Re: [Xen-users] Xen and networking.
if you want to get Gigabit performance on your domU (using HVM
you MUST compile the xen unmodified_drivers (in particular Netfront) and
those drivers as kernel modules on your domU.
Then you must change the guest machine xen file using netfront insted of
for the network interface. I have written a page on how to do it but it
is written in italian.
Anyway if you follow the instruction you should understand looking at
the bare commands.
of couse the xen source coude depends on the xen version you are using
on your dom0.
Actually I was not satisfied of Xen 3.0.2 used on RHEL5 so we build rpm
for Xen 3.1.2
and actually we are using those.
tmac ha scritto:
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
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
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