Re: mmap + mprotect + malloc strange behaviour

[David Addison]

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.


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/