Investigate why small transfer is slow in AsyncSshTransport

[khsrali]

Here #6626 (comment)

I ran some tests comparing small file transfers between core.ssh_async and core.ssh
The one for core.ssh_async is slower.

I originally thought because the I/O for small tasks are not really blocking that much so that one is slow because it has async over heads.

But I may be wrong, so a more careful look is needed. Suggestions from @giovannipizzi

• One can check the scaling by limiting async workers to 2-4-8, etc.
• Try to change number of files to see the scaling
• Or it might be slow becasue BeeGfs has limits on concurrent tasks thor server (where I perfomed those test)

[danielhollas]

@khsrali If you could include the scripts that you used for the original benchmarking (and any additional details about your approach) I could at least try to reproduce your results.

[khsrali]

@danielhollas fair point 😅
I'll polish my script adding comments, etc. and will put it here soon.. stay tuned