Reset initial affinity in children processes
If OpenMP is initialized before fork()-ing occurs and affinity is set to
something like compact, then the master thread will be pinned to a single HW
thread/core after initialization. If the master (or any other thread) then
forks N processes, all N processes will then be pinned to that same single HW
thread/core. To reset the affinity for the new child process, the atfork
handler for the child process can call kmp_set_thread_affinity_mask_initial()
to reset its affinity to the initial affinity of the application before it
re-initializes libomp. The parent process will not be affected and still
keeps its affinity setting.
Differential Revision: https://reviews.llvm.org/D34118
llvm-svn: 305306
diff --git a/openmp/runtime/src/z_Linux_util.cpp b/openmp/runtime/src/z_Linux_util.cpp
index 2f83c02..a0d1639 100644
--- a/openmp/runtime/src/z_Linux_util.cpp
+++ b/openmp/runtime/src/z_Linux_util.cpp
@@ -1280,6 +1280,12 @@
++__kmp_fork_count;
+#if KMP_AFFINITY_SUPPORTED && KMP_OS_LINUX
+ // reset the affinity in the child to the initial thread
+ // affinity in the parent
+ kmp_set_thread_affinity_mask_initial();
+#endif
+
__kmp_init_runtime = FALSE;
#if KMP_USE_MONITOR
__kmp_init_monitor = 0;