11:10 a.m.
Hi,
I'm trying to set exact CPU topology to qemu-kvm domains to match
host's topology. In my case, host topology is: 1 socket, 2 cores and 2
threads. If I set the XML like this:
<domain type='kvm'>
..
<vcpu placement='static'>4</vcpu>
<os>
<type arch='i686' machine='pc-0.15'>hvm</type>
<boot dev='hd'/>
</os>
<cpu mode='host-model'>
<model fallback='allow'/>
<topology sockets='1' cores='2' threads='2'/>
</cpu>
..
The qemu commandline launched for this domain looks like this:
/usr/bin/qemu-kvm -name fedora17-2 -S -M pc-0.15 -cpu
core2duo,+lahf_lm,+rdtscp,+aes,+popcnt,+sse4.2,+sse4.1,+pdcm,+xtpr,+cx16,+tm2,+est,+smx,+vmx,+ds_cpl,+dtes64,+pclmuldq,+pbe,+tm,+ht,+ss,+acpi,+ds
-enable-kvm -m 1152 -smp 4,sockets=1,cores=2,threads=2 -uuid
c573342b-2876-05b8-098e-6d5314cab062 -nodefconfig -nodefaults -chardev
socket,id=charmonitor,path=/home/zeenix/.config/libvirt/qemu/lib/fedora17-2.monitor,server,nowait
-mon chardev=charmonitor,id=monitor,mode=control -rtc
base=utc,driftfix=slew -no-kvm-pit-reinjection -no-shutdown -no-acpi
-device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -device
virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x5 -drive
file=/home/zeenix/.local/share/gnome-boxes/images/fedora17-2,if=none,id=drive-virtio-disk0,format=qcow2,cache=none
-device
virtio-blk-pci,scsi=off,bus=pci.0,addr=0x6,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1
-drive
file=/extra-data/ISOs/Fedora-17-i686-Live-Desktop.iso,if=none,id=drive-ide0-1-0,readonly=on,format=raw
-device ide-cd,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0
-netdev user,id=hostnet0 -device
rtl8139,netdev=hostnet0,id=net0,mac=52:54:00:21:6f:6e,bus=pci.0,addr=0x3
-chardev pty,id=charserial0 -device
isa-serial,chardev=charserial0,id=serial0 -chardev
spicevmc,id=charchannel0,name=vdagent -device
virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=com.redhat.spice.0
-device usb-tablet,id=input0 -spice
port=5900,addr=127.0.0.1,disable-ticketing -vga qxl -global
qxl-vga.vram_size=67108864 -device AC97,id=sound0,bus=pci.0,addr=0x4
-device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x7
Despite the '-smp 4,sockets=1,cores=2,threads=2', I see only 1 CPU
reported by '/proc/cpuinfo' in the guest F17 live.
However, when I manually launch a very similar commandline,':
/usr/bin/qemu-kvm -name fedora17-2 -M pc-0.15 -cpu
core2duo,+lahf_lm,+rdtscp,+aes,+popcnt,+sse4.2,+sse4.1,+pdcm,+xtpr,+cx16,+tm2,+est,+smx,+vmx,+ds_cpl,+dtes64,+pclmuldq,+pbe,+tm,+ht,+ss,+acpi,+ds
-m 1G -smp 4,cores=2,threads=2,sockets=1 -uuid
c573342b-2876-05b8-098e-6d5314cab062 -nodefconfig -enable-kvm -cdrom
/home/zeenix/ISOs/Fedora-17-i686-Live-Desktop.iso
I see 4 CPUs reported by '/proc/cpuinfo in the guest. Any clues?
--
Regards,
Zeeshan Ali (Khattak)
FSF member#5124
5:36 p.m.
On Sat, Jul 7, 2012 at 11:10 AM, Zeeshan Ali (Khattak)
<zeeshanak(a)gnome.org> wrote:
Hi,
I'm trying to set exact CPU topology to qemu-kvm domains to match
host's topology. In my case, host topology is: 1 socket, 2 cores and 2
threads. If I set the XML like this:
<snip>
The qemu commandline launched for this domain looks like this:
/usr/bin/qemu-kvm -name fedora17-2 -S -M pc-0.15 -cpu
core2duo,+lahf_lm,+rdtscp,+aes,+popcnt,+sse4.2,+sse4.1,+pdcm,+xtpr,+cx16,+tm2,+est,+smx,+vmx,+ds_cpl,+dtes64,+pclmuldq,+pbe,+tm,+ht,+ss,+acpi,+ds
-enable-kvm -m 1152 -smp 4,sockets=1,cores=2,threads=2 -uuid
<snip>
Despite the '-smp 4,sockets=1,cores=2,threads=2', I see only 1 CPU
reported by '/proc/cpuinfo' in the guest F17 live.
However, when I manually launch a very similar commandline,':
/usr/bin/qemu-kvm -name fedora17-2 -M pc-0.15 -cpu
core2duo,+lahf_lm,+rdtscp,+aes,+popcnt,+sse4.2,+sse4.1,+pdcm,+xtpr,+cx16,+tm2,+est,+smx,+vmx,+ds_cpl,+dtes64,+pclmuldq,+pbe,+tm,+ht,+ss,+acpi,+ds
-m 1G -smp 4,cores=2,threads=2,sockets=1 -uuid
c573342b-2876-05b8-098e-6d5314cab062 -nodefconfig -enable-kvm -cdrom
/home/zeenix/ISOs/Fedora-17-i686-Live-Desktop.iso
I see 4 CPUs reported by '/proc/cpuinfo in the guest. Any clues?
What version of qemu-kvm are you using? Sounds like a bug in
qemu-kvm's command line arg parsing code.
--
Doug Goldstein
7:57 p.m.
On Sun, Jul 8, 2012 at 1:36 AM, Doug Goldstein <cardoe(a)gentoo.org> wrote:
On Sat, Jul 7, 2012 at 11:10 AM, Zeeshan Ali (Khattak)
<zeeshanak(a)gnome.org> wrote:
> Hi,
> I'm trying to set exact CPU topology to qemu-kvm domains to match
> host's topology. In my case, host topology is: 1 socket, 2 cores and 2
> threads. If I set the XML like this:
<snip>
> The qemu commandline launched for this domain looks like this:
>
> /usr/bin/qemu-kvm -name fedora17-2 -S -M pc-0.15 -cpu
>
core2duo,+lahf_lm,+rdtscp,+aes,+popcnt,+sse4.2,+sse4.1,+pdcm,+xtpr,+cx16,+tm2,+est,+smx,+vmx,+ds_cpl,+dtes64,+pclmuldq,+pbe,+tm,+ht,+ss,+acpi,+ds
> -enable-kvm -m 1152 -smp 4,sockets=1,cores=2,threads=2 -uuid
<snip>
>
> Despite the '-smp 4,sockets=1,cores=2,threads=2', I see only 1 CPU
> reported by '/proc/cpuinfo' in the guest F17 live.
>
> However, when I manually launch a very similar commandline,':
>
> /usr/bin/qemu-kvm -name fedora17-2 -M pc-0.15 -cpu
>
core2duo,+lahf_lm,+rdtscp,+aes,+popcnt,+sse4.2,+sse4.1,+pdcm,+xtpr,+cx16,+tm2,+est,+smx,+vmx,+ds_cpl,+dtes64,+pclmuldq,+pbe,+tm,+ht,+ss,+acpi,+ds
> -m 1G -smp 4,cores=2,threads=2,sockets=1 -uuid
> c573342b-2876-05b8-098e-6d5314cab062 -nodefconfig -enable-kvm -cdrom
> /home/zeenix/ISOs/Fedora-17-i686-Live-Desktop.iso
>
> I see 4 CPUs reported by '/proc/cpuinfo in the guest. Any clues?
What version of qemu-kvm are you using? Sounds like a bug in
qemu-kvm's command line arg parsing code.
I was able to reproduce this with both qemu from git master and
qemu-kvm from stock F17 packages (1.0).
--
Regards,
Zeeshan Ali (Khattak)
FSF member#5124
4:54 a.m.
On Sat, Jul 07, 2012 at 07:10:53PM +0300, Zeeshan Ali (Khattak) wrote:
Hi,
I'm trying to set exact CPU topology to qemu-kvm domains to match
host's topology. In my case, host topology is: 1 socket, 2 cores and 2
threads. If I set the XML like this:
<domain type='kvm'>
..
<vcpu placement='static'>4</vcpu>
<os>
<type arch='i686' machine='pc-0.15'>hvm</type>
<boot dev='hd'/>
</os>
<cpu mode='host-model'>
<model fallback='allow'/>
<topology sockets='1' cores='2' threads='2'/>
</cpu>
..
The qemu commandline launched for this domain looks like this:
/usr/bin/qemu-kvm -name fedora17-2 -S -M pc-0.15 -cpu
core2duo,+lahf_lm,+rdtscp,+aes,+popcnt,+sse4.2,+sse4.1,+pdcm,+xtpr,+cx16,+tm2,+est,+smx,+vmx,+ds_cpl,+dtes64,+pclmuldq,+pbe,+tm,+ht,+ss,+acpi,+ds
-enable-kvm -m 1152 -smp 4,sockets=1,cores=2,threads=2 -uuid
c573342b-2876-05b8-098e-6d5314cab062 -nodefconfig -nodefaults -chardev
socket,id=charmonitor,path=/home/zeenix/.config/libvirt/qemu/lib/fedora17-2.monitor,server,nowait
-mon chardev=charmonitor,id=monitor,mode=control -rtc
base=utc,driftfix=slew -no-kvm-pit-reinjection -no-shutdown -no-acpi
I debugged this together with Zeeshan, and the issue comes from this -no-acpi flag
which libvirt added because the domain XML was missing
<features><acpi/></features>
So in the end that was a bug in Boxes, not really a libvirt/qemu issue.
Unless libvirt/qemu should be taught that CPU topology won't work without ACPI
and complain about it?
Christophe
2:02 p.m.
On Tue, Jul 10, 2012 at 11:54:05AM +0200, Christophe Fergeau wrote:
On Sat, Jul 07, 2012 at 07:10:53PM +0300, Zeeshan Ali (Khattak)
wrote:
> Hi,
> I'm trying to set exact CPU topology to qemu-kvm domains to match
> host's topology. In my case, host topology is: 1 socket, 2 cores and 2
> threads. If I set the XML like this:
>
> <domain type='kvm'>
> ..
> <vcpu placement='static'>4</vcpu>
> <os>
> <type arch='i686' machine='pc-0.15'>hvm</type>
> <boot dev='hd'/>
> </os>
> <cpu mode='host-model'>
> <model fallback='allow'/>
> <topology sockets='1' cores='2' threads='2'/>
> </cpu>
> ..
>
> The qemu commandline launched for this domain looks like this:
>
> /usr/bin/qemu-kvm -name fedora17-2 -S -M pc-0.15 -cpu
>
core2duo,+lahf_lm,+rdtscp,+aes,+popcnt,+sse4.2,+sse4.1,+pdcm,+xtpr,+cx16,+tm2,+est,+smx,+vmx,+ds_cpl,+dtes64,+pclmuldq,+pbe,+tm,+ht,+ss,+acpi,+ds
> -enable-kvm -m 1152 -smp 4,sockets=1,cores=2,threads=2 -uuid
> c573342b-2876-05b8-098e-6d5314cab062 -nodefconfig -nodefaults -chardev
>
socket,id=charmonitor,path=/home/zeenix/.config/libvirt/qemu/lib/fedora17-2.monitor,server,nowait
> -mon chardev=charmonitor,id=monitor,mode=control -rtc
> base=utc,driftfix=slew -no-kvm-pit-reinjection -no-shutdown -no-acpi
I debugged this together with Zeeshan, and the issue comes from this -no-acpi flag
which libvirt added because the domain XML was missing
<features><acpi/></features>
So in the end that was a bug in Boxes, not really a libvirt/qemu issue.
Unless libvirt/qemu should be taught that CPU topology won't work without ACPI
and complain about it?
I don't think it's really impossible for any guest OS to recognize the
CPU topology or boot the other CPUs without ACPI. It looks like it's
just a limitation of (most?) guest OSes. If that's the case, libvirt or
QEMU can't prevent the user from running a (possibly valid)
configuration just because it's not very common.
--
Eduardo
9:19 p.m.
New subject: [libvirt] [Qemu-devel] Problem setting CPU topology
On Tue, Jul 10, 2012 at 2:02 PM, Eduardo Habkost <ehabkost(a)redhat.com> wrote:
On Tue, Jul 10, 2012 at 11:54:05AM +0200, Christophe Fergeau wrote:
> On Sat, Jul 07, 2012 at 07:10:53PM +0300, Zeeshan Ali (Khattak) wrote:
> > Hi,
> > I'm trying to set exact CPU topology to qemu-kvm domains to match
> > host's topology. In my case, host topology is: 1 socket, 2 cores and 2
> > threads. If I set the XML like this:
> >
> > <domain type='kvm'>
> > ..
> > <vcpu placement='static'>4</vcpu>
> > <os>
> > <type arch='i686' machine='pc-0.15'>hvm</type>
> > <boot dev='hd'/>
> > </os>
> > <cpu mode='host-model'>
> > <model fallback='allow'/>
> > <topology sockets='1' cores='2' threads='2'/>
> > </cpu>
> > ..
> >
> > The qemu commandline launched for this domain looks like this:
> >
> > /usr/bin/qemu-kvm -name fedora17-2 -S -M pc-0.15 -cpu
> >
core2duo,+lahf_lm,+rdtscp,+aes,+popcnt,+sse4.2,+sse4.1,+pdcm,+xtpr,+cx16,+tm2,+est,+smx,+vmx,+ds_cpl,+dtes64,+pclmuldq,+pbe,+tm,+ht,+ss,+acpi,+ds
> > -enable-kvm -m 1152 -smp 4,sockets=1,cores=2,threads=2 -uuid
> > c573342b-2876-05b8-098e-6d5314cab062 -nodefconfig -nodefaults -chardev
> >
socket,id=charmonitor,path=/home/zeenix/.config/libvirt/qemu/lib/fedora17-2.monitor,server,nowait
> > -mon chardev=charmonitor,id=monitor,mode=control -rtc
> > base=utc,driftfix=slew -no-kvm-pit-reinjection -no-shutdown -no-acpi
>
> I debugged this together with Zeeshan, and the issue comes from this -no-acpi flag
> which libvirt added because the domain XML was missing
> <features><acpi/></features>
> So in the end that was a bug in Boxes, not really a libvirt/qemu issue.
> Unless libvirt/qemu should be taught that CPU topology won't work without ACPI
> and complain about it?
I don't think it's really impossible for any guest OS to recognize the
CPU topology or boot the other CPUs without ACPI. It looks like it's
just a limitation of (most?) guest OSes. If that's the case, libvirt or
QEMU can't prevent the user from running a (possibly valid)
configuration just because it's not very common.
--
Eduardo
Isn't MPS and APIC support required for a guest OS to really handle
the topology correctly? Now days ACPI provides most of that
information so its likely that QEMU doesn't support plain old MPS +
APIC. Its also possible that QEMU does support this but the kernel got
confused because I see the CPUID +acpi specified in the command line
while -no-acpi is on the command line as you noted.
--
Doug Goldstein
6:58 a.m.
New subject: [libvirt] [Qemu-devel] Problem setting CPU topology
On Tue, Jul 10, 2012 at 09:19:37PM -0500, Doug Goldstein wrote:
On Tue, Jul 10, 2012 at 2:02 PM, Eduardo Habkost
<ehabkost(a)redhat.com> wrote:
> On Tue, Jul 10, 2012 at 11:54:05AM +0200, Christophe Fergeau wrote:
>> On Sat, Jul 07, 2012 at 07:10:53PM +0300, Zeeshan Ali (Khattak) wrote:
>> > Hi,
>> > I'm trying to set exact CPU topology to qemu-kvm domains to match
>> > host's topology. In my case, host topology is: 1 socket, 2 cores and 2
>> > threads. If I set the XML like this:
>> >
>> > <domain type='kvm'>
>> > ..
>> > <vcpu placement='static'>4</vcpu>
>> > <os>
>> > <type arch='i686'
machine='pc-0.15'>hvm</type>
>> > <boot dev='hd'/>
>> > </os>
>> > <cpu mode='host-model'>
>> > <model fallback='allow'/>
>> > <topology sockets='1' cores='2'
threads='2'/>
>> > </cpu>
>> > ..
>> >
>> > The qemu commandline launched for this domain looks like this:
>> >
>> > /usr/bin/qemu-kvm -name fedora17-2 -S -M pc-0.15 -cpu
>> >
core2duo,+lahf_lm,+rdtscp,+aes,+popcnt,+sse4.2,+sse4.1,+pdcm,+xtpr,+cx16,+tm2,+est,+smx,+vmx,+ds_cpl,+dtes64,+pclmuldq,+pbe,+tm,+ht,+ss,+acpi,+ds
>> > -enable-kvm -m 1152 -smp 4,sockets=1,cores=2,threads=2 -uuid
>> > c573342b-2876-05b8-098e-6d5314cab062 -nodefconfig -nodefaults -chardev
>> >
socket,id=charmonitor,path=/home/zeenix/.config/libvirt/qemu/lib/fedora17-2.monitor,server,nowait
>> > -mon chardev=charmonitor,id=monitor,mode=control -rtc
>> > base=utc,driftfix=slew -no-kvm-pit-reinjection -no-shutdown -no-acpi
>>
>> I debugged this together with Zeeshan, and the issue comes from this -no-acpi
flag
>> which libvirt added because the domain XML was missing
>> <features><acpi/></features>
>> So in the end that was a bug in Boxes, not really a libvirt/qemu issue.
>> Unless libvirt/qemu should be taught that CPU topology won't work without
ACPI
>> and complain about it?
>
> I don't think it's really impossible for any guest OS to recognize the
> CPU topology or boot the other CPUs without ACPI. It looks like it's
> just a limitation of (most?) guest OSes. If that's the case, libvirt or
> QEMU can't prevent the user from running a (possibly valid)
> configuration just because it's not very common.
>
> --
> Eduardo
>
Isn't MPS and APIC support required for a guest OS to really handle
the topology correctly? Now days ACPI provides most of that
information so its likely that QEMU doesn't support plain old MPS +
APIC. Its also possible that QEMU does support this but the kernel got
confused because I see the CPUID +acpi specified in the command line
while -no-acpi is on the command line as you noted.
QEMU + Seabios have plain old MPS working, and from my tests it looks
like:
- Seabios is able to init all VCPUs correctly.
- The MP-table contains only 1 entry for each CPU package (not for each
core+thread). I don't understand why exactly, but I am assuming that
this is a feature, not a bug (there's some discussion about it at
[1]).
- The CPUID information exposed by QEMU reflect the topology correctly.
With that information, nothing really prevents the guest from trying to
init the other cores/threads in each package after parsing the MP-table.
On the other hand, I don't think there's any spec that recommends an
algorithm for that (as the MPS spec is too old to have any mention of
multi-core or hyper-threading).
[1] http://www.coreboot.org/pipermail/coreboot/2009-November/054119.html
--
Eduardo
4517
days inactive
4521
days old
6 comments
4 participants
participants (4)
-
Christophe Fergeau -
Doug Goldstein -
Eduardo Habkost -
Zeeshan Ali (Khattak)