[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [Bug 607204] Re: New qemu instances often cannot be started
From: |
Thomas Huth |
Subject: |
[Qemu-devel] [Bug 607204] Re: New qemu instances often cannot be started if host system is under load |
Date: |
Mon, 07 Nov 2016 18:30:34 -0000 |
Can you still reproduce this problem with the latest version of QEMU?
** Changed in: qemu
Status: New => Incomplete
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/607204
Title:
New qemu instances often cannot be started if host system is under
load
Status in QEMU:
Incomplete
Bug description:
I've got a problem where I cannot start any new VMs with qemu-kvm if
the host machine is under high CPU load. The problem is not 100%
reproducible (it works sometimes), but under load conditions, it
happens most of the time - roughly 95%.
I'm usually using libvirt to start and stop KVM VMs. When using virsh
to start a new VM under those conditions, the output looks like this:
virsh # start testserver-a
error: Failed to start domain testserver-a
error: monitor socket did not show up.: Connection refused
(There is a very long wait after the command has been sent until the
error message shows up.)
This is (an example of) the command line that libvirtd uses to start
up qemu:
----- snip -----
LC_ALL=C PATH=/sbin:/usr/sbin:/bin:/usr/bin HOME=/root USER=root LOGNAME=root
QEMU_AUDIO_DRV=none /usr/bin/qemu-kvm -S -M pc-0.12 -enable-kvm -m 256 -smp
1,sockets=1,cores=1,threads=1 -name testserver-a -uuid
7cbb3665-4d58-86b8-ce8f-20541995a99c -nodefaults -chardev
socket,id=monitor,path=/usr/local/var/lib/libvirt/qemu/testserver-a.monitor,server,nowait
-mon chardev=monitor,mode=readline -rtc base=utc -no-acpi -boot c -device
lsi,id=scsi0,bus=pci.0,addr=0x7 -drive
file=/data/testserver-a-system.img,if=none,id=drive-scsi0-0-1,boot=on -device
scsi-disk,bus=scsi0.0,scsi-id=1,drive=drive-scsi0-0-1,id=scsi0-0-1 -drive
file=/data/testserver-a-data1.img,if=none,id=drive-virtio-disk1 -device
virtio-blk-pci,bus=pci.0,addr=0x4,drive=drive-virtio-disk1,id=virtio-disk1
-drive file=/data/testserver-a-data2.img,if=none,id=drive-virtio-disk2 -device
virtio-blk-pci,bus=pci.0,addr=0x5,drive=drive-virtio-disk2,id=virtio-disk2
-drive
file=/data/gentoo-install-amd64-minimal-20100408.iso,if=none,media=cdrom,id=drive-ide0-0-0,readonly=on
-device ide-drive,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0 -drive
file=/data/testserver-a_configfloppy.img,if=none,id=drive-fdc0-0-0 -global
isa-fdc.driveA=drive-fdc0-0-0 -device
e1000,vlan=0,id=net0,mac=52:54:00:84:6d:69,bus=pci.0,addr=0x6 -net
tap,fd=24,vlan=0,name=hostnet0 -usb -vnc 127.0.0.1:1,password -k de -vga cirrus
-device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3
----- snip -----
Copy-pasting this to a commandline on the host to start qemu manually
leads to a non-functional qemu process that "just sits there" with
nothing happening. The monitor socket
/usr/local/var/lib/libvirt/qemu/testserver-a.monitor will, indeed, not
show up.
I've tried starting qemu with the same commandline but without the
parameters for redirecting the monitor to a socket, without the fd
parameter for the network interface and without the vnc parameter.
This resulted in a black window with the title "QEMU (testserver-a)
[Stopped]". I could not access the monitor console in graphical mode
either. When I press Ctrl-Alt-2 in graphical mode to access the
monitor console, qemu will sometimes (but not always) crash with a
segfault about 2 seconds after.
Some experimentation I've done suggests that this problem only happens
if the high cpu load is caused by another qemu process, not if it is
caused by something else running on the machine.
The bug appears much less often if I leave off the -nodefaults
parameter.
The bug will still appear if I start qemu as qemu-system-x86_64
instead of qemu-kvm and replace the -enable-kvm parameter with -no-
kvm.
The host machine I'm running this on has got 16 cores in total. It
looks like it is sufficient for this bug to surface if at least one of
these cores is brought to near 100% use by a qemu process.
The version of qemu I'm using is qemu-kvm 0.12.4, built from source.
Libvirt is version 0.8.1, built from source as well. The host OS is
Fedora 12. The Kernel version is 2.6.32.12-115.fc12.x86_64.
Attached is an strace of attempting to start qemu which I hope will
help someone with a better understanding of qemu's internals see
what's actually going on there.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/607204/+subscriptions
[Prev in Thread] |
Current Thread |
[Next in Thread] |
- [Qemu-devel] [Bug 607204] Re: New qemu instances often cannot be started if host system is under load,
Thomas Huth <=