Poor network performance in domU in unstable

Poor network performance in domU in unstable

[Jacob Gorm Hansen]

hi,

with unstable as of April 21st, I am getting fairly bad networking 
performance in my domUs, e.g 125Mbits/s TCP with iPerf over a gigabit 
link, where dom0 gets around 700Mbits/s.

This is with a non-debug build of Xen, with a bridged setup created with 
vmtools, and both with and without use of grant tables.

If I run Xen with hyperthreading enabled, the figure improves somewhat, 
to 165Mbits/s in domU.

Is anyone else seeing the same behaviour with unstable? Is there some 
magic switch I need to flip (that perhaps vmtools does not know about) 
to prevent domain I/O being throttled by Xen?

thanks,
Jacob

Re: Poor network performance in domU in unstable

[Steven Hand]

>with unstable as of April 21st, I am getting fairly bad networking 
>performance in my domUs, e.g 125Mbits/s TCP with iPerf over a gigabit 
>link, where dom0 gets around 700Mbits/s.

Is this vanilla Xen/XenLinux or have you any local changes?

Always worth upgrading to latest unstable in any case; binary chop
on csets can help narrow things down. 

cheers,

S.

Re: Poor network performance in domU in unstable

[Nivedita Singhvi]

Jacob Gorm Hansen wrote:
> hi,
> 
> with unstable as of April 21st, I am getting fairly bad networking 
> performance in my domUs, e.g 125Mbits/s TCP with iPerf over a gigabit 
> link, where dom0 gets around 700Mbits/s.

Hi Jacob,

What were you getting on domU earlier to April 21st? You seemed
to be implying 4/21 build changed something? Was it better before?

thanks,
Nivedita

Re: Poor network performance in domU in unstable

[Jacob Gorm Hansen]

Steven Hand wrote:
>>with unstable as of April 21st, I am getting fairly bad networking 
>>performance in my domUs, e.g 125Mbits/s TCP with iPerf over a gigabit 
>>link, where dom0 gets around 700Mbits/s.
> 
> 
> Is this vanilla Xen/XenLinux or have you any local changes?

This is the vanilla versions, except using vmtools instead of xend. I 
will try this with xend and report back to see if that helps anything.

 > Always worth upgrading to latest unstable in any case; binary chop
 > on csets can help narrow things down.

Yes, unfortunately the latest unstable crashes dom0 on domain creation 
(as described by me and others on the list), which is why I picked at 
random semi-recent version instead.

Jacob

Re: Poor network performance in domU in unstable

[Jacob Gorm Hansen]

Nivedita Singhvi wrote:
> Jacob Gorm Hansen wrote:
> 
>> hi,
>>
>> with unstable as of April 21st, I am getting fairly bad networking 
>> performance in my domUs, e.g 125Mbits/s TCP with iPerf over a gigabit 
>> link, where dom0 gets around 700Mbits/s.
> 
> 
> Hi Jacob,
> 
> What were you getting on domU earlier to April 21st? You seemed
> to be implying 4/21 build changed something? Was it better before?

Hi,

I am not sure, as before I did not test against a vanilla Xen, but I 
think the problem was also present in the ~1 month old unstable I was 
using before.

Jacob

Re: Poor network performance in domU in unstable

[Andrew Theurer]

Jacob Gorm Hansen wrote:

> Steven Hand wrote:
>
>>> with unstable as of April 21st, I am getting fairly bad networking 
>>> performance in my domUs, e.g 125Mbits/s TCP with iPerf over a 
>>> gigabit link, where dom0 gets around 700Mbits/s.
>>
>>
>>
>> Is this vanilla Xen/XenLinux or have you any local changes?
>
>
> This is the vanilla versions, except using vmtools instead of xend. I 
> will try this with xend and report back to see if that helps anything.

I am actually seeing the same thing, about 215 Mbit on domU using NAT.  
I don't beleive I saw this before April 21st as well.

>
> > Always worth upgrading to latest unstable in any case; binary chop
> > on csets can help narrow things down.
>
> Yes, unfortunately the latest unstable crashes dom0 on domain creation 
> (as described by me and others on the list), which is why I picked at 
> random semi-recent version instead.

Domain creation has crashed for me since 1.1367, and recent builds wont 
fully boot dom0 for me.

-Andrew

Re: Poor network performance in domU in unstable

[Jacob Gorm Hansen]

Andrew Theurer wrote:
> Jacob Gorm Hansen wrote:

> Domain creation has crashed for me since 1.1367, and recent builds wont 
> fully boot dom0 for me.

Btw. I just noticed that if xcs is not running, vmtools' vm-create will 
take down Xen (not just dom0).

Jacob

Re: Poor network performance in domU in unstable

[Jacob Gorm Hansen]

Jacob Gorm Hansen wrote:
> hi,
> 
> with unstable as of April 21st, I am getting fairly bad networking 
> performance in my domUs, e.g 125Mbits/s TCP with iPerf over a gigabit 
> link, where dom0 gets around 700Mbits/s.
> 
> This is with a non-debug build of Xen, with a bridged setup created with 
> vmtools, and both with and without use of grant tables.
> 
> If I run Xen with hyperthreading enabled, the figure improves somewhat, 
> to 165Mbits/s in domU.
> 
> Is anyone else seeing the same behaviour with unstable? Is there some 
> magic switch I need to flip (that perhaps vmtools does not know about) 
> to prevent domain I/O being throttled by Xen?

This seems to have been a configuration issue, as instead of migrating 
my old .config files using the arch/xen/config/* files got domU back to 
normal performance.

Thanks,
Jacob