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Thread: Picking up the disk scheduler?

  1. #1
    Join Date
    Oct 2009
    Posts
    11

    Default Picking up the disk scheduler?

    I've been running some disk and filesystem suite benchmarks on openSUSE 11.2 RC2 and uploading the results to Phoronix Global. In browsing them, I see that the software (2.0) is capable of discovering which filesystem is in use. I'm running scheduler tests too, and it would be nice if the suite could pick that up automatically too. Here's some bash code to do it:

    export SCHED=`sed 's/^.*\[//' /sys/block/sda/queue/scheduler | sed 's/\].*
    $//'`

  2. #2

    Default

    Hi znmeb,

    The support can be added so that when a disk test is run, it will report the scheduler to the "Notes" area of the results viewer. I may be able to squeeze this feature in before the 2.2 release.

  3. #3

    Default

    http://phorogit.com/index.php?p=phor...dc7ed96a904a91

    - pts-core: Report the disk scheduler to the test notes area when a disk test is run
    - phodevi: Add property to disk object for reading the scheduler in use
    Is in 2.2 Yields:

    http://global.phoronix-test-suite.co...45-29847-32023

  4. #4
    Join Date
    Oct 2009
    Posts
    11

    Default Disk scheduler

    Looks good! One note: you can set the scheduler independently at run time for each block device! So you might want a table - I just used "sda" because that's the only active disk I'm testing.

  5. #5
    Join Date
    Oct 2009
    Posts
    11

    Default Ubuntu defaults to CFQ too?

    Quote Originally Posted by znmeb View Post
    Looks good! One note: you can set the scheduler independently at run time for each block device! So you might want a table - I just used "sda" because that's the only active disk I'm testing.
    Oh ... Ubuntu defaults to CFQ too? openSUSE does, and I normally run tests and set it at boot time. The last few tests I ran (openSUSE 11.2 Milestone 8) showed "deadline" was the winner on iozone (upstream, not yours). Once I get the filesystem runs done, I'm rerunning the scheduler tests for the winner. ;-)

    At boot time, add "elevator=xxx" to the kernel line, where "xxx" is "cfq", "noon", "anticipatory" or "deadline". At run time, do as root:

    echo xxx > /sys/block/sda/queue/scheduler

  6. #6
    Join Date
    Jul 2008
    Posts
    1,731

    Default

    cfq is a good choice for most people, so they use it. I had some horrible experiences with deadline.

    And with horrible I mean coasters when trying to burn dvds etc. Really, really bad. cfq on the other hand never let me down. I do not care that some benchmark might be running better somewhere somehow.

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