virtual machines network goes 100Mbit when interface is Gbit

virtual machines network goes 100Mbit when interface is Gbit

[Miguel Araujo]

Hello all,

I'm testing the last kvm version, 62. I was doing an iperf benchmark to 
test the network performance in a Feisty virtual machine and I got 
values surround 100Mbits when my card is actually 1Gbit.  The testing 
environment is conformed by 2 machines, both with Gbit interfaces. The 
vm in kvm is running in server mode, the other (not virtualized one) is 
the client. The vm interface is going to a bridge called br0. Ethtool 
says the interface is running 100Mbits but it doesn't let me change the 
speed or any other parameter in the vm.

I can't either change tap0 parameters in kvm host. ¿Is anyone having the 
same issue?¿am I forgetting something?

Thanks for your time in advanced,
     Miguel

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Re: virtual machines network goes 100Mbit when interface is Gbit

[Haydn Solomon]

What emulated nic are you using? I think only the e1000 emulated nic 
supports 1 GB.

Miguel Araujo wrote:
> Hello all,
>
> I'm testing the last kvm version, 62. I was doing an iperf benchmark to 
> test the network performance in a Feisty virtual machine and I got 
> values surround 100Mbits when my card is actually 1Gbit.  The testing 
> environment is conformed by 2 machines, both with Gbit interfaces. The 
> vm in kvm is running in server mode, the other (not virtualized one) is 
> the client. The vm interface is going to a bridge called br0. Ethtool 
> says the interface is running 100Mbits but it doesn't let me change the 
> speed or any other parameter in the vm.
>
> I can't either change tap0 parameters in kvm host. ¿Is anyone having the 
> same issue?¿am I forgetting something?
>
> Thanks for your time in advanced,
>      Miguel
>
> -------------------------------------------------------------------------
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Re: virtual machines network goes 100Mbit when interface is Gbit

[Victor Abeytua Garcia]

Hello,
    I'm not sure if I understand you. Do you mean that the physical
network cards should be e1000 or that the virtual machines must somehow
emulate e1000 network cards?

    As I understand Miguel's post, he is finding an issue with the
bridge's speed (two virtual machines running on the same physical
machine are limited to 100 Mbps between themselves).

    Best regards,
    Víctor


Haydn Solomon escribió:
> What emulated nic are you using? I think only the e1000 emulated nic 
> supports 1 GB.
>
> Miguel Araujo wrote:
>   
>> Hello all,
>>
>> I'm testing the last kvm version, 62. I was doing an iperf benchmark to 
>> test the network performance in a Feisty virtual machine and I got 
>> values surround 100Mbits when my card is actually 1Gbit.  The testing 
>> environment is conformed by 2 machines, both with Gbit interfaces. The 
>> vm in kvm is running in server mode, the other (not virtualized one) is 
>> the client. The vm interface is going to a bridge called br0. Ethtool 
>> says the interface is running 100Mbits but it doesn't let me change the 
>> speed or any other parameter in the vm.
>>
>> I can't either change tap0 parameters in kvm host. ¿Is anyone having the 
>> same issue?¿am I forgetting something?
>>
>> Thanks for your time in advanced,
>>      Miguel
>>
>> -------------------------------------------------------------------------
>> This SF.net email is sponsored by: Microsoft
>> Defy all challenges. Microsoft(R) Visual Studio 2008.
>> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
>> _______________________________________________
>> kvm-devel mailing list
>> kvm-devel@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/kvm-devel
>>   
>>     
>
>
>
> -------------------------------------------------------------------------
> This SF.net email is sponsored by: Microsoft
> Defy all challenges. Microsoft(R) Visual Studio 2008.
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> kvm-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/kvm-devel
>   


-- 
Víctor Abeytua García

-----------
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Nosys AJjV S.L.
Networked Open SYStems
Tecnologías de la Información - Seguridad

C/ Isla Graciosa 2, Loft 18
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Re: virtual machines network goes 100Mbit when interface is Gbit

[Miguel Araujo]

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Hello all,

Thanks for your answer Haydn, but I did not understand the issue too. 
Victor has explained my problem clearly, is kvm uncapable of running the 
bridge at 1GBit if it is not a e1000 network card?

Thanks a lot in advanced,
Miguel
> Hello,
>     I'm not sure if I understand you. Do you mean that the physical
> network cards should be e1000 or that the virtual machines must somehow
> emulate e1000 network cards?
>
>     As I understand Miguel's post, he is finding an issue with the
> bridge's speed (two virtual machines running on the same physical
> machine are limited to 100 Mbps between themselves).
>
>     Best regards,
>     Víctor
>
>
> Haydn Solomon escribió:
>   
>> What emulated nic are you using? I think only the e1000 emulated nic 
>> supports 1 GB.
>>
>> Miguel Araujo wrote:
>>   
>>     
>>> Hello all,
>>>
>>> I'm testing the last kvm version, 62. I was doing an iperf benchmark to 
>>> test the network performance in a Feisty virtual machine and I got 
>>> values surround 100Mbits when my card is actually 1Gbit.  The testing 
>>> environment is conformed by 2 machines, both with Gbit interfaces. The 
>>> vm in kvm is running in server mode, the other (not virtualized one) is 
>>> the client. The vm interface is going to a bridge called br0. Ethtool 
>>> says the interface is running 100Mbits but it doesn't let me change the 
>>> speed or any other parameter in the vm.
>>>
>>> I can't either change tap0 parameters in kvm host. ¿Is anyone having the 
>>> same issue?¿am I forgetting something?
>>>
>>> Thanks for your time in advanced,
>>>      Miguel
>>>
>>> -------------------------------------------------------------------------
>>> This SF.net email is sponsored by: Microsoft
>>> Defy all challenges. Microsoft(R) Visual Studio 2008.
>>> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
>>> _______________________________________________
>>> kvm-devel mailing list
>>> kvm-devel@lists.sourceforge.net
>>> https://lists.sourceforge.net/lists/listinfo/kvm-devel
>>>   
>>>     
>>>       
>>
>> -------------------------------------------------------------------------
>> This SF.net email is sponsored by: Microsoft
>> Defy all challenges. Microsoft(R) Visual Studio 2008.
>> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
>> _______________________________________________
>> kvm-devel mailing list
>> kvm-devel@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/kvm-devel
>>   
>>     
>
>
>   


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Re: virtual machines network goes 100Mbit when interface is Gbit

[Felix Leimbach]

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>  Thanks for your answer Haydn, but I did not understand the issue too.
>  Victor has explained my problem clearly, is kvm uncapable of running
>  the bridge at 1GBit if it is not a e1000 network card?

Hey Miguel,

what Haydn meant was to force qemu to *emulate* a e1000 NIC instead of 
the default RTL8139. That emulation is done by qemu in userspace and has 
absolutely nothing to do with your physical NIC por the bridge.
Chosing a NIC is done with the "model=" parameter.
kvm -net nic,model=e1000

Even better performance-wise would be to use the new virtio interface 
which paravirtualizes your physical NIC instead of emulating one.
For that, use:
kvm -net nic,model=virtio

Of course you'll need to install the corresponding drivers in your 
guest. The e1000 should be supported in every guest and for the virtio 
interface there are windows guest drivers (see the kvm-announce mailing 
list for that) as well as linux guest drivers included in kernel 2.6.25 
upwards.

By the way: This is good stuff f you're interested in hard disk 
performance, too: http://kvm.qumranet.com/kvmwiki/Virtio

Felix

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Re: virtual machines network goes 100Mbit when interface is Gbit

[Haydn Solomon]

[-- Attachment #1.1: Type: text/plain, Size: 1787 bytes --]

See also
http://www.linux-kvm.com/content/tip-how-setup-windows-guest-paravirtual-network-drivers

On Thu, Apr 3, 2008 at 10:54 AM, Felix Leimbach <felix.leimbach@gmx.net>
wrote:

>  > Thanks for your answer Haydn, but I did not understand the issue too.
> > Victor has explained my problem clearly, is kvm uncapable of running
> > the bridge at 1GBit if it is not a e1000 network card?
>
> Hey Miguel,
>
> what Haydn meant was to force qemu to *emulate* a e1000 NIC instead of the
> default RTL8139. That emulation is done by qemu in userspace and has
> absolutely nothing to do with your physical NIC por the bridge.
> Chosing a NIC is done with the "model=" parameter.
> kvm -net nic,model=e1000
>
> Even better performance-wise would be to use the new virtio interface
> which paravirtualizes your physical NIC instead of emulating one.
> For that, use:
> kvm -net nic,model=virtio
>
> Of course you'll need to install the corresponding drivers in your guest.
> The e1000 should be supported in every guest and for the virtio interface
> there are windows guest drivers (see the kvm-announce mailing list for that)
> as well as linux guest drivers included in kernel 2.6.25 upwards.
>
> By the way: This is good stuff f you're interested in hard disk
> performance, too: http://kvm.qumranet.com/kvmwiki/Virtio
>
> Felix
>
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> https://lists.sourceforge.net/lists/listinfo/kvm-devel
>
>

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Re: virtual machines network goes 100Mbit when interface is Gbit

[Miguel Araujo]

[-- Attachment #1.1: Type: text/plain, Size: 2313 bytes --]

Hello again,

I want to thank you for the information given. Now I understand what you 
mean, I'm going to test virtio drivers with the last kernel possible. 
Thanks a lot.

Regards,
    Miguel

Haydn Solomon escribió:
> See also
>
> http://www.linux-kvm.com/content/tip-how-setup-windows-guest-paravirtual-network-drivers
>
> On Thu, Apr 3, 2008 at 10:54 AM, Felix Leimbach 
> <felix.leimbach@gmx.net <mailto:felix.leimbach@gmx.net>> wrote:
>
>     > Thanks for your answer Haydn, but
>     I did not understand the issue too.
>
>     > Victor has explained my problem clearly, is kvm uncapable of
>     running
>
>     > the bridge at 1GBit if it is not a e1000 network card?
>
>
>     Hey Miguel,
>
>     what Haydn meant was to force qemu to *emulate* a e1000 NIC
>     instead of the default RTL8139. That emulation is done by qemu in
>     userspace and has absolutely nothing to do with your physical NIC
>     por the bridge.
>     Chosing a NIC is done with the "model=" parameter.
>     kvm -net nic,model=e1000
>
>     Even better performance-wise would be to use the new virtio
>     interface which paravirtualizes your physical NIC instead of
>     emulating one.
>     For that, use:
>     kvm -net nic,model=virtio
>
>     Of course you'll need to install the corresponding drivers in your
>     guest. The e1000 should be supported in every guest and for the
>     virtio interface there are windows guest drivers (see the
>     kvm-announce mailing list for that) as well as linux guest drivers
>     included in kernel 2.6.25 upwards.
>
>     By the way: This is good stuff f you're interested in hard disk
>     performance, too: http://kvm.qumranet.com/kvmwiki/Virtio
>
>     Felix
>
>     -------------------------------------------------------------------------
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>     It's the best place to buy or sell services for
>     just about anything Open Source.
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>     _______________________________________________
>     kvm-devel mailing list
>     kvm-devel@lists.sourceforge.net
>     <mailto:kvm-devel@lists.sourceforge.net>
>     https://lists.sourceforge.net/lists/listinfo/kvm-devel
>
>


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