Re: Lost of performance over AMD-V with KVM?

[Gleb Natapov <gleb@redhat.com>]

On Tue, Jul 09, 2013 at 05:30:26PM +0200, Victor fernandez wrote:
> Hi Gleb,
> 
>     root@vfalbor-desktop:~# uname -a
> *Linux vfalbor-desktop 2.6.32-24-generic *#43-Ubuntu SMP Thu Sep 16
> 14:58:24 UTC 2010 x86_64 GNU/Linux
> 
>     root@vfalbor-desktop:~# dpkg --list | grep qemu
>     ii  qemu-common *0.12.3+noroms-0ubuntu9.21 * qemu common
> functionality (bios, documentati
>     ri  qemu-kvm *0.12.3+noroms-0ubuntu9.21*
> Full virtualization on i386 and amd64 hardwa
> 
Ugh, those are ancient and vendor packages. I thought you were running
Scientific Linux 6 as a host too which also has vendor specific
packages, but at least something that I can easily look into :)
Can you reproduce with upstream kernel/qemu? If it works on upstream you
can open bug in Ubuntu.

>     One of the things that we did, we try to update libvirt to the
> last versions
>     because we are using for our cloud the version of ubuntu 10.04 and the
>     last stable version of libvirt was 0.7.5-5ubuntu27.23, but when
> we try to
>     get the capabilities, we get the following:
This is definitely not libvirt fault. This is either kernel or qemu.
Looking into git history 3dnow/3dnowext support was introduce into the
kernel kvm component before 2.6.32 though.

> 
>     root@vfalbor-desktop:~/# virsh capabilities | grep 3dnow
>       <feature name='*3dnowprefetch*'/>
>     root@vfalbor-desktop:~/#
> 
>     but in the cpu_map.xml file we find the 3dnow and 3dnowext for
> our architecture:
> 
>     root@vfalbor-desktop:~/# cat /usr/share/libvirt/cpu_map.xml |
> grep 3dnow
>             <feature name='*3dnowext*'> <!-- CPUID_EXT2_3DNOWEXT -->
>             <feature name='3dnow'> <!-- CPUID_EXT2_3DNOW -->
>             <feature name='3dnowprefetch'> <!--
> CPUID_EXT3_3DNOWPREFETCH -->
> 
>     Thanks Gleb,
>         Víctor Fdez.
> 
> El 09/07/13 17:16, Gleb Natapov escribió:
> >On Tue, Jul 09, 2013 at 05:07:57PM +0200, Victor fernandez wrote:
> >>Yep,
> >>
> >>     -> this is for the host:
> >>
> >>     root@vfalbor-desktop:~# cat /proc/cpuinfo | grep flags | uniq
> >>     flags        : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr
> >>pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx
> >>mmxext fxsr_opt pdpe1gb rdtscp lm 3dnowext 3dnow constant_tsc
> >>rep_good nonstop_tsc extd_apicid amd_dcm pni monitor cx16 popcnt
> >>lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse
> >>3dnowprefetch osvw ibs skinit wdt nodeid_msr
> >>
> >>     -> this is for the VM:
> >>     [root@sl6 ~]# cat /proc/cpuinfo | grep flags | uniq
> >>     flags        : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr
> >>pge mca cmov pat pse36 clflush mmx fxsr sse sse2 syscall nx mmxext
> >>fxsr_opt pdpe1gb lm rep_good extd_apicid pni cx16 popcnt lahf_lm
> >>cmp_legacy cr8_legacy abm sse4a misalignsse 3dnowprefetch
> >>
> >Hmm, what is your kernel and qemu versions?
> >
> >>El 09/07/13 17:00, Gleb Natapov escribió:
> >>>On Tue, Jul 09, 2013 at 04:57:13PM +0200, Victor fernandez wrote:
> >>>>     2.- with the "-cpu host" parameter:
> >>>>
> >>>>/usr/bin/kvm *-cpu host* -m 2048 -smp 1 -name i-2-11-VM -monitor
> >>>>telnet:127.0.0.1:9941,server,nowait -boot c /mnt/b07f7f29-7b9b-3d4b-b170-77876d10e7b1/134bc689-1207-487c-ae95-6c0dc2e0f285
> >>>>-parallel none -usb -usbdevice tablet -vnc :0 -vga cirrus -net
> >>>>nic,macaddr=06:00:90:00:00:08,vlan=0,model=e1000,name=e1000.0 -net
> >>>>tap,script=/usr/bin/qemu-ifup,vlan=0,name=tap.0
> >>>>
> >>>With this command line can you provide output of /proc/cpuinfo on the
> >>>host and the guest?
> >>>
> >>>--
> >>>			Gleb.
> >>>--
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> >--
> >			Gleb.
> 

--
			Gleb.