[Openmp-commits] [PATCH] D95263: [OpenMP] Add environment variable to force monotonic dynamic scheduling

[Terry Wilmarth via Phabricator via Openmp-commits]

tlwilmar created this revision.
tlwilmar added reviewers: AndreyChurbanov, hbae, jlpeyton.
tlwilmar added a project: OpenMP.
Herald added subscribers: guansong, yaxunl.
tlwilmar requested review of this revision.
Herald added a reviewer: jdoerfert.
Herald added a subscriber: sstefan1.

This patch introduces a new environment variable to force monotonic behavior for users that absolutely need it.  This is in anticipation of a 5.0 spec change that uses non-monotonic behavior for dynamic scheduling by default. Fixes for that and the actual switch are coming soon.

Patch by Johnny Peyton.


Repository:
  rOMP OpenMP

https://reviews.llvm.org/D95263

Files:
  openmp/runtime/src/kmp.h
  openmp/runtime/src/kmp_dispatch.cpp
  openmp/runtime/src/kmp_global.cpp
  openmp/runtime/src/kmp_settings.cpp


Index: openmp/runtime/src/kmp_settings.cpp
===================================================================
--- openmp/runtime/src/kmp_settings.cpp
+++ openmp/runtime/src/kmp_settings.cpp
@@ -3823,6 +3823,18 @@
 #endif
 
 // -----------------------------------------------------------------------------
+// KMP_FORCE_MONOTONIC_DYNAMIC_SCHEDULE
+static void __kmp_stg_parse_kmp_force_monotonic(char const *name,
+                                                char const *value, void *data) {
+  __kmp_stg_parse_bool(name, value, &(__kmp_force_monotonic));
+} // __kmp_stg_parse_kmp_hand_thread
+
+static void __kmp_stg_print_kmp_force_monotonic(kmp_str_buf_t *buffer,
+                                                char const *name, void *data) {
+  __kmp_stg_print_bool(buffer, name, __kmp_force_monotonic);
+} // __kmp_stg_print_kmp_hand_thread
+
+// -----------------------------------------------------------------------------
 // KMP_ATOMIC_MODE
 
 static void __kmp_stg_parse_atomic_mode(char const *name, char const *value,
@@ -4898,6 +4910,9 @@
     {"KMP_DISP_HAND_THREAD", __kmp_stg_parse_kmp_hand_thread,
      __kmp_stg_print_kmp_hand_thread, NULL, 0, 0},
 #endif
+    {"KMP_FORCE_MONOTONIC_DYNAMIC_SCHEDULE",
+     __kmp_stg_parse_kmp_force_monotonic, __kmp_stg_print_kmp_force_monotonic,
+     NULL, 0, 0},
     {"KMP_ATOMIC_MODE", __kmp_stg_parse_atomic_mode,
      __kmp_stg_print_atomic_mode, NULL, 0, 0},
     {"KMP_CONSISTENCY_CHECK", __kmp_stg_parse_consistency_check,
Index: openmp/runtime/src/kmp_global.cpp
===================================================================
--- openmp/runtime/src/kmp_global.cpp
+++ openmp/runtime/src/kmp_global.cpp
@@ -163,6 +163,7 @@
 int __kmp_ncores = 0;
 #endif
 int __kmp_chunk = 0;
+int __kmp_force_monotonic = 0;
 int __kmp_abort_delay = 0;
 #if KMP_OS_LINUX && defined(KMP_TDATA_GTID)
 int __kmp_gtid_mode = 3; /* use __declspec(thread) TLS to store gtid */
Index: openmp/runtime/src/kmp_dispatch.cpp
===================================================================
--- openmp/runtime/src/kmp_dispatch.cpp
+++ openmp/runtime/src/kmp_dispatch.cpp
@@ -80,7 +80,7 @@
   if (loc->get_openmp_version() < 50)
     monotonicity = SCHEDULE_MONOTONIC;
 
-  if (use_hier)
+  if (use_hier || __kmp_force_monotonic)
     monotonicity = SCHEDULE_MONOTONIC;
   else if (SCHEDULE_HAS_NONMONOTONIC(schedule))
     monotonicity = SCHEDULE_NONMONOTONIC;
Index: openmp/runtime/src/kmp.h
===================================================================
--- openmp/runtime/src/kmp.h
+++ openmp/runtime/src/kmp.h
@@ -2963,6 +2963,7 @@
 extern enum sched_type __kmp_guided; /* default guided scheduling method */
 extern enum sched_type __kmp_auto; /* default auto scheduling method */
 extern int __kmp_chunk; /* default runtime chunk size */
+extern int __kmp_force_monotonic; /* whether monotonic scheduling forced */
 
 extern size_t __kmp_stksize; /* stack size per thread         */
 #if KMP_USE_MONITOR


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