文章目錄
- 1.重新編譯qemu
- 2.log方式
-
- 2.1.預設效果
- 2.2.分析代碼
- 2.3.檢視到日志檔案中列印
- 2.4.對接libvirt
- 3.添加自定義trace-event
- Reference
1.重新編譯qemu
編譯參數–enable-trace-backends可以指定trace系統使用的後端系統（backend），如果指定為log，這樣trace函數如下
圖1-1
如果後端為simple（預設值），則trace函數為
圖1-2
圖1-3
各種不同的trace方式的詳細解釋可以參考qemu文檔qemu-2.8.0\docs\tracing.txt
2.log方式
2.1.預設效果
打開某個event的開關，然後進行操作，預設可以列印在qemu monitor上
(qemu) trace-event migration_thread_setup_complete on
(qemu) migrate -d tcp:0:4444
(qemu)
(qemu)
(qemu)
(qemu) [email protected]:migration_thread_setup_complete
2.2.分析代碼
qemu_logfile
$1 = 0x7fddf6411450 "%[email protected]%zd.%06zd:migration_thread_setup_complete \n"
(gdb) p qemu_logfile
$2 = (FILE *) 0x7fddeff521c0 <_IO_2_1_stderr_>
可以看到預設列印在标準輸出stderr上
qemu_logfile = fopen(logfilename, log_append ? “a” : “w”);
圖2-1 設定logfile
這裡沒有設定logfilename，是以qemu_logfile = stderr，是以
#全局搜尋logfilename，得到，但是打斷點之後發現并沒有走這裡，是以繼續跟蹤該函數調用情況。
圖2-2
全局搜尋qemu_set_log_filename
圖2-3
trace_init_file函數會被調用，并且file為空，是以qemu_set_log_filename才沒有執行，繼續跟蹤調用棧
vl.c:4129 trace_init_file(trace_file);
圖2-4
然後發現不是這裡，這裡是backend為其他選項的時候的處理，log應該是另外一個地方也調用了qemu_set_log_filename，是下面vl.c:4134處
if (log_file) {
qemu_set_log_filename(log_file, &error_fatal);
}
圖2-5
搜尋QEMU_OPTION_D
DEF("D", HAS_ARG, QEMU_OPTION_D, \
"-D logfile output log to logfile (default stderr)\n",
使用方式應該是-D /var/log/qemu/qemu.log
2.3.檢視到日志檔案中列印
[[email protected] ~]# cat /var/log/qemu/qemu.log
[email protected]:migration_thread_setup_complete
2.4.對接libvirt
xml中使用qemu:commandline配置log檔案路徑
[[email protected] mydisk1]# cat vm1.xml
<domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
<name>vm1</name>
<memory unit='M'>2048</memory>
<metadata>
<app1:foo xmlns:app1="http://app1.org/app1/">..</app1:foo>
<app2:bar xmlns:app2="http://app1.org/app2/">..</app2:bar>
</metadata>
<qemu:commandline>
<qemu:arg value='-D'/>
<qemu:arg value='/var/log/qemu/qemu.log'/>
</qemu:commandline>
.....
</domain>
[[email protected] mydisk1]# virsh start vm1
error: Failed to start domain vm1
error: internal error: process exited while connecting to monitor: /var/log/qemu/qemu.log: Permission denied
解決方法：關閉selinux
檢視程序
[[email protected] mydisk1]# ps -ef|grep qemu
root 899 1 0 Jan03 ? 00:00:00 /usr/bin/qemu-ga --method=virtio-serial --path=/dev/virtio-ports/org.qemu.guest_agent.0 --blacklist=guest-file-open,guest-file-close,guest-file-read,guest-file-write,guest-file-seek,guest-file-flush,guest-exec,guest-exec-status -F/etc/qemu-ga/fsfreeze-hook
root 21360 1 28 16:31 ? 00:00:01 /usr/bin/qemu-system-x86_64 -name guest=vm1,debug-threads=on -S -object secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-7-vm1/master-key.aes -machine pc-i440fx-2.6,accel=kvm,usb=off -cpu Broadwell,+vme,+ss,+ht,+vmx,+osxsave,+f16c,+rdrand,+hypervisor,+arat,+tsc_adjust,+xsaveopt,+pdpe1gb,+abm -m 2048 -realtime mlock=off -smp 2,sockets=1,cores=2,threads=1 -uuid 36a5008d-2da8-4790-955b-57fc1f32c376 -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/domain-7-vm1/monitor.sock,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=localtime -no-shutdown -boot order=c,menu=on,strict=on -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x4 -drive file=/home/mydisk1/ubuntu-14.04-server.qcow2,format=qcow2,if=none,id=drive-ide0-0-0 -device ide-hd,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0 -netdev tap,fd=24,id=hostnet0 -device rtl8139,netdev=hostnet0,id=net0,mac=00:02:02:00:a0:04,bus=pci.0,addr=0x3 -chardev socket,id=charserial0,host=0.0.0.0,port=4003,telnet,server,nowait -device isa-serial,chardev=charserial0,id=serial0 -chardev socket,id=charchannel0,path=/var/lib/libvirt/qemu/test.agent,server,nowait -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=org.qemu.guest_agent.0 -vnc 0.0.0.0:0 -k en-us -device cirrus-vga,id=video0,bus=pci.0,addr=0x2 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5 -D /var/log/qemu/qemu.log -msg timestamp=on
root 21388 20174 0 16:32 pts/1 00:00:00 grep --color=auto qemu
通過virsh打開trace-event
#列出已經打開的trace-event
3.添加自定義trace-event
qemu目錄下每個子系統都有一個trace-events檔案，裡面申明了很多靜态的trace events
[[email protected] qemu-2.8.0]# ll */trace-events
-rw-r--r--. 1 user user 822 Dec 21 2016 audio/trace-events
-rw-r--r--. 1 user user 8024 Dec 21 2016 block/trace-events
-rw-r--r--. 1 user user 1655 Dec 21 2016 crypto/trace-events
-rw-r--r--. 1 user user 4083 Dec 21 2016 io/trace-events
-rw-r--r--. 1 user user 834 Dec 21 2016 linux-user/trace-events
-rw-r--r--. 1 user user 13764 Dec 21 2016 migration/trace-events
-rw-r--r--. 1 user user 1323 Dec 21 2016 net/trace-events
-rw-r--r--. 1 user user 2032 Dec 21 2016 qapi/trace-events
-rw-r--r--. 1 user user 333 Dec 21 2016 qom/trace-events
-rw-r--r--. 1 user user 693 Dec 21 2016 target-arm/trace-events
-rw-r--r--. 1 user user 352 Dec 21 2016 target-i386/trace-events
-rw-r--r--. 1 user user 252 Dec 21 2016 target-ppc/trace-events
-rw-r--r--. 1 user user 1133 Dec 21 2016 target-s390x/trace-events
-rw-r--r--. 1 user user 2079 Dec 21 2016 target-sparc/trace-events
-rw-r--r--. 1 user user 3004 Dec 21 2016 ui/trace-events
-rw-r--r--. 1 user user 1697 Dec 21 2016 util/trace-events
這裡用migration/trace-events做實驗
[[email protected] qemu-2.8.0]# cat migration/trace-events |grep migration_thread_
migration_thread_after_loop(void) ""
migration_thread_file_err(void) ""
migration_thread_setup_complete(void) ""
migration_thread_huangxun(void) ""
migration_thread_low_pending(uint64_t pending) "%" PRIu64
仿照migration_thread_setup_complete寫一個migration_thread_huangxun，
括号裡面是參數，“”是格式，可以參考qemu源碼主目錄下的trace-events檔案的講解，添加完成後，重新編譯qemu
檢視新生成的代碼
[[email protected] qemu-2.8.0]# grep -l -r 'huangxun'
qemu-img
trace/generated-tracers.o
trace/generated-tracers.h
trace/generated-tracers.h-timestamp
trace/generated-tracers.c
trace/generated-tracers.c-timestamp
qemu-io
migration/trace-events
i386-softmmu/qemu-system-i386
ivshmem-server
qemu-nbd
libqemuutil.a
trace-events-all
qemu-ga
x86_64-softmmu/qemu-system-x86_64
fsdev/virtfs-proxy-helper
#[[email protected] qemu-2.8.0]# cat trace/generated-tracers.h|less
static inline void trace_migration_thread_huangxun(void)
{
if (true) {
if (trace_event_get_state(TRACE_MIGRATION_THREAD_HUANGXUN)) {
struct timeval _now;
gettimeofday(&_now, NULL);
qemu_log_mask(LOG_TRACE, "%[email protected]%zd.%06zd:migration_thread_huangxun " "" "\n",
getpid(),
(size_t)_now.tv_sec, (size_t)_now.tv_usec
);
}
}
}
#[[email protected] qemu-2.8.0]# cat trace/generated-tracers.c|less
TraceEvent _TRACE_MIGRATION_THREAD_HUANGXUN_EVENT = {
.id = 0,
.vcpu_id = TRACE_VCPU_EVENT_NONE,
.name = "migration_thread_huangxun",
.sstate = TRACE_MIGRATION_THREAD_HUANGXUN_ENABLED,
.dstate = &_TRACE_MIGRATION_THREAD_HUANGXUN_DSTATE
};
[[email protected] qemu-2.8.0]# cat trace-events-all|less
migration_thread_after_loop(void) ""
migration_thread_file_err(void) ""
migration_thread_setup_complete(void) ""
migration_thread_huangxun(void) ""
使用新增加的event
圖3-1
進行熱遷移測試
源端啟動參數
/usr/bin/qemu-system-x86_64 -m 256 -cpu host -drive file=/home/mydisk1/ubuntu-14.04-server.qcow2 -smp 2 -enable-kvm -net nic,model=virtio,macaddr=00:00:00:00:00:01 -net tap,ifname=tap0,script=no,downscript=no -serial telnet:0.0.0.0:4000,server,nowait -nographic -vnc 0:0 -D /var/log/qemu/qemu.log
目的端啟動參數
/usr/bin/qemu-system-x86_64 -m 256 -cpu host -drive file=/home/mydisk1/ubuntu-14.04-server.qcow2 -smp 2 -enable-kvm -net nic,model=virtio,macaddr=00:00:00:00:00:01 -net tap,ifname=tap1,script=no,downscript=no -serial telnet:0.0.0.0:4001,server,nowait -nographic -incoming tcp:0:4444 -vnc 0:1 -D /var/log/qemu/qemu2.log
打開event開關，并進行遷移操作
(qemu) trace-event migration_thread_huangxun on
(qemu) migrate -d tcp:0:4444
檢視log，成功列印event資訊
[[email protected] ~]# cat /var/log/qemu/qemu.log
[email protected]:migration_thread_huangxun
Reference
[1]QEMU 與塊裝置
http://docs.ceph.org.cn/rbd/qemu-rbd/
[2]qemu monitor protocol簡介
https://blog.csdn.net/fulaidai/article/details/23714561
錯誤處理
暫無