Arch Linux

Bestiapeluda

Member

From: Buenos Aires, Argentina

Registered: 2007-10-16

Posts: 181

scheduler

Is it possible to recompile the kernel and choose the old scheduler instead of CFS ?
How was the old one called ?

mico

Member

From: Slovenia

Registered: 2004-02-08

Posts: 247

Re: scheduler

It's an O(1) scheduler. I don't know if it has a particular name at all. Browse the options when you are configuring the kernel.

http://en.wikipedia.org/wiki/O%281%29_scheduler

lucke

Member

From: Poland

Registered: 2004-11-30

Posts: 4,018

Re: scheduler

You can't choose schedulers when compiling.

shining

Pacman Developer

Registered: 2006-05-10

Posts: 2,043

Re: scheduler

Is it possible to recompile the kernel and choose the old scheduler instead of CFS ?
How was the old one called ?

The old code was replaced, it isn't there anymore. You simply can't do that, just revert to the last kernel that didn't have CFS.
But that sounds really stupid, why you would do that? Just report any problems you have to CFS developers.

Just in case, don't confuse process schedulers with io schedulers where you do have several alternatives at compile time :
CONFIG_IOSCHED_NOOP=y
CONFIG_IOSCHED_AS=y
CONFIG_IOSCHED_DEADLINE=y
CONFIG_IOSCHED_CFQ=y
CONFIG_DEFAULT_IOSCHED="cfq"

---

pacman roulette : pacman -S $(pacman -Slq | LANG=C sort -R | head -n $((RANDOM % 10)))

oli

Member

From: 127.0.0.1

Registered: 2006-02-07

Posts: 164

Website

Re: scheduler

>But that sounds really stupid, why you would do that?

Because some people are actually working with their computer? Or is Arch just for nerds with lot of spare time? CFS has got a lot of problems, especially with some drivers in the kernel.

---

Use UNIX or die.

shining

Pacman Developer

Registered: 2006-05-10

Posts: 2,043

Re: scheduler

>But that sounds really stupid, why you would do that?

Because some people are actually working with their computer? Or is Arch just for nerds with lot of spare time? CFS has got a lot of problems, especially with some drivers in the kernel.

Are you kidding me? You have the time to recompile a kernel and post on forums, but not to report a bug?

---

pacman roulette : pacman -S $(pacman -Slq | LANG=C sort -R | head -n $((RANDOM % 10)))

iphitus

Forum Fellow

From: Melbourne, Australia

Registered: 2004-10-09

Posts: 4,927

Re: scheduler

>But that sounds really stupid, why you would do that?

Because some people are actually working with their computer? Or is Arch just for nerds with lot of spare time? CFS has got a lot of problems, especially with some drivers in the kernel.

report bug? and reference that, what drivers?

Kernel scheduler shouldnt have a significant affect on any drivers really -- it's a bug if it does.

James

Bestiapeluda

Member

From: Buenos Aires, Argentina

Registered: 2007-10-16

Posts: 181

Re: scheduler

Well, my problem is with games in Wine. WoW in particular.
Since the CFS patch in 2.6.23 I have a stutter in the game every 15 seconds.
Im not having this issue with older kernels. Many in other threads say its because of the CFS scheduler.
TBH this issue only happens when im connected, but i dont think its lag related, because it works with other kernels and distros.

lucke

Member

From: Poland

Registered: 2004-11-30

Posts: 4,018

Re: scheduler

Try recompiling kernel with CONFIG_FAIR_GROUP_SCHED and CONFIG_FAIR_USER_SCHED disabled - those used to make my system feel sluggish under load - or/and try kernel26zen (in AUR).

Incidentally, I tried forkbombing my kernel on Athlon X2 with 2 cpuburn-ins and a file copy going - audio and video didn't skip once and desktop was quite snappy (should've tried DVD burning too ;-)). Old mainline scheduler wouldn't handle that gracefully, original CK's staircase probably either.

Last edited by lucke (2008-03-14 20:27:11)

Bestiapeluda

Member

From: Buenos Aires, Argentina

Registered: 2007-10-16

Posts: 181

Re: scheduler

I solved my problem by altering the schedulers granularity as suggested in another thread.
I still think that the stock Arch linux kernel needs some tweaking

kishd

Member

Registered: 2006-06-14

Posts: 401

Re: scheduler

Why not try booting with the elevator=deadline/as etc kernel options to use a different scheduler and see if it solves the problem.

http://www.redhat.com/magazine/008jun05 … chedulers/

Last edited by kishd (2008-03-19 15:01:02)

---

---for there is nothing either good or bad, but only thinking makes it so....
Hamlet, W Shakespeare

Bestiapeluda

Member

From: Buenos Aires, Argentina

Registered: 2007-10-16

Posts: 181

Re: scheduler

Over at Gentoo, people are having problems with CFS too. Many are disabling CONFIG_FAIR_GROUP_SCHED and CONFIG_FAIR_USER_SCHED because they feel the system is laggy under load.

So , its not an Arch problem...

Last edited by Bestiapeluda (2008-03-22 20:23:28)

tomk

Forum Fellow

From: Ireland

Registered: 2004-07-21

Posts: 9,839

Re: scheduler

Why not try booting with the elevator=deadline/as etc

As already noted by shining above - deadline, as, etc are I/O schedulers, not the CPU scheduler.

kishd

Member

Registered: 2006-06-14

Posts: 401

Re: scheduler

tomk, did not explain myself clearly. I found on my system that the lag in audio etc when the system was under load was alleviated by using elevator=deadline and thought that this might help as the CPU scheduler cannot be changed.

---

---for there is nothing either good or bad, but only thinking makes it so....
Hamlet, W Shakespeare