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Re: [Xen-users] Xen network performance issue
I've found some additional information which is hopefully useful.
Firstly, the kernel on dom0 is:
Linux pm04 3.2.0-4-amd64 #1 SMP Debian 3.2.54-2 x86_64 GNU/Linux
I am using the debian packages as follows:
dpkg -l | grep xen
ii libxen-4.1 4.1.4-3+deb7u1 amd64 Public libs for Xen
ii libxenstore3.0 4.1.4-3+deb7u1 amd64 Xenstore
communications library for Xen
ii xen-hypervisor-4.1-amd64 4.1.4-3+deb7u1 amd64
Xen Hypervisor on AMD64
ii xen-linux-system-3.2.0-4-amd64 3.2.54-2
amd64 Xen system with Linux 3.2 on 64-bit PCs (meta-package)
ii xen-linux-system-amd64 3.2+46 amd64 Xen
system with Linux for 64-bit PCs (meta-package)
ii xen-system-amd64 4.1.4-3+deb7u1 amd64 Xen
System on AMD64 (meta-package)
ii xen-utils-4.1 4.1.4-3+deb7u1 amd64 XEN
administrative tools
ii xen-utils-common 4.1.4-3+deb7u1 all Xen
administrative tools - common files
ii xenstore-utils 4.1.4-3+deb7u1 amd64 Xenstore
utilities for Xen
Also, on the domU I had a process which would call fping to ping 31
addresses on the LAN once per second, so sending 31 ICMP each second.
When I stop this process, it drastically improved performance (ie, the
amount of time before ping times escalated to over 1s), but it does
still happen sometimes.
So it definitely looks like a load related issue, so when the network is
idle, it doesn't cause any problem, but when busy, it gets "overloaded"
and "backed up", until it eventually recovers.
Any suggestions or assistance would be greatly appreciated.
Regards,
Adam
On 03/03/14 14:38, Adam Goryachev wrote:
Hi all,
I've got a stable working xen platform which has been working well for
some time, but I recently converted a linux physical machine to a VM
and have an issue with networking.
This VM required 2 x network interfaces (it is a firewall machine),
one from the "Internet" and the second for the LAN.
The dom0 (physycal machine) has this config:
auto lo
iface lo inet loopback
# The primary network interface
allow-hotplug eth0
auto xenbr0
iface xenbr0 inet static
address 10.10.10.34
netmask 255.255.240.0
gateway 10.10.10.254
bridge_maxwait 5
bridge_ports regex eth0
auto xenbr5
iface xenbr5 inet manual
bridge_ports eth0.5
So actually, xenbr5 is based on eth0.5 which is configured on the
switch as a vlan (number 5), the WAN router is connected as untagged
for vlan5 and not a member of any other vlan. The dom0 machines are
configured with untagged for vlan4 (normal LAN network) and tagged for
vlan5.
If I migrate the domU to another physical machine, the problem moves
to the other machine, it also affects all VM's (incl the dom0) for the
physical machine this new "mail" vm is on.
brctl show
bridge name bridge id STP enabled interfaces
xenbr0 8000.f46d04efe254 no eth0
vif6.0
vif6.0-emu
xenbr5 8000.f46d04efe254 no eth0.5
vif6.1
vif6.1-emu
route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use
Iface
0.0.0.0 10.30.10.254 0.0.0.0 UG 0 0 0 xenbr0
10.30.0.0 0.0.0.0 255.255.240.0 U 0 0 0 xenbr0
kernel = "/usr/lib/xen-4.1/boot/hvmloader"
builder = 'hvm'
device_model = '/usr/lib/xen-4.1/bin/qemu-dm'
boot = 'dc'
localtime = 1
vnc = 1
vncviewer = 0
vncconsole = 0
vncdisplay = 9
vncunused = 0
stdvga = 0
acpi = 1
apic = 1
name = "mail"
hostname = 'mail'
disk = ['phy:/dev/mapper/mpathmail,xvda,w' ]
memory = 2048
cpus = "4,5" # Which physical CPU's to allow
vcpus = 2 # How many Virtual CPU's to present
vif = ['bridge=xenbr5, mac=00:16:3e:43:a8:09', 'bridge=xenbr0,
mac=00:16:3e:43:d8:09']
The problem can be seen by pinging either the physical machine, or the
VM's IP, with ping times around a few ms, and then escalating to 5
seconds or more, and then reducing back to normal, etc...
ping 10.10.10.34
PING 10.10.10.34 (10.10.10.34) 56(84) bytes of data.
64 bytes from 10.10.10.34: icmp_seq=1 ttl=64 time=0.289 ms
64 bytes from 10.10.10.34: icmp_seq=2 ttl=64 time=0.277 ms
64 bytes from 10.10.10.34: icmp_seq=3 ttl=64 time=0.281 ms
64 bytes from 10.10.10.34: icmp_seq=4 ttl=64 time=340 ms
64 bytes from 10.10.10.34: icmp_seq=5 ttl=64 time=0.260 ms
64 bytes from 10.10.10.34: icmp_seq=6 ttl=64 time=79.9 ms
64 bytes from 10.10.10.34: icmp_seq=7 ttl=64 time=0.269 ms
64 bytes from 10.10.10.34: icmp_seq=8 ttl=64 time=0.264 ms
64 bytes from 10.10.10.34: icmp_seq=9 ttl=64 time=182 ms
64 bytes from 10.10.10.34: icmp_seq=10 ttl=64 time=311 ms
64 bytes from 10.10.10.34: icmp_seq=11 ttl=64 time=717 ms
64 bytes from 10.10.10.34: icmp_seq=12 ttl=64 time=1029 ms
64 bytes from 10.10.10.34: icmp_seq=13 ttl=64 time=1422 ms
64 bytes from 10.10.10.34: icmp_seq=14 ttl=64 time=1725 ms
64 bytes from 10.10.10.34: icmp_seq=15 ttl=64 time=1627 ms
64 bytes from 10.10.10.34: icmp_seq=16 ttl=64 time=2080 ms
64 bytes from 10.10.10.34: icmp_seq=17 ttl=64 time=2385 ms
64 bytes from 10.10.10.34: icmp_seq=18 ttl=64 time=2375 ms
64 bytes from 10.10.10.34: icmp_seq=19 ttl=64 time=2876 ms
64 bytes from 10.10.10.34: icmp_seq=20 ttl=64 time=2830 ms
64 bytes from 10.10.10.34: icmp_seq=21 ttl=64 time=2418 ms
64 bytes from 10.10.10.34: icmp_seq=22 ttl=64 time=1420 ms
64 bytes from 10.10.10.34: icmp_seq=23 ttl=64 time=421 ms
64 bytes from 10.10.10.34: icmp_seq=24 ttl=64 time=0.292 ms
64 bytes from 10.10.10.34: icmp_seq=25 ttl=64 time=0.286 ms
64 bytes from 10.10.10.34: icmp_seq=26 ttl=64 time=0.257 ms
^C
--- 10.10.10.34 ping statistics ---
26 packets transmitted, 26 received, 0% packet loss, time 25016ms
rtt min/avg/max/mdev = 0.257/932.656/2876.987/1016.327 ms, pipe 3
On dom0, if I run "tcpdump -tn -i eth0" (or xenbr0) then I do not see
any packets that should be on the WAN side (ie, packets for the WAN
VLAN don't seem to be leaking out), if I run "tcpdump -tn -i eth0.5
(or xenbr5) then equally I don't see any of the LAN packets, and only
see the WAN packets.
One thought I had was that perhaps I should use a specific network
card type, by default it seems to be using a rtl8139, though since it
is impacting dom0, I don't think how xen presents the card to the domU
should make any difference.
I'm assuming I've somehow managed to create a loop, or something
equally stupid somewhere, but I'm running out of places to look, and
not sure how to work it out. Any assistance would be greatly appreciated.
Regards,
Adam
--
Adam Goryachev Website Managers www.websitemanagers.com.au
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