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Thread: Enable noop scheduler by default for an SSD

  1. #1
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    Lightbulb Enable noop scheduler by default for an SSD

    I was reading this which suggests using the noop scheduler for SSDs. I've just got an X301 with a 128Gb SSD so I'd like to try this.

    I found two ways to enable the noop scheduler.

    Firstly, adding elevator=noop to grub. I believe "elevator=noop" can be prepended to both the existing entries in /boot/grub/menu.lst and the "defoptions = " line to add it automatically to new kernels.

    Secondly, by installing sysfsutils and adding "block/sda/queue/scheduler = noop" to /etc/sysfs.conf.

    Can anyone recommend which option would be better? Do they achieve the same thing?

    I guess if it caused problems I could more easily revert it in the grub options. I'll try that first and see how I get on. Any advice would be appreciated.
    Love & joy - Callum

  2. #2
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    Re: Enable noop scheduler by default for an SSD

    Bump. Any suggestions?
    Love & joy - Callum

  3. #3
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    Re: Enable noop scheduler by default for an SSD

    You should be able to change which scheduler by echoing to
    /sys/block/sda/queue/scheduler. http://www.linuxhowtos.org/System/iosched.htm

    I'd just use the grub option myself. If it's a clean install using JFS as disk format might also help. Or just ext2 unless you really need the journalling.
    Last edited by Yashiro; February 12th, 2009 at 01:17 PM.

  4. #4
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    Re: Enable noop scheduler by default for an SSD

    Awesome, thanks for the link Yashiro, I just changed my scheduler!

    I think I'll use the grub approach, seems the easiest.
    Love & joy - Callum

  5. #5
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    Re: Enable noop scheduler by default for an SSD

    As this thread is one of the top results for "ssd scheduler" I figured I'd add a bit of info to this thread. There is a small difference between the method where you modify menu.lst and the method where you modify sysfs.conf. The menu.lst method sets it for all drives, and the sysfs method changes it only for the drives you specify. For example the line

    Code:
    block/sda/queue/scheduler = noop
    only changes the scheduler for the drive "sda". The two methods do the same thing only if you have one drive. If you have a mix of actual hard drives and SSDs, you'll want to use the sysfs method to enable it only on the SSDs. If you only have SSDs, it's easiest to use the menu.lst method.
    Last edited by Blazeix; March 5th, 2009 at 09:19 PM. Reason: fixed code block

  6. #6
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    Re: Enable noop scheduler by default for an SSD

    Thanks Blazeix, I've just updated to the sysfs.conf method. I occassionally plug in USB spinning disks, so I think it makes sense to set the noop schedulere just for sda.
    Love & joy - Callum

  7. #7
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    Re: Enable noop scheduler by default for an SSD

    Does it make any difference? Have you compared performance with noop to performance with cfq? I've read some conflicting results.

  8. #8
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    Re: Enable noop scheduler by default for an SSD

    To be honest, I haven't noticed any performance difference, but I haven't run any tests. I think there's a chance it puts slightly less wear on the drive, so I'm happy to switch for that reason. My laptop is usually under fairly low load so I don't really notice disk performance.
    Love & joy - Callum

  9. #9
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    Exclamation Re: Enable noop scheduler by default for an SSD

    I've summarized current information about SSD configuration in Ubuntu 10.10, including the information in this thread, here:

    https://wiki.ubuntu.com/MagicFab/SSDchecklist

    Thanks for any comments/suggestions.
    Fabián Rodríguez
    Ubuntu Quebec LoCo Team contact, UCP, UCI

  10. #10
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    Wink Re: Enable noop scheduler by default for an SSD

    @MagicFab

    Thanks for the link, it is awfully complete and good guide!!!

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