dom0 kernel v2.6.32.41 network problem

dom0 kernel v2.6.32.41 network problem

[Hui Kang]

[-- Attachment #1.1: Type: text/plain, Size: 495 bytes --]

Hi,
I am running two hosts with xen-4.0.1 and dom0 kernel 2.6.32.41. The two hosts are connected to a Gigbit switch. Then I use iperf to measure the bandwidth and got the results of 200Mbit/second, which is only 1/5 of the available bandwidth.
Then I boot these two hosts using a vanilla kernel of 2.6.32.34. The iperf reports 937Mbis/s, which is very close to the available link bandwidth.
So why the pvops dom0 kernel performs so bad? Does anyone observe similar problem? Thanks.

- Hui

[-- Attachment #1.2: Type: text/html, Size: 877 bytes --]

[-- Attachment #2: Type: text/plain, Size: 138 bytes --]

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel

Re: dom0 kernel v2.6.32.41 network problem

[Konrad Rzeszutek Wilk]

On Fri, Jul 15, 2011 at 05:54:11PM +0000, Hui Kang wrote:
> Hi,
> I am running two hosts with xen-4.0.1 and dom0 kernel 2.6.32.41. The two hosts are connected to a Gigbit switch. Then I use iperf to measure the bandwidth and got the results of 200Mbit/second, which is only 1/5 of the available bandwidth.
> Then I boot these two hosts using a vanilla kernel of 2.6.32.34. The iperf reports 937Mbis/s, which is very close to the available link bandwidth.
> So why the pvops dom0 kernel performs so bad? Does anyone observe similar problem? Thanks.

Weird. No idea - I get around 911Mb/s with my dom0 - which is 3.0.0-rc7. Do you
have some debug options turned on?
> 
> - Hui

> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel

Re: dom0 kernel v2.6.32.41 network problem

[Ian Campbell]

On Fri, 2011-07-15 at 19:19 +0100, Konrad Rzeszutek Wilk wrote:
> On Fri, Jul 15, 2011 at 05:54:11PM +0000, Hui Kang wrote:
> > Hi,
> > I am running two hosts with xen-4.0.1 and dom0 kernel 2.6.32.41. The two hosts are connected to a Gigbit switch. Then I use iperf to measure the bandwidth and got the results of 200Mbit/second, which is only 1/5 of the available bandwidth.
> > Then I boot these two hosts using a vanilla kernel of 2.6.32.34. The iperf reports 937Mbis/s, which is very close to the available link bandwidth.
> > So why the pvops dom0 kernel performs so bad? Does anyone observe similar problem? Thanks.

It is definitely worth checking that you don't have any debug options
enabled in your kernel .config. Some of those options are far more
expensive under Xen than native. (unfortunately I'm drawing a blank on
precisely which options we've seen this with right now, anything to do
with debugging page allocations etc would be a good bet).

Ian.