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From: David Addison <addy@quadrics.com>
To: Kaloian Manassiev <kmanassieff@yahoo.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: mmap + mprotect + malloc strange behaviour
Date: Mon, 26 Jul 2004 14:18:21 +0100	[thread overview]
Message-ID: <4105049D.9000008@quadrics.com> (raw)
In-Reply-To: <20040726130106.63000.qmail@web13605.mail.yahoo.com>

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.



  reply	other threads:[~2004-07-26 13:18 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-07-26 13:01 mmap + mprotect + malloc strange behaviour Kaloian Manassiev
2004-07-26 13:18 ` David Addison [this message]
  -- strict thread matches above, loose matches on Subject: below --
2004-07-21 21:38 Kaloian Manassiev

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