[Bug 390247] Re: Change I/O scheduler to NOOP when installing in SSD Drive or virtual machines

[Marius Kotsbak]

I saw a very easy way to add this here:
http://www.danielscottlawrence.com/should-i-changing-my-disk-scheduler-
to-noop-from-cfq-for-my-ssd/#comment-144

using a udev rule like this:

ACTION=="add|change", KERNEL=="sd[a-z]", ATTR{queue/rotational}=="0",
ATTR{queue/scheduler}="noop"

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https://bugs.launchpad.net/bugs/390247

Title:
  Change I/O scheduler to NOOP when installing in SSD Drive or virtual
  machines

Status in “ubiquity” package in Ubuntu:
  Confirmed

Bug description:
    When install Linux in SSD Drives ( EeePC, pendrive, etc ) or Virtual
  machines the default Linux I/O scheduler ( CFQ ) make disk access very
  slower, causing sometimes system/application freeze.

    If the scheduler is changed to NOOP the access to disk have a big
  improvement :

    Kernel compilation
    CFQ   : 4161 seconds
    NOOP: 3653 seconds ( 13% faster )

    Link: http://www.alphatek.info/2009/02/02/ssd-performance-vs-linux-
  kernel-io-scheduler-in-fedora-10/

  
    "The NOOP scheduler is a simple FIFO queue and uses the minimal amount of CPU/instructions per I/O to accomplish the basic merging and sorting functionality to complete the I/O. It assumes performance of the I/O has been or will be optimized at the block device (memory-disk) or with an intelligent HBA or externally attached controller."

    Link: http://www.redhat.com/magazine/008jun05/features/schedulers/

    But, the most end-users don't know about this option/tunning and
  will very helpful automatic add "elevator=noop" to kernel
  initialization when ubiquity is installing Ubuntu in this devices.

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