On 2015-03-26 14:48, Nitin Deokate wrote:
Hi Lars,
I had reported same issue around 8-9 months back. Please refer this mail
thread: http://www.libssh2.org/mail/libssh2-devel-archive-2014-06/0001.shtml
Is anybody already looking into this issue to fix?
I will try to solve this, I need better speed in SFTP download. I found
a way to get more then the internal datasize, but didn't get improvment
in speed.
I report back when I have an solution!
/Lars
Thanks
Nitin
-----Original Message-----
From: libssh2-devel [mailto:libssh2-devel-boun...@cool.haxx.se] On Behalf Of
Lars Nordin
Sent: Thursday, March 26, 2015 4:50 AM
To: libssh2-devel@cool.haxx.se
Subject: Re: SFTP slow read in libssh2 compared to SecureCRT
On 2015-03-25 23:53, Daniel Stenberg wrote:
On Wed, 25 Mar 2015, Lars Nordin wrote:
and I get 2000 bytes each time. The testfile is 116K.
Let me explain in rough terms why you see this 2000 bytes data and how
the libssh2 SFTP code works.
The SFTP code will take your given buffer size and split it into 2000
bytes chunks and ask the server for such data packets, as many as can
fit in your buffer.
A 20000 buffer thus ends up asking for 10 such packets - at once.
libssh2 will then return data back as soon as there is data to return,
which initially could be a single 2000 bytes packet but over time
should become a whole bunch of such packets assuming the bandwidth is
good enough.
But the code is just returning one packet of data, ie 2000 bytes (as I get
all the time)
rc32 = _libssh2_ntohu32(data + 5);
...
if(rc32 > 0) {
/* we must return as we wrote some data to the buffer
*/
return rc32;
the buffer is just one chunk, from your explanation I thought I would find
something like:
outlen +=rc32
and a buffer-pointer slider through the receive-buffer in the
sftp_read() parameter.
This concept is used because SFTP requires ACKs for ever packet it
asks for so it better ask for a whole bunch at once to suffer less RTT
pains.
My WireShark session tells different, I see a client package, and the 1 to 4
server packages, the output should be 10 client packages asking for data (or
maybe only one??) and then 10 server packages (using your example)
I will try to read the code and add some debug.
My 76M file transfers in 44 minutes using SFTP_read, 81s using SecureCRT
SFTP_read and 12s using scp...
/Lars
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