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

[Andrew Lyon <andrew.lyon@xxxxxxxxx>]

On Fri, Dec 11, 2009 at 6:24 PM, Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:
> 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?

>From the description I believe they are the rebased novell forward
ported patches which I rebased to apply to vanilla without other
novell/suse patches and made available for download at
http://code.google.com/p/gentoo-xen-kernel/downloads/list



>
>    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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>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>> http://lists.xensource.com/xen-devel
>>
>>
>
>
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