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Diffstat (limited to 'results/classifier/gemma3:12b/network/1297487')
| -rw-r--r-- | results/classifier/gemma3:12b/network/1297487 | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/results/classifier/gemma3:12b/network/1297487 b/results/classifier/gemma3:12b/network/1297487 new file mode 100644 index 000000000..93cd9cf1b --- /dev/null +++ b/results/classifier/gemma3:12b/network/1297487 @@ -0,0 +1,169 @@ + +MTU not honored in virtio vnet + +I am observing a potential regression/different behavior between rel. 14.04 (dev branch) and release 13.04. + +My hardware is: Cisco UCS blade B200-M3 and the network adapter card: Cisco UCS VIC 1240. + +lsb_release -rd +Description: Ubuntu Trusty Tahr (development branch) +Release: 14.04 + +uname -a +Linux konan2 3.13.0-19-generic #40-Ubuntu SMP Mon Mar 24 02:36:06 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux + +The problem: +After starting a kvm with virtio interfaces I am passing HTTP traffic via an external network traffic simulator. +The tool is sending a TCP packet of 3481B, because the tool MTU is set to 1400B, it splits the packets into 3 TCP segments. +When the 3 segments are received at the host eth1 interface, the host (ubuntu 14.04) reassembles the TCP packets into a larger packet (GRO), then passes the packet up on vnet1. At this point, because vnet1 MTU is 1500B, it is supposed to re-segment the packet and pass the 3 segments up to the VM. But it passes the big 3481B packet instead. + +This behavior did not happen when I tried the same scenario in release 13.04 + +I can disable this behavior by disabling TSO (TCP segment offloading in the vnet), but I did not have to do this in rel. 13.04 and I feel the MTU is not honored as it should be with rel. 14.04. + + ip link show | grep eth1 +3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq master br1 state UP mode DEFAULT group default qlen 1000 + ip link show | grep vnet1 +16: vnet1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master br1 state UNKNOWN mode DEFAULT group default qlen 500 + +I am attaching two tcpdump/pcap traces that show a TCP transaction passing on vnet1 when TSO is on and when TSO is off. + +Please see: + +- vnet1_tso_on.pcap +- vnet1_tso_off.pcap + +in attachment. + +I noticed there was a driver upgrade in rel. 14.04: + +in 14.04: + +ethtool -i eth1 +driver: enic +version: 2.1.1.50 +firmware-version: 2.1(3a) +bus-info: 0000:07:00.0 +supports-statistics: yes +supports-test: no +supports-eeprom-access: no +supports-register-dump: no +supports-priv-flags: no + +ethtool -i vnet1 +driver: tun +version: 1.6 +firmware-version: +bus-info: tap +supports-statistics: no +supports-test: no +supports-eeprom-access: no +supports-register-dump: no +supports-priv-flags: no + +ethtool -k vnet1 +Features for vnet1: +rx-checksumming: off [fixed] +tx-checksumming: on + tx-checksum-ipv4: off [fixed] + tx-checksum-ip-generic: on + tx-checksum-ipv6: off [fixed] + tx-checksum-fcoe-crc: off [fixed] + tx-checksum-sctp: off [fixed] +scatter-gather: on + tx-scatter-gather: on + tx-scatter-gather-fraglist: on +tcp-segmentation-offload: off + tx-tcp-segmentation: off + tx-tcp-ecn-segmentation: off + tx-tcp6-segmentation: off +udp-fragmentation-offload: on +generic-segmentation-offload: on +generic-receive-offload: on +large-receive-offload: off [fixed] +rx-vlan-offload: off [fixed] +tx-vlan-offload: on +ntuple-filters: off [fixed] +receive-hashing: off [fixed] +highdma: off [fixed] +rx-vlan-filter: off [fixed] +vlan-challenged: off [fixed] +tx-lockless: off [fixed] +netns-local: off [fixed] +tx-gso-robust: off [fixed] +tx-fcoe-segmentation: off [fixed] +tx-gre-segmentation: off [fixed] +tx-ipip-segmentation: off [fixed] +tx-sit-segmentation: off [fixed] +tx-udp_tnl-segmentation: off [fixed] +tx-mpls-segmentation: off [fixed] +fcoe-mtu: off [fixed] +tx-nocache-copy: on +loopback: off [fixed] +rx-fcs: off [fixed] +rx-all: off [fixed] +tx-vlan-stag-hw-insert: on +rx-vlan-stag-hw-parse: off [fixed] +rx-vlan-stag-filter: off [fixed] +l2-fwd-offload: off [fixed] + + + +in 13.04 : + +ethtool -i eth1 +driver: enic +version: 2.1.1.39 +firmware-version: 2.1(3a) +bus-info: 0000:07:00.0 +supports-statistics: yes +supports-test: no +supports-eeprom-access: no +supports-register-dump: no +supports-priv-flags: no + + +ethtool -i vnet1 +driver: tun +version: 1.6 +firmware-version: +bus-info: tap +supports-statistics: no +supports-test: no +supports-eeprom-access: no +supports-register-dump: no +supports-priv-flags: no + + +ethtool -k vnet1 +Features for vnet1: +rx-checksumming: off [fixed] +tx-checksumming: on + tx-checksum-ipv4: off [fixed] + tx-checksum-ip-generic: on + tx-checksum-ipv6: off [fixed] + tx-checksum-fcoe-crc: off [fixed] + tx-checksum-sctp: off [fixed] +scatter-gather: on + tx-scatter-gather: on + tx-scatter-gather-fraglist: on +tcp-segmentation-offload: on + tx-tcp-segmentation: on + tx-tcp-ecn-segmentation: on + tx-tcp6-segmentation: on +udp-fragmentation-offload: on +generic-segmentation-offload: on +generic-receive-offload: on +large-receive-offload: off [fixed] +rx-vlan-offload: off [fixed] +tx-vlan-offload: off [fixed] +ntuple-filters: off [fixed] +receive-hashing: off [fixed] +highdma: off [fixed] +rx-vlan-filter: off [fixed] +vlan-challenged: off [fixed] +tx-lockless: off [fixed] +netns-local: off [fixed] +tx-gso-robust: off [fixed] +tx-fcoe-segmentation: off [fixed] +fcoe-mtu: off [fixed] \ No newline at end of file |