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  1. #1

    Reducing the reserved memory for kernel


    Hi Everybody,
    I am working on montavista linux, on broadcom chipset, mips processor...having 32Mb RAM..out of which top 2Mb has been given for DMA access..remaining 30Mb should be available. But in cat /proc/meminfo it only shows 26Mb free, in dmesg..it shows that 4.7Mb is reserved for kernel. That is far too much that i expect as I have heard it ahuld not be more than 2-3% of total memory. How to reduce it? I am having busybox utilities.
    here is the output:
    cat /proc/meminfo

    total: used: free: shared: buffers: cached:
    Mem: 27181056 7303168 19877888 0 53248 5435392
    Swap: 0 0 0
    MemTotal: 26544 kB
    MemFree: 19412 kB
    MemShared: 0 kB
    Buffers: 52 kB
    Cached: 5308 kB
    SwapCached: 0 kB
    Active: 720 kB
    Inactive: 4984 kB
    HighTotal: 0 kB
    HighFree: 0 kB
    LowTotal: 26544 kB
    LowFree: 19412 kB
    SwapTotal: 0 kB
    SwapFree: 0 kB
    Committed_AS: 1056 kB
    VmallocTotal: 1048560 kB
    VmallocUsed: 448 kB
    VmallocChunk: 1048112 kB



    dmesg|grep [Mm]em


    Setting memory region to 0x2000000
    Environment [0] : <memsize=32>
    5200 mem=30M ramdisk_size=8192 nfsroot=10.240.4.61:/home/canoop/target
    U-BOOT Environment: bootargs = root=/dev/ram console=ttyS0,115200 mem=30M
    memory: 02000000 @ 00000000 (usable)
    memory: 01e00000 @ 00000000 (usable)
    Kernel command line: yroot=/dev/ra console=ttyS0,115200 mem=30M
    Memory: 25996k/30720k available (1474k kernel code, 4724k reserved, 92k data, 80k init, 0k
    highmem)
    Disabling the Out Of Memory Killer
    Freeing initrd memory: 466k freed
    Freeing unused kernel memory: 80k freed




    Theres also another instance where dmesg doent show reserved space for kernel. So, I am wondering without this reserved space, it can work.....I have to reduce the memory by 3Mb. Any suggestions?

    Can I reduce the buffer cache, right now its almost 5.4Mb..I think that I can reduce by 1 Mb....any idea, how much effect will it have over perormance?

    /*What my suspicion is: Does Montavista linux has some limitation abt the minimum reserved space?*/




    Thanks,
    sudip

  2. #2

    mobilinux

    first of all you shouls say me how can I find Montavista linux Sorce code?

    I realy need it .

    thanks.

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