Qemu Trace系统使用
文章目录
- 1.重新编译qemu
- 2.log方式
-
- 2.1.默认效果
- 2.2.分析代码
- 2.3.查看到日志文件中打印
- 2.4.对接libvirt
- 3.添加自定义trace-event
- Reference
1.重新编译qemu
[root@localhost qemu-2.8.0]# ./configure --target-list=x86_64-softmmu,i386-softmmu --enable-kvm --prefix=/usr --enable-debug --enable-numa --enable-trace-backends=log
编译参数–enable-trace-backends可以指定trace系统使用的后端系统（backend），如果指定为log，这样trace函数如下
图1-1
如果后端为simple（默认值），则trace函数为
图1-2
图1-3
各种不同的trace方式的详细解释可以参考qemu文档qemu-2.8.0\docs\tracing.txt
2.log方式
2.1.默认效果
打开某个event的开关，然后进行操作，默认可以打印在qemu monitor上
(qemu) trace-event migration_thread_setup_complete on
(qemu) migrate -d tcp:0:4444
(qemu)
(qemu)
(qemu)
(qemu) 39288@1545806882.716352:migration_thread_setup_complete
2.2.分析代码
qemu_logfile
$1 = 0x7fddf6411450 "%d@%zd.%06zd:migration_thread_setup_complete \n"
(gdb) p qemu_logfile
$2 = (FILE *) 0x7fddeff521c0 <_IO_2_1_stderr_>
可以看到默认打印在标准输出stderr上
qemu_logfile = fopen(logfilename, log_append ? “a” : “w”);
图2-1 设置logfile
这里没有设置logfilename，因此qemu_logfile = stderr，所以
#全局搜索logfilename，得到，但是打断点之后发现并没有走这里，因此继续跟踪该函数调用情况。
图2-2
全局搜索qemu_set_log_filename
图2-3
trace_init_file函数会被调用，并且file为空，因此qemu_set_log_filename才没有执行，继续跟踪调用栈
vl.c:4129 trace_init_file(trace_file);
图2-4
然后发现不是这里，这里是backend为其他选项的时候的处理，log应该是另外一个地方也调用了qemu_set_log_filename，是下面vl.c:4134处
if (log_file) {
qemu_set_log_filename(log_file, &error_fatal);
}
图2-5
搜索QEMU_OPTION_D
DEF("D", HAS_ARG, QEMU_OPTION_D, \
"-D logfile output log to logfile (default stderr)\n",
使用方式应该是-D /var/log/qemu/qemu.log
2.3.查看到日志文件中打印
[root@localhost ~]# cat /var/log/qemu/qemu.log
[email protected]:migration_thread_setup_complete
2.4.对接libvirt
xml中使用qemu:commandline配置log文件路径
[root@localhost 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>
[root@localhost 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
解决方法：关闭selinux
查看进程
[root@localhost 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
通过virsh打开trace-event
[root@localhost ~]# virsh qemu-monitor-command vm1 --hmp "trace-event migration_thread_setup_complete on"
#列出已经打开的trace-event
[root@localhost ~]# virsh qemu-monitor-command vm1 --hmp "info trace-events"
3.添加自定义trace-event
qemu目录下每个子系统都有一个trace-events文件，里面申明了很多静态的trace events
[root@localhost 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
这里用migration/trace-events做实验
[root@localhost 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写一个migration_thread_huangxun，
括号里面是参数，“”是格式，可以参考qemu源码主目录下的trace-events文件的讲解，添加完成后，重新编译qemu
查看新生成的代码
[root@localhost 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
#[root@localhost 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, "%d@%zd.%06zd:migration_thread_huangxun " "" "\n",
getpid(),
(size_t)_now.tv_sec, (size_t)_now.tv_usec
);
}
}
}
#[root@localhost 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
};
[root@localhost 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
[root@localhost qemu-2.8.0]# vim migration/migration.c
图3-1
进行热迁移测试
源端启动参数
/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
目的端启动参数
/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
打开event开关，并进行迁移操作
(qemu) trace-event migration_thread_huangxun on
(qemu) migrate -d tcp:0:4444
查看log，成功打印event信息
[root@localhost ~]# cat /var/log/qemu/qemu.log
13096@1546839795.152836:migration_thread_huangxun
Reference
[1]QEMU 与块设备
http://docs.ceph.org.cn/rbd/qemu-rbd/
[2]qemu monitor protocol简介
https://blog.csdn.net/fulaidai/article/details/23714561
错误处理
暂无