That's great stuff, I wonder how it compares to wdt[0] when there's only one TCP path. This has been my go-to tool to transfer files on the network.

0: https://github.com/facebook/wdt

Looks like a cool project! There's no network functionality in wcp at the moment, but it's definitely something I'd consider adding in the future.

I'd like to see more performance analysis.

10 years ago I found there was little benefit for async i/o to a disk, even though it great for networking.

With SSD it coukd he different if you have a very long q depth, but he shows charts for copies over nfs where async i/o might find a lot of latency to hide.

The chart is showing data from an NFS copy, but the listed speeds in the blog and on github[1] are from a copy on a local SSD. That is a bit confusing though, maybe I should make it more clear. I used the network copy for ETA calculation because it was an easy way to make the transfer take longer - if the whole copy is only a few seconds long it's difficult to meaningfully compare ETA estimation accuracy between two approaches. I would like to have more performance data though.

1: https://github.com/wheybags/wcp/#how-fast

I would love to see a comparison between scp and wcp over NFS, more specifically large single file sizes, if folks are looking to discern more performance parameters.

wcp is good stuff!

I would expect pretty much any plain copying program over NFS to beat scp, since scp has the overhead of encryption. On a slow disk with a fast CPU it might roughly match though.