Gigabit LAN only 200Mbit/s - suggestions?

Hi all,

On a gigabit LAN I am only getting around 200 - 250 mbps (~30MB/s) when transferring files between 2 computers.
My setup is:
CAT5e cables - longest 10m
Switch Linksys SD2008 - in tests got 980 mbps/s throughput

Code:

http://soltesz.net/sd2008/part3.html

1.PC - CPU C2D E8400, MB gigabyte ep45-ds3l with realtek 8111b integrated PCIe NIC, 4gb ram, Windows 7 professional 64bit, Eset smart security, chimney offload enabled, auto-tuning normal, MTU 1500
2.PC - CPU Atom D525 (2cores, 4 threads, 1.8Ghz), integrated realtek 8111b PCIe NIC, 2gb ram, Windows 7 professional 32bit, comodo firewall, avira antivir, chimney offload enabled, auto-tuning normal, MTU 1500

The hard drives can manage around 60MB/s, but on the network I am getting only 30MB/s when transferring files between windows shares. Iperf gives similar results.
When looking at the Atom computer, resource monitor shows one (1 out of 4) thread utilized to 100% and the other 3 threads are at few %. Therefore I am thinking that this is causing the slow speed.
Can anyone point me to reason why would Win7 use only one thread when processing network traffic (SMB)? Is there anything I can do to fix this?

Any help is greatly appreciated.
Thank you
Laserjet,

Firstly, Hi and welcome to the forums....check me out I sound liike a pro now !! lol.

Great description of your kit!!
think we should be able to speed it a bit !!

first you may want to turn off your "chimney offload", this technology is for use with specific hardware (nics) which have onboard processors, sometimes also referred to as TOE cards. see here for more info.Information about the TCP Chimney Offload, Receive Side Scaling, and Network Direct Memory Access features in Windows Server 2008

secondly a common overlook when dealing with throughput is to confirm that there isn't a fault with your cabling.

to fully appreciate the max you can get out of your setup you should disable both AV and firewalls. NB you may need to fully uninstall them so packet filters and the like aren't interfering. as soon as you've completed your tests reinstall (if needs be) and turn them back on.

let us know how you get on...

ant

oh yeah, just remembered, to get the quickest connection between machines, swap the cat5 to the router(s) for a single X over cable, if you have one, connecting both machines.

May not apply, but often overlooked...

Keep the Cat5 cables as straight as possible, no loops or bunching.

Thanks for the welcome and quick reply.
I sure hope its not the cables. Changing them is not impossible, but something I really would like to avoid. But I will borrow a cat6e xover tomorrow and give it a try. I have tried disabling the firewall (though not uninstalling) had no effect.
I have played with the chimney, which had no effect.
But its an interesting thing. The chip in the Atom board is 8111e and this is was realtek says on their product page:

The RTL8111E is fully compliant with Microsoft NDIS5, NDIS6 (IPv4, IPv6, TCP, UDP) Checksum and Segmentation Task-offload (Large send and Giant send) features, and supports IEEE 802 IP Layer 2 priority encoding and IEEE 802.1Q Virtual bridged Local Area Network (VLAN). The above features contribute to lowering CPU utilization, especially benefiting performance when in operation on a network server.

The windows ethernet controller options lets me enable or disable all sorts of offload (tx/rx for checksum, ets.) BUT, when I netstat -t, it tells me all connections are processed in host and not offloaded. Are these 2 different things? (the realtek's specs and windows chimney offload)

Well, I was afraid that the Atom was the bottleneck (saturating one thread) but your reply suggests other things are more likely, right?
As I to suspect the cabling, I will get the short xover and try. I will let you know.
Thanks,

if you are using software initiators then it won't offload properly, I can only presume this is why MS introduced the chimney, but think about it, the CPU is still going to have to be involved.
MS has so many good ideas around putting trying to emulate these sort of hardware features into their OS's the last big F up was software RAID, GOOD GOD MAN NO!! LOL !!

If your NICs are capable as you suggest then maybe there is a POST (pre windows boot) configuration setting that would allow you to make the iSCSI connection outside of windows.

pparks1 said:

DeVandal said:

May not apply, but often overlooked...

Keep the Cat5 cables as straight as possible, no loops or bunching.

This shouldn't make a difference at all.

to be fair DeVandal is right to some degree, CAT6 cabling requires extra care around handling of the ends, have you seen the size of the boots and clearance in floor boxes needed on those mother hubbards....:)

Also I have been on a number of sites, where the user has loose laid cables and damaged them by running their wheeled chairs over them....so never say never.

The radius of bends in Cat5 cable should be > = 4x cable diameter. This maintains the integrity of the standard.

Loops can become kinks.

Damn, always doing that missing the obvious, the stats you quote in the OP, are they your figures or advertised?

if they are advertised they have probably used NICs with Jumbo packets configured. This means setting your MTU to 9000!!! instead of your normal 1500.

however still doesn't explain why other machines have got reasonable throughput and these machines are pants.

lets have a little bit more of a think.