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From "Daniel F. Savarese" <...@savarese.org>
Subject Re: [vfs] FTP extremely slow compared to SFTP
Date Fri, 14 Dec 2007 00:14:39 GMT

In message <47618A9E.70408@gmail.com>, =?ISO-8859-1?Q?Thorbj=F8rn_Ravn_Andersen
?= writes:
>Depends on your compression method.  If the network is fast it doesn't 
>take much CPU cycles/byte before the transmission is slowed down.

Of course the behavior is going to be a function of the CPU speed,
the memory hierarchy, the network latency and throughput, the
compression algorithm used, the implementation of the algorithm, the
nature of the data, etc.

Getting back on topic, I had not looked at the reported numbers when I
wrote my initial comments, which were based on large files.  SFTP should
do worse on small files.  The reported numbers are exactly the opposite
of what one would expect for compressible data (not that the larger
file sizes were all that large).  I continue to recommend examining
how VFS is using the two libraries (e.g., does VFS do an FTP directory
listing for each file transfer).  All I can say is that I can transfer
hundreds of files in succession with FTPClient at basically the same rate
as command-line FTP.  If I can't reproduce the problem at the FTPClient
level, then either that's not where the problem is or I don't understand
the problem (which is a good possibility since I'm jumping in mid-thread).
The best way to proceed to resolve the issue is to open a bug report and
provide a test case that reproduces the problem so that we can figure out
what's going on and try to fix it.


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