scp slow against Cygwin sshd

Discussion:

Mario Kuechler

2003-09-04 11:50:45 UTC

Hi,

when scp'ing files to or from Windows (2000) boxes with Cygwin sshd
installed (out of the box installation) transfer speed is not higher than
100 KB/s. All other network operations work as expected (100 MBit).

Where to start debugging?

Regards,
Mario

Christopher Faylor

2003-09-04 13:57:22 UTC

Permalink

Post by Mario Kuechler
when scp'ing files to or from Windows (2000) boxes with Cygwin sshd
installed (out of the box installation) transfer speed is not higher than
100 KB/s. All other network operations work as expected (100 MBit).
Where to start debugging?

http://cygwin.com/problems.html

Mario Kuechler

2003-09-04 14:21:45 UTC

Permalink

Post by Christopher Faylor

Post by Mario Kuechler
Where to start debugging?

http://cygwin.com/problems.html

So the first step is the cygcheck output? It's attached.

Regards,
Mario

Igor Pechtchanski

2003-09-04 15:33:31 UTC

Permalink

Post by Mario Kuechler

Post by Christopher Faylor

Post by Mario Kuechler
Where to start debugging?

http://cygwin.com/problems.html

So the first step is the cygcheck output? It's attached.
Regards,
Mario

Cygwin DLL version info:
DLL version: 1.3.22
^^^^^^
cygwin 1.3.22-1
^^^^^^^^
openssh 3.6.1p1-2
^^^^^^^^^

Does upgrading to the latest Cygwin (1.5.3-1) and openssh (3.6.1p2-2)
solve this problem? It's usually a good idea to upgrade to the latest
version before problem reports.

If the latest Cygwin and openssh don't solve this problem, try running
"scp -vvv" and see if that provides any clues. There's also strace ("man
strace"), which can tell you where the time is going. Please make an
effort to understand and analyze the strace output before dumping gobs of
data to this list.
Igor

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Mario Kuechler

2003-09-04 16:14:28 UTC

Permalink

Post by Igor Pechtchanski
Does upgrading to the latest Cygwin (1.5.3-1) and openssh (3.6.1p2-2)
solve this problem? It's usually a good idea to upgrade to the latest
version before problem reports.

Well, yes. But Cygwin 1.3 just works. Anyway, I upgraded to the new 1.5 and
nothing changed.

Post by Igor Pechtchanski
If the latest Cygwin and openssh don't solve this problem, try running
"scp -vvv" and see if that provides any clues. There's also strace ("man

This shows TCP window size(?) related adjustments:

debug2: channel 0: window 49152 sent adjust 81920
20m 0% 144KB 144.1KB/s 02:14 ETA
debug2: channel 0: window 49152 sent adjust 81920
20m 0% 192KB 96.0KB/s 03:21 ETA
debug2: channel 0: window 49152 sent adjust 81920

But these adjustments can also be watched when scp'ing from a Solaris 8
(Server - openssh) to Cygwin (client - scp):

debug2: channel 0: window 57344 sent adjust 73728
debug2: channel 0: window 57344 sent adjust 73728
debug2: channel 0: window 57344 sent adjust 73728

Post by Igor Pechtchanski
strace"), which can tell you where the time is going. Please make an

I had a first look at the strace output. Mmh. Just too much. I'll another
look later.

Post by Igor Pechtchanski
effort to understand and analyze the strace output before dumping gobs of
data to this list.

Sure, I won't :)

Cheers,
Mario