> Sun, 17 Feb 2013 09:03:39 -0500 Ben Kibbey <b...@luxsci.net> >> On Wed, 16 Jan 2013 18:24:04 -0800, Nathan Myers writes: >> This patch seems to improve matters, for the slow.c just posted. >> I'm not sure I understand all the implications of moving the adjust >> after the read, but I don't see how to know the right adjustment to >> apply without reading first: I very frequently get short reads from >> this function.
> This patch works well for me. Without it and when doing alot of short > reads from an SSH server the download rate drops sharply after about > 200K. With this patch applied the speed is as it is from the beginning > for the duration of the entire transfer. Just for the record, I'm not suggesting using this patch in production. It's just a way of demonstrating the effect of window-adjust latency. One cause of the slowdown is that window adjustment messages are being lost, as a result of a bug in _libssh2_transport_send that I am preparing a fix for. (See trac #256) I think, too, that we need to maintain a minimum window not just the size of the user read buffer, but of that plus the bandwidth-delay product. If the total of readable bytes plus the remaining receive window goes below, say, 32K, that is probably a failure. If the receive window size ever reaches zero on an empty buffer, that's a serious failure. Nathan Myers _______________________________________________ libssh2-devel http://cool.haxx.se/cgi-bin/mailman/listinfo/libssh2-devel
