[RndTbl] Network performance tuning

[Sean Walberg]

IIRC UDP needs you to pass the desired bandwidth, otherwise it defaults to a
megabit.

Sean

On Mon, Apr 5, 2010 at 9:43 PM, Kevin McGregor
<kevin.a.mcgregor at gmail.com>wrote:

> When I choose UDP, I get
>  0.0-15.0 sec  1.88 MBytes  1.05 Mbits/sec  6.154 ms    0/ 1339 (0%)
>
> No packet loss. 0.1% utilization!
>
>
> On Mon, Apr 5, 2010 at 8:12 PM, Sean Walberg <swalberg at gmail.com> wrote:
>
>> On a LAN, window sizes aren't going to make that much of a difference.
>>
>> First look for the usual suspects - errors on the swich port or NIC.
>>
>> If you can grab a copy of the traffic, such as with tcpdump -w test.pcap
>> tcp port 5001, you can pull it into wireshark and look for TCP zero window
>> conditions, retransmits, and duplicate ACKs. The TCP performance graph will
>> also show whether or not the transmission is stalling.
>>
>> Is the performance similar using the UDP test? Does it show loss?
>>
>> Sean
>>
>> On Mon, Apr 5, 2010 at 7:27 PM, Kevin McGregor <
>> kevin.a.mcgregor at gmail.com> wrote:
>>
>>> I've been trying to narrow down where my performance bottleneck(s) is
>>> (are). I just ran "iperf" from a Windows PC (XP SP3) to my Ubuntu 9.10
>>> server. With iperf in "server" mode on the PC, and the client running on the
>>> Ubuntu machine, I get
>>>  0.0-60.0 sec  4.23 GBytes   606 Mbits/sec
>>>
>>> Reversed (iperf "server" running on Ubuntu server, client running on the
>>> PC), I get
>>>  0.0-60.0 sec  1.13 GBytes   162 Mbits/sec
>>>
>>> Wha...?? Both client and server runs on the PC report TCP window size to
>>> be 8 KB, but the Linux client reports 22.4 KB and the Linux server reports
>>> 85.3 KB. Increasing that to 256K on both ends has little effect. Does anyone
>>> have any suggestions?
>>>
>>> The Windows NIC is a Realtek RTL8169/8110 Family Gigabit Ethernet; the
>>> Ubuntu server is using the Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI
>>> Express Gigabit Ethernet controller (rev 01). Time to replace a NIC or two?
>>>
>>> Kevin
>>>
>>> _______________________________________________
>>> Roundtable mailing list
>>> Roundtable at muug.mb.ca
>>> http://www.muug.mb.ca/mailman/listinfo/roundtable
>>>
>>>
>>
>>
>> --
>> Sean Walberg <sean at ertw.com>    http://ertw.com/
>>
>> _______________________________________________
>> Roundtable mailing list
>> Roundtable at muug.mb.ca
>> http://www.muug.mb.ca/mailman/listinfo/roundtable
>>
>>
>
> _______________________________________________
> Roundtable mailing list
> Roundtable at muug.mb.ca
> http://www.muug.mb.ca/mailman/listinfo/roundtable
>
>


-- 
Sean Walberg <sean at ertw.com>    http://ertw.com/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.muug.mb.ca/pipermail/roundtable/attachments/20100405/f2e4158a/attachment.html