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Thu, 28 Mar 2024 10:50:34 +0000 (GMT) Received: from [9.200.52.3] (unknown [9.200.52.3]) by smtpav04.wdc07v.mail.ibm.com (Postfix) with ESMTP for ; Thu, 28 Mar 2024 10:50:33 +0000 (GMT) Content-Type: multipart/alternative; boundary="------------gyqqbd0zy5ZmXuKhgE2Qc3XJ" Message-ID: <3352e507-528e-4666-8d14-ff6522d06d76@linux.vnet.ibm.com> Date: Thu, 28 Mar 2024 18:50:32 +0800 User-Agent: Mozilla Thunderbird Subject: Re: qemu process consumes 100% host CPU after reverting snapshot From: Chun Feng Wu To: qemu-devel@nongnu.org References: Content-Language: en-US In-Reply-To: X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: rWrOPTGhdf1rcoTKXUbpPdqe2Yeopjvy X-Proofpoint-GUID: rWrOPTGhdf1rcoTKXUbpPdqe2Yeopjvy X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-03-28_10,2024-03-27_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 suspectscore=0 malwarescore=0 lowpriorityscore=0 phishscore=0 bulkscore=0 priorityscore=1501 adultscore=0 mlxscore=0 clxscore=1015 spamscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2403210000 definitions=main-2403280072 Received-SPF: none client-ip=148.163.156.1; envelope-from=wucf@linux.vnet.ibm.com; helo=mx0a-001b2d01.pphosted.com X-Spam_score_int: -19 X-Spam_score: -2.0 X-Spam_bar: -- X-Spam_report: (-2.0 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, HTML_MESSAGE=0.001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org This is a multi-part message in MIME format. --------------gyqqbd0zy5ZmXuKhgE2Qc3XJ Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit BTW, if I download qemu8.0(https://download.qemu.org/qemu-8.0.0.tar.xz), compile and install it in my ubuntu22.04, launch vm with the same command(just update --machine to be "pc"), the host cpu usage is not high, it seems to be a bug in QEMU6 Also, I have another question, for disk iotune or throttle group, after reverting snapshot, if I login vm, and run fio, I/O performance drops a lot in both QEMU6 and QEMU8, do anyone know the reason? Any explanation would be appreciated! On 2024/3/28 07:32, Chun Feng Wu wrote: > > Hi, > > I am testing throttle filter chain(multiple throttle-groups on disk) > with the following steps: > 1. start guest vm(chained throttle filters applied on disk per > https://github.com/qemu/qemu/blob/master/docs/throttle.txt) > 2. take snapshot > 3. revert snapshot > > after step3, I noticed qemu process in host consumes 100% cpu, and > after I login guest vm, vm cannot(or slowly) response my cmd (it works > well before reverting). > > /    PID     USER      PR  NI    VIRT    RES         SHR S  %CPU  > %MEM     TIME+ COMMAND >    65455 root      20   0 9659924 891328  20132 R 100.3 5.4    > 29:39.93 qemu-system-x86/ > > / > / > > Does anybody know why such issue happens?  is it a bug or I > misunderstand something? > > my cmd: > > /qemu-system-x86_64 \ >   -name ubuntu-20.04-vm,debug-threads=on \ >   -machine pc-i440fx-jammy,usb=off,dump-guest-core=off \ >   -accel kvm \ >   -cpu > Broadwell-IBRS,vme=on,ss=on,vmx=on,f16c=on,rdrand=on,hypervisor=on,arat=on,tsc-adjust=on,md-clear=on,stibp=on,ssbd=on,xsaveopt=on,pdpe1gb=on,abm=on,tsx-ctrl=off,hle=off,rtm=off > \ >   -m 8192 \ >   -overcommit mem-lock=off \ >   -smp 2,sockets=1,dies=1,cores=1,threads=2 \ >   -numa node,nodeid=0,cpus=0-1,memdev=ram \ >   -object memory-backend-ram,id=ram,size=8192M \ >   -uuid d2d68f5d-bff0-4167-bbc3-643e3566b8fb \ >   -display none \ >   -nodefaults \ >   -monitor stdio \ >   -rtc base=utc,driftfix=slew \ >   -no-shutdown \ >   -boot strict=on \ >   -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 \ >   -object > '{"qom-type":"throttle-group","id":"limit0","limits":{"bps-total":0,"bps-read":0,"bps-write":0,"iops-total":200,"iops-read":0,"iops-write":0,"bps-total-max":0,"bps-read-max":0,"bps-write-max":0,"iops-total-max":200,"iops-read-max":0,"iops-write-max":0,"iops-size":0,"bps-total-max-length":1,"bps-read-max-length":1,"bps-write-max-length":1,"iops-total-max-length":1,"iops-read-max-length":1,"iops-write-max-length":1}}' > \ >     -object > '{"qom-type":"throttle-group","id":"limit1","limits":{"bps-total":0,"bps-read":0,"bps-write":0,"iops-total":250,"iops-read":0,"iops-write":0,"bps-total-max":0,"bps-read-max":0,"bps-write-max":0,"iops-total-max":250,"iops-read-max":0,"iops-write-max":0,"iops-size":0,"bps-total-max-length":1,"bps-read-max-length":1,"bps-write-max-length":1,"iops-total-max-length":1,"iops-read-max-length":1,"iops-write-max-length":1}}' > \ >     -object > '{"qom-type":"throttle-group","id":"limit2","limits":{"bps-total":0,"bps-read":0,"bps-write":0,"iops-total":300,"iops-read":0,"iops-write":0,"bps-total-max":0,"bps-read-max":0,"bps-write-max":0,"iops-total-max":300,"iops-read-max":0,"iops-write-max":0,"iops-size":0,"bps-total-max-length":1,"bps-read-max-length":1,"bps-write-max-length":1,"iops-total-max-length":1,"iops-read-max-length":1,"iops-write-max-length":1}}' > \ >     -object > '{"qom-type":"throttle-group","id":"limit012","limits":{"bps-total":0,"bps-read":0,"bps-write":0,"iops-total":400,"iops-read":0,"iops-write":0,"bps-total-max":0,"bps-read-max":0,"bps-write-max":0,"iops-total-max":400,"iops-read-max":0,"iops-write-max":0,"iops-size":0,"bps-total-max-length":1,"bps-read-max-length":1,"bps-write-max-length":1,"iops-total-max-length":1,"iops-read-max-length":1,"iops-write-max-length":1}}' > \ >   -blockdev > '{"driver":"file","filename":"/virt/images/focal-server-cloudimg-amd64.img","node-name":"libvirt-4-storage","auto-read-only":true,"discard":"unmap"}' > \ >   -blockdev > '{"node-name":"libvirt-4-format","read-only":false,"driver":"qcow2","file":"libvirt-4-storage","backing":null}' > \ >   -device > virtio-blk-pci,bus=pci.0,addr=0x4,drive=libvirt-4-format,id=virtio-disk0,bootindex=1 > \ >   -blockdev > '{"driver":"file","filename":"/virt/disks/vm1_disk_1.qcow2","node-name":"libvirt-3-storage","auto-read-only":true,"discard":"unmap"}' > \ >   -blockdev > '{"node-name":"libvirt-3-format","read-only":false,"driver":"qcow2","file":"libvirt-3-storage","backing":null}' > \ >   -blockdev > '{"driver":"throttle","node-name":"libvirt-5-filter","throttle-group":"limit0","file":"libvirt-3-format"}' > \ >   -blockdev > '{"driver":"throttle","node-name":"libvirt-6-filter","throttle-group":"limit012","file":"libvirt-5-filter"}' > \ >   -device > virtio-blk-pci,bus=pci.0,addr=0x5,drive=libvirt-6-filter,id=virtio-disk1 \ >   -blockdev > '{"driver":"file","filename":"/virt/disks/vm1_disk_2.qcow2","node-name":"libvirt-2-storage","auto-read-only":true,"discard":"unmap"}' > \ >   -blockdev > '{"node-name":"libvirt-2-format","read-only":false,"driver":"qcow2","file":"libvirt-2-storage","backing":null}' > \ >   -blockdev > '{"driver":"throttle","node-name":"libvirt-3-filter","throttle-group":"limit1","file":"libvirt-2-format"}' > \ >   -blockdev > '{"driver":"throttle","node-name":"libvirt-4-filter","throttle-group":"limit012","file":"libvirt-3-filter"}' > \ >   -device > virtio-blk-pci,bus=pci.0,addr=0x6,drive=libvirt-4-filter,id=virtio-disk2 \ >   -blockdev > '{"driver":"file","filename":"/virt/disks/vm1_disk_3.qcow2","node-name":"libvirt-1-storage","auto-read-only":true,"discard":"unmap"}' > \ >   -blockdev > '{"node-name":"libvirt-1-format","read-only":false,"driver":"qcow2","file":"libvirt-1-storage","backing":null}' > \ >   -blockdev > '{"driver":"throttle","node-name":"libvirt-1-filter","throttle-group":"limit2","file":"libvirt-1-format"}' > \ >   -blockdev > '{"driver":"throttle","node-name":"libvirt-2-filter","throttle-group":"limit012","file":"libvirt-1-filter"}' > \ >   -device > virtio-blk-pci,bus=pci.0,addr=0x7,drive=libvirt-2-filter,id=virtio-disk3 \ >   -netdev user,id=user0,hostfwd=tcp::2222-:22 \ >   -device > virtio-net-pci,netdev=user0,id=net0,mac=52:54:00:12:34:56,bus=pci.0,addr=0x3 > \ >   -chardev pty,id=charserial0 \ >   -device isa-serial,chardev=charserial0,id=serial0,index=0 \ >   -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x2 \ >   -sandbox > on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \ >   -msg timestamp=on/ > > > snapshot and reverting: > > /(qemu) info status > VM status: running > (qemu) savevm snapshot1 > (qemu) loadvm snapshot1/ > > > my env: > /:~# qemu-system-x86_64 --version > QEMU emulator version 6.2.0 (Debian 1:6.2+dfsg-2ubuntu6.17) > Copyright (c) 2003-2021 Fabrice Bellard and the QEMU Project developers > > :~# lsb_release -a > No LSB modules are available. > Distributor ID:    Ubuntu > Description:    Ubuntu 22.04.4 LTS > Release:    22.04 > Codename:    jammy/ > > -- > Thanks and Regards, > > Wu -- Thanks and Regards, Wu --------------gyqqbd0zy5ZmXuKhgE2Qc3XJ Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit

BTW, if I download qemu8.0(https://download.qemu.org/qemu-8.0.0.tar.xz), compile and install it in my ubuntu22.04, launch vm with the same command(just update --machine to be "pc"), the host cpu usage is not high, it seems to be a bug in QEMU6

Also, I have another question, for disk iotune or throttle group, after reverting snapshot, if I login vm, and run fio, I/O performance drops a lot in both QEMU6 and QEMU8, do anyone know the reason? Any explanation would be appreciated!



On 2024/3/28 07:32, Chun Feng Wu wrote:

Hi,

I am testing throttle filter chain(multiple throttle-groups on disk) with the following steps:
1. start guest vm(chained throttle filters applied on disk per https://github.com/qemu/qemu/blob/master/docs/throttle.txt)
2. take snapshot
3. revert snapshot

after step3, I noticed qemu process in host consumes 100% cpu, and after I login guest vm, vm cannot(or slowly) response my cmd (it works well before reverting).

    PID     USER      PR  NI    VIRT    RES         SHR    S  %CPU  %MEM     TIME+ COMMAND
   65455 root      20   0 9659924 891328  20132 R 100.3   5.4    29:39.93 qemu-system-x86


Does anybody know why such issue happens?  is it a bug or I misunderstand something?

my cmd:

qemu-system-x86_64 \
  -name ubuntu-20.04-vm,debug-threads=on \
  -machine pc-i440fx-jammy,usb=off,dump-guest-core=off \
  -accel kvm \
  -cpu Broadwell-IBRS,vme=on,ss=on,vmx=on,f16c=on,rdrand=on,hypervisor=on,arat=on,tsc-adjust=on,md-clear=on,stibp=on,ssbd=on,xsaveopt=on,pdpe1gb=on,abm=on,tsx-ctrl=off,hle=off,rtm=off \
  -m 8192 \
  -overcommit mem-lock=off \
  -smp 2,sockets=1,dies=1,cores=1,threads=2 \
  -numa node,nodeid=0,cpus=0-1,memdev=ram \
  -object memory-backend-ram,id=ram,size=8192M \
  -uuid d2d68f5d-bff0-4167-bbc3-643e3566b8fb \
  -display none \
  -nodefaults \
  -monitor stdio \
  -rtc base=utc,driftfix=slew \
  -no-shutdown \
  -boot strict=on \
  -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 \
  -object '{"qom-type":"throttle-group","id":"limit0","limits":{"bps-total":0,"bps-read":0,"bps-write":0,"iops-total":200,"iops-read":0,"iops-write":0,"bps-total-max":0,"bps-read-max":0,"bps-write-max":0,"iops-total-max":200,"iops-read-max":0,"iops-write-max":0,"iops-size":0,"bps-total-max-length":1,"bps-read-max-length":1,"bps-write-max-length":1,"iops-total-max-length":1,"iops-read-max-length":1,"iops-write-max-length":1}}' \
    -object '{"qom-type":"throttle-group","id":"limit1","limits":{"bps-total":0,"bps-read":0,"bps-write":0,"iops-total":250,"iops-read":0,"iops-write":0,"bps-total-max":0,"bps-read-max":0,"bps-write-max":0,"iops-total-max":250,"iops-read-max":0,"iops-write-max":0,"iops-size":0,"bps-total-max-length":1,"bps-read-max-length":1,"bps-write-max-length":1,"iops-total-max-length":1,"iops-read-max-length":1,"iops-write-max-length":1}}' \
    -object '{"qom-type":"throttle-group","id":"limit2","limits":{"bps-total":0,"bps-read":0,"bps-write":0,"iops-total":300,"iops-read":0,"iops-write":0,"bps-total-max":0,"bps-read-max":0,"bps-write-max":0,"iops-total-max":300,"iops-read-max":0,"iops-write-max":0,"iops-size":0,"bps-total-max-length":1,"bps-read-max-length":1,"bps-write-max-length":1,"iops-total-max-length":1,"iops-read-max-length":1,"iops-write-max-length":1}}' \
    -object '{"qom-type":"throttle-group","id":"limit012","limits":{"bps-total":0,"bps-read":0,"bps-write":0,"iops-total":400,"iops-read":0,"iops-write":0,"bps-total-max":0,"bps-read-max":0,"bps-write-max":0,"iops-total-max":400,"iops-read-max":0,"iops-write-max":0,"iops-size":0,"bps-total-max-length":1,"bps-read-max-length":1,"bps-write-max-length":1,"iops-total-max-length":1,"iops-read-max-length":1,"iops-write-max-length":1}}' \
  -blockdev '{"driver":"file","filename":"/virt/images/focal-server-cloudimg-amd64.img","node-name":"libvirt-4-storage","auto-read-only":true,"discard":"unmap"}' \
  -blockdev '{"node-name":"libvirt-4-format","read-only":false,"driver":"qcow2","file":"libvirt-4-storage","backing":null}' \
  -device virtio-blk-pci,bus=pci.0,addr=0x4,drive=libvirt-4-format,id=virtio-disk0,bootindex=1 \
  -blockdev '{"driver":"file","filename":"/virt/disks/vm1_disk_1.qcow2","node-name":"libvirt-3-storage","auto-read-only":true,"discard":"unmap"}' \
  -blockdev '{"node-name":"libvirt-3-format","read-only":false,"driver":"qcow2","file":"libvirt-3-storage","backing":null}' \
  -blockdev '{"driver":"throttle","node-name":"libvirt-5-filter","throttle-group":"limit0","file":"libvirt-3-format"}' \
  -blockdev '{"driver":"throttle","node-name":"libvirt-6-filter","throttle-group":"limit012","file":"libvirt-5-filter"}' \
  -device virtio-blk-pci,bus=pci.0,addr=0x5,drive=libvirt-6-filter,id=virtio-disk1 \
  -blockdev '{"driver":"file","filename":"/virt/disks/vm1_disk_2.qcow2","node-name":"libvirt-2-storage","auto-read-only":true,"discard":"unmap"}' \
  -blockdev '{"node-name":"libvirt-2-format","read-only":false,"driver":"qcow2","file":"libvirt-2-storage","backing":null}' \
  -blockdev '{"driver":"throttle","node-name":"libvirt-3-filter","throttle-group":"limit1","file":"libvirt-2-format"}' \
  -blockdev '{"driver":"throttle","node-name":"libvirt-4-filter","throttle-group":"limit012","file":"libvirt-3-filter"}' \
  -device virtio-blk-pci,bus=pci.0,addr=0x6,drive=libvirt-4-filter,id=virtio-disk2 \
  -blockdev '{"driver":"file","filename":"/virt/disks/vm1_disk_3.qcow2","node-name":"libvirt-1-storage","auto-read-only":true,"discard":"unmap"}' \
  -blockdev '{"node-name":"libvirt-1-format","read-only":false,"driver":"qcow2","file":"libvirt-1-storage","backing":null}' \
  -blockdev '{"driver":"throttle","node-name":"libvirt-1-filter","throttle-group":"limit2","file":"libvirt-1-format"}' \
  -blockdev '{"driver":"throttle","node-name":"libvirt-2-filter","throttle-group":"limit012","file":"libvirt-1-filter"}' \
  -device virtio-blk-pci,bus=pci.0,addr=0x7,drive=libvirt-2-filter,id=virtio-disk3 \
  -netdev user,id=user0,hostfwd=tcp::2222-:22 \
  -device virtio-net-pci,netdev=user0,id=net0,mac=52:54:00:12:34:56,bus=pci.0,addr=0x3 \
  -chardev pty,id=charserial0 \
  -device isa-serial,chardev=charserial0,id=serial0,index=0 \
  -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x2 \
  -sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \
  -msg timestamp=on


snapshot and reverting:

(qemu) info status
VM status: running
(qemu) savevm snapshot1
(qemu) loadvm snapshot1


my env:
:~# qemu-system-x86_64 --version
QEMU emulator version 6.2.0 (Debian 1:6.2+dfsg-2ubuntu6.17)
Copyright (c) 2003-2021 Fabrice Bellard and the QEMU Project developers

:~# lsb_release -a
No LSB modules are available.
Distributor ID:    Ubuntu
Description:    Ubuntu 22.04.4 LTS
Release:    22.04
Codename:    jammy

-- 
Thanks and Regards,

Wu
-- 
Thanks and Regards,

Wu
--------------gyqqbd0zy5ZmXuKhgE2Qc3XJ--