07-29-2008
malloc returning NULL if freemem high & swapmem low (MPRAS version 3.03 )
Hi All,
In my application malloc is returning NULL even though there is sufficient amount of free memory available but the swap memory is low.
Is this possible that, if free memory is high & swap memory is low, malloc will not be able to allocate memory & return NULL ?
Few details:
my system running on a x86 platform
2 Pentium III processors
MPRAS version 3.03
output of OS level and current kernel patch level 03.03.02.15
Commands I used to measure free memory and swap :
[ app001-0 root:/ ] sar -r 1 10
app001-0 app001-0 4.2 3.3 SDS2 06/03/08
06:56:32 freemem freeswp
06:56:33 513222 10197
06:56:34 513205 10197
06:56:35 513210 10197
06:56:36 513210 10197
06:56:37 513231 10197
06:56:38 513271 10197
06:56:39 513271 10197
06:56:40 513268 10197
06:56:41 513258 10197
06:56:42 513258 10197
Kindly look into the issue as I am not able to start my application in the above mentioned condition.
Thanks & Regards,
Ritesh
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FREE(1) User Commands FREE(1)
NAME
free - Display amount of free and used memory in the system
SYNOPSIS
free [options]
DESCRIPTION
free displays the total amount of free and used physical and swap memory in the system, as well as the buffers used by the kernel. The
shared memory column should be ignored; it is obsolete.
OPTIONS
-b, --bytes
Display the amount of memory in bytes.
-k, --kilo
Display the amount of memory in kilobytes. This is the default.
-m, --mega
Display the amount of memory in megabytes.
-g, --giga
Display the amount of memory in gigabytes.
--tera Display the amount of memory in terabytes.
-h, --human
Show all output fields automatically scaled to shortest three digit unit and display the units of print out. Following units are
used.
B = bytes
K = kilos
M = megas
G = gigas
T = teras
If unit is missing, and you have petabyte of RAM or swap, the number is in terabytes and columns might not be aligned with header.
-c, --count count
Display the result count times. Requires the -s option.
-l, --lohi
Show detailed low and high memory statistics.
-o, --old
Display the output in old format, the only difference being this option will disable the display of the "buffer adjusted" line.
-s, --seconds seconds
Continuously display the result delay seconds apart. You may actually specify any floating point number for delay, usleep(3) is
used for microsecond resolution delay times.
--si Use power of 1000 not 1024.
-t, --total
Display a line showing the column totals.
--help Print help.
-V, --version
Display version information.
FILES
/proc/meminfo
memory information
SEE ALSO
ps(1), slabtop(1), top(1), vmstat(8).
AUTHORS
Written by Brian Edmonds.
REPORTING BUGS
Please send bug reports to <procps@freelists.org>
procps-ng September 2011 FREE(1)