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       memtester - stress test to find memory subsystem faults.


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


       memtester  is  an  effective  userspace  tester  for stress-testing the
       memory 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
       operating  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
       allocate  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
       successfully 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 available (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.


       -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
              memory, arrange to have  that  memory  allocated  by  your  test
              software,  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.

              (optional) number of  loops  to  iterate  through.   Default  is


       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.


       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


       Written by Charles Cazabon.


       Report bugs to <>.


       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