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Windows 2000/XP http download speed vs linux.


Sfor

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I found an interesting issue while testing download speeds from different computers with and without proxy. I did use the same server and file on it and the same 20/4 Mbit Internet connection.

 

From Windows 2000/XP I can get up to 497kb/s, while from Linux (CentOS) it goes to 1,4Mb/s. What's more interesting while downloading from Windows 2000 using proxy server on the same Linux computer I did get over 1MB/s as well.

 

The best results were with WGET, but the similar differences were visible in Firefox, as well.

 

There has to be something slowing down HTTP downloads in windows 2000/XP, since it is possible to get around it by using proxy server working on Linux computer. Using a proxy on Windows XP did not increase the download speed and the result was almost the same as direct download. I used 3proxy, as it is available on both Windows and Linux systems.

Edited by Sfor
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Started the experiments with TCPWindowSize. Apparently it does not seem to change anything by itself.

 

On the other hand, the Tcp1323Opts can prevent some applications from working properly. Apparently Large TCP Window support is not 100% compatible.

 

I heard about the TcpIP patch in relation with the Windows XP limit of half open connections, but I see no relation to Windows 2000, what so ever.

 

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After a thought. For some reason the connections with proxy server can get much higher data rate, than direct connections with HTTP server. But I had no opportunity to make any tests with a remote proxy server, as I have no access to a sufficiently fast one.

 

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I did test the registry tweaks from "Recommended settings for Windows 2000 / XP". The result was no change, at all. But, after setting TCPWindowSize below 64240 the download speed went down about 10%.

 

I was unable to test the benefits of the Tcp1323Opts=1 needed for large TCPWindowSize, as both Firefox 12 and WGET are not connecting at all in such a case.

Edited by Sfor
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I did test all of these registry changes, already. According to my predictions some applications should stop working, after applying the patch. Also my Internet services provides a low latency Ethernet 100 Mbit connection. So, I'm not in this particular patch target group.

 

The biggest problem is the "Tcp1323Opts"=dword:00000001" line. For some reason it causes WGET and PopTray to be unable to connect to servers. The Firefox 12 can not download files from some servers, as well.

 

Also the "TcpWindowSize"=dword:0003ebc0" is problematic. I found some Microsoft article about bugs in the Windows 2000. The work around was to use values lower than 64240 with it, or to use GlobalMaxTcpWindowSize instead.

Edited by Sfor
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  • 4 weeks later...

I decided to try to tweak the Windows XP, and the results were significant.

 

At the beginning the download speed was around 460kBps. After applying TcpWindowSize="256960" the download speed went up to 2MBps. So, the TCP window setting is very effective in Windows XP, but for some reason, it doesn't seem to work with Windows 2000.

Edited by Sfor
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Well I did try the GlobalMaxTcpWindowSize="256960" as suggested in the Microsoft article, but it seems it does not affect the download performance in any significant way. I'm starting to believe the Windows 2000 has a hardcoded limit for TCP window size.

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Well I did try the GlobalMaxTcpWindowSize="256960" as suggested in the Microsoft article, but it seems it does not affect the download performance in any significant way. I'm starting to believe the Windows 2000 has a hardcoded limit for TCP window size.

 

I will try again ;):

 

 

 

it seems like on Windows 2000 you need to have 3 (three) parameters, ALL of them properly set:

 

  1. GlobalTcpMaxWindowSize
  2. TcpWindowSize
  3. Tcp1323Opts

jaclaz

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Finally. I can see some improvement. The download speed went up from 460 to 940kBps on Windows 2000.
How?By sheer magic :w00t: or using WHICH settings?The given ones? 
GlobalTcpMaxWindowSize REG_DWORD 131400 (decimal)TcpWindowSize REG_DWORD 131400 (decimal)Tcp1323Opts REG_DWORD 3
What happens if you increase both the 131400 (which is 90*1460, while the 256960 is 176*1460) to the next multiples of 1460?LIke (say):166600189800219000248200:unsure: jaclaz
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