> >>>>>>>>
> >>>>>>>> len=46 ip=192.168.0.112 ttl=64 id=52245 tos=0 iplen=40
> >>>>>>>> icmp_seq=5 rtt=3.7 ms
> >>>>>>>> ICMP timestamp: Originate=52299891 Receive=52299895 Transmit=52299895
> >>>>>>>> ICMP timestamp RTT tsrtt=3
> >>>>>>>>
> >>>>>>>> ^C
> >>>>>>>> --- 192.168.0.112 hping statistic ---
> >>>>>>>> 6 packets tramitted, 6 packets received, 0% packet loss
> >>>>>>>> round-trip min/avg/max = 3.7/51.1/235.9 ms
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> BR.
> >>>>>>>> Risto
> >>>>>>>>
> >>>>>>>> On 2.12.2018 23:32, Risto Pajula wrote:
> >>>>>>>>> Hello.
> >>>>>>>>>
> >>>>>>>>> You can most likely ignore the "DF Bit, mtu bug when forwarding"
> >>>>>>>>> case. There isn't actually big IP packets on the wire, instead
> >>>>>>>>> there is burst of packets on the wire, which are combined by the
> >>>>>>>>> GRO... And thus dropping them should not happen. Sorry about the
> >>>>>>>>> invalid bug report.
> >>>>>>>>>
> >>>>>>>>> However the poor latency from intenal network to the internet still
> >>>>>>>>> remain, both GRO enabled and disabled. I will try to study
> >>>>>>>>> further...
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>> BR.
> >>>>>>>>> Risto
> >>>>>>>>>
> >>>>>>>>>
> >>>>>>>>> On 2.12.2018 14:01, Risto Pajula wrote:
> >>>>>>>>>> Hello.
> >>>>>>>>>>
> >>>>>>>>>> I have encountered a weird performance problem in Linux IP
> >>>>>>>>>> fragmentation when using video streaming services behind the NAT.
> >>>>>>>>>> Also I have studied a possible bug in the DF bit (don't fragment)
> >>>>>>>>>> handling when forwarding the IP packets.
> >>>>>>>>>>
> >>>>>>>>>> First the system setup description:
> >>>>>>>>>>
> >>>>>>>>>> [host1]-int lan-(eth1)[linux router](eth0)-extlan-[fibre
> >>>>>>>>>> router]-internet
> >>>>>>>>>>
> >>>>>>>>>> where:
> >>>>>>>>>> host1: is a Netgem N7800 "cable box" for online video streaming
> >>>>>>>>>> services provided by local telco (Can access Netflix, HBO nordic,
> >>>>>>>>>> "live TV", etc.)
> >>>>>>>>>> linux router: Linux computer with Dualcore Intel Celeron G1840,
> >>>>>>>>>> running currently Linux kernel 4.20.0-rc2, and openSUSE Leap 15.0
> >>>>>>>>>> eth1: Linux Routers internal (NAT) interface, 192.168.0.1/24
> >>>>>>>>>> network, mtu set to 1500, RTL8169sb/8110sb
> >>>>>>>>>> eth0: Linux Routers internet facing interface, public ip address,
> >>>>>>>>>> mtu set to 1500, RTL8168evl/8111evl
> >>>>>>>>>> fibre router: Alcatel Lucent fibre router (I-241G-Q), directly
> >>>>>>>>>> connected to the eth0 of the Linux router.
> >>>>>>>>>>
> >>>>>>>>>> And now when using the Netgem N7800 with online video services
> >>>>>>>>>> (Netflix, HBO nordic, etc) the Linux router will receive very BIG
> >>>>>>>>>> IP packets in the eth0 upto ~20kB, this seems to lead to the
> >>>>>>>>>> following problems in the Linux IP stack.
> >>>>>>>>>>
> >>>>>>>>>> IP fragmentation performance:
> >>>>>>>>>> When the Linux router receives these large IP packets in the eth0
> >>>>>>>>>> everything works, but it seems that them cause very large
> >>>>>>>>>> performance degradation from internal network to the internet
> >>>>>>>>>> regarding the latency when the IP fragmentation is performed. The
> >>>>>>>>>> ping latency from internal network to the internel network
> >>>>>>>>>> increases from stable 15ms-20ms up to 700-800ms AND also the ping
> >>>>>>>>>> from the internal network to the linux router eth1 (192.168.0.).
> >>>>>>>>>> However up link works perfectly, the ping is still stable when
> >>>>>>>>>> streaming the online services (From linux router to the internet).
> >>>>>>>>>> It seems that the IP fragmentation is somehow blocking the eth1
> >>>>>>>>>> reception or transmission for very long time (which it shouldn't).
> >>>>>>>>>> I'm able to test and debug the issue further, but advice regarding
> >>>>>>>>>> where to look would be appreciated.
> >>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>> DF Bit, mtu bug when forwarding:
> >>>>>>>>>> I have started to study the above mentioned problem and have found
> >>>>>>>>>> a possible bug in the DF bit and mtu handling in IP forwarding.
> >>>>>>>>>> The BIG packets received from streaming services all have the "DF
> >>>>>>>>>> bit" set and the question is that should we be forwarding them at
> >>>>>>>>>> all as that would result them being fragmented? Apparently we
> >>>>>>>>>> currently are... I have traced this down to the ip_forward.c
> >>>>>>>>>> function ip_exceeds_mtu(), and the following patch seems to fix
> >>>>>>>>>> that.
> >>>>>>>>>>
> >>>>>>>>>> --- net/ipv4/ip_forward.c.orig 2018-12-02 11:09:32.764320780 +0200
> >>>>>>>>>> +++ net/ipv4/ip_forward.c 2018-12-02 12:53:25.031232347 +0200
> >>>>>>>>>> @@ -49,7 +49,7 @@ static bool ip_exceeds_mtu(const struct
> >>>>>>>>>> return false;
> >>>>>>>>>>
> >>>>>>>>>> /* original fragment exceeds mtu and DF is set */
> >>>>>>>>>> - if (unlikely(IPCB(skb)->frag_max_size > mtu))
> >>>>>>>>>> + if (unlikely(skb->len > mtu))
> >>>>>>>>>> return true;
> >>>>>>>>>>
> >>>>>>>>>> if (skb->ignore_df)
> >>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>> This seems to work (in some ways) - after the change IP packets
> >>>>>>>>>> that are too large to the internal network get dropped and we are
> >>>>>>>>>> sending "ICMP Destination unreachable, The datagram is too big"
> >>>>>>>>>> messages to the originator (as we should?). However it seems that
> >>>>>>>>>> not all services really like this... Netflix behaves as expected
> >>>>>>>>>> and ping is stable from internal network to the internet, but for
> >>>>>>>>>> example HBO nordic will not work anymore (too little buffering?
> >>>>>>>>>> Retransimissions not working?). So it seems the original issue
> >>>>>>>>>> should be also fixed (And the fragmention should be allowed?).
> >>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>>
> >>>>>>>>>> Any advice would be appreciated. Thanks!
> >>>>>>>>>>
> >>>>>>>>>> PS. Watching TV was not this intensive 20 years ago :)
> >>>>>>>>>>
Did you disable ethernet flow control? Ethernet flow control is
usually a bad idea, it can cause head of line blocking. Unfortunately,
most devices default to on.
