Just a few more important points that I forgot to mention.
This work has been helped and guided by Rainer. He will also continue to
use the tool for further research. :-)
This new component can be enabled via option --enable-memchecker. When
disabled, there won't be any influence for Open MPI and application.
The patch has been tested based on a version of Open MPI a few month
ago, but it should be easy to move to the latest OMPI trunk. I will make
a bitbucket branch for merging it back.
I would like explain more details in the call today.
On 2012-10-08 3:05 PM, Shiqing Fan wrote:
*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:
* *MEMPIN_RUNNING_WITH_PIN*: Checks whether the user application is
running under MemPin and Pin
* *MEMPIN_REG_MEM_WATCH*: Registers the memory entry for specific
memory operation
* *MEMPIN_UPDATE_MEM_WATCH:* Updates the memory entry parameters for
specific memory operation
* *MEMPIN_UNREG_MEM_WATCH*: Unregisters one memory entry
* *MEMPIN_UNREG_ALL_MEM_WATCH*: Unregisters all the memory entries
* *MEMPIN_SEARCH_MEM_INDEX*: Returns the memory entry index from the
memory address storage
* *MEMPIN_PRINT_CALLSTACK*: Prints the current callstack to standard
output or a file
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
--
---------------------------------------------------------------
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:f...@hlrs.de
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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: f...@hlrs.de
