Re: [Xen-users] Xen and networking.

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

Most people seem to be assuming you are running PV guests.  Are we correct in 
thinking this i the case?

Cheers,
Mark

On Friday 28 December 2007, tmac wrote:
> I have a beefy machine
> (Intel dual-quad core, 16GB memory 2 x GigE)
>
> I have loaded RHEL5.1-xen on the hardware and have created two logical
> systems: 4 cpus, 7.5 GB memory 1 x Gige
>
> Following RHEL guidelines, I have it set up so that eth0->xenbr0 and
> eth1->xenbr1
> Each of the two RHEL5.1 guests uses one of the interfaces and this is
> verified at the
> switch by seeing the unique MAC addresses.
>
> If I do a crude test from one guest over nfs,
> dd if=/dev/zero of=/nfs/test bs=32768 count=32768
>
> This yields almost always 95-100MB/sec
>
> When I run two simultaneously, I cannot seem to get above 25MB/sec from
> each. It starts off with a large burst like each can do 100MB/sec, but then
> in a couple
> of seconds, tapers off to the 15-40MB/sec until the dd finishes.
>
> Things I have tried (installed on the host and the guests)
>
>  net.core.rmem_max = 16777216
>  net.core.wmem_max = 16777216
>  net.ipv4.tcp_rmem = 4096 87380 16777216
>  net.ipv4.tcp_wmem = 4096 65536 16777216
>
>  net.ipv4.tcp_no_metrics_save = 1
>  net.ipv4.tcp_moderate_rcvbuf = 1
>  # recommended to increase this for 1000 BT or higher
>  net.core.netdev_max_backlog = 2500
>  sysctl -w net.ipv4.tcp_congestion_control=cubic
>
> Any ideas?



-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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