从dmesg我们得到非常奇怪的行
[6484420.812643] raid6: using avx2x2 recovery algorithm
[6484420.859086] Btrfs loaded
[6484426.278636] nr_pdflush_threads exported in /proc is scheduled for removal
[6484708.776239] ixgbe 0000:04:00.0: invalid short VPD tag 06 at offset 4
[6900952.098901] perf: interrupt took too long (6247 > 6167), lowering kernel.perf_event_max_sample_rate to 32000
[7372848.819396] Peer 0000:0000:0000:0000:0000:ffff:0a15:f030:1054/8042 unexpectedly shrunk window 3002395993:3002395997 (repaired)
[8139485.039423] Turbo disabled by BIOS or unavailable on processor
[8380300.891343] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380320.890541] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380440.896206] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380460.895001] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380463.207397] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380467.316531] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380468.363352] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380469.332044] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380489.330943] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380509.329849] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380529.328678] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380549.468256] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380569.326474] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380589.340946] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380609.339969] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380619.870472] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380620.964216] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380621.979847] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380641.869255] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380661.883737] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380681.867153] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380701.881531] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380721.864752] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380741.879282] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380761.878160] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380781.876977] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380801.875853] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380821.874754] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380841.873636] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380861.872533] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380881.871408] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380901.870340] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380921.884773] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380956.392645] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380957.392566] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380958.517530] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380978.384846] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8380998.383622] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8381018.387820] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8381038.390564] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8381058.395931] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8381060.052209] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8381061.114504] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8381062.115355] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
[8381082.053988] UDP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
是那行:
DP: bad checksum. From 73.2.33.11:5353 to 82.2.33.1:5353 ulen 69
表示严重的问题?
那些“ UDP错误”是UDP校验和卸载。NIC负责校验和,因此在CPU级别上不执行此操作以节省CPU资源。VMWare可以做到这一点,我认为KVM也可以做到(不仅如此)。因此,在使用tcpdump
或查看系统日志时,在OS / VM级别看不到正确的校验和。
不幸的是,有时我们在Wireshark中看到的不是我们期望的。发生这种情况的一种情况是,操作系统将TCP / IP操作卸载到了网络接口卡(NIC)。卸载的常用操作是分段和校验和计算。也就是说,它允许OSNIC而不是OS使用CPU来分割TCP数据包,而是使用自己的处理器来执行分割。这样可以节省CPU,并重要地减少了与NIC之间的总线通信。
另请参见Linux网络:如何禁用/启用卸载功能,RX / TX校验和,分散,收集以及其他功能
tcpdump输出中的UDP / TCP校验和错误
如果您启用了卸载功能,并且在tcpdump输出中看到cksum错误,没有任何数据包错误并且您的网络正常运行:不必担心,因为校验和实际上是在网络适配器上计算的,并且tcpdump显示了计算出的校验和在内核级别。
从UDP / TCP校验从tcpdump的和NIC硬件卸载错误
在检查了活动的NIC硬件卸载选项之后,您可以看到明显的
$ sudo ethtool -k eth0 | grep在
rx-checksumming上:在
tx-checksumming:上
分散-聚集:在
generic-segmentation-offload:上
generic-receive-offload:在
rx-vlan-offload:上
tx-vlan-offload:上在NIC上为TX / RX禁用TCO(tcp卸载)后,问题消失了
$ sudo ethtool -K eth0 tx关闭rx关闭
在完成调试网络问题后,请务必重新打开优化,因为关闭这些性能会降低性能。
TLDR这些“错误”是Linux VM的常见现象,一旦您知道它们是基线的一部分,就不会为之着迷。另外,请记住,在查看日志或调试网络问题时,您在内核级别看到的不一定是在有线级别看到的。
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