site_archiver@lists.apple.com Delivered-To: Macnetworkprog@lists.apple.com ----- Original Message ----- From: "Peter Sichel" <psichel@sustworks.com> To: <Macnetworkprog@lists.apple.com> Sent: Sunday, October 02, 2005 3:26 PM Subject: Re: What exactly is net.inet.tcp.sockthreshold?

On 9/30/05, Chris McFarling wrote:

...

Is there a way to force AFP to use a specific window size? Long story short...when two Gb OS X clients send simultaneously to our XServe (via AFP), the transfer rate for each drops to about 6MB/s. (when either machine is sending by itself, the transfer rate is ~ 30-40MB/s). I've duplicated this behavior with iperf as well. Using iperf, I've found that by decreasing the window size, the performance is dramatically improved.

I would love to be able to make AFP use a smaller window size as well, at least to test and see if it makes a difference.

Simultaneous upload and download performance is a classic problem with TCP/IP.

<http://homepage.ntlworld.com/robin.d.h.walker/cmtips/downup.html>

You might want to consider using a rate limiter like IPNetSentryX:

<http://sustworks.com/site/app_note_1006.html>

It adjusts the TCP window size on the fly to improve traffic flow (especially when large buffers are involved).

You might also use IPNetTunerX to experiment with various settings on the fly, and IPNetMonitorX see the corresponding effect.

Kind Regards,

- Peter Sichel Sustainable Softworks

Well, the actual problem in this case is not simultaneous uploading/downloading. It's simultaneous *uploads* to a single server from, in my testing, two clients. The scenario descibed in the above link does not really apply here. In my case, two clients send to the server simultaneously over our LAN (all are on gigabit). The transfer rate of each client drops to ~6-8MB/s. Whereas, each individual client is capable of sending to the same server at ~30-40MB/s. While there is obviously going to be a decrease in performance when two Gb devices are sending to one Gb device, I would expect a better transfer rate than 6MB/s. So anyway, based on the fact that the AFP server overrides the system default TCP window size by using SO_RCVBUF, is IPNetSentryX able to override that behavior of AFP? _______________________________________________ Do not post admin requests to the list. They will be ignored. Macnetworkprog mailing list (Macnetworkprog@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/macnetworkprog/site_archiver%40lists.... This email sent to site_archiver@lists.apple.com