default I/O scheduler should be change from CFQ to deadline

Bug #631871 reported by DLHDavidLH on 2010-09-06
32
This bug affects 4 people
Affects Status Importance Assigned to Milestone
Ubuntu
Wishlist
Unassigned

Bug Description

i think that the default I/O scheduler

 should be change from CFQ to deadline

---------------------------------------------------------------------

i have test CFQ and deadline I/O scheduler

on a DELL Latitude 120L with 1GB of RAM and 40GB hard drive

with EXT4 filesystem and GPT with both I/O schedulers

and Found that deadline I/O scheduler is the fastest

--------------------------------------

also tested
 EXT3 with MBR and deadline I/O scheduler
 EXT3 with GPT and deadline I/O scheduler

 EXT4 with MBR and deadline I/O scheduler
 EXT4 with GPT and deadline I/O scheduler

 EXT4 with MBR and Noop I/O scheduler
 EXT4 with GPT and Noop I/O scheduler

-- all are faster with
deadline I/O scheduler -OR- Noop I/O scheduler

ubuntu versions tested - Ubuntu 9.04, Ubuntu 10.04 (LTS), Xubuntu 10.04

--------------------------------------------------------------------

also test both I/O schedulers on two other computers (total of 3 computers)

the deadline I/O scheduler preformed faster then CFQ scheduler

Noop I/O scheduler preformed best ( faster then deadline )

-----------------------------------------------------------------

also went deadline I/O scheduler is put in Grub ( etc/default/grub OR grub.cfg )
the boot speed is increased and desktop speed

OR went deadline I/O scheduler is put in rc.local ( etc/rc.local )
the desktop speed is increased only

--------------------------------------------------------------------

http://en.wikipedia.org/wiki/Deadline_scheduler
http://en.wikipedia.org/wiki/Noop_scheduler
http://en.wikipedia.org/wiki/GUID_Partition_Table
http://en.wikipedia.org/wiki/Ext4
http://itezer.com/blog/ubuntu-linux/125-Four_Tweaks_for_Using_Ubuntu_with_SSD.html

http://en.wikipedia.org/wiki/CFQ

DLHDavidLH (dlhdavidlh-yahoo) wrote :

deadline I/O scheduler is good with both

 SSD (solid-state-drives) and HDD (Hard disk drive)

--------------------------------------------------------------------------------

Source:

http://tombuntu.com/index.php/2008/09/04/four-tweaks-for-using-linux-with-solid-state-drives/

http://itezer.com/blog/ubuntu-linux/125-Four_Tweaks_for_Using_Ubuntu_with_SSD.html

DLHDavidLH (dlhdavidlh-yahoo) wrote :

deadline I/O scheduler

    * write_expire - the number of milliseconds before a write IO request expires

i think that the default write_expire should be 2500

   in stead of the default write_expire of 5000

--------------------------------------------------------------------------------------------------

http://wiki.linuxquestions.org/wiki/Deadline

DLHDavidLH (dlhdavidlh-yahoo) wrote :

i think there should be more testing for the

Default I/O scheduler...........

---------------------------------------------------------------------

CFQ [cfq] (Completely Fair Queuing) is an I/O scheduler for the Linux kernel and default under many Linux distributions.

Noop scheduler (noop) is the simplest I/O scheduler for the Linux kernel based upon FIFO queue concept.

Anticipatory scheduler (anticipatory) is an algorithm for scheduling hard disk input/output as well as old scheduler which is replaced by CFQ

Deadline scheduler (deadline) - it attempt to guarantee a start service time for a request.

-------------------------------------------------------------

http://en.wikipedia.org/wiki/I/O_scheduling

http://en.wikipedia.org/wiki/Deadline_scheduler
http://en.wikipedia.org/wiki/Noop_scheduler
http://en.wikipedia.org/wiki/Anticipatory_scheduling
http://en.wikipedia.org/wiki/CFQ

http://lwn.net/Articles/114770/
http://www.cyberciti.biz/faq/linux-change-io-scheduler-for-harddisk/

DLHDavidLH (dlhdavidlh-yahoo) wrote :

distro's could make simple applet to change i/o scheduler.

And later on users depending on their workloads can choose whatever they want.

------------------------------

* CFQ I/O scheduler

* Noop I/O scheduler

* Deadline I/O scheduler

* Anticipatory I/O scheduler

DLHDavidLH (dlhdavidlh-yahoo) wrote :

maybe ubuntu could make simple applet to
change etc/rc.local file
 to change I/O scheduler

DLHDavidLH (dlhdavidlh-yahoo) wrote :

-- idea - -

use Deadline I/O scheduler for boot up ( etc/default/grub OR grub.cfg )

and

switch to CFQ I/O scheduler for Desktop (etc/rc.local file)

-- idea - -

Charlie Kravetz (charlie-tca) wrote :

Thank you for your suggestion. However, the changes you are requesting aren't really a bug and require more discussion, which should be done on an appropriate mailing list or forum. http://www.ubuntu.com/support/community/mailinglists might be a good start for determining which mailing list to use.

Changed in ubuntu:
status: New → Invalid
DLHDavidLH (dlhdavidlh-yahoo) wrote :

elevator=cfq (default) cause starvation

DLHDavidLH (dlhdavidlh-yahoo) wrote :

i get better speed / performance out of

Noop I/O scheduler - OR - Deadline I/O scheduler

----------------------------------------------

both work better then CFQ I/O scheduler

Changed in ubuntu:
status: Invalid → Opinion
DLHDavidLH (dlhdavidlh-yahoo) wrote :

Noop I/O scheduler works best at these time

- Dell Latitude 120L , 1GB RAM , 40GB hard drive (disk)(HDD)

--------------------------------------------------------

Noop works better then Deadline

Deadline works better the CFQ

(this is what i have test on the Dell Latitude 120L)

---------------------------------------------------------------

Linux installed only (no dual boot) on this computer

DLHDavidLH (dlhdavidlh-yahoo) wrote :

with Noop I/O scheduler i can get up to load average: 3 to 4 +

with Deadline I/O scheduler i can get up to load average: 2 to 3 +

with CFQ I/O scheduler i can get up to load average: 1 to 2

...before system / computer SLOW DOWN

Changed in ubuntu:
status: Opinion → Invalid
status: Invalid → Won't Fix
DLHDavidLH (dlhdavidlh-yahoo) wrote :

bug in CFQ I/O scheduler ?

description: updated
Pete Graner (pgraner) wrote :

@Charlie, DLHDavidLH,

The correct place to discuss this is on the ubuntu kernel team mailing list: <email address hidden>

JLR (artirj) wrote :

I also think that the elevators should be benchmarked individually under a range of situations and pick the best one for the general user.

Maybe the guys over Phoronix can help us with that. They are da best benchmarking stuff.

DLHDavidLH (dlhdavidlh-yahoo) wrote :

i am testing as a general user

--------------------------------------------

the testing i am doing is using the desktop app's / programs

- like open many firefox tabs and windows
(use www.hulu.com with flash)

- all the games that come default

- all of openoffice

- video editor

- music player

- many more....

---------------------------------

with trying different I/O schedulers

--------------------------------------------

Pete Graner (pgraner) on 2010-09-07
Changed in ubuntu:
importance: Undecided → Wishlist
status: Won't Fix → Opinion

> i am testing as a general user

You're testing as what you consider a general user. In my daily
activities I compile numerous packages, listen to music, and a lot of
other things. Ubuntu covers a very wide audience and the best overall
makes the most sense. You tested also only on a single system.

Marius B. Kotsbak (mariusko) wrote :

See bug #1008400. Seems like the default is now changed to deadline.

samuel (samuel-h) wrote :

I agree with this, my first impression after installing was file copying seemed to lock up my system, with deadline it doesn't

samuel (samuel-h) wrote :

Also it has been changed for the server, but not the desktop.

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