What:

A new memory checking tool named MemPin was developed based on the Intel Pin framework. It uses a callback mechanism to do the similar tasks as Valgrind Memcheck. The new tool is tiny and flexible, and user may implement his own callback function for different purposes.

The basic idea here for Open MPI is to watch over the communication buffers. Every access to the buffers will be detected, and for specific memory operation (read/write), a memory check callback will be triggered.

Only the required memory will be taken care of, so the shadow memory can be kept to be as small as possible. The implemented shadow memory for Open MPI is handled in bit-wise, i.e. every byte of memory has 2 bits of shadow (4 different states. This doesn't provide bit-wise validity of the memory like Valgirnd, where every byte of memory has 9 bits of shadow. However, the shadow memory for this new tool is extensible.

Several predefined macros that may be used in user application and Open MPI:

The new component mempin will have the same memchecker API as valgrind component.

WHY:

This new implementation has similar functionalities as Valgrind Memcheck, but it is lightweight, faster, extensible and flexible. It also supports for Windows platforms.

WHERE:
      opal/mca/memchecker/
      ompi/include/ompi/memchecker.h or another header file.
      ompi/mca/pml/ob1    several memchecker macro need to be updated.


WHEN:
     If everything is fine, probably some time next week or later this month.


We probably can also discuss it in the next teleconf.


Thanks,
Shiqing
-- 
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Shiqing Fan
High Performance Computing Center Stuttgart (HLRS)
Tel: ++49(0)711-685-87234      Nobelstrasse 19
Fax: ++49(0)711-685-65832      70569 Stuttgart
http://www.hlrs.de/organization/people/shiqing-fan/
email: fan@hlrs.de