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    SubjectRe: mmap + mprotect + malloc strange behaviour
    Kaloian Manassiev wrote:

    >Nevermind, I found it :)
    >
    >I just found out (by reading
    >/usr/src/linux-2.4.20-8/Documentation/sysctl/vm.txt)
    >that there is a limit on the number of mappings that a
    >process may have and that for some reason malloc
    >consumes mappings.
    >
    >I just increased the limit by editing the file
    >/proc/sys/vm/max_map_count. This works okay for my
    >application...
    >
    >Does someone know what repercussions this could have
    >on the "normal" operation of the system?
    >
    >Cheers,
    >Kaloian.
    >
    >
    >
    >
    The glibc malloc heap switches to using mmap()/munmap() for large
    allocations (>=128kbytes ?). This behaviour can be turned off by setting;

    export MALLOC_TRIM_THRESHOLD_=-1
    export MALLOC_MMAP_MAX_=0

    See also the mallopt() library call.


    Cheers
    Addy.


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