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RE: [Xen-users] low network performance


  • To: "Schmidt, Werner \(Werner\)" <wernerschmidt@xxxxxxxxx>, xen-users@xxxxxxxxxxxxxxxxxxx
  • From: funk menera <funkmenera@xxxxxxxx>
  • Date: Fri, 1 Jun 2007 14:43:27 +0200 (CEST)
  • Delivery-date: Fri, 01 Jun 2007 05:41:55 -0700
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  • List-id: Xen user discussion <xen-users.lists.xensource.com>



"Schmidt, Werner (Werner)" <wernerschmidt@xxxxxxxxx> schrieb:
> -----Original Message-----
> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of
> funk menera
> Sent: 31 May 2007 17:32
> To: xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-users] low network performance
>
> Hi @list !
>
> This is my first posting so please have patience with
> me ;)
>
> As the titel says, i have some problems with the
> network performance.
> I'm using Xen3.0.3 with Debian on domO and all over
> domUs
> Maybe the Hardware is interesting too...
> AthlonXP 1700+ on MSI.K7T266Pro2 with 1GB RAM, 3
> IDE-HDs without RAID and two Networkdevices with
> Realtek chipset:
> NIC1: 1GBit r8169 -> for LAN
> NIC2: 100MBit 8139 -> for DSL
> on the LAN-device is a D-LINK GBit 8-Port Switch
> connected.
>
> Well i experienced the problems while listening to a
> mp3 file on a domU using Samba. Or when extracting
> sth. from/to a domU form/to my Laptop. Same for a
> transport from domU <-> domU
> Basically it feels laggy or not as fast as i'm used to
> (as comparison: the same hardware on a debian-srv
> withou XEN) and there are hang-ups
>
>
> So a short test with netio shows me sth. like this:
> Laptop -> domO         : 11000 KByte/s for Tx and Rx
> domO   -> domU-mainsrv :
> TCP connection established.
> Packet size  1k bytes:  1870 KByte/s Tx,  12293
> KByte/s Rx.
> Packet size  2k bytes:  1659 KByte/s Tx,  13503
> KByte/s Rx.
> Packet size  4k bytes:  1893 KByte/s Tx,  14072
> KByte/s Rx.
> Packet size  8k bytes:  1869 KByte/s Tx,  16355
> KByte/s Rx.
> Packet size 16k bytes:  1810 KByte/s Tx,  14836
> KByte/s Rx.
> Packet size 32k bytes:  1636 KByte/s Tx,  16829
> KByte/s Rx.
> Done.
>
> as i go on
> domU -> domU-efw21(Endian Firewall 2.1):
> TCP connection established.
> Packet size  1k bytes:  6753 KByte/s Tx,  5481 KByte/s
> Rx.
> Packet size  2k bytes:  6005 KByte/s Tx,  5532 KByte/s
> Rx.
> Packet size  4k bytes:  6216 KByte/s Tx,  5271 KByte/s
> Rx.
> Packet size  8k bytes:  5811 KByte/s Tx,  5491 KByte/s
> Rx.
> Packet size 16k bytes:  6236 KByte/s Tx,  5603 KByte/s
> Rx.
> Packet size 32k bytes:  5846 KByte/s Tx,  5588 KByte/s
> Rx.
> Done.
>
> That's terrific if i compare it with the speed which i
> had before ... 28MByte/s ~ 50MB/s
>
> So i read some pages in the mailing list archive and
> found sth. about para-virtual drivers which looked
> like it could give me more bandwidth.
> Anyhow i just got confused ...
> Is para-virtualsiation meanwhile standard for
> Linux-domUs ?
> If not where can i get these drivers ?
 
>
> Maybe the reason for the low network performance is
> somewhere else ?
 
 
Note that i had similar problems in my tests (I tested the domU and dom0 network performance of multiple machines connected via Gigabit lan with ?iperf ?)
;
If you use the standard bridge configuration (which I assume is true for your system), you might try to get a better performance by modifying the ?txqueuelen? parameter of the vif devices connecting the domUs to the dom0 bridge (?ifconfig vifx.y? will show the value of this parameter)
You can see with  ?brctl show? which vifs are involved.
 
In my case, the value was set to ?32?
I got substantially better results of dom0->domU performance (and domU -> domU performance) by changing this value to 128 ..512:
?ip link set vifx.y txqueuelen <value>? will do this change for you
 
Werner
 
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Thanks for the reply.
But changing the txqueuelen on all doms to 512 dind't bring
up some performance enhancements on my system.
Well the value before was a 0 at domO and 1000 at domUs... what ever that
means.

And i'm using the standard bridge-mode to connect the
doms. But to get sure u may have a look at:
http://www.neobiker.de/wiki/index.php?title=XEN_Netzwerk_f%C3%BCr_Firewall
because i'm using this script for configuring the
network.
But as i understand this script uses bridging ...

Well, do u also have a one-core CPU, so the problem
might be comparible to my or do u use a
dualcore-/quadcore-cpu or dual/quad-system with single
CPUs ?
This point is interesting for me anyway, because in a
previous mail a Xen-USer told me about that the
performance would be much better on such a system.

So therefore i want to ask all of U@list what kind of
system are u using and how good the performance is?
So do u use ...
a) a antiquated ;) single-core single CPU system as i
do ?
b) 'normal' dual singlecore-cpu System ?
c) 1 dualcore/quadcore cpu ?
d) more then 1 dualcore/quadcore cpu ? ... maybe 4 of
them :O ? ... don't wanna know how big the overhead
might be in this case :X

And basically which version would u suggest to run the
best performance? furthermoire i'd like to know if there is a important performance difference between a AMD or Intel system ?

Allthough i'm not in the situation (as a poor student)
to spend some hundred bucks for a new system :( i'm
interested in that point ... U'll never know where u
find some money ;)

So i just wanna know about the performance to solve my
question if the system would run as i was used to or
if there remains some bottlenecks ?
Basically i don't need high cpu-power bout a good and
reliable network and harddisk performance !

Reagrds,
fuki

P.S. Any other hint/tips/link for giving my system
better performance is highly desired !


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