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?
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 _______________________________________________ libssh2-devel http://cool.haxx.se/cgi-bin/mailman/listinfo/libssh2-devel _______________________________________________ libssh2-devel http://cool.haxx.se/cgi-bin/mailman/listinfo/libssh2-devel
