kvm初体验
硬件环境如下：一台host主机，上面安装的是CentOS 5.4，ip地址为200.200.77.163，内核已被我升级为支持kvm的2.6.30：
[root@localhost kvm]# cat /etc/issue
CentOS release 5.4 (Final)
Kernel \r on an \m
[root@localhost linux-2.6.30]# uname -a
Linux localhost.localdomain 2.6.30 #5 SMP Tue Aug 10 00:56:36 CST 2010 x86_64 x86_64 x86_64 GNU/Linux
[root@localhost kvm]# ifconfig eth0 | grep inet
inet addr:200.200.77.163 Bcast:200.200.0.255 Mask:255.255.252.0
inet6 addr: fe80::201:29ff:fe50:4673/64 Scope:Link
[root@localhost kvm]#
要让内核支持kvm功能，只需选中如下一些内核编译选项即可：
--- Virtualization <M> Kernel-based Virtual Machine (KVM) support <M> KVM for Intel processors support < > KVM for AMD processors support (NEW) [*] KVM trace support <M> PCI driver for virtio devices (EXPERIMENTAL) < > Virtio balloon driver (EXPERIMENTAL)
kvm还需cpu的虚拟化支持，检查/proc/cpuinfo，如果在cpu flags字段看到了vmx（intel）或smx（amd），那么你的处理器就支持KVM，另外，要真正能够使用它当然还需要在BIOS内开启：
[root@localhost ~]# cat /proc/cpuinfo | grep vmx
这些条件都满足后，执行modprobe kvm-intel或modprobe kvm-amd，把对应的模块加载上，一切准备OK，开始KVM体验。
这台机器放在实验室里，而我的操作是通过另外主机（安装xp系统，以下称之为client主机）上的Xshell远程到该host主机的ssh server进行的，操作界面当然是cli接口。
首先准备kvm的应用层工具，这只需从http://sourceforge.net/projects/kvm/files/qemu-kvm/下载到最新的qemu-kvm-release.tar.gz即可，我这里是qemu-kvm-1.0.tar.gz，解压安装（./configure; make; make install）后，先创建一个磁盘镜像：
[root@localhost kvm]# ls CentOS-5.5-x86_64-bin-DVD-1of2.iso qemu-kvm-1.0 qemu-kvm-1.0.tar.gz [root@localhost kvm]# qemu-img create -f qcow2 vdisk.img 160G Formatting 'vdisk.img', fmt=qcow2 size=171798691840 encryption=off cluster_size=65536 [root@localhost kvm]# ls -lsh total 4.2G 4.1G -rwxr-xr-x 1 root root 4.1G Nov 24 2010 CentOS-5.5-x86_64-bin-DVD-1of2.iso 24K drwxrwxr-x 50 root root 20K Apr 12 18:03 qemu-kvm-1.0 6.0M -rw-r--r-- 1 root root 6.0M Apr 12 01:17 qemu-kvm-1.0.tar.gz 144K -rw-r--r-- 1 root root 195K Apr 12 20:19 vdisk.img [root@localhost kvm]#
这是一个160GB的磁盘镜像，不过不用当心会等很久，因为它采用的是Copy on write策略，并不会一开始就占用160G的实体磁盘，而只是在使用过程中逐步增大，当然最大上限是160GB。
CentOS-5.5-x86_64-bin-DVD-1of2.iso是我们的CentOS光盘iso镜像，下面用它来安装一个全新CentOS的KVM虚拟客户机（以下称之为kvm客户机）：
[root@localhost kvm]# qemu-system-x86_64 -hda vdisk.img -cdrom CentOS-5.5-x86_64-bin-DVD-1of2.iso -m 1024 -vnc :1 -daemonize
由于我的host主机并没有启动X Window，所以这里加上-vnc选项（http://www.linux-kvm.com/content/tip-how-run-headless-guest-machine-using-vnc-kvm）以便我可以从client主机直接远程链接到kvm客户机，在client主机上安装好vnc客户端后，就可以链接kvm客户机了。我这里安装vnc-P4_2_5-x86_win32_PConline.exe，然后执行开始 –> 所有程序 –> RealVNC –> VNC Viewer 4 –> Run VNC Viewer，在Server:里输入200.200.77.163:1，Encryption:里选择Default，点OK按钮后就连上了：
接下来的CentOS-6.2系统安装无需多说，安装完成后自动重启，正常进入系统，看来我人品比较好，一切OK：
发现kvm客户机只有一个cpu，此时可通过-smp指定，比如指定两个cpu：
[root@localhost kvm]# qemu-system-x86_64 -hda vdisk.img -cdrom CentOS-5.5-x86_64-bin-DVD-1of2.iso -m 1024 -vnc :1 -daemonize -smp 2 [root@localhost kvm]#
退出kvm客户机的话，执行halt即可。当然，粗暴点的方法也有，比如直接在host主机里kill掉对应的qemu进程。
在进行初步的性能测试，首先下载应用层工具源码：
http://sourceforge.net/projects/bridge/
bridge-utils-1.5.tar.gz
http://sourceforge.net/projects/tunctl/
tunctl-1.5.tar.gz
安装：
[root@localhost kvm]# tar xzf tunctl-1.5.tar.gz [root@localhost kvm]# tar xzf bridge-utils-1.5.tar.gz [root@localhost kvm]# cd tunctl-1.5 [root@localhost tunctl-1.5]# make ... [root@localhost tunctl-1.5]# make install ... [root@localhost tunctl-1.5]# cd ../bridge-utils-1.5 [root@localhost bridge-utils-1.5]# autoconf [root@localhost bridge-utils-1.5]# ./configure ... [root@localhost bridge-utils-1.5]# make ... [root@localhost bridge-utils-1.5]# make install ... [root@localhost bridge-utils-1.5]#
设置并启动虚拟机：
[root@localhost bridge-utils-1.5]# cd ../ [root@localhost kvm]# brctl addbr br0 [root@localhost kvm]# brctl addif br0 eth8 [root@localhost kvm]# cat network/qemu-ifup #!/bin/sh set -x switch=br0 if [ -n "$1" ];then tunctl -u `whoami` -t $1 sleep 0.5s ip link set $1 up brctl addif $switch $1 exit 0 else echo "Error: no interface specified" exit 1 fi [root@localhost kvm]# qemu-system-x86_64 -hda vdisk.img -cdrom CentOS-5.5-x86_64-bin-DVD-1of2.iso -m 1024 -vnc :1 -daemonize -cpu host -net nic,macaddr=00:0C:29:AF:66:66,model=virtio -net tap,script=/home/kvm/network/qemu-ifup + switch=br0 + '[' -n tap0 ']' ++ whoami + tunctl -u root -t tap0 TUNSETIFF: Device or resource busy + sleep 0.5s + ip link set tap0 up + brctl addif br0 tap0 + exit 0 [root@localhost kvm]#
启动后，在kvm客户机里给eth0配置ip：ifconfig eth0 192.168.166.2，在host主机内给br0设置ip：
[root@localhost kvm]# ifconfig br0 192.168.166.1 [root@localhost kvm]# ping 192.168.166.2 PING 192.168.166.2 (192.168.166.2) 56(84) bytes of data. 64 bytes from 192.168.166.2: icmp_seq=1 ttl=64 time=0.164 ms 64 bytes from 192.168.166.2: icmp_seq=2 ttl=64 time=0.129 ms ^C --- 192.168.166.2 ping statistics --- 2 packets transmitted, 2 received, 0% packet loss, time 999ms rtt min/avg/max/mdev = 0.129/0.146/0.164/0.021 ms [root@localhost kvm]#
再在kvm客户机内ping 192.168.166.1，OK。
在client主机（加一个ip地址：192.168.166.166）ping 192.168.166.2，OK。
在kvm客户机内ping 192.168.166.166，OK。
进行轰流量测试，在host主机内和kvm客户机内都装好iperf：http://sourceforge.net/projects/iperf/，以host主机为例：
[root@localhost kvm]# tar xzf iperf-2.0.5.tar.gz [root@localhost kvm]# cd iperf-2.0.5 [root@localhost iperf-2.0.5]# ./configure ... [root@localhost iperf-2.0.5]# make ... [root@localhost iperf-2.0.5]# make install ... [root@localhost iperf-2.0.5]#
测试结果如下（这里，kvm客户机只使用了一个cpu，性能结果不具备代表性，仅以描述测试过程），执行过程中如果提示“connect failed: No route to host”则需先关闭防火墙：
[root@localhost iperf-2.0.5]# /etc/init.d/iptables stop
kvm客户机内：
[root@localhost iperf-2.0.5]# uname -a Linux localhost.localdomain 2.6.18-194.el5 #1 SMP Fri Apr 2 14:58:14 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux [root@localhost iperf-2.0.5]# cat /proc/cpuinfo processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 23 model name : Pentium(R) Dual-Core CPU E6700 @ 3.20GHz stepping : 10 cpu MHz : 3303.978 cache size : 4096 KB fpu : yes fpu_exception : yes cpuid level : 13 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss syscall nx lm constant_tsc up pni cx16 lahf_lm bogomips : 6607.95 clflush size : 64 cache_alignment : 64 address sizes : 40 bits physical, 48 bits virtual power management: [root@localhost iperf-2.0.5]# src/iperf -w 64000 -i 1 -p 5005 -s #udp ------------------------------------------------------------ Server listening on TCP port 5005 TCP window size: 125 KByte (WARNING: requested 62.5 KByte) ------------------------------------------------------------ [ 4] local 192.168.166.2 port 5005 connected with 192.168.166.1 port 39589 [ ID] Interval Transfer Bandwidth [ 4] 0.0- 1.0 sec 208 MBytes 1.75 Gbits/sec [ 4] 1.0- 2.0 sec 200 MBytes 1.68 Gbits/sec [ 4] 2.0- 3.0 sec 196 MBytes 1.64 Gbits/sec [ 4] 3.0- 4.0 sec 191 MBytes 1.60 Gbits/sec [ 4] 4.0- 5.0 sec 207 MBytes 1.73 Gbits/sec [ 4] 5.0- 6.0 sec 202 MBytes 1.69 Gbits/sec [ 4] 6.0- 7.0 sec 207 MBytes 1.73 Gbits/sec [ 4] 7.0- 8.0 sec 195 MBytes 1.63 Gbits/sec [ 4] 8.0- 9.0 sec 174 MBytes 1.46 Gbits/sec [ 4] 9.0-10.0 sec 194 MBytes 1.63 Gbits/sec [ 4] 10.0-11.0 sec 187 MBytes 1.57 Gbits/sec [ 4] 11.0-12.0 sec 203 MBytes 1.70 Gbits/sec [ 4] 12.0-13.0 sec 204 MBytes 1.72 Gbits/sec [ 4] 13.0-14.0 sec 187 MBytes 1.57 Gbits/sec [ 4] 14.0-15.0 sec 202 MBytes 1.69 Gbits/sec [ 4] 15.0-16.0 sec 204 MBytes 1.71 Gbits/sec [ 4] 16.0-17.0 sec 199 MBytes 1.67 Gbits/sec [ 4] 17.0-18.0 sec 203 MBytes 1.71 Gbits/sec [ 4] 18.0-19.0 sec 199 MBytes 1.67 Gbits/sec [ 4] 19.0-20.0 sec 195 MBytes 1.63 Gbits/sec [ 4] 0.0-20.0 sec 3.86 GBytes 1.66 Gbits/sec
host主机内：
[root@localhost iperf-2.0.5]# iperf -w 64000 -p 5005 -i 1 -t 20 -c 192.168.166.2 ------------------------------------------------------------ Client connecting to 192.168.166.2, TCP port 5005 TCP window size: 125 KByte (WARNING: requested 62.5 KByte) ------------------------------------------------------------ [ 3] local 192.168.166.1 port 39589 connected with 192.168.166.2 port 5005 [ ID] Interval Transfer Bandwidth [ 3] 0.0- 1.0 sec 208 MBytes 1.75 Gbits/sec [ 3] 1.0- 2.0 sec 200 MBytes 1.68 Gbits/sec [ 3] 2.0- 3.0 sec 196 MBytes 1.64 Gbits/sec [ 3] 3.0- 4.0 sec 191 MBytes 1.61 Gbits/sec [ 3] 4.0- 5.0 sec 207 MBytes 1.73 Gbits/sec [ 3] 5.0- 6.0 sec 202 MBytes 1.69 Gbits/sec [ 3] 6.0- 7.0 sec 206 MBytes 1.73 Gbits/sec [ 3] 7.0- 8.0 sec 195 MBytes 1.64 Gbits/sec [ 3] 8.0- 9.0 sec 174 MBytes 1.46 Gbits/sec [ 3] 9.0-10.0 sec 194 MBytes 1.63 Gbits/sec [ 3] 10.0-11.0 sec 188 MBytes 1.57 Gbits/sec [ 3] 11.0-12.0 sec 203 MBytes 1.70 Gbits/sec [ 3] 12.0-13.0 sec 204 MBytes 1.71 Gbits/sec [ 3] 13.0-14.0 sec 188 MBytes 1.57 Gbits/sec [ 3] 14.0-15.0 sec 202 MBytes 1.69 Gbits/sec [ 3] 15.0-16.0 sec 204 MBytes 1.71 Gbits/sec [ 3] 16.0-17.0 sec 199 MBytes 1.67 Gbits/sec [ 3] 17.0-18.0 sec 203 MBytes 1.70 Gbits/sec [ 3] 18.0-19.0 sec 199 MBytes 1.67 Gbits/sec [ 3] 19.0-20.0 sec 194 MBytes 1.63 Gbits/sec [ 3] 0.0-20.0 sec 3.86 GBytes 1.66 Gbits/sec [root@localhost iperf-2.0.5]#
参考：
http://www.linux-kvm.com/
http://www.linux-kvm.org/
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