SCP with Resume Feature

rapier rapier at
Wed Apr 7 13:36:57 AEST 2021

On 4/6/21 10:04 PM, Damien Miller wrote:
> On Tue, 6 Apr 2021, rapier wrote:
>> Looking at the performance - on my systems sftp seems to be a bit slower
>> than scp when dealing with a lot of small files. Not sure why this is
>> the case as I haven't looked at the sftp code in years.
> the OpenSSH sftp client doesn't do inter-file pipelining - it only
> pipelines read/writes within a transfer, so each new file causes a
> stall.
> This is all completely fixable on the client side, and shouldn't apply
> to things like sshfs at all.

Gotcha. Is this because of how it sequentially loops through the 
readdirs in two _dir_internal functions? If so I'm wondering if you 
could spawn per file threads to get some concurrency within a directory. 
Just curious and this is the first time I've looked at the sftp code in 
years. I hope you don't mind the questions.


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