On 06/23/2011 01:28 PM, Tim Nelson wrote:
> ----- Original Message -----
>> I was trying to do some performance testing between using iSCSI on the
>> host as a diskfile to a guest vs the VM guest using the iSCSI device
>> directly.
>>
>> However, in the process of trying to establish a baseline performance
>> figure, I started increasing the MTU settings on the PCI-express NICs
>> with RTL8168B chips.
>>
>> First bottleneck was discovering the max MTU allowed on these is 7K
>> instead of 9K but googling seems to indicate that the RTL8168B is only
>> capable of 4K frames.
>>
>> I assumed 4K would still be better than nothing but unfortunately
>> bumping up the MTU to anything else but 1.5K caused the file transfers
>> (using NFS for easy testing), to hang at random points or more
>> accurate slow to a crawl.
>>
>> Checking the syslog, I discovered warnings that increasing MTU with
>> this adapter may cause problems.
>>
>> Searching around, it seems to be a common problem but there doesn't
>> appear to be any clear cut fix, including some suggestions to use a
>> third party driver.
>>
>> Does anybody know of a proven solution or is the Realtek chip itself
>> irrevocably broken/bugged that anything above the default 1500 will
>> simply not work?
>
> Realtek NICs are known to be some of the poorest interfaces available. A quality Intel or Broadcom NIC will set you back very little in terms of cost. Just replace it and be done. :)
>
> --Tim
I second this. I switched out for fairly inexpensive Intel Pro/1000CT
adapters. They're to be had for ~$30~40 in Canada and work perfectly at
9kb JFs.
Realtek is really built down to cost, and is not viable outside of basic
web browsing, imho.
--
Digimer
E-Mail: digimer@xxxxxxxxxxx
Freenode handle: digimer
Papers and Projects: http://alteeve.com
Node Assassin: http://nodeassassin.org
"I feel confined, only free to expand myself within boundaries."
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