Man page or keyword search:   man All Sections 1 - General Commands 2 - System Calls 3 - Subroutines, Functions 4 - Special Files 5 - File Formats 6 - Games and Screensavers 7 - Macros and Conventions 8 - Maintenence Commands 9 - Kernel Interface New Commands Server 4.4BSD AIX Alpinelinux Archlinux Aros BSDOS BSDi Bifrost CentOS Cygwin Darwin Debian DigitalUNIX DragonFly ElementaryOS Fedora FreeBSD Gentoo GhostBSD HP-UX Haiku Hurd IRIX Inferno JazzOS Kali Knoppix LinuxMint MacOSX Mageia Mandriva Manjaro Minix MirBSD NeXTSTEP NetBSD OPENSTEP OSF1 OpenBSD OpenDarwin OpenIndiana OpenMandriva OpenServer OpenSuSE OpenVMS Oracle PC-BSD Peanut Pidora Plan9 QNX Raspbian RedHat Scientific Slackware SmartOS Solaris SuSE SunOS Syllable Tru64 UNIXv7 Ubuntu Ultrix UnixWare Xenix YellowDog aLinux   17060 pages apropos Keyword Search (all sections) Output format html ascii pdf view pdf save postscript

memtester(8)		     Maintenance Commands		  memtester(8)

NAME
       memtester - stress test to find memory subsystem faults.

SYNOPSIS
       memtester [-p PHYSADDR] <MEMORY> [ITERATIONS]

DESCRIPTION
       memtester  is an effective userspace tester for stress-testing the mem‐
       ory subsystem.  It is very effective at finding intermittent  and  non-
       deterministic  faults.	Note  that  problems  in  other hardware areas
       (overheating CPU, out-of-specification power supply,  etc.)  can	 cause
       intermittent memory faults, so it is still up to you to determine where
       the fault lies through normal hardware diagnostic procedures; memtester
       just helps you determine whether a problem exists.

       memtester  will	malloc(3) the amount of memory specified, if possible.
       If this fails, it will decrease the amount of memory requested until it
       succeeds.   It  will then attempt to mlock(3) this memory; if it cannot
       do so, testing will be slower and much less effective.	Run  memtester
       as root so that it can mlock the memory it tests.

       Note  that the maximum amount of memory that memtester can test will be
       less than the total amount of memory installed in the system; the oper‐
       ating  system,  libraries,  and	other  system  limits take some of the
       available memory.  memtester is also limited to the  amount  of	memory
       available  to  a	 single	 process; for example, on 32-bit machines with
       more than 4GB of memory, memtester is still limited to less than 4GB.

       Note that it is up to you to know how much memory you can safely	 allo‐
       cate  for  testing.   If	 you  attempt  to allocate more memory than is
       available,  memtester  should  figure  that  out,  reduce  the	amount
       slightly,  and try again.  However, this can lead to memtester success‐
       fully allocating and mlocking essentially all free memory on the system
       --  if  other programs are running, this can lead to excessive swapping
       and slowing the system down to the point that it is difficult  to  use.
       If  the system allows allocation of more memory than is actually avail‐
       able (overcommit), it may lead to a deadlock, where the	system	halts.
       If  the	system	has  an	 out-of-memory	process	 killer	 (like Linux),
       memtester or another process may be killed by the OOM killer.

       So choose wisely.

OPTIONS
       -p PHYSADDR
	      tells memtester to test a specific region of memory starting  at
	      physical	 address   PHYSADDR  (given  in	 hex),	by  mmap(2)ing
	      /dev/mem.	 This is mostly of use	to  hardware  developers,  for
	      testing  memory-mapped  I/O  devices and similar.	 Note that the
	      memory region will be overwritten during testing, so it  is  not
	      safe  to specify memory which is allocated for the system or for
	      other applications; doing so will cause them to crash.   If  you
	      absolutely must test a particular region of actual physical mem‐
	      ory, arrange to have that memory allocated by  your  test	 soft‐
	      ware, and hold it in this allocated state, then run memtester on
	      it with this option.

       MEMORY the amount of memory to  allocate	 and  test,  in	 megabytes  by
	      default.	 You can include a suffix of B, K, M, or G to indicate
	      bytes, kilobytes, megabytes, or gigabytes respectively.

       ITERATIONS
	      (optional) number of loops to iterate through.  Default is infi‐
	      nite.

NOTE
       memtester  must	be  run	 with  root  privileges to mlock(3) its pages.
       Testing memory without locking the pages in place is  mostly  pointless
       and slow.

EXIT CODE
       memtester's  exit code is 0 when everything works properly.  Otherwise,
       it is the logical OR of the following values:

       x01    error allocating or locking memory, or invocation error

       x02    error during stuck address test

       x04    error during one of the other tests

AUTHOR
       Written by Charles Cazabon.

REPORTING BUGS
       Report bugs to <charlesc-memtester-bugs@pyropus.ca>.

COPYRIGHT
       Copyright © 2009 Charles Cazabon
       This is free software; see the file  COPYING  for  copying  conditions.
       There  is  NO  warranty;	 not even for MERCHANTABILITY or FITNESS FOR A
       PARTICULAR PURPOSE.

memtester 4			   July 2009			  memtester(8)

Vote for polarhome