Need help applying settings from Iperf to Vista

[Dustie]

I have been testing a bit with Iperf because my LAN seems slow. With the default settings I get ~250MBit/s. Changing the buffer length to 64 gives me a result of ~750Mbits/sec. What I don't get is how do I apply those settings to Windows Vista?

Changing TCP window size also gives me a speed boost but again i don't know how to apply it since tcpwindowsize isn't a option in Vista.

 

[thiggins]

Don't mess with the settings in Vista (or XP for that matter).

Iperf/jperf's default settings are not optimal. Vista self-tunes TCP/IP parameters for best performance.

 

[Dustie]

Okay I'll leave the settings alone. . I heard of the auto tuning but something seems to be wrong then. Big file transfers has the same speed as ipref report. ~250MBit. Could it be that Vista doesn't like me transferring to/from Linux?

I'll test in Linux to Linux and Vista to Vista and see if it helps. That could be interesting

 

[00Roush]

Don't forget to add "socket options = SO_RCVBUF=65536 SO_SNDBUF=65536" to your smb.conf file on linux. Most Samba installs have a default of 8192 which can limit gigabit performance. Also make sure that your disks in both your linux and windows machines can actually transfer data faster than 250 Mbits/sec (~31 MB/sec). You could also test with FTP instead of Samba.

00Roush

 

[Dustie]

Isn't iperf working correctly then? Because i can easily get above 700Mbit with tweaked settings in i/jperf. From what information i have gathered on the net the auto tuning in Vista is far from working as it should.

 

[Dustie]

Okay, here are my results so far..

From xjperf:
Vista <-> Linux = ~250Mbit/s
Linux <->Linux = ~750Mbit/s

I tried transferring files using SMB to see how accurate the results were. I got exactly the same numbers as using xjperf. So it does seem that something is wrong here when using Vista. I'll would try Vista to Vista to see if that makes any difference but I'm not sure if the numbers would be any good as the second Vista machine is not the same as i used in the above test.

EDIT: I can't test Vista to Vista. I forgot that the laptop doesn't have a fast enough net card.

 

[00Roush]

You mentioned in your first post that when you use the defaults you get 250 Mbit/s and when you use buffer length of 64 (same as window size) you get 750 Mbit/s. This is on your Vista machine correct? I think your hang up is the fact that you are thinking you need to change the TCP window size on Vista to get the 750 Mbit/s. As Thiggins said Vista is auto tuning and it modifies the window size dynamically and usually on large files window size is set to 64k or larger on a local LAN.

Now the speeds you are seeing for file copies are a completely different matter. Iperf just measures the max TCP/IP speed between two computers at a given window size. Which is basically the max speed you COULD see for file transfers. File copy speed can be affected by many other factors. If your disks can only read at 30 MB/sec you will only be able to copy files at a max of 30 MB/sec. Also if SMB settings on linux are not set correctly speeds will suffer no matter what client OS you are using. (see my previous post for settings)

If you are seeing 700+ Mbit/s with iperf using a window (or buffer) size of 64k then I wouldn't worry about your TCP/IP settings until you are seeing file transfer speeds close to that.

Try testing with FTP instead of Samba. On the Vista client use a program like Filezilla client as it is much faster than the native FTP client in Vista.

For reference the Iperf command line I use is iperf -w 64k -c 192.168.0.2.

Hope that helps.
00Roush

 

[Dustie]

I'm not sure I understand your point. If I test from my own (Vista) machine to my girlfriends linux machine I get slow results both in iperf and with filetransfers (I'm testing with a 700MB ISO file). Now that I'm running linux on my own machine I get a lot faster results with both methods.

 

[00Roush]

Could you post the command line you use? Also when iperf runs what is the TCP window size.

Not sure if this will help or not... http://forums.smallnetbuilder.com/showthread.php?t=1118

00Roush