- to sleep increases linearly with the number of previously failed testk.
-
-
-\subsection options_model_smpi_use_shared_malloc smpi/use-shared-malloc: Factorize malloc()s
-
-\b Default: 1
-
-SMPI can use shared memory by calling shm_* functions; this might speed up the simulation.
-This opens or creates a new POSIX shared memory object, kept in RAM, in /dev/shm.
-
-If you want to disable this behavior, set the value to 0.
+ to sleep increases linearly with the number of previously failed tests. This
+ behavior can be disabled by setting smpi/grow-injected-times to no. This will
+ also disable this behavior for MPI_Iprobe.
+
+
+\subsection options_model_smpi_shared_malloc smpi/shared-malloc: Factorize malloc()s
+
+\b Default: global
+
+If your simulation consumes too much memory, you may want to modify
+your code so that the working areas are shared by all MPI ranks. For
+example, in a bloc-cyclic matrix multiplication, you will only
+allocate one set of blocs, and every processes will share them.
+Naturally, this will lead to very wrong results, but this will save a
+lot of memory so this is still desirable for some studies. For more on
+the motivation for that feature, please refer to the
+<a href="https://simgrid.github.io/SMPI_CourseWare/topic_understanding_performance/matrixmultiplication/">relevant
+section</a> of the SMPI CourseWare (see Activity #2.2 of the pointed
+assignment). In practice, change the call to malloc() and free() into
+SMPI_SHARED_MALLOC() and SMPI_SHARED_FREE().
+
+SMPI provides 2 algorithms for this feature. The first one, called \c
+local, allocates one bloc per call to SMPI_SHARED_MALLOC() in your
+code (each call location gets its own bloc) and this bloc is shared
+amongst all MPI ranks. This is implemented with the shm_* functions
+to create a new POSIX shared memory object (kept in RAM, in /dev/shm)
+for each shared bloc.
+
+With the \c global algorithm, each call to SMPI_SHARED_MALLOC()
+returns a new adress, but it only points to a shadow bloc: its memory
+area is mapped on a 1MiB file on disk. If the returned bloc is of size
+N MiB, then the same file is mapped N times to cover the whole bloc.
+At the end, no matter how many SMPI_SHARED_MALLOC you do, this will
+only consume 1 MiB in memory.
+
+You can disable this behavior and come back to regular mallocs (for
+example for debugging purposes) using \c "no" as a value.