Subject: [libssh2] [ libssh2-Bugs-1538093 ] Slow Transfer Speeds

[libssh2] [ libssh2-Bugs-1538093 ] Slow Transfer Speeds

From: SourceForge.net <noreply_at_sourceforge.net>
Date: Mon, 03 Dec 2007 03:10:31 -0800

Bugs item #1538093, was opened at 2006-08-10 16:24
Message generated for change (Comment added) made by bagder
You can respond by visiting:
https://sourceforge.net/tracker/?func=detail&atid=703942&aid=1538093&group_id=125852

Please note that this message will contain a full copy of the comment thread,
including the initial issue submission, for this request,
not just the latest update.
Category: None
Group: None
>Status: Closed
>Resolution: Invalid
Priority: 5
Private: No
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Nobody/Anonymous (nobody)
Summary: Slow Transfer Speeds

Initial Comment:
Hi.

Using ssh on high-speed internet links can see poor
performance with TCP Window size adjustments.

For openssh, there is a workaround for this slow speed,
which increases the window size inside of the channel:

If you are using openssh-3.5pl, the line to change is
119 of channels.h. Change value of
CHAN_SES_WINDOW_DEFAULT from 4*CHAN_SES_PACKET_DEFAULT to
100*CHAN_SES_PACKET_DEFAULT.
Below is an excerpt from an updated channels.h, with
the change indicated in red:
#define CHAN_EXTENDED_IGNORE 0
#define CHAN_EXTENDED_READ 1
#define CHAN_EXTENDED_WRITE 2
/* default window/packet sizes for tcp/x11-fwd-channel */
#define CHAN_SES_PACKET_DEFAULT (32*1024)
#define CHAN_SES_WINDOW_DEFAULT
(100*CHAN_SES_PACKET_DEFAULT) /*?
ORBITAL: changed from 4 to 100 */
#define CHAN_TCP_PACKET_DEFAULT (32*1024)
#define CHAN_TCP_WINDOW_DEFAULT (4*CHAN_TCP_PACKET_DEFAULT)
#define CHAN_X11_PACKET_DEFAULT (16*1024)
#define CHAN_X11_WINDOW_DEFAULT (4*CHAN_X11_PACKET_DEFAULT)

However, I cannot find a similar place inside of
libssh2's codebase to make a change that will work
along these lines. I have tried changing

LIBSSH2_CHANNEL_WINDOW_DEFAULT
LIBSSH2_CHANNEL_PACKET_DEFAULT

with no success.

----------------------------------------------------------------------

>Comment By: Daniel Stenberg (bagder)
Date: 2007-12-03 12:10

Message:
Logged In: YES
user_id=1110
Originator: NO

Slow transfers aren't really a bug in libssh2 but unfortunately still
mostly a design-issue.

I don't see how any references to openssh helps us, nor do I believe it
has to do with the TCP window size. I would not be surprised however if the
SSH window size is involved.

----------------------------------------------------------------------

You can respond by visiting:
https://sourceforge.net/tracker/?func=detail&atid=703942&aid=1538093&group_id=125852

-------------------------------------------------------------------------
SF.Net email is sponsored by: The Future of Linux Business White Paper
from Novell. From the desktop to the data center, Linux is going
mainstream. Let it simplify your IT future.
http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4
_______________________________________________
libssh2-devel mailing list
libssh2-devel_at_lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/libssh2-devel
Received on 2007-12-03