VERY(!) slow FTP sometimes

[Arnout Vandecappelle]

Leon Pollak wrote:
> Hello, all.
>
> I incorporated the RTEMS ftpd to my MPC8247 at 150MHz based board with 100BT FCC 
> controller and made several main tests - everything seems to work fine. I can 
> upload/download files by Linux ftp client, FireFox in Linux and IE in 
> Windows.
>
> Now, when I decided to test the speed, I encountered the following VERY 
> strange numbers:
> 1. IE as a client: in 100% of attempts the speed was about 14-16 KB/s.
> 2. FireFox(Linux) as a client:
> 	- in 90% of attempts the speed was about 400-460KB/s
> 	- in about 10% - 7-8 KB/s.
> Even in the "good" FireFox tests (above 400KB/s) the behavior looks also 
> strange a bit: it immediately starts at some number (once at 410KB/s, then at 
> 450KB/s, etc...) and does not change never more.
>
> 1. What may be the cause of the VERY low speed cases?
> 2. Is the "good" speed really good for my case? Can somebody provide numbers 
> from his/her experience?
 I think you'll need to collect more information.  Here are some hints:
* I guess all machines are connected to the same switch?  Try doing a
similar ftp from IE to the Linux box and see if it behaves similarly.
* During a slow transfer from the linux box, look at the output of
ifconfig and netstat -t; check if there are errors or long TCP queues.
* Try with something different than ftp.  E.g., use the netdemo
application from network-demos and connect to its echo port (24742). 
You can send a large file to it using netcat: time /bin/nc -q 1 -n -vv
[IP addr] 24742 < [some large file] > /dev/null
It reports at the end how many bytes were transferred, from that and the
time info you can derive speed.  The -q 1 is to force netcat to wait for
the echo response at the end of the file.
* In the netdemo application, you can also print network statistics with
the 's' command on the console.

 Good luck!
 Regards,
 Arnout

-- 
Arnout Vandecappelle                     arnout at mind be
Senior Embedded Software Architect       +32-16-286540
Mind Embedded Development (an Essensium division)
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