Red Hat Bugzilla – Bug 985113
SFTP transfers handled by kio_sftp are much slower than those handled by scp
Last modified: 2015-06-29 08:05:16 EDT
Description of problem:
On a gigabit network, I can transfer files with an average throughput of 80 Mib/s with scp. Transferring the exact files using Dolphin and kio_sftp gives an average throughput of only 12 MiB/s.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
0.a. Setup a gigabit network with at least two machines
0.b. Set up ssh access on machine 2
1. On machine1 open Dolphin
2. Click on the "address" bar. The bar becomes editable
3. enter "sftp://<user>@<ip_of_machine2>:/home/<user>"
4. Enter password when prompted for one
5. After directory loads, "copy"(Ctrl-C) a large local, and "paste" (Ctrl-V) it in the Dolphin window. This starts the transfer.
6. Use the "Network Management" widget to observe transfer speed
7. Try to copy the same or a similar file with scp:
$ scp large.file <user>@<ip_of_machine2>:/home/<user>/
8 Observe the transfer speed either by watching scp output, or using the "Network Management" widget.
kio_sftp: about 12 MiB/s average throughput, and 80% cpu (core) usage
scp: about 80 MiB/s average throughput, and 35% cpu (core) usage
Same throughput using both scp and kio_sftp, and same cpu usage.
I transferred one contiguous 8 GiB file. The network was comprised of standard CAT 5E cabling with a low-cost gigabit switch.
Ping? Issue is still here with latest F20 packages.
We're not likely to work on this downstream in fedora (largely due to time and expertise constraints).
If you have continued interest in resolving this, contacting upstream (via bugs.kde.org or mailing lists) will have a better chance at yielding results.
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