i/O Slowing the desktop? Is this true for openSUSE as well?

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#1

Saw this on slashdot and curious as to how it applies to openSUSE.

Slashdot Ask Slashdot Story | The State of Linux IO Scheduling For the Desktop?

“I’ve used Linux as my work & play OS for 5+ years. The one thing that constantly drives me mad is its IO scheduling. When I’m copying a large amount of data in the background, everything else slows down to a crawl while the CPU utilization stays at 1-2%. The process which does the actual copying is highly prioritized in terms of I/O. This is completely unacceptable for a desktop OS. I’ve heard about the efforts of Con Kolivas and his Brain**** Scheduler, but it’s unsupported now and probably incompatible with latest kernels. Is there any way to fix this? How do you deal with this? I have a feeling that if this issue was to be fixed, the whole desktop would become way more snappier, even if you’re not doing any heavy IO in the background.”

#2

Yes,
You can modify the I/O Scheduling priority.

Possibly the easiest way to do this is if you’re running KDE 4.x (or later).

  1. Invoke System Activity by CTL-ESC
  2. Rt-click on the process you want to modify and select “Renice process…”

You’ll see displayed graphically options (slide bar) to increase or decrease niceness (application priority) and the I/O Scheduler. Note that renice only advises the Schedular and is not a hard setting which would be dangerous. Also, increasing the application’s priority beyond its default setting will prompt for root permissions.

HTH,
Tony

#3

I never observed what is described on slashdot. I/O very often needs a lot of CPU.

#4

I can not confirm this behaviour - I often move huge files to another harddrive and still can work nicely meanwhile, even though files get encrypted when moving to this other HD. I also do not experience any slowdowns when copying files within the same partition.

Con Kolivas’ approach was not aiming at I/O-scheduling (as in copying / moving files) but general desktop performance (as in process scheduling). After CK stopped working for the Kernel branch, this was implemented by Ingo Molnárs →Completely Fair Scheduler. The CFS is based on Con Kolivas’ ideas.

#5

On 2010-10-25 05:06, gropiuskalle wrote:
>
> I can not confirm this behaviour - I often move huge files to another
> harddrive and still can work nicely meanwhile, even though files get
> encrypted when moving to this other HD. I also do not experience any
> slowdowns when copying files within the same partition.

I have. Not always, not all computers, not all file operations. But it happens.

Specially if you start using another application that “now” also needs some I/O. It certainly will
run slower, as it has to compete - how much, depends.

–
Cheers / Saludos,

Carlos E. R.
(from 11.2 x86_64 “Emerald” at Telcontar)