[K12OSN] More feedback on Fedora 10 + LTSP

David Hopkins dahopkins429 at gmail.com
Wed Apr 29 01:59:04 UTC 2009

> With k12ltsp you should be able to enable ssh on the clients so you could
> connect and run ifconfig.   Did you measure the server NIC throughput under
> CentOS5.2+LTSP4.2 to see if there is a large difference?  I think you
> mentioned the switch having flow control enabled.  Can you turn it off?
> http://www.smallnetbuilder.com/index2.php?option=com_content&task=view&id=30212&pop=1&page=0&Itemid=54


The switches had flow control turned on which apparently was limiting
the Gig-E link to appr 100Mbps. I turned it off and launched 21
sessions of Tuxmath. It wasn't playable but once I backed it down to
around 8-10 sessions, it was tolerable. However, tracking the
throughput on the switch as I backed it down, the max I ever saw was
400Mbps and it stayed closer to 300Mbps.  Load on the server never
exceeded 8 (on an 8cpu system).  So, while a lot better, something is
still limiting the throughput. I thought it might be packet size
related, so I ran NetIO from this system to another on a Gig-E link
with  the folllowing typical results:

TCP connection established.
Packet size  1k bytes:  82750 KByte/s Tx,  112086 KByte/s Rx.
Packet size  2k bytes:  87499 KByte/s Tx,  113424 KByte/s Rx.
Packet size  4k bytes:  95495 KByte/s Tx,  112055 KByte/s Rx.
Packet size  8k bytes:  94037 KByte/s Tx,  114064 KByte/s Rx.
Packet size 16k bytes:  102218 KByte/s Tx,  114743 KByte/s Rx.
Packet size 32k bytes:  104406 KByte/s Tx,  114689 KByte/s Rx.

These are representative (I ran the test 10 times).  So, I'm not
totally sure what is up with the Tx numbers.

Still, thanks to everyone ... I at least have a good idea of where to
look now. And, worst case, I can get a card and just use channel
bonding to get the throughput up if I have to with some hope that it
will actually work.

Dave Hopkins
Newark Charter School

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