Subject: Re: sshd and scp/sftp: slow throughput on windows machines
From: Kevin K <[email-masked]>
To: Max Stein <[email-masked]>
Cc: <[email-masked]>
Date: Sat, 18 Mar 2006 16:10:39 -0600

On Mar 17, 2006, at 7:49 PM, Max Stein wrote:

> Unfortunately, the performance of the cygwin sshd server is very  
> poor when it comes to copying large files. I have made this  
> observation on several new and fast machines (3 GHz, 512 MB RAM,  
> 100 MB/s Intel Pro network card) running with Windows XP or Windows  
> 2003 Server. The best speed achievable was about 4 MB/s when  
> copying a file from the SSH client to the SSH server; when doing it  
> the other way round, the throughput was even worse, about 2.3 MB/s.  
> I tried it on three different machines running the newest version  
> of cygwin's sshd und scp/sftp. The results were approximately the  
> same.
> Neither the client's nor the server's processor was really busy.  
> The CPU usage oscillated around 30-40%.
>
> Setting up the same scenario on linux yielded a completely  
> different picture. Using the Knoppix disc 4.0.2 on the client and  
> the server machine I easily achieved a throughput of 10.8 MB/ in  
> both directions (pushing a file to the server or downloading a file  
> from it).
>
> What could be done to improve the performance of cygwin's SSH  
> server? There were already some older posts dealing with the same  
> problem but nobody had really a constructive idea or proposal.
>
>
> Max Stein

For what it is worth, I've also noticed his using the Putty tools,  
including Putty's scp client.  At first I thought it had to do with  
my wifi connection, but even when both computers were connected  
directly to a switch together, it was much slower than I would have  
expected.

The numbers you quoted above are in the ballpark of what I've  
measured with Cygwin's clients.

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