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Re: sshd and scp/sftp: slow throughput on windows machines

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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