Restrict HWLOC's interference with Windows process affninity (#1457)

On Windows systems with multiple processor groups, HWLOC x86 backend might interfere with process affinity mask leading applications trying to set process affinity mask to fail. --------- Signed-off-by: Isaev, Ilya <[email protected]>
uxlfoundation · Jul 29, 2024 · 4d0dc6a · 4d0dc6a
1 parent 2360b48
commit 4d0dc6a
Showing 1 changed file with 10 additions and 7 deletions.
diff --git a/src/tbbbind/tbb_bind.cpp b/src/tbbbind/tbb_bind.cpp
@@ -1,5 +1,5 @@
 /*
-    Copyright (c) 2019-2023 Intel Corporation
+    Copyright (c) 2019-2024 Intel Corporation
 
     Licensed under the Apache License, Version 2.0 (the "License");
     you may not use this file except in compliance with the License.
@@ -88,12 +88,15 @@ class system_topology {
         if ( hwloc_topology_init( &topology ) == 0 ) {
             initialization_state = topology_allocated;
 #if __TBBBIND_HWLOC_TOPOLOGY_FLAG_RESTRICT_TO_CPUBINDING_PRESENT
-            if ( groups_num == 1 &&
-                 hwloc_topology_set_flags(topology,
-                     HWLOC_TOPOLOGY_FLAG_IS_THISSYSTEM |
-                     HWLOC_TOPOLOGY_FLAG_RESTRICT_TO_CPUBINDING
-                 ) != 0
-            ) {
+            unsigned long flags = 0;
+            if (groups_num > 1) {
+                // HWLOC x86 backend might interfere with process affinity mask on
+                // Windows systems with multiple processor groups.
+                flags = HWLOC_TOPOLOGY_FLAG_DONT_CHANGE_BINDING;
+            } else {
+                flags = HWLOC_TOPOLOGY_FLAG_IS_THISSYSTEM | HWLOC_TOPOLOGY_FLAG_RESTRICT_TO_CPUBINDING;
+            }
+            if (hwloc_topology_set_flags(topology, flags) != 0) {
                 return;
             }
 #endif