Bigmem in Linux 7.3


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Thread: Bigmem in Linux 7.3

  1. #1
    Join Date
    Dec 2003
    Posts
    54

    Question Bigmem in Linux 7.3

    I currently have kernel 2.4.18-3bigmem running on Linux Redhat 7.3, the computer has 3.7Gb of Ram, at 2.0Gb my application quit because no more memory was been made available. Some one suggest, I install kernel-bigmem-2.4.20-28.7, which I tried but could not do, because the dependecies(modutils-2.4.18) have not been installed, when I tried to install the modutils I get error messages that its in conflict with modutils-2.4.14-3 which is already on the computer.
    My questions are:
    1.) What is the difference b/w this 2 kernels ?
    2) Is there a switch of some kind for the
    2.4.18-3bigmem so that it will take advantage of the memory ?
    3) Can force the modutil-2.4.18 to be installed over modutils-2.4.14-3 without creating any problems for my self.
    4) is there a way to have both modutils and kernels working.
    I will apprecaite good and practical answers.

  2. #2
    Join Date
    Sep 2002
    Posts
    766
    as far as i know 2.4.18 contains a VM system very similar to 2.4.20
    i think when compiled with the
    CONFIG_HIGHMEM4G=y
    the option suposedly to use if you have between 1 and 4 gigs of physical ram
    you get just under 1 gig mapped into the kernel's permanent address space
    with the remaining 3 (or in your case 2.7) left for individual processes

    now it is my understanding that the redhat bigmem branch of kernel developement is like a few other branches for machines with MORE THAN -- SOMETIMES LOTS MORE THAN
    4 gigs of ram -- these really big machines present unique chalanges
    as the 1/3 virtual memory mapping creates a bottleneck...
    (lowmem becomes dangerously used up because the mem_map[] is allocated out of the kernel part of the memory-- for a very big physical memory say 32gigs or even 200gigs mem_map[] becomes very large and fills up the entire 1 gig kernel allocation and won't even let the kernel boot)
    so i'm not sure but the bigmem kernel might actually be your problem
    as it might be allocating a full 2 gigs to you kernel to make room for a possibly hugely large mem_map[]?????????? that would leave only 2gigs for individual processes.
    this is just a guess !!!!!!!!

    i think try a kernel that is not bigmem
    you coud get the source for 2.4.18 and compile it yourself !!
    Last edited by GaryJones32; 01-26-2004 at 04:25 AM.

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