Re: [Xen-devel] Poor NIC performance on domUs / Crashing

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

On 12/05/09 09:40, ryan@xxxxxxxxxxxx wrote:
> Hi All,
>
> Setup is as follows:
>
> Hardware:
>
> AMD Sempron 2800+ (No VT)
> 3GB RAM
> 8x250GB IDE Drives in RAID5
>
> Software
> Xen-3.4.1
>
> dom0: Gentoo built with Sources 2.6.29-r4
> domU: Gentoo built with Sources 2.6.29-r4
>
> dom0 is running as my firewall while domU is running mail/web services.
> Here's my dd tests on both the dom0 and domU:
>    
Do you know what source base these kernels are based on?  Are they 
pvops?  Novell forward-port?  In particular, what's the origin of the 
2.6.29 dom0?
    J

> dom0:
>
> fs ~ # time dd if=/dev/sda of=/dev/null bs=1M count=500
> 500+0 records in
> 500+0 records out
> 524288000 bytes (524 MB) copied, 4.71219 s, 111 MB/s
>
> real    0m4.718s
> user    0m0.000s
> sys     0m1.844s
>
> fs ~ # time hdparm -t /dev/sda
>
> /dev/sda:
>   Timing buffered disk reads:  598 MB in  3.19 seconds = 187.22 MB/sec
>
> real    0m6.598s
> user    0m0.131s
> sys     0m2.059s
>
>
> domU:
>
> mail ~ # time dd if=/dev/xvda of=/dev/null bs=1M count=500
> 500+0 records in
> 500+0 records out
> 524288000 bytes (524 MB) copied, 9.39719 s, 55.8 MB/s
>
> real    0m9.404s
> user    0m0.000s
> sys     0m1.317s
>
> mail ~ # time hdparm -t /dev/xvda
>
> /dev/xvda:
>   Timing buffered disk reads:  568 MB in  3.00 seconds = 189.19 MB/sec
>
> real    0m6.161s
> user    0m0.121s
> sys     0m1.789s
>
> Here's my config file for the domU:
>
> fs ~ # cat /etc/xen/mail
> # general
> name    = "mail";
> memory  = 1024;
>
> # booting
> kernel  = "/mnt/data/vms/xen/kernels/vmlinuz-2.6.29-r4-xenU";
>
> # virtual harddisk
> disk = [ "file:/mnt/data/vms/mail/domU-mail,xvda,w" ];
> root = "/dev/xvda ro";
>
> # virtual network
> vif = [ "ip=10.9.18.13, vifname=eth3" ];
> #vif = [ "" ];
> #dhcp = "dhcp";
>
> # If you can't see anything from init in your "xm console" command try
> uncommenting this line.
> extra = 'xencons=tty'
>
>
> When I run rsync from a network host into the domU my pings to the domU go
> to 1000ms and my write speed is around 1MB/s. I've already set the ethtool
> -K eth0 tx off on the domU:
>
> mail ~ # ethtool -k eth0
> Offload parameters for eth0:
> Cannot get device rx csum settings: Operation not supported
> rx-checksumming: off
> tx-checksumming: off
> scatter-gather: off
> tcp segmentation offload: off
> udp fragmentation offload: off
> generic segmentation offload: off
>
>
> Also, I've had the whole kernel crash on the dom0 when doing moderate
> network activity to the domU. Got some message about insufficient memory on
> the eth0 interface (WAN facing on the dom0).
>
> Any ideas as to how to troubleshoot this?
>
> Thanks!
> Ryan
>
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>
>    

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