64-bit kernel shmmax - Suse

This is a discussion on 64-bit kernel shmmax - Suse ; Hi, What is the upper limit for shmmax on 64-bit kernel? -- GI...

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Thread: 64-bit kernel shmmax

  1. 64-bit kernel shmmax

    Hi,

    What is the upper limit for shmmax on 64-bit kernel?

    --
    GI

  2. Re: 64-bit kernel shmmax

    On Sun, 12 Oct 2008, Ivan Gustin wrote:-

    >Hi,
    >
    >What is the upper limit for shmmax on 64-bit kernel?


    Well, for a 32bit kernel it's (only) 4GB. For a 64big kernel, it's a
    little bit larger:

    davjam@adder:/local2/possible-viruses> sudo /sbin/sysctl kernel.shmmax
    root's password:
    kernel.shmmax = 18446744073709551615

    Which is one byte less than:

    17,179,869,184 GiB (Gibibyte[0])
    16,777,216 TiB (Tebibyte[0])
    16,384 PiB (Pebibyte[0])
    16 EiB (Exbibyte[0])


    [0] Explanations of these can be found here:



    Regards,
    David Bolt

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  3. Re: 64-bit kernel shmmax

    David Bolt:
    >> What is the upper limit for shmmax on 64-bit kernel?

    > Well, for a 32bit kernel it's (only) 4GB. For a 64big kernel, it's a
    > little bit larger:
    > davjam@adder:/local2/possible-viruses> sudo /sbin/sysctl kernel.shmmax
    > root's password:
    > kernel.shmmax = 18446744073709551615


    OK, tnx. That's 2^64, like 2^32 for 32-bit kernel. I was just wondering
    if there is some other lower limit caused by kernel itself or by
    something else.

    --
    GI

  4. Re: 64-bit kernel shmmax

    On 2008-10-12 23:08, David Bolt wrote:
    > On Sun, 12 Oct 2008, Ivan Gustin wrote:-
    >
    >> Hi,
    >>
    >> What is the upper limit for shmmax on 64-bit kernel?

    >
    > Well, for a 32bit kernel it's (only) 4GB. For a 64big kernel, it's a
    > little bit larger:
    >
    > davjam@adder:/local2/possible-viruses> sudo /sbin/sysctl kernel.shmmax
    > root's password:
    > kernel.shmmax = 18446744073709551615
    >
    > Which is one byte less than:
    >
    > 17,179,869,184 GiB (Gibibyte[0])
    > 16,777,216 TiB (Tebibyte[0])
    > 16,384 PiB (Pebibyte[0])
    > 16 EiB (Exbibyte[0])
    >
    >
    > [0] Explanations of these can be found here:
    >
    >
    >
    > Regards,
    > David Bolt
    >


    Those numbers look like a recommended shmem tuning for Oracle :-)

    /bb

  5. Re: 64-bit kernel shmmax

    On Mon, 13 Oct 2008 16:38:07 +0200
    bb wrote:

    >Those numbers look like a recommended shmem tuning for Oracle :-)
    >


    ROFLMAO!

    (Recommended, but not yet optimum, right?) ;-)


    --
    Kevin Nathan (Arizona, USA)
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  6. Re: 64-bit kernel shmmax

    bb:
    > Those numbers look like a recommended shmem tuning for Oracle :-)


    :-D

    Well, you're not far from truth. It's about growing PostgreSQL database.

    --
    GI

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