Re: RHEL 4.5 guest virtual network performace

[Dor Laor <dlaor@redhat.com>]

On 08/17/2010 12:51 AM, Alex Rixhardson wrote:
> I tried with 'notsc divider=10' (since it's 64 bit guest), but the
> results are the still same :-(. The guest is idle at the time of
> testing. It has 2 CPU and 1024 MB RAM available.

Hmm, are you using e1000 or virtio for the 4.5 guest?
e1000 should be slow since it's less suitable for virtualization (3 
mmio/packet)


>
> On Mon, Aug 16, 2010 at 11:35 PM, Dor Laor<dlaor@redhat.com>  wrote:
>> On 08/17/2010 12:22 AM, Alex Rixhardson wrote:
>>>
>>> Thanks for the suggestion.
>>>
>>> I tried with the netperf. I ran netserver on host and netperf on RHEL
>>> 5.5 and RHEL 4.5 guests. This are the results of 60 seconds long
>>> tests:
>>>
>>> RHEL 4.5 guest:
>>> Throughput (10^6bits/sec) = 145.80
>>
>> At least it bought you another 5Mb/s over iperf ...
>>
>> It might be time related, 5.5 has kvmclock but rhel4 does not.
>> If it's 64 bit guest add this to the 4.5 guest cmdline  'notsc divider=10'.
>> If it's 32 use 'clock=pmtmr divider=10'.
>> The divider is probably new and is in rhel4.8 only, it's ok w/o it too.
>>
>> What's the host load for the 4.5 guest?
>>
>>>
>>> RHEL 5.5 guest:
>>> Throughput (10^6bits/sec) = 3760.24
>>>
>>> The results are really bad on RHEL 4.5 guest. What could be wrong?
>>>
>>> Regards,
>>> Alex
>>>
>>> On Mon, Aug 16, 2010 at 9:49 PM, Dor Laor<dlaor@redhat.com>    wrote:
>>>>
>>>> On 08/16/2010 10:00 PM, Alex Rixhardson wrote:
>>>>>
>>>>> Hi guys,
>>>>>
>>>>> I have the following configuration:
>>>>>
>>>>> 1. host is RHEL 5.5, 64bit with KVM (version that comes out of the box
>>>>> with RHEL 5.5)
>>>>> 2. two guests:
>>>>> 2a: RHEL 5.5, 32bit,
>>>>> 2b: RHEL 4.5, 64bit
>>>>>
>>>>> If I run iperf between host RHEL 5.5 and guest RHEL 5.5 inside the
>>>>> virtual network subnet I get great results (>      4Gbit/sec). But if I
>>>>> run
>>>>> iperf between guest RHEL 4.5 and either of the two RHELs 5.5 I get bad
>>>>> network performance (around 140Mbit/sec).
>>>>
>>>> Please try netperf, iperf known to be buggy and might consume cpu w/o
>>>> real
>>>> justification
>>>>
>>>>>
>>>>> The configuration was made thru virtual-manager utility, nothing
>>>>> special. I just added virtual network device to both guests.
>>>>>
>>>>> Could you guys give me some tips on what should I check?
>>>>>
>>>>> Regards,
>>>>> Alex
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>>
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