So if I remove '-mem-prealloc' option, the qemu will not mmap while starting guest vm? Or will mmap after some thing? Or will mmap when admin to trigger it by qemu command?
2017-10-25 18:44 GMT+08:00 Dr. David Alan Gilbert <dgilb...@redhat.com>: > * Sam (batmanu...@gmail.com) wrote: > > Hi all, > > > > I'm using qemu to start vm in huge page enviroment, I use CMD1 and CMD2 > to > > test the time of start of a vm, CMD1 contains option '-mem-prealloc', > CMD2 > > does not contain this. > > > > I found while using CMD1, the time to run this command is longer then > CMD2. > > For words, I know this option is to wait memory ready, but for code, I > > don't know where is the different with CMD1 and CMD2. > > > > As I print log of CMD1 and CMD2, I found for CMD1, there are about 10 > > second to print first log. I don't know for '-mem-prealloc' option, what > > qemu wait for? thank you~ > > It's waiting for the kernel to allocate that 40GB of RAM that you asked > for, and as huge pages. > > If you strace it you'll probably see it sitting in an madvise or mmap > for all the extra time. > > Dave > > > > > detail of test: > > > > CMD1="$QEMU_CMD -D qemu.log -trace events=qemu-events-all -enable-kvm > -cpu > > qemu64,+vmx,+ssse3,+sse4.1,+sse4.2,+x2apic,+aes,+avx,+vme, > +pat,+ss,+pclmulqdq,+xsave,level=13 > > -machine pc,accel=kvm -chardev > > socket,id=hmqmondev,port=55908,host=127.0.0.1,nodelay,server,nowait -mon > > chardev=hmqmondev,id=hmqmon,mode=readline -rtc > > base=utc,clock=host,driftfix=none -usb -device usb-tablet -daemonize > > -nodefaults -nodefconfig -no-kvm-pit-reinjection -global > > kvm-pit.lost_tick_policy=discard -vga std -k en-us -smp 8 -name > > gangyewei-qemutime-1 -m 40960 -boot order=cdn -vnc :8,password -drive > > file=$DISK_0,if=none,id=drive_0,format=qcow2,cache=none,aio=native > -device > > virtio-blk-pci,id=dev_drive_0,drive=drive_0,bus=pci.0,addr=0x5 -drive > > file=$DISK_1,if=none,id=drive_1,format=qcow2,cache=none,aio=native > -device > > virtio-blk-pci,id=dev_drive_1,drive=drive_1,bus=pci.0,addr=0x6 -drive > > file=$DISK_2,if=none,id=drive_2,format=qcow2,cache=none,aio=native > -device > > virtio-blk-pci,id=dev_drive_2,drive=drive_2,bus=pci.0,addr=0x7 -device > > ide-cd,drive=ide0-cd0,bus=ide.1,unit=1 -drive > > id=ide0-cd0,media=cdrom,if=none -chardev > > socket,id=char-n-52b49b80,path=/usr/local/var/run/ > openvswitch/n-52b49b80,server > > -netdev type=vhost-user,id=n-52b49b80,chardev=char-n-52b49b80, > vhostforce=on > > -device > > virtio-net-pci,netdev=n-52b49b80,mac=00:22:52:b4:9b: > 80,id=netdev-n-52b49b80,addr=0xf$(nic_speed > > 10000) -object > > memory-backend-file,id=mem,size=40960M,mem-path=/mnt/huge,share=on -numa > > node,memdev=mem -pidfile $PID_FILE -chardev > > socket,path=/opt/cloud/workspace/servers/4511f52a- > f450-40d3-9417-a1e0a27ed507/qga.sock,server,nowait,id=qga0 > > -device virtio-serial -device > > virtserialport,chardev=qga0,name=org.qemu.guest_agent.0" > > > > CMD2="$QEMU_CMD -D qemu.log -trace events=qemu-events-all -enable-kvm > -cpu > > qemu64,+vmx,+ssse3,+sse4.1,+sse4.2,+x2apic,+aes,+avx,+vme, > +pat,+ss,+pclmulqdq,+xsave,level=13 > > -machine pc,accel=kvm -chardev > > socket,id=hmqmondev,port=55908,host=127.0.0.1,nodelay,server,nowait -mon > > chardev=hmqmondev,id=hmqmon,mode=readline -rtc > > base=utc,clock=host,driftfix=none -usb -device usb-tablet -daemonize > > -nodefaults -nodefconfig -no-kvm-pit-reinjection -global > > kvm-pit.lost_tick_policy=discard -vga std -k en-us -smp 8 -name > > gangyewei-qemutime-1 -m 40960 -boot order=cdn -vnc :8,password -drive > > file=$DISK_0,if=none,id=drive_0,format=qcow2,cache=none,aio=native > -device > > virtio-blk-pci,id=dev_drive_0,drive=drive_0,bus=pci.0,addr=0x5 -drive > > file=$DISK_1,if=none,id=drive_1,format=qcow2,cache=none,aio=native > -device > > virtio-blk-pci,id=dev_drive_1,drive=drive_1,bus=pci.0,addr=0x6 -drive > > file=$DISK_2,if=none,id=drive_2,format=qcow2,cache=none,aio=native > -device > > virtio-blk-pci,id=dev_drive_2,drive=drive_2,bus=pci.0,addr=0x7 -device > > ide-cd,drive=ide0-cd0,bus=ide.1,unit=1 -drive > > id=ide0-cd0,media=cdrom,if=none -chardev > > socket,id=char-n-52b49b80,path=/usr/local/var/run/ > openvswitch/n-52b49b80,server > > -netdev type=vhost-user,id=n-52b49b80,chardev=char-n-52b49b80, > vhostforce=on > > -device > > virtio-net-pci,netdev=n-52b49b80,mac=00:22:52:b4:9b: > 80,id=netdev-n-52b49b80,addr=0xf$(nic_speed > > 10000) -object > > memory-backend-file,id=mem,size=40960M,mem-path=/mnt/huge,share=on -numa > > node,memdev=mem -mem-prealloc -pidfile $PID_FILE -chardev > > socket,path=/opt/cloud/workspace/servers/4511f52a- > f450-40d3-9417-a1e0a27ed507/qga.sock,server,nowait,id=qga0 > > -device virtio-serial -device > > virtserialport,chardev=qga0,name=org.qemu.guest_agent.0" > > > > > > time to run CMD1: > > [root@yf-mos-test-net14 4511f52a-f450-40d3-9417-a1e0a27ed507]# sh > startvm > > ls: cannot access > > /opt/cloud/workspace/servers/4511f52a-f450-40d3-9417- > a1e0a27ed507/STATEFILE*: > > No such file or directory > > Wed Oct 25 16:52:51 CST 2017 (unix time is 1508921571) > > qemu-system-x86_64_2.6.0:qemu-events-all:1045: WARNING: trace event > > 'qxl_interface_set_mm_time' is not traceable > > qemu-system-x86_64_2.6.0:qemu-events-all:1046: WARNING: trace event > > 'qxl_io_write_vga' is not traceable > > qemu-system-x86_64_2.6.0:qemu-events-all:1318: WARNING: trace event > > 'exec_tb' is not traceable > > qemu-system-x86_64_2.6.0:qemu-events-all:1319: WARNING: trace event > > 'exec_tb_nocache' is not traceable > > qemu-system-x86_64_2.6.0:qemu-events-all:1320: WARNING: trace event > > 'exec_tb_exit' is not traceable > > qemu-system-x86_64_2.6.0: -no-kvm-pit-reinjection: warning: deprecated, > > replaced by -global kvm-pit.lost_tick_policy=discard > > Wed Oct 25 16:53:02 CST 2017 (unix time is 1508921582) > > qemu started > > > > first log of CMD1: > > 45704@1508921581.767831:qio_channel_socket_new Socket new > ioc=0x55555640efd0 > > I don't know why first log happends in 1508921581, not the start up time, > > which is 1508921571. > > > > > > time to run CMD2: > > [root@yf-mos-test-net14 4511f52a-f450-40d3-9417-a1e0a27ed507]# sh > startvm > > ls: cannot access > > /opt/cloud/workspace/servers/4511f52a-f450-40d3-9417- > a1e0a27ed507/STATEFILE*: > > No such file or directory > > Wed Oct 25 18:15:35 CST 2017 > > qemu-system-x86_64_2.6.0:qemu-events-all:1045: WARNING: trace event > > 'qxl_interface_set_mm_time' is not traceable > > qemu-system-x86_64_2.6.0:qemu-events-all:1046: WARNING: trace event > > 'qxl_io_write_vga' is not traceable > > qemu-system-x86_64_2.6.0:qemu-events-all:1318: WARNING: trace event > > 'exec_tb' is not traceable > > qemu-system-x86_64_2.6.0:qemu-events-all:1319: WARNING: trace event > > 'exec_tb_nocache' is not traceable > > qemu-system-x86_64_2.6.0:qemu-events-all:1320: WARNING: trace event > > 'exec_tb_exit' is not traceable > > qemu-system-x86_64_2.6.0: -no-kvm-pit-reinjection: warning: deprecated, > > replaced by -global kvm-pit.lost_tick_policy=discard > > Wed Oct 25 18:15:36 CST 2017 > > qemu started > > > > first log of CMD1: > > 45167@1508926535.502360:qio_channel_socket_new Socket new > ioc=0x55555640efd0 > -- > Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK >
