commit eb2440207f14db79cb0cadaca5386ecd0cd35656
author Jonathan Peyton <jonathan.l.peyton@intel.com> Fri Jan 22 14:45:45 2021 -0600
committer Copybara-Service <copybara-worker@google.com> Fri Feb 05 03:23:37 2021 -0800
tree 993458ff8e60f5f9064cc0661c936ab40bdc5682
parent 4171e251d0afe21b1a6546b66fa42b4885e6a7bd

[OpenMP] Add environment variable to force monotonic dynamic scheduling

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

Differential Revision: https://reviews.llvm.org/D95263

GitOrigin-RevId: 67773681c0ef2a778a3c34d23b365899cd33e0c3

runtime/src/kmp.h

diff --git a/runtime/src/kmp.h b/runtime/src/kmp.h
index ca57bf7..163dc0e 100644
--- a/runtime/src/kmp.h
+++ b/runtime/src/kmp.h
@@ -3004,6 +3004,7 @@
 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

runtime/src/kmp_dispatch.cpp

diff --git a/runtime/src/kmp_dispatch.cpp b/runtime/src/kmp_dispatch.cpp
index a805ee4..3e9fc7c 100644
--- a/runtime/src/kmp_dispatch.cpp
+++ b/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;

runtime/src/kmp_global.cpp

diff --git a/runtime/src/kmp_global.cpp b/runtime/src/kmp_global.cpp
index afe7232..0f508e8 100644
--- a/runtime/src/kmp_global.cpp
+++ b/runtime/src/kmp_global.cpp
@@ -166,6 +166,7 @@
 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 */

runtime/src/kmp_settings.cpp

diff --git a/runtime/src/kmp_settings.cpp b/runtime/src/kmp_settings.cpp
index 3d9bdb3..b7d5d3b 100644
--- a/runtime/src/kmp_settings.cpp
+++ b/runtime/src/kmp_settings.cpp
@@ -4137,6 +4137,18 @@
 #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_force_monotonic
+
+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_force_monotonic
+
+// -----------------------------------------------------------------------------
 // KMP_ATOMIC_MODE
 
 static void __kmp_stg_parse_atomic_mode(char const *name, char const *value,
@@ -5224,6 +5236,9 @@
     {"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,