Parallel transfers with sftp (call for testing / advice)

Cyril Servant cyril.servant at
Mon May 18 23:38:53 AEST 2020

Hi David,

> I've lost track of who the original poster is, but you seem to be at least involved.
> Per my previous email, I'm still curious to know what performance do you get (using an unpatched sftp) when you use "-R 640"?

With the "-R" option, you're still bound to the power of a single core of your
CPU for encryption / decryption. The proposed patch creates a new ssh
connection per thread. So if you have at least 2 cores on your CPU (client and
server-side), you will be able to use 2 times more bandwidth with "-n 2".

I just made some tests to be sure, and the "-R 640" option slows down transfers
(a bit). I guess it's because the transfer speed is limited by CPU power and
not network bandwidth speed.


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