[solved]Cannot do heavy I/O tasks with deadline/BFQ

Roberth · 2015-10-29 10:41:05

Regardsless of using BFS or CFS cpu scheduler, I cannot do I/O intensive tasks, expamples of these are compiling llvm-svn or creating a virtual machine image with virtualbox with neither BFQ or deadline, but it works fine with CFQ.
What happens is that the computer completely locks up almost, only the mouse cursor responds but extremely poorly, I can I move the mouse as much as I want but it moves EXTREMELY slow.
Is this suposed to happen? If not is it a hardware problem or are there tunables I can easily adjust to solve this?

Hardware specifications:

Intel Core i5-4570 CPU
Intel Z87 Express Motherboard
Crucial m4 SSD 128 GB

Last edited by Roberth (2015-10-31 19:15:50)

dice · 2015-10-29 12:42:31

Are you sure this lock up is caused by the disk IO and not by cpu utilization?
Which file system are you using?

Roberth · 2015-10-29 12:49:55

Let's take the compilation of llvm as an example, with bfs and bfq I get an lockup, with bfs and cfq, I dont get a lockup. To me it's obvious that the IO scheduler is to blame AFAIK.

XFS.

ooo · 2015-10-29 13:24:02

Did you try vanilla kernel with bfq/deadline? It could be that bfs is causing your issue with certain io schedulers.

frostschutz · 2015-10-29 13:30:20

noop works best for me ... ymmv

Roberth · 2015-10-29 13:31:41

I have only tried vanilla kernel with deadline. Same thing. vanilla kernel with cfq does not cause the lockup.

I will try vanilla kernel with bfq.

Roberth · 2015-10-29 16:55:17

So I tried the vanilla kernel with BFQ, that didn't cause any lockup. But while I compiled llvm-svn while watching youtube videos with chromium, the video- audio playback lag a little bit here and there, which they never did with BFS with CFQ, and the with CFS and BFQ the desktop(plasma 5) wasn't as responsive as BFS and CFQ.

So unless there is no easy sollution to the issue with BFS and BFQ, I would just stick to BFS and CFQ, that is the best compromise to get better responsiveness without any lockups so far.

ooo · 2015-10-29 20:45:18

Maybe you could report your problem to bfq developers at https://groups.google.com/forum/#!forum/bfq-iosched
they are usually quite helpful with any kind of issues regarding bfq

I'm also using bfs+bfq and also experience some short lags during heavy IO, for example installing large packages with pacman, but your issue seems different to me. Also I'm pretty sure I have the same lags with cfq with or without bfs.

Last edited by ooo (2015-10-29 20:46:01)

brebs · 2015-10-30 07:01:00

Roberth wrote:

compiled llvm-svn while watching youtube videos with chromium

I'm surprised you haven't mentioned CPU process prioritization - i.e. giving the GUI processes higher priority.

Roberth · 2015-10-31 19:15:35

I noticed that I haven't updated the ucode for the cpu, I did that and all I experienced was a few small slow down in chromium when compiling llvm-svn with BFS and BFQ. So I would say it's solved now.

Arch Linux

#1 2015-10-29 10:41:05

[solved]Cannot do heavy I/O tasks with deadline/BFQ

#2 2015-10-29 12:42:31

Re: [solved]Cannot do heavy I/O tasks with deadline/BFQ

#3 2015-10-29 12:49:55

Re: [solved]Cannot do heavy I/O tasks with deadline/BFQ

#4 2015-10-29 13:24:02

Re: [solved]Cannot do heavy I/O tasks with deadline/BFQ

#5 2015-10-29 13:30:20

Re: [solved]Cannot do heavy I/O tasks with deadline/BFQ

#6 2015-10-29 13:31:41

Re: [solved]Cannot do heavy I/O tasks with deadline/BFQ

#7 2015-10-29 16:55:17

Re: [solved]Cannot do heavy I/O tasks with deadline/BFQ

#8 2015-10-29 20:45:18

Re: [solved]Cannot do heavy I/O tasks with deadline/BFQ

#9 2015-10-30 07:01:00

Re: [solved]Cannot do heavy I/O tasks with deadline/BFQ

#10 2015-10-31 19:15:35

Re: [solved]Cannot do heavy I/O tasks with deadline/BFQ

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