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Re: sshd and scp/sftp: slow throughput on windows machines
- From: Kevin K <k_krieser at sbcglobal dot net>
- To: Max Stein <Grizzly99 at gmx dot de>
- Cc: <cygwin at cygwin dot com>
- Date: Sat, 18 Mar 2006 16:10:39 -0600
- Subject: Re: sshd and scp/sftp: slow throughput on windows machines
- References: <003501c64a2e$3dede630$f4598350@HAUPTPC>
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
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
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.
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
The numbers you quoted above are in the ballpark of what I've
measured with Cygwin's clients.
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