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Full Discussion: realloc fails in C : what next ?
Top Forums Programming realloc fails in C : what next ? Post 302457523 by jossojjos on Tuesday 28th of September 2010 08:12:04 AM
Old 09-28-2010
realloc fails in C : what next ?
Hi all

I'm trying to use someone else's software, which has a realloc that fails in it. This is probably due to memory limitations, as it only happens when I use this software on huge datasets.

First question : how to diagnose if it's a soft or hard limitation? I mean, if it's due to my computer's memory limits, or to some limits the compiler / my C implementation imposes?
I'm running Mandriva Linux, 64 bit, with 4Gb RAM and 6GB swap, I don't think I'm reaching those limits.
The same failure happens on our computer cluster, which has about 60Gb of RAM ...

I used the makefile that came with the software, which adds these options to the gcc command :
CFLAGS = -O4 -funroll-loops -fomit-frame-pointer -finline-functions

More questions might follow depending on the answer, but the obvious question is : how to get around this limit ?
 

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LEARN ABOUT XFREE86

plimit

plimit(1)							   User Commands							 plimit(1)

NAME

       plimit - get or set the resource limits of running processes

SYNOPSIS

       plimit [-km] pid...

       plimit {-cdfnstv} soft,hard... pid...

DESCRIPTION

       If  one	or more of the cdfnstv options is specified, plimit sets the soft (current) limit and/or the hard (maximum) limit of the indicated
       resource(s) in the processes identified by the process-ID list, pid. Otherwise plimit reports the resource limits of the processes  identi-
       fied by the process-ID list, pid.

       Only  the  owner  of a process or the super-user is permitted either to get or to set the resource limits of a process. Only the super-user
       can increase the hard limit.

OPTIONS

       The following options are supported:

       -k	On output, show file sizes in kilobytes (1024 bytes) rather than in 512-byte blocks.

       -m	On output, show file and memory sizes in megabytes (1024*1024 bytes).

       The remainder of the options are used to change specified resource limits. They each accept an argument of the form:

	      soft,hard

       where soft specifies the soft (current) limit and hard specifies the hard (maximum) limit. If the hard limit is not  specified,	the  comma
       may  be	omitted. If the soft limit is an empty string, only the hard limit is set. Each limit is either the literal string unlimited, or a
       number, with an optional scaling factor, as follows:

       nk	n kilobytes

       nm	n megabytes (minutes for CPU time)

       nh	n hours (for CPU time only)

       mm:ss	minutes and seconds (for CPU time only)

       The soft limit cannot exceed the hard limit.

       -c soft,hard    Set core file size limits (default unit is 512-byte blocks).

       -d soft,hard    Set data segment (heap) size limits (default unit is kilobytes).

       -f soft,hard    Set file size limits (default unit is 512-byte blocks).

       -n soft,hard    Set file descriptor limits (no default unit).

       -s soft,hard    Set stack segment size limits (default unit is kilobytes).

       -t soft,hard    Set CPU time limits (default unit is seconds).

       -v soft,hard    Set virtual memory size limits (default unit is kilobytes).

OPERANDS

       The following operands are supported.

       pid	Process ID list.

EXIT STATUS

       plimit returns the exit value zero on success, non-zero on failure (such as no such process, permission denied, or invalid option).

FILES

       /proc/pid/*     process information and control files

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWesu			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       ulimit(1), proc(1), getrlimit(2), setrlimit(2), proc(4), attributes(5),

SunOS 5.10							    8 Jun 1998								 plimit(1)
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