Hello everybody,
I have noticed that when I download something with gftp (slack 9.1) from my local ftp server (linux based), is much faster than when I download the same file with Windows XP from the same machine...
Could someone help me explain this?

Thread handling.

I was baffled the first time I encountered it too. However, after considering that Linux was built from the ground up as a Network Operating System (NOS), it came as no suprise that it performs well in this area.

Windows, on the other hand, (especially the non-server builds like 95, 98, ME, and to some extent XP... more likely XP Home Edition), has a legacy of a non-networked OS. The network support was (probably hastily) integrated during the Internet boom. However, XP's network performance is more reliable than earlier versions (sans Win2K, but this is just my opinion).

This post is more of an expression of opinion, I don't work for MS nor any Linux distro company, nor am I a kernel hacker. So my opinions might even be completely unfounded.

hmm ... i don't think that is it, though there would be a minimal component.

i'd say that the reason is that your interpretation of "faster" is not quite there. The distinction is the one i usually mistake namely that different programs represent throughput very differently:

some programs, such as IE like to show you a nice stable speed, you are downloading at 2.7Kb/s ... and your variation in this is minimal, the reason you see it that way, is that ie averages this out for you, ie your speed fluctuates, but you've downloaded XMB in Y minutes, therefore your speed is X/Y

Konqueror, on the other hand shows a different picture, it shows your current speed, ie right at this moment, which is why you often get a "stalled" readout, then the speed jumps up and levels of again. I'd say this may be due to speed fluctuation, or multi threading, in that the system is busy doing something else, so it cuts konqueror out for a little while, so when it finally gets updates again it goes "WHOA" and recalculates your speed, then eventually realises the error of its ways ...

dunno about gftp (which is a nice client), but one easy way of checking what reality looks like would be download the same file from the same server using both win and lin and time it using a stop watch.

Well, I don't think that the case is the way different applications show the download speed (current or average). I have noticed that the difference is more than 30 or even 40 %. I don't know if it has something to do with the fact that the ftp server is running linux too...Anyone can help?

Interesting .... See, i'm either on a dialup, and that gives me the bottom of the barrell in terms of speed, so i don't get such great time differences - downloading 30 MB takes "long", not minutes. And when i worked, we didn't have Linux or windows systems on comparable connections (Linux servers on fat pipes, and Windows terminals on 10/100), but:

i just connected my laptop (Linux 2.6.6) and my Desktop (Windows 2000) to ftp.au.kernel.org

i grabbed linux-2.4.26.tar.bz2

Because i'm unco, i didn't manage to start them exactly same, and linux limped behind.
after about 30 seconds, Linux was winning by about 30% speed. with 9.3MB transfered, and Windows still at about 6.5MB

So yeah ... significantly faster (and yes, that's a very reasonable connection to start with).

So yes, you are quite right, my original theory clearly is wrong.

So ... the plot thickens.

Now this deffinately needs testing! Off to kernel.org !