linux – kvm来宾计算机上的随机临时网络冻结

我在KVM下运行两台客户机.主机运行Arch Linux(内核版本2.6.38.2),客户端都是CentOS 5.5(内核版本2.6.18).我将网络设置为桥梁,或多或少如下(当然,我不是手工完成 – 它通过系统启动脚本分散)

# /usr/sbin/brctl addbr br0
# /usr/sbin/brctl addif br0 eth0
# /sbin/ifconfig br0 192.168.3.30 netmask 255.255.255.0 broadcast 192.168.3.255 up
# qemu-kvm -hda <disk-image1> -m 2048 -vga std -vnc :3 -net nic,vlan=0 -net tap,vlan=0,ifname=tap0,script=/etc/qemu-ifup
# qemu-kvm -hda <disk-image2> -m 2048 -vga std -vnc :4 -net nic,ifname=tap1,script=/etc/qemu-ifup
# cat /etc/qemu-ifup
#!/bin/sh
sudo /sbin/ifconfig $1 0.0.0.0 promisc up
sudo /usr/sbin/brctl addif br0 $1

配置主要有效.奇怪的是,我经常出现网络“暂停”.我与虚拟机的大多数交互都是通过ssh或Web浏览器进行的.通常情况下,特别是在空闲时间之后,我会在会话中输入内容或访问网页,但不会发生任何事情.最终,在10-15秒后,正常活动将恢复而不会出错.从死亡时间开始的ssh击键匆匆通过. Web请求似乎丢失了,但快速“重新加载页面”可以毫不拖延地获得结果.整个虚拟机继续运行,正如我通过观察到控制台的VNC会话所看到的那样.两位客人都是这样独立的.有时两者都会同时被冻结,但有时候一个人会正常工作而另一个人会被冻结.冻结时,主机或客人端的dmesg没有错误.

任何想法,解决方案,原因或进一步诊断？

(补充资料,7/27)

这是主机上’ifconfig -a’的输出：

hope 5$sudo ifconfig -a
br0       Link encap:Ethernet  HWaddr 4A:F0:CA:32:F5:88  
          inet addr:192.168.3.30  Bcast:192.168.3.255  Mask:255.255.255.0
          inet6 addr: fe80::7271:bcff:fea2:f4c4/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:140947463 errors:0 dropped:0 overruns:0 frame:0
          TX packets:66981660 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:192776331275 (183845.8 Mb)  TX bytes:9469675717 (9030.9 Mb)

br0:1     Link encap:Ethernet  HWaddr 4A:F0:CA:32:F5:88  
          inet addr:192.168.3.31  Bcast:192.168.3.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

br0:2     Link encap:Ethernet  HWaddr 4A:F0:CA:32:F5:88  
          inet addr:192.168.3.32  Bcast:192.168.3.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

eth0      Link encap:Ethernet  HWaddr 70:71:BC:A2:F4:C4  
          inet6 addr: fe80::7271:bcff:fea2:f4c4/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:141848164 errors:0 dropped:0 overruns:0 frame:0
          TX packets:68852413 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:195831275369 (186759.2 Mb)  TX bytes:9559920997 (9117.0 Mb)
          Interrupt:20 Memory:d0300000-d0320000 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:27197534 errors:0 dropped:0 overruns:0 frame:0
          TX packets:27197534 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:127242745992 (121348.1 Mb)  TX bytes:127242745992 (121348.1 Mb)

sit0      Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  
          NOARP  MTU:1480  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

tap0      Link encap:Ethernet  HWaddr 4A:F0:CA:32:F5:88  
          inet6 addr: fe80::48f0:caff:fe32:f588/64 Scope:Link
          UP BROADCAST RUNNING PROMISC MULTICAST  MTU:1500  Metric:1
          RX packets:397512 errors:0 dropped:0 overruns:0 frame:0
          TX packets:668318 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:500 
          RX bytes:38045826 (36.2 Mb)  TX bytes:750358170 (715.5 Mb)

tap1      Link encap:Ethernet  HWaddr 56:92:5E:DE:93:67  
          inet6 addr: fe80::5492:5eff:fede:9367/64 Scope:Link
          UP BROADCAST RUNNING PROMISC MULTICAST  MTU:1500  Metric:1
          RX packets:25635 errors:0 dropped:0 overruns:0 frame:0
          TX packets:88846 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:500 
          RX bytes:1999805 (1.9 Mb)  TX bytes:17071986 (16.2 Mb)

主机上’brctl show’的输出：

hope 6$sudo brctl show
bridge name bridge id               STP enabled     interfaces
br0         8000.4af0ca32f588       no              eth0
                                                    tap0
                                                    tap1

来自一个guest虚拟机的’ifconfig -a’的输出：

guest1# ifconfig -a
eth0      Link encap:Ethernet  HWaddr 52:54:00:12:34:56  
          inet addr:192.168.3.35  Bcast:192.168.3.255  Mask:255.255.255.0
          inet6 addr: fe80::5054:ff:fe12:3456/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:323061 errors:0 dropped:0 overruns:0 frame:0
          TX packets:210150 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:298541685 (284.7 MiB)  TX bytes:25958962 (24.7 MiB)
          Interrupt:11 Base address:0x4000 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:2305 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2305 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:481780 (470.4 KiB)  TX bytes:481780 (470.4 KiB)

sit0      Link encap:IPv6-in-IPv4  
          NOARP  MTU:1480  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

和另一位客人一样：

guest2# ifconfig -a
eth0      Link encap:Ethernet  HWaddr 52:54:00:12:34:56  
          inet addr:192.168.3.36  Bcast:192.168.3.255  Mask:255.255.255.0
          inet6 addr: fe80::5054:ff:fe12:3456/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:62641 errors:0 dropped:0 overruns:0 frame:0
          TX packets:25718 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:10789140 (10.2 MiB)  TX bytes:2012261 (1.9 MiB)
          Interrupt:11 Base address:0x4000 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:182 errors:0 dropped:0 overruns:0 frame:0
          TX packets:182 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:25798 (25.1 KiB)  TX bytes:25798 (25.1 KiB)

sit0      Link encap:IPv6-in-IPv4  
          NOARP  MTU:1480  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

解决方法

我终于找到了正确答案.

简短回答：MAC地址冲突.

答案很长：对于每个虚拟机,qemu都会创建一个虚拟网卡.它为此虚拟NIC分配MAC地址.默认情况下,它为每个NIC分配一个固定地址(52：54：00：12：34：56).如果您在同一主机上启动多个guest虚拟机,则它们都会获得相同的固定地址.您甚至可以在原始问题的ifconfig输出中看到这一点.当然,如果您将guest虚拟机连接在一起,这是一个问题,因为它与在同一网络上具有相同MAC地址的两台物理机相同. ARP做到最好,并在它们之间来回翻转,但是超时很长,给我的结果我看到了.

因此,解决方案是为每个guest虚拟机的-net参数添加“macaddr = …”标志,以使每个guest虚拟机具有唯一的MAC地址.例：

# qemu-kvm -hda <disk-image1> -m 2048 -vga std -vnc :3 -net nic,macaddr=52:54:00:00:00:03 -net tap,macaddr=52:54:00:00:00:04 -net tap,script=/etc/qemu-ifup

在我看来,qemu的默认行为应该更加明智,但我认为每个访客每次启动时都获得相同的MAC地址是相当重要的,无论他们的启动顺序如何.也许作者无法想到一种确保这一点的方法.

无论如何,如果您在同一网络(虚拟或其他)上运行多个guest虚拟机,请确保明确且唯一地设置MAC地址.否则,你会遇到同样的问题.