[arch-general] KDE plasma, baloo and UI/video playback freezes

Carsten Mattner carstenmattner at gmail.com
Tue May 8 21:19:59 UTC 2018

On 5/8/18, Francesco Porro <frapox at gmail.com> wrote:
> In data martedì 8 maggio 2018 21:08:35 CEST, Carsten Mattner ha scritto:
>> Linux block layer's writeback system was supposed to fix this,
>> but I've also noticed that the mechanism isn't perfect and
>> you can still have a "hanging" application when doing the
>> infamous USB-to-USB transfer that kills the VM subsystem.
>> Another way I can reproduce it is when there SSD-to-thumb-drive
>> and you decide to some disk activity, too.
>> https://lwn.net/Articles/682582/
>> The problem is that VM gets pressured a lot and the whole
>> construct fails in a way, while working as designed,
>> manifesting as hanging programs.
> Ok, but I'm talking about HDD on Sata bus. No Usb-to-usb transfers
> involved. And, as said before, I've altready tweaked the
> vm.dirty{writeback,background_ratio} to partialy word around this,
> either on Debian or Arch linux.

It's easier to trigger with slow devices but ultimately the
same issue of block layer and vm subsystem getting overwhelmed.

>> First, to confirm, if you manage to run the indexer like
>> you would `ionice -c idle <the-indexer>`, and it shows
>> less hangs, you know the issue is unfair I/O queuing.
> The indexer's process autostarts and rapidly kills himself in a bunch of
> seconds... its impossible to renice the process, however I saw (by
> Ksysguard) it's always 19 as nice value... meaning high fairness both
> for the CPU, and I think for the IO too.
>> You can compare the block layer kernel configuration of
>> Debian vs Arch.
> Sorry, how to? Which are the keyword for searching?

On both systems there should be /proc/config.gz of the
running kernel. If you have a suspicion which kernel
option is responsible, you can check if it's different
between Arch and Debian.

>> You can try deadline or bfq schedulers. One is dead simple
>> and the other optimizes for desktop responsiveness.
> As a last chance, I'll look into these alternatives schedulers. But now,
> either Debian or Arch are using the same one: Cfq. So I don't think this
> is the cause of the problem.

Sounds true. Is it only that one application or others as well
when they cause much I/O?

More information about the arch-general mailing list