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.

On Mon, Aug 16, 2010 at 11:35 PM, Dor Laor <dl...@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<dl...@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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>
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