Re: Strange network behaviour

Mike
2007-12-05T09:42:49Z

I did a single test, only 1 guest running with kvm activated.
The ping peaks are still there.

How do I disable swapping?

Mike

Dor Laor schrieb:
> Mike wrote:
>> Hello Lynn,
>>
>> I'm using a bridge, which is configured in my /etc/network/interfaces
>> like this:
>> auto br0
>> iface br0 inet static
>> address 195.24.77.169
>> netmask 255.255.255.0
>> gateway 195.24.77.1
>> bridge_ports eth0
>> bridge_stp off
>> bridge_maxwait 5
>>
>> an I have a file called qemu-ifup in /etc which has the following content:
>> #!/bin/sh
>> /sbin/ifconfig $1 0.0.0.0 promisc up
>> /usr/sbin/brctl addif br0 $1
>> sleep 2
>>
>> Every guest has it's own tap device, atm tap0 - tap4 are in use.
>> Those peaks are coming after +/- 10 mins (not always the same time,
>> sometimes after 5 mins, it changes). Within this time, the guests have
>> normal pings.
>>
>>
>>
> It might be related to swapping (the host swaps guest pages).
> Please check the ram size used by the guest.
>
> Can you re-run the test with a single test or with disabling the swapping?
> Thanks,
> Dor.
>> Lynn Kerby schrieb:
>>
>>> Hi Mike,
>>>
>>> Glad to hear that your networks are up now, but what are you using to
>>> connect/bridge them? Those response times are horrible across the
>>> board!
>>>
>>> All my VMs are connected to my internal network via a bridge on the
>>> host through their tap interfaces and a few lucky machines share
>>> another bridge that is on my DMZ with static IPs. I think the
>>> network bridge method I use is based on some stuff I picked up a few
>>> years ago when working with the UML virtualization stuff. I see sub
>>> millisecond ping responses in both directions and to all VMs (usually
>>> I've got 3 or 4 active, soon to expand to a few more).
>>>
>>> My HOST config is similar though I've got a only 4GB of memory and
>>> I'm still running KVM-52 modules. My guests are Ubuntu 7.10, Fedora
>>> 8, and FreeBSD 6.2 at the moment with Mint4.0 and JeOS on the drawing
>>> board.
>>>
>>> Lynn Kerby
>>> San Martin, CA
>>>
>>> On Dec 4, 2007, at 2:44 PM, Mike wrote:
>>>
>>>
>>>
>>>> Hello,
>>>> I already spoke to Izik Eidus. He told me to publish the results to
>>>> the
>>>> problem at the mailinglist.
>>>>
>>>> Some time ago I wrote to the kvm-devel mailinglist that I had a
>>>> problem
>>>> with my guests' networking dying.
>>>> I got the hint to change the network card emulation. That worked.
>>>>
>>>> Now I noticed a strange behaviour.
>>>> I have a gameserver running in a guest os. No problems on performance
>>>> side, really fast.
>>>> The only thing, when I make a ping test after unspecific time
>>>> periods I
>>>> get this: (this peaks are even there if the gameserver isn't running)
>>>>
>>>> Reply from 195.24.77.170: bytes=32 time=36ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=34ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=123ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=98ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=116ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=241ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=72ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=382ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=135ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=397ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=647ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=857ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=1156ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=692ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=604ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=35ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=34ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=35ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=188ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=39ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=46ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=34ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=34ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=39ms TTL=57
>>>>
>>>> This ping peaks are on *all* guests I'm currently running.
>>>> I did a ping test the same time to the Host, with this result:
>>>>
>>>> Reply from 195.24.77.169: bytes=32 time=38ms TTL=57
>>>> Reply from 195.24.77.169: bytes=32 time=34ms TTL=57
>>>> Reply from 195.24.77.169: bytes=32 time=39ms TTL=57
>>>> Reply from 195.24.77.169: bytes=32 time=33ms TTL=57
>>>> Reply from 195.24.77.169: bytes=32 time=38ms TTL=57
>>>> Reply from 195.24.77.169: bytes=32 time=34ms TTL=57
>>>> Reply from 195.24.77.169: bytes=32 time=34ms TTL=57
>>>> Reply from 195.24.77.169: bytes=32 time=33ms TTL=57
>>>> Reply from 195.24.77.169: bytes=32 time=35ms TTL=57
>>>> Reply from 195.24.77.169: bytes=32 time=40ms TTL=57
>>>> Reply from 195.24.77.169: bytes=32 time=33ms TTL=57
>>>> Reply from 195.24.77.169: bytes=32 time=33ms TTL=57
>>>> Reply from 195.24.77.169: bytes=32 time=34ms TTL=57
>>>> Reply from 195.24.77.169: bytes=32 time=35ms TTL=57
>>>> Reply from 195.24.77.169: bytes=32 time=34ms TTL=57
>>>> Reply from 195.24.77.169: bytes=32 time=35ms TTL=57
>>>> Reply from 195.24.77.169: bytes=32 time=37ms TTL=57
>>>> Reply from 195.24.77.169: bytes=32 time=33ms TTL=57
>>>> Reply from 195.24.77.169: bytes=32 time=33ms TTL=57
>>>> Reply from 195.24.77.169: bytes=32 time=35ms TTL=57
>>>> Reply from 195.24.77.169: bytes=32 time=33ms TTL=57
>>>> Reply from 195.24.77.169: bytes=32 time=34ms TTL=57
>>>> Reply from 195.24.77.169: bytes=32 time=34ms TTL=57
>>>> Reply from 195.24.77.169: bytes=32 time=33ms TTL=57
>>>>
>>>> As you can see, no peaks.
>>>> Example of start command from a guest:
>>>> kvm -hda apache.img -hdb apache_storage.img -m 512 -boot c -net
>>>> nic,vlan=0,macaddr=00:16:3e:00:00:01,model=rtl8139 -net tap -nographic
>>>> -daemonize
>>>>
>>>> Here the pings from the guest started with the command line listed
>>>> above:
>>>>
>>>> Reply from 195.24.77.171: bytes=32 time=37ms TTL=57
>>>> Reply from 195.24.77.171: bytes=32 time=37ms TTL=57
>>>> Reply from 195.24.77.171: bytes=32 time=97ms TTL=57
>>>> Reply from 195.24.77.171: bytes=32 time=60ms TTL=57
>>>> Reply from 195.24.77.171: bytes=32 time=186ms TTL=57
>>>> Reply from 195.24.77.171: bytes=32 time=363ms TTL=57
>>>> Reply from 195.24.77.171: bytes=32 time=368ms TTL=57
>>>> Reply from 195.24.77.171: bytes=32 time=972ms TTL=57
>>>> Reply from 195.24.77.171: bytes=32 time=673ms TTL=57
>>>> Reply from 195.24.77.171: bytes=32 time=1133ms TTL=57
>>>> Reply from 195.24.77.171: bytes=32 time=1198ms TTL=57
>>>> Reply from 195.24.77.171: bytes=32 time=1881ms TTL=57
>>>> Reply from 195.24.77.171: bytes=32 time=2341ms TTL=57
>>>> Reply from 195.24.77.171: bytes=32 time=2401ms TTL=57
>>>> Reply from 195.24.77.171: bytes=32 time=2006ms TTL=57
>>>> Reply from 195.24.77.171: bytes=32 time=2638ms TTL=57
>>>> Reply from 195.24.77.171: bytes=32 time=3590ms TTL=57
>>>> Reply from 195.24.77.171: bytes=32 time=383ms TTL=57
>>>> Reply from 195.24.77.171: bytes=32 time=35ms TTL=57
>>>> Reply from 195.24.77.171: bytes=32 time=35ms TTL=57
>>>> Reply from 195.24.77.171: bytes=32 time=34ms TTL=57
>>>> Reply from 195.24.77.171: bytes=32 time=35ms TTL=57
>>>> Reply from 195.24.77.171: bytes=32 time=34ms TTL=57
>>>>
>>>> So I tried disabling kvm when starting a guest.
>>>> and here the guest *with* -no-kvm in the command line:
>>>>
>>>> Reply from 195.24.77.170: bytes=32 time=35ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=36ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=34ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=34ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=34ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=35ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=36ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=37ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=33ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=34ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=38ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=33ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=35ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=34ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=35ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=34ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=37ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=34ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=34ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=33ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=34ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=34ms TTL=57
>>>> Reply from 195.24.77.170: bytes=32 time=34ms TTL=57
>>>>
>>>> The other guest, without -no-kvm have the ping peaks. Also here, no
>>>> ping
>>>> peaks from the host.
>>>> Server load is really really low at the moment of the tests.
>>>>
>>>> Maybe you have an idea where this peaks are coming from?
>>>> I'm using KVM-55 on Ubuntu 7.10 server with Kernel Linux A050
>>>> 2.6.22-14-server #1 SMP Sun Oct 14 22:09:15 GMT 2007 x86_64 GNU/Linux.
>>>> My CPU is an AMD Athlon 64 X2 5600+ (Dual Core) with 8GByte of RAM.
>>>>
>>>> Greetings from Luxembourg.
>>>> Mike Weimichkirch
>>>>
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>>>>
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