Hi, Regarding your question about marking memory read only and using this for MPI Message checking I would recommend, you read the following paper from a former colleque of mine:
Memory Debugging of MPI-Parallel Applications in Open MPI Rainer Keller, Shiqing Fan, and Michael Resch I'm currently re-evaluating the implementation with respect to a major Open MPI version update. If you are interested in it do not hesitate to contact me. Best regards Christoph Niethammer -- Christoph Niethammer High Performance Computing Center Stuttgart (HLRS) Nobelstrasse 19 70569 Stuttgart Tel: ++49(0)711-685-87203 email: nietham...@hlrs.de http://www.hlrs.de/people/niethammer ----- Original Message ----- From: "John Reiser" <jrei...@bitwagon.com> To: "valgrind-users" <valgrind-users@lists.sourceforge.net> Sent: Wednesday, March 9, 2016 5:25:25 PM Subject: Re: [Valgrind-users] can memchecker mark memory as read-only ? > Currently, my understanding is that valgrind memchecker can mark a > memory area as non accessible via the VALGRIND_MAKE_MEM_NOACCESS() > macro, but there is currently no way to mark it as read-only. Yes. READ_ONLY is not a recognized state. > if yes, is there any plan to develop such a feature ? No. The accounting bits are organized into two phases: is the address legal at all, and is the byte writable and initialized. Adding a new state READ_ONLY would be a large task with significant runtime costs. It might be best applied to the first phase, but complications regarding overlap [or splitting] between existing regions and new READ_ONLY regions, plus granularity assumptions (pages now, bytes for READ_ONLY) probably would be messy. >>From an OpenMPI developer point of view, it would be nice to mark the send > buffer as read-only between MPI_Isend() and MPI_Wait() so valgrind can trap > incorrect user code that modifies the send buffer when it is not allowed. Use LD_PRELOAD to intercept MPI_Isend() [etc.]. Allocate a new buffer, copy the message into it, mark the original buffer as NOACCESS, call the original MPI_Isend on the new buffer. Reverse the effects after the original MPI_Isend() is complete, waited, and checked. See the manual page for "man dlsym" and the RTLD_NEXT functionality. Search the web, too. ------------------------------------------------------------------------------ Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://pubads.g.doubleclick.net/gampad/clk?id=278785111&iu=/4140 _______________________________________________ Valgrind-users mailing list Valgrind-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/valgrind-users ------------------------------------------------------------------------------ Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://pubads.g.doubleclick.net/gampad/clk?id=278785231&iu=/4140 _______________________________________________ Valgrind-users mailing list Valgrind-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/valgrind-users
