[Xen-users] low network performance

funk menera
2007-05-31T16:32:15Z

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 ?
Could someone give me good options for the (tcp_rmem
and so) variables in /et/sysctl.conf ? I found a howto
therefore but changing the values didn''t had a
reliable performance enhancement.

A other reason could be that the domO is ''sucking'' in
network traffic ... ?!
Or that i run the system with 100MHz instead of 133MHz
busfrequency ?! But i don''t think so cause i did that
before too.

For any hints, tips or links i will be very thankfully
!


Regards,
funki








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