Re: What exactly is net.inet.tcp.sockthreshold?
Re: What exactly is net.inet.tcp.sockthreshold?
- Subject: Re: What exactly is net.inet.tcp.sockthreshold?
- From: "Chris McFarling" <email@hidden>
- Date: Sun, 2 Oct 2005 23:08:52 -0500
----- Original Message -----
From: "Peter Sichel" <email@hidden>
To: <email@hidden>
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?
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