kvm

硬件，os，内核模块，用户空间工具，命令行具体参数，日志

[root@localhost ~]# yum install pciutils

[root@localhost ~]# lscpu;lspci

Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                4
On-line CPU(s) list:   0-3
Thread(s) per core:    2
Core(s) per socket:    2
Socket(s):             1
NUMA node(s):          1
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 60
Model name:            Intel(R) Core(TM) i3-4170 CPU @ 3.70GHz
Stepping:              3
CPU MHz:               3700.000
BogoMIPS:              7399.71
Virtualization:        VT-x
L1d cache:             32K
L1i cache:             32K
L2 cache:              256K
L3 cache:              3072K
NUMA node0 CPU(s):     0-3

00:00.0 Host bridge: Intel Corporation 4th Gen Core Processor DRAM Controller (rev 06)
00:02.0 VGA compatible controller: Intel Corporation 4th Generation Core Processor Family Integrated Graphics Controller (rev 06)
00:03.0 Audio device: Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor HD Audio Controller (rev 06)
00:14.0 USB controller: Intel Corporation 9 Series Chipset Family USB xHCI Controller
00:16.0 Communication controller: Intel Corporation 9 Series Chipset Family ME Interface #1
00:19.0 Ethernet controller: Intel Corporation Ethernet Connection I217-V
00:1a.0 USB controller: Intel Corporation 9 Series Chipset Family USB EHCI Controller #2
00:1b.0 Audio device: Intel Corporation 9 Series Chipset Family HD Audio Controller
00:1c.0 PCI bridge: Intel Corporation 9 Series Chipset Family PCI Express Root Port 1 (rev d0)
00:1c.3 PCI bridge: Intel Corporation 9 Series Chipset Family PCI Express Root Port 4 (rev d0)
00:1d.0 USB controller: Intel Corporation 9 Series Chipset Family USB EHCI Controller #1
00:1f.0 ISA bridge: Intel Corporation 9 Series Chipset Family H97 Controller
00:1f.2 RAID bus controller: Intel Corporation SATA Controller [RAID mode]
00:1f.3 SMBus: Intel Corporation 9 Series Chipset Family SMBus Controller
02:00.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev 41)

[root@localhost ~]# cat /etc/centos-release
CentOS Linux release 7.2.1511 (Core)

[root@localhost ~]# lsmod |grep kvm
kvm_intel             162153  3
kvm                   525259  1 kvm_intel
[root@localhost ~]# ll /lib/modules/3.10.0-327.el7.x86_64/kernel/arch/x86/kvm/
total 1180
-rw-r--r--. 1 root root 104261 Nov 20  2015 kvm-amd.ko
-rw-r--r--. 1 root root 271245 Nov 20  2015 kvm-intel.ko
-rw-r--r--. 1 root root 824605 Nov 20  2015 kvm.ko

[root@localhost ~]# yum install bridge-utils qemu-kvm
[root@localhost ~]# rpm -qa|grep kvm
qemu-kvm-common-1.5.3-105.el7_2.4.x86_64
qemu-kvm-1.5.3-105.el7_2.4.x86_64

[root@localhost ~]# /usr/libexec/qemu-kvm -version
QEMU emulator version 1.5.3 (qemu-kvm-1.5.3-105.el7_2.4), Copyright (c) 2003-2008 Fabrice Bellard

[root@localhost ~]# /usr/libexec/qemu-kvm -machine ?

[root@localhost ~]# /usr/libexec/qemu-kvm -M ?

Supported machines are:
none                 empty machine
pc                   RHEL 7.0.0 PC (i440FX + PIIX, 1996) (alias of pc-i440fx-rhel7.0.0)
pc-i440fx-rhel7.0.0  RHEL 7.0.0 PC (i440FX + PIIX, 1996) (default)
rhel6.6.0            RHEL 6.6.0 PC
rhel6.5.0            RHEL 6.5.0 PC
rhel6.4.0            RHEL 6.4.0 PC
rhel6.3.0            RHEL 6.3.0 PC
rhel6.2.0            RHEL 6.2.0 PC
rhel6.1.0            RHEL 6.1.0 PC
rhel6.0.0            RHEL 6.0.0 PC

[root@localhost ~]# /usr/libexec/qemu-kvm -cpu ?

x86           qemu64  QEMU Virtual CPU version 1.5.3
x86           phenom  AMD Phenom(tm) 9550 Quad-Core Processor
x86         core2duo  Intel(R) Core(TM)2 Duo CPU     T7700  @ 2.40GHz
x86            kvm64  Common KVM processor
x86           qemu32  QEMU Virtual CPU version 1.5.3
x86            kvm32  Common 32-bit KVM processor
x86          coreduo  Genuine Intel(R) CPU           T2600  @ 2.16GHz
x86              486
x86          pentium
x86         pentium2
x86         pentium3
x86           athlon  QEMU Virtual CPU version 1.5.3
x86             n270  Intel(R) Atom(TM) CPU N270   @ 1.60GHz
x86      cpu64-rhel6  QEMU Virtual CPU version (cpu64-rhel6)
x86           Conroe  Intel Celeron_4x0 (Conroe/Merom Class Core 2)
x86           Penryn  Intel Core 2 Duo P9xxx (Penryn Class Core 2)
x86          Nehalem  Intel Core i7 9xx (Nehalem Class Core i7)
x86         Westmere  Westmere E56xx/L56xx/X56xx (Nehalem-C)
x86      SandyBridge  Intel Xeon E312xx (Sandy Bridge)
x86          Haswell  Intel Core Processor (Haswell)
x86        Broadwell  Intel Core Processor (Broadwell)
x86       Opteron_G1  AMD Opteron 240 (Gen 1 Class Opteron)
x86       Opteron_G2  AMD Opteron 22xx (Gen 2 Class Opteron)
x86       Opteron_G3  AMD Opteron 23xx (Gen 3 Class Opteron)
x86       Opteron_G4  AMD Opteron 62xx class CPU
x86       Opteron_G5  AMD Opteron 63xx class CPU
x86             host  KVM processor with all supported host features (only available in KVM mode)

Recognized CPUID flags:
  pbe ia64 tm ht ss sse2 sse fxsr mmx acpi ds clflush pn pse36 pat cmov mca pge mtrr sep apic cx8 mce pae msr tsc pse de vme fpu
  hypervisor rdrand f16c avx osxsave xsave aes tsc-deadline popcnt movbe x2apic sse4.2|sse4_2 sse4.1|sse4_1 dca pcid pdcm xtpr cx16 fma cid ssse3 tm2 est smx vmx ds_cpl monitor dtes64 pclmulqdq|pclmuldq pni|sse3
  avx512cd avx512er avx512pf smap adx rdseed avx512f mpx rtm invpcid erms bmi2 smep avx2 hle bmi1 fsgsbase
  3dnow 3dnowext lm|i64 rdtscp pdpe1gb fxsr_opt|ffxsr mmxext nx|xd syscall
  perfctr_nb perfctr_core topoext tbm nodeid_msr tce fma4 lwp wdt skinit xop ibs osvw 3dnowprefetch misalignsse sse4a abm cr8legacy extapic svm cmp_legacy lahf_lm
  pmm-en pmm phe-en phe ace2-en ace2 xcrypt-en xcrypt xstore-en xstore
  kvm_pv_unhalt kvm_pv_eoi kvm_steal_time kvm_asyncpf kvmclock kvm_mmu kvm_nopiodelay kvmclock
  pfthreshold pause_filter decodeassists flushbyasid vmcb_clean tsc_scale nrip_save svm_lock lbrv npt

[root@localhost lib]# /usr/libexec/qemu-kvm -device ?

Controller/Bridge/Hub devices:
name "i82801b11-bridge", bus PCI
name "ioh3420", bus PCI, desc "Intel IOH device id 3420 PCIE Root Port"
name "pci-bridge", bus PCI, desc "Standard PCI Bridge"
name "usb-host", bus usb-bus
name "usb-hub", bus usb-bus
name "x3130-upstream", bus PCI, desc "TI X3130 Upstream Port of PCI Express Switch"
name "xio3130-downstream", bus PCI, desc "TI X3130 Downstream Port of PCI Express Switch"

USB devices:
name "ich9-usb-ehci1", bus PCI
name "ich9-usb-ehci2", bus PCI
name "ich9-usb-uhci1", bus PCI
name "ich9-usb-uhci2", bus PCI
name "ich9-usb-uhci3", bus PCI
name "ich9-usb-uhci4", bus PCI
name "ich9-usb-uhci5", bus PCI
name "ich9-usb-uhci6", bus PCI
name "nec-usb-xhci", bus PCI
name "piix3-usb-uhci", bus PCI
name "piix4-usb-uhci", bus PCI
name "usb-ehci", bus PCI
name "vt82c686b-usb-uhci", bus PCI

Storage devices:
name "ich9-ahci", bus PCI, alias "ahci"
name "ide-cd", bus IDE, desc "virtual IDE CD-ROM"
name "ide-drive", bus IDE, desc "virtual IDE disk or CD-ROM (legacy)"
name "ide-hd", bus IDE, desc "virtual IDE disk"
name "scsi-block", bus SCSI, desc "SCSI block device passthrough"
name "scsi-cd", bus SCSI, desc "virtual SCSI CD-ROM"
name "scsi-disk", bus SCSI, desc "virtual SCSI disk or CD-ROM (legacy)"
name "scsi-generic", bus SCSI, desc "pass through generic scsi device (/dev/sg*)"
name "scsi-hd", bus SCSI, desc "virtual SCSI disk"
name "usb-bot", bus usb-bus
name "usb-storage", bus usb-bus
name "virtio-blk-device", bus virtio-bus
name "virtio-blk-pci", bus PCI, alias "virtio-blk"
name "virtio-scsi-device", bus virtio-bus
name "virtio-scsi-pci", bus PCI

Network devices:
name "e1000", bus PCI, desc "Intel Gigabit Ethernet"
name "rtl8139", bus PCI
name "virtio-net-device", bus virtio-bus
name "virtio-net-pci", bus PCI, alias "virtio-net"

Input devices:
name "ccid-card-passthru", bus ccid-bus, desc "passthrough smartcard"
name "isa-serial", bus ISA
name "pci-serial", bus PCI
name "usb-ccid", bus usb-bus, desc "CCID Rev 1.1 smartcard reader"
name "usb-kbd", bus usb-bus
name "usb-mouse", bus usb-bus
name "virtconsole", bus virtio-serial-bus
name "virtio-serial-device", bus virtio-bus
name "virtio-serial-pci", bus PCI, alias "virtio-serial"
name "virtserialport", bus virtio-serial-bus

Display devices:
name "cirrus-vga", bus PCI, desc "Cirrus CLGD 54xx VGA"
name "qxl", bus PCI, desc "Spice QXL GPU (secondary)"
name "qxl-vga", bus PCI, desc "Spice QXL GPU (primary, vga compatible)"
name "sga", bus ISA, desc "Serial Graphics Adapter"
name "VGA", bus PCI

Sound devices:
name "AC97", bus PCI, desc "Intel 82801AA AC97 Audio"
name "hda-duplex", bus HDA, desc "HDA Audio Codec, duplex (line-out, line-in)"
name "hda-micro", bus HDA, desc "HDA Audio Codec, duplex (speaker, microphone)"
name "hda-output", bus HDA, desc "HDA Audio Codec, output-only (line-out)"
name "ich9-intel-hda", bus PCI, desc "Intel HD Audio Controller (ich9)"
name "intel-hda", bus PCI, desc "Intel HD Audio Controller (ich6)"

Misc devices:
name "i6300esb", bus PCI
name "ib700", bus ISA
name "isa-debug-exit", bus ISA
name "isa-debugcon", bus ISA
name "kvm-pci-assign", bus PCI, alias "pci-assign", desc "KVM-based PCI passthrough"
name "pc-testdev", bus ISA
name "pci-testdev", bus PCI, desc "PCI Test Device"
name "usb-redir", bus usb-bus
name "usb-tablet", bus usb-bus
name "vfio-pci", bus PCI, desc "VFIO-based PCI device assignment"
name "virtio-balloon-device", bus virtio-bus
name "virtio-balloon-pci", bus PCI, alias "virtio-balloon"
name "virtio-rng-device", bus virtio-bus
name "virtio-rng-pci", bus PCI

Uncategorized devices:
name "pvpanic", bus ISA

[root@localhost lib]# /usr/libexec/qemu-kvm -device VGA,?

VGA.vgamem_mb=uint32
VGA.mmio=on/off
VGA.addr=pci-devfn
VGA.romfile=string
VGA.rombar=uint32
VGA.multifunction=on/off
VGA.command_serr_enable=on/off

[root@localhost lib]# /usr/libexec/qemu-kvm -device qxl,?

qxl.ram_size=uint32
qxl.vram_size=uint32
qxl.revision=uint32
qxl.debug=uint32
qxl.guestdebug=uint32
qxl.cmdlog=uint32
qxl.ram_size_mb=uint32
qxl.vram_size_mb=uint32
qxl.vram64_size_mb=uint32
qxl.vgamem_mb=uint32
qxl.surfaces=int32
qxl.addr=pci-devfn
qxl.romfile=string
qxl.rombar=uint32
qxl.multifunction=on/off
qxl.command_serr_enable=on/off

[root@localhost lib]# /usr/libexec/qemu-kvm -device e1000,?

e1000.mac=macaddr
e1000.vlan=vlan
e1000.netdev=netdev
e1000.bootindex=int32
e1000.autonegotiation=on/off
e1000.addr=pci-devfn
e1000.romfile=string
e1000.rombar=uint32
e1000.multifunction=on/off
e1000.command_serr_enable=on/off

命令行参数

[root@localhost lib]# /usr/libexec/qemu-kvm -h|more
QEMU emulator version 1.5.3 (qemu-kvm-1.5.3-105.el7_2.4), Copyright (c) 2003-2008 Fabrice Bellard

WARNING: Direct use of qemu-kvm from the command line is not supported by Red Hat.
WARNING: Use libvirt as the stable management interface.
WARNING: Some command line options listed here may not be available in future releases.

-machine
-cpu
-smp n			set the number of CPUs to 'n' [default=1]
-boot			[order=drives]	'drives': floppy (a), hard disk (c), CD-ROM (d), network (n)
-m megs         set virtual RAM size to megs MB [default=128]
-name 			string1[,process=string2]
                set the name of the guest
-cdrom file
-display sdl[,frame=on|off][,alt_grab=on|off][,ctrl_grab=on|off]
            [,window_close=on|off]|curses|none|
            vnc=<display>[,<optargs>]
                select display type
-nographic      disable graphical output and redirect serial I/Os to console
-spice [port=port][,password=<secret>]
				at least one of {port, tls-port} is mandatory
-vga [std|cirrus|vmware|qxl|xenfb|none]
                select video card type
-full-screen    start in full screen
-vnc display    start a VNC server on display

-net nic　　其中，“-net nic”这个是必须的参数，表明这是一个网卡的配置。如果没有，虚拟机启动后就不会有网卡
-net user 用户网络模式
http://www.diyoms.com/cloud/836.html
http://qemu.weilnetz.de/qemu-doc.html#Using-TAP-network-interfaces

用户模式客户机可以直接连接宿主机和外部网络,而且完全由qemu自身完全实现，不依赖于(bridge,dnsmasq,iptables等),不需要root权限
Qemu使用slirp实现了一套Tcp/ip协议栈，而且用这个协议栈实现了一套虚拟的NAT网络。
qemu-kvm默认使用：-net nic -net user
优点:简单、独立性好、不需要root权限、客户机网络隔离性好。
缺点:
1、性能差
2、不支持部分网络功能(如ICMP),所以不能再客户机中使用ping命令测试,
3、不能从宿主机或外部网络直接访问客户机

-net user

dhcpstart=addr  设置分配给客户机的第一个Ip,在qemu内嵌的DHCP服务器中有16个IP地址可以分配，默认是(如10.0.2.15~10.0.2.30)
dns=addr   指定虚拟的DNS地址，该地址不能与宿主机一样，默认为网络中的第三个IP地址（如:10.0.2.3）

qemu-kvm   centos6u5.img  -m 1024  -smp 2 -net nic -net user,tftp=/root/tftp,hostfwd=tcp::5022-hostfwd=tcp::5080-:80

-net none       use it alone to have zero network devices. If no -net option
                is provided, the default is '-net nic -net user'
-net nic -net bridge

Linux/Multiboot boot specific:
-kernel bzImage use 'bzImage' as kernel image
-append cmdline use 'cmdline' as kernel command line
-initrd file    use 'file' as initial ram disk
-dtb    file    use 'file' as device tree image

-daemonize      daemonize QEMU after initializing
-echr chr       set terminal escape character instead of ctrl-a
During emulation, the following keys are useful:
ctrl-alt-f      toggle full screen
ctrl-alt-n      switch to virtual console 'n'
ctrl-alt        toggle mouse and keyboard grab

When using -nographic, press 'ctrl-a h' to get some help.

命令行参数解释及实例

在qemu-kvm命令行中，添加“-nographic”参数可以完全关闭QEMU的图形界面输出，从而让QEMU在该模式下完全成为简单的命令行工具。而QEMU中模拟产生的串口被重定向到了当前的控制台（console）中，所以如果在客户机中对其内核进行配置从而让内核的控制台输出重定向到串口后，就依然可以在非图形模式下管理客户机系统或调试客户机的内核。

在命令行直接安装虚拟机
mount -o loop CentOS-6.5-x86_64-bin-DVD1.iso /mnt
qemu-img create -f qcow2 cs66.qcow2 8G
/usr/libexec/qemu-kvm  -boot order=dc -hda cs66.qcow2 -cdrom CentOS-6.5-x86_64-bin-DVD1.iso -m 1024 -nographic -append console=ttyS0 -kernel /mnt/isolinux/vmlinuz -initrd /mnt/isolinux/initrd.img
kill 掉上面的进程，重启去掉一些参数再如下启动
/usr/libexec/qemu-kvm  -boot order=dc -hda cs66.qcow2 -m 1024 -nographic

宿主机是cs72,虚拟机是cs65
安装好系统之后，先用spice启动
1.先启动/usr/libexec/qemu-kvm -boot order=dc -hda cs65.qcow2 -m 1024 -spice port=9987,password=1234
2.windows的spice客户端去连接，进去之后，vi /boot/grub/grub.cfg,在内核行后加入console=ttyS0然后保存关机
3.再加-nographic参数后启动，/usr/libexec/qemu-kvm -boot order=dc -hda cs65.qcow2 -m 1024 -nographic
这样就在宿主机本地启动了

man qemu-kvm
debug/expert options

/usr/libexec/qemu-kvm -enable-kvm -monitor stdio

服务器启动 /usr/libexec/qemu-kvm -boot dc -hda disk/cs65.qcow2 -m 1024 -vnc :2 -daemonize -net bridge -net nic -enable-kvm -monitor telnet:192.168.10.101:4444,server,nowait

客户端连接 telnet 192.168.10.101 4444

/usr/libexec/qemu-kvm -boot dc -hda disk/cs65.qcow2 -m 1024 -vnc :2 -daemonize -net bridge -net nic -enable-kvm -monitor tcp:192.168.10.101:4445,server,nowait

nc 192.168.10.101 4445

    tcp – raw tcp sockets  #下面第2点，我的举例是RAW TCP socket
    telnet – the telnet protocol is used instead of raw tcp sockets. This is the preferred option over tcp as you can break out of the monitor using Ctrl-] then typing quit. You can’t break out of the monitor like this after connecting with the raw socket option
    10.1.77.82 – Listen on this host/IP only. You can use 127.0.0.1 if you want to only allow connections locally. If you want to listen on any ip address on the server, just leave this blank so you end up with two consecutive colons ie “::” .
    4444 – port number to listen on.
    server – listening in server mode
    nowait – qemu will wait for a client socket application to connect to the port before continuing unless this option is used. In most cases you’ll want to use the nowait option.

日志问题追查

Jul 31 11:02:59 localhost kernel: kvm [1463]: vcpu0 disabled perfctr wrmsr: 0xc2 data 0xffff
Jul 31 11:02:59 localhost kernel: kvm [1463]: vcpu0 unhandled rdmsr: 0x570

cpu标志
[root@localhost ~]# cat /proc/cpuinfo
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 fma cx16 xtpr pdcm pcid sse4_1 sse4_2 movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm arat pln pts dtherm tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid xsaveopt

日志中kvm报出来的关于cpu的情况
[root@localhost ~]# tail -20 /var/log/messages-20160731
Jul 31 11:02:59 localhost kernel: kvm [1463]: vcpu0 disabled perfctr wrmsr: 0xc2 data 0xffff
Jul 31 11:02:59 localhost kernel: kvm [1463]: vcpu0 unhandled rdmsr: 0x570

这是kvm支持的cpu特征
[root@localhost ~]# /usr/libexec/qemu-kvm -cpu ?|grep msr
  pbe ia64 tm ht ss sse2 sse fxsr mmx acpi ds clflush pn pse36 pat cmov mca pge mtrr sep apic cx8 mce pae msr tsc pse de vme fpu
  perfctr_nb perfctr_core topoext tbm nodeid_msr tce fma4 lwp wdt skinit xop ibs osvw 3dnowprefetch misalignsse sse4a abm cr8legacy extapic svm cmp_legacy lahf_lm

cpu flag msr概念
Model Specific Register (MSR) as the name implies is model specific and may change from processor model number (n) to processor model number (n+1).
读写方法
MSR 是CPU 的一组64 位寄存器，可以分别通过RDMSR 和WRMSR 两条指令进行读和写的操作，前提要在ECX 中写入MSR 的地址。对于RDMSR 指令，将会返回相应的MSR 中64bit 信息到(EDX：EAX)寄存器中；对于WRMSR 指令，把要写入的信息存入(EDX：EAX)中，执行写指令后，即可将相应的信息存入ECX 指定的MSR 中。MSR 的指令必须执行在level 0 或实模式下。
作用
MSR 总体来是为了设置CPU 的工作环境和标示CPU 的工作状态，包括温度控制，性能监控等，具体来说，分为以下几项:

[root@localhost ~]# lsmod|grep papi
[root@localhost ~]# modprobe papi
modprobe: FATAL: Module papi not found.

[root@localhost ~]# lsmod |grep perfctr
[root@localhost ~]# modprobe perfctr
modprobe: FATAL: Module perfctr not found.

# modprobe perfctr 加载模块
lsmod 显示模块
rmmod perfctr移除模块
若perfctr模块安装成功后，你将看到perfctr模块，并且你可以在 /lib/modules/2.6.19-zkl-perfctr/kernel/drivers/perfctr中看到perfctr模块perfctr.ko

需要使用PAPI得到硬件级的数据，即与微指令相关的数据，
例如 L1/L2 cache miss、TLB miss、Cycle等，而PAPI需要perfctr（Performance-monitoring counters support）模块的支持，
而Linux内核当中默认没有perfctr模块，并且perfctr只在某些内核上被支持，它实际上是内核的一个补丁，需要重新编译内核，打上补丁才能在内核上运行perfctr模块。更多信息参考papi和perfctr的INSTALL文件。

PAPI (Performance Application Programming Interface),它是一套API,通过它可以访问CPU性能计数器的数据,
例如 L1/L2 Cache,CPU Cycle,CPU Instruction,TLB等.
PAPI官网是: http://icl.cs.utk.edu/papi/

[root@localhost ~]# yum search papi
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirrors.hust.edu.cn
 * extras: mirrors.neusoft.edu.cn
 * updates: mirrors.neusoft.edu.cn
=================================================== N/S matched: papi ====================================================
papi-devel.i686 : Header files for the compiling programs with PAPI
papi-devel.x86_64 : Header files for the compiling programs with PAPI
papi-static.i686 : Static libraries for the compiling programs with PAPI
papi-static.x86_64 : Static libraries for the compiling programs with PAPI
papi-testsuite.x86_64 : Set of tests for checking PAPI functionality
papi.i686 : Performance Application Programming Interface
papi.x86_64 : Performance Application Programming Interface
pcp-pmda-papi.x86_64 : Performance Co-Pilot (PCP) metrics for Performance API and hardware counters

virt-manager做快照，其实是将当前状态整个保存在磁盘上，从下面可以看到容量的变量，做完以后，snapshot -l才会增加一条记录，对oracle4作了一次快照7.4G,用了10多分钟。

[root@kvm disk]# pwd
/home/kvm/disk
[root@kvm disk]# ll
total 273772440
-rw------- 1 qemu qemu   2238185472 Nov  9 15:48 asm-crs.qcow2
-rw------- 1 qemu qemu   8532787200 Nov  9 15:48 asm-data1.qcow2
-rw------- 1 qemu qemu   6071648256 Nov  9 15:48 asm-data2.qcow2
-rw------- 1 qemu qemu   9287696384 Nov  9 15:48 asm-fra.qcow2
-rw------- 1 root root  53695545344 Dec  9  2016 iscsi-share.qcow2
-rw-r--r-- 1 root root  87976050688 Dec  2 14:41 oracle1.qcow2
-rw------- 1 qemu qemu  75245158400 Dec 15 10:42 oracle3.qcow2
-rw------- 1 qemu qemu  19414646784 Dec 15 10:42 oracle4-db-file.qcow2
-rw------- 1 qemu qemu  18080858112 Dec 15 10:42 oracle4-db-fra.qcow2
-rw------- 1 qemu qemu  13367050240 Dec 15 10:41 oracle4-db-soft.qcow2
-rw------- 1 qemu qemu  36824350720 Dec 15 10:41 oracle4-os.qcow2
-rw------- 1 qemu qemu 111209349120 Dec 15 10:42 oracle-test.qcow2
-rw-r--r-- 1 root root  53695545344 Nov 30  2016 rac1.qcow2
-rw------- 1 root root  53695545344 Dec  3  2016 rac2.qcow2
-rw------- 1 root root  53695545344 Nov 29  2016 rac-share.qcow2
-rw-r--r-- 1 root root  21478375424 Jan 14  2017 test.qcow2

[root@kvm disk]# qemu-img snapshot -l oracle1.qcow2
Snapshot list:
ID        TAG                 VM SIZE                DATE       VM CLOCK
1         snapshot1              7.9G 2017-01-26 14:16:35   01:13:03.990

[root@kvm disk]# qemu-img snapshot -l oracle4-db-file.qcow2
Snapshot list:
ID        TAG                 VM SIZE                DATE       VM CLOCK
1         snapshot1                 0 2017-03-11 10:42:52   01:34:06.874
2         snapshot2                 0 2017-12-14 11:06:23   53:46:10.040

[root@kvm disk]# qemu-img snapshot -l oracle4-db-fra.qcow2
Snapshot list:
ID        TAG                 VM SIZE                DATE       VM CLOCK
1         snapshot1                 0 2017-03-11 10:42:52   01:34:06.874
2         snapshot2                 0 2017-12-14 11:06:23   53:46:10.040

[root@kvm disk]# qemu-img snapshot -l oracle4-db-soft.qcow2
Snapshot list:
ID        TAG                 VM SIZE                DATE       VM CLOCK
1         snapshot1                 0 2017-03-11 10:42:52   01:34:06.874
2         snapshot2                 0 2017-12-14 11:06:23   53:46:10.040

[root@kvm disk]# qemu-img snapshot -l oracle4-os.qcow2
Snapshot list:
ID        TAG                 VM SIZE                DATE       VM CLOCK
1         snapshot1              7.4G 2017-03-11 10:42:52   01:34:06.874
2         snapshot2              7.7G 2017-12-14 11:06:23   53:46:10.040

[root@kvm disk]# qemu-img info oracle4-os.qcow2
image: oracle4-os.qcow2
file format: qcow2
virtual size: 15G (16106127360 bytes)
disk size: 24G
cluster_size: 65536
Snapshot list:
ID        TAG                 VM SIZE                DATE       VM CLOCK
1         snapshot1              7.4G 2017-03-11 10:42:52   01:34:06.874
2         snapshot2              7.7G 2017-12-14 11:06:23   53:46:10.040
Format specific information:
    compat: 1.1
    lazy refcounts: true