[EN] KDE's slowness (fuse)

[gour]

Hello!

Few days ago I migrated to siduction - KDE spin - trying out KDE after many years. It's very polished environment, but, unfortunately, while restoring data from my previous install I do experience significant slowness...

I do use restic for backup – single ssd drive for OS and two raid1/btrfs hdds for /home. While restoring I usually use restic's mount cmd which does fuser-mount of external hdd (rdx cartridge) and then with mc I manually select the folders I want to restore.

I've noticed that under KDE, the whole process is very slow - mc shows throughput of about 7.5 MB/s which makes  the process of restoring >1.5TB unacceptably slow.

Not being able to deduce possible cause of the slowness, I've installed xfce-desktop and tried the same thing and I get > 25MB/s which makes it significantly (>3x) faster than under KDE.

I'd like to investigate the issue further before deciding to fully migrate back to Xfce, so humbly asking if you have some idea why cp-ing files in mc under KDE is more than 3x times slower on the same distro/hardware?

Sincerely,
gour

[Mister00X]

IIrc there (was) a bug in kio or kiofuse which reduced the transfer speed significantly, unfortunately I can't remember where I read this (and google was also unhelpful this time).

Just to clarify some things:

1. Do you mount this fuse filesystem using the command line or do you use dolphin to mount it?

2. If you do mount it via dolphin have you tried mounting it via the command line and  check if there is a difference in speed?

Another thing that could impact your transfer speed is the baloo file indexing service. Depending on your configuration if you for example have file indexing set up to your $HOME and you also mount your backup to a subdirectory in $HOME baloo could start trying to index this directory which will slow down your transfer speed because now multiple processes try to read from the same disk (I don't know this for sure, it could be not indexing fuse mounts).
So you could have a look at htop and check if baloo is running once you mount your backup. If that's the case you could exclude your mountpoint in .config/baloofilerc, stop indexing your entire $HOME altogether and only index certain directories or disable indexing entirely. You can see the currently indexed directories in systemsettings -> search -> file search

[gour]

IIrc there (was) a bug in kio or kiofuse which reduced the transfer speed significantly, unfortunately I can't remember where I read this (and google was also unhelpful this time).

Hmm, interesting...

1. Do you mount this fuse filesystem using the command line or do you use dolphin to mount it?

I'm mounting using the command line, iow. restic's mount cmd:

Code: [Select]

$restic -r /path/to my/mounted/drive restic /mnt/point


2. If you do mount it via dolphin have you tried mounting it via the command line and  check if there is a difference in speed?

It does not apply.

Another thing that could impact your transfer speed is the baloo file indexing service. Depending on your configuration if you for example have file indexing set up to your $HOME and you also mount your backup to a subdirectory in $HOME baloo could start trying to index this directory which will slow down your transfer speed because now multiple processes try to read from the same disk (I don't know this for sure, it could be not indexing fuse mounts).

I do mount to

Code: [Select]

/mnt/fuse, so probably it is not prone to baloo's indexing.

You can see the currently indexed directories in systemsettings -> search -> file search

OK, thank you.

I've also tried xfce-terminal under KDE and it's ~2x quicker - about 14MB/s than Konsole, which makes me think that despite KDE's general slowness caused by something, part of the problem is Konsole itself.

Moreover, I've tried with Kitty terminal emulator - both under KDE & Xfce and it does perform similar to xfce-terminal under KDE & Xfce.

Currently, I'm doing backup under Xfce and then will follow your advice checking what is the status of indexing service...before possibly migrating back to Xfce. 

[Mister00X]

I've also tried xfce-terminal under KDE and it's ~2x quicker - about 14MB/s than Konsole, which makes me think that despite KDE's general slowness caused by something, part of the problem is Konsole itself.

Moreover, I've tried with Kitty terminal emulator - both under KDE & Xfce and it does perform similar to xfce-terminal under KDE & Xfce.

This is (incredible) weird, your terminal emulator in general should have no impact on I/O speed. I'm no expert on terminal emulators though.

One thing you could also do is to have a look at iotop (needs root permissions) while doing the the transfer, this should give you a top like view of processes doing I/O at the moment.

You can also have a look if you see some unexpected process in the output of

Code: [Select]

# lsof +f -- PATH_TO_YOUR_MOUNTPOINT
You need to execute this as root.

Btw nothing is preventing you from using any terminal emulator you like on KDE

[hendrikL]

https://www.reddit.com/r/kde/comments/zr8qdy/what_is_the_problem_with_transfer_speeds_withing/

well maybe this was the article.

Well, try krusader, if i read it right.

[gour]

https://www.reddit.com/r/kde/comments/zr8qdy/what_is_the_problem_with_transfer_speeds_withing/

well maybe this was the article.

Well, try krusader, if i read it right.

I'll test with it, but I got slowness in Konsole/mc, not using Dolphin...

[gour]

After re-installing siduction/kde on my desktop machine, the issue somehow disappeared and now I'm getting decent io while restoring my fuser-mounted data with mc. 

Very pleased with KDE!