Bugs item #1538093, was opened at 2006-08-10 16:24
Message generated for change (Comment added) made by bagder
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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.
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Received on 2007-12-03