RHEL 6 – Controlling Cache Memory / Page Cache Size

Ramdev

I have started unixadminschool.com ( aka gurkulindia.com) in 2009 as my own personal reference blog, and later sometime i have realized that my leanings might be helpful for other unixadmins if I manage my knowledge-base in more user friendly format. And the result is today's' unixadminschool.com. You can connect me at - https://www.linkedin.com/in/unixadminschool/

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3 Responses

  1. Avatar Manoj K says:

    Hi,

    Thanks for the valid information. By default in all RHEL 6 systems I am putting the value as follows and found it is very effective.

    vm.swappiness=0
    vm.dirty_background_ratio=3
    vm.dirty_ratio=15
    vm.dirty_expire_centisecs=500
    vm.dirty_writeback_centisecs=100

    What is you opinion on this

    Thanks and Regards,
    Manoj K

  2. Avatar JC says:

    “vm.dirty_expire_centisecs ( default = 3000 , mentioned in milliseconds)” – Isn’t the number actually hundreths of a second, not thousandths? IE the default is 30 seconds.

  3. Avatar Phoenix_fr says:

    Hi Ramdev ! Thanks for the article.
    I think there’s a mistake on how to change the kernel Parameters.
    1) AFAIK the ‘sysctl -w’ command does not make persitent changes (next reboot, all your tuning would be lost).
    Man page says: ”
    sysctl is used to modify kernel parameters at runtime.
    (…)
    -w Use this option when you want to change a sysctl setting

    I did confirm this behaviour with a Red Hat 6 VM

    2) using the ‘echo’ command works, but is not wise as there’s no control on what you write (sysctl will warn you in case of bad argument and so on …)

    Regards.

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