From: degomme <augustin.degomme@unibas.ch>
Date: Wed, 29 Mar 2017 10:51:38 +0000 (+0200)
Subject: Add a smpi/shared-malloc-blocksize option. This is relevant only when global shared... 
X-Git-Tag: v3.16~416^2~2
X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/commitdiff_plain/76d5ed561fdd3411adbed2c3b659a1312e138284

Add a smpi/shared-malloc-blocksize option. This is relevant only when global shared mallocs mode is used.
This allows to change the size of the fake file used (default 1MB), to potentially limit the number of mappings for large runs.
---

diff --git a/src/simgrid/sg_config.cpp b/src/simgrid/sg_config.cpp
index e30c0fc95c..dd0df36f20 100644
--- a/src/simgrid/sg_config.cpp
+++ b/src/simgrid/sg_config.cpp
@@ -482,6 +482,7 @@ void sg_config_init(int *argc, char **argv)
                             "Whether SMPI_SHARED_MALLOC is enabled. Disable it for debugging purposes.");
     xbt_cfg_register_alias("smpi/shared-malloc", "smpi/use-shared-malloc");
     xbt_cfg_register_alias("smpi/shared-malloc", "smpi/use_shared_malloc");
+    xbt_cfg_register_double("smpi/shared-malloc-blocksize", 1UL << 20, nullptr, "Size of the bogus file which will be created for global shared allocations");
 
     xbt_cfg_register_double("smpi/cpu-threshold", 1e-6, nullptr, "Minimal computation time (in seconds) not discarded, or -1 for infinity.");
     xbt_cfg_register_alias("smpi/cpu-threshold", "smpi/cpu_threshold");
diff --git a/src/smpi/smpi_shared.cpp b/src/smpi/smpi_shared.cpp
index 011499aa49..a717d39a03 100644
--- a/src/smpi/smpi_shared.cpp
+++ b/src/smpi/smpi_shared.cpp
@@ -212,6 +212,8 @@ void *smpi_shared_malloc(size_t size, const char *file, int line)
     if (smpi_shared_malloc_bogusfile == -1) {
       /* Create a fd to a new file on disk, make it smpi_shared_malloc_blocksize big, and unlink it.
        * It still exists in memory but not in the file system (thus it cannot be leaked). */
+      smpi_shared_malloc_blocksize = static_cast<unsigned long>(xbt_cfg_get_double("smpi/shared-malloc-blocksize"));
+      XBT_DEBUG("global shared allocation. Blocksize %lu", smpi_shared_malloc_blocksize);
       char* name                   = xbt_strdup("/tmp/simgrid-shmalloc-XXXXXX");
       smpi_shared_malloc_bogusfile = mkstemp(name);
       unlink(name);
@@ -230,7 +232,8 @@ void *smpi_shared_malloc(size_t size, const char *file, int line)
       void* res = mmap(pos, smpi_shared_malloc_blocksize, PROT_READ | PROT_WRITE, MAP_FIXED | MAP_SHARED | MAP_POPULATE,
                        smpi_shared_malloc_bogusfile, 0);
       xbt_assert(res == pos, "Could not map folded virtual memory (%s). Do you perhaps need to increase the "
-                             "STARPU_MALLOC_SIMULATION_FOLD environment variable or the sysctl vm.max_map_count?",
+                             "size of the mapped file using --cfg=smpi/shared-malloc-blocksize=newvalue (default 1048576) ?",
+                             "You can also try using  the sysctl vm.max_map_count",
                  strerror(errno));
     }
     if (size % smpi_shared_malloc_blocksize) {
@@ -238,7 +241,8 @@ void *smpi_shared_malloc(size_t size, const char *file, int line)
       void* res = mmap(pos, size % smpi_shared_malloc_blocksize, PROT_READ | PROT_WRITE,
                        MAP_FIXED | MAP_SHARED | MAP_POPULATE, smpi_shared_malloc_bogusfile, 0);
       xbt_assert(res == pos, "Could not map folded virtual memory (%s). Do you perhaps need to increase the "
-                             "STARPU_MALLOC_SIMULATION_FOLD environment variable or the sysctl vm.max_map_count?",
+                             "size of the mapped file using --cfg=smpi/shared-malloc-blocksize=newvalue (default 1048576) ?",
+                             "You can also try using  the sysctl vm.max_map_count",
                  strerror(errno));
     }