X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmisc.cpp;h=7a23b7a9c930791ce41c254ac3834fbff2941978;hp=7075dd3cdc8498192cd8f256740fcc497cb63827;hb=2ec626ddae9c81af6338f72296df8a1465b5e036;hpb=9eccba776198c210563666787a9b5fe44b386fdc

diff --git a/src/misc.cpp b/src/misc.cpp
index 7075dd3c..7a23b7a9 100644
--- a/src/misc.cpp
+++ b/src/misc.cpp
@@ -21,9 +21,19 @@
 #ifdef _WIN32
 #if _WIN32_WINNT < 0x0601
 #undef  _WIN32_WINNT
-#define _WIN32_WINNT 0x0601 // Force to include newest API (Win 7 or later)
+#define _WIN32_WINNT 0x0601 // Force to include needed API prototypes
 #endif
-#include <windows.h> // For processor groups
+#include <windows.h>
+// The needed Windows API for processor groups could be missed from old Windows
+// versions, so instead of calling them directly (forcing the linker to resolve
+// the calls at compile time), try to load them at runtime. To do this we need
+// first to define the corresponding function pointers.
+extern "C" {
+typedef bool(*fun1_t)(LOGICAL_PROCESSOR_RELATIONSHIP,
+                      PSYSTEM_LOGICAL_PROCESSOR_INFORMATION_EX, PDWORD);
+typedef bool(*fun2_t)(USHORT, PGROUP_AFFINITY);
+typedef bool(*fun3_t)(HANDLE, CONST GROUP_AFFINITY*, PGROUP_AFFINITY);
+}
 #endif
 
 #include <fstream>
@@ -215,15 +225,14 @@ int get_group(size_t idx) {
   DWORD returnLength = 0;
   DWORD byteOffset = 0;
 
-  // Early exit if the needed API are not available at runtime
+  // Early exit if the needed API is not available at runtime
   HMODULE k32 = GetModuleHandle("Kernel32.dll");
-  if (   !GetProcAddress(k32, "GetLogicalProcessorInformationEx")
-      || !GetProcAddress(k32, "GetNumaNodeProcessorMaskEx")
-      || !GetProcAddress(k32, "SetThreadGroupAffinity"))
+  auto fun1 = (fun1_t)GetProcAddress(k32, "GetLogicalProcessorInformationEx");
+  if (!fun1)
       return -1;
 
   // First call to get returnLength. We expect it to fail due to null buffer
-  if (GetLogicalProcessorInformationEx(RelationAll, nullptr, &returnLength))
+  if (fun1(RelationAll, nullptr, &returnLength))
       return -1;
 
   // Once we know returnLength, allocate the buffer
@@ -231,7 +240,7 @@ int get_group(size_t idx) {
   ptr = buffer = (SYSTEM_LOGICAL_PROCESSOR_INFORMATION_EX*)malloc(returnLength);
 
   // Second call, now we expect to succeed
-  if (!GetLogicalProcessorInformationEx(RelationAll, buffer, &returnLength))
+  if (!fun1(RelationAll, buffer, &returnLength))
   {
       free(buffer);
       return -1;
@@ -278,15 +287,31 @@ int get_group(size_t idx) {
 
 void bindThisThread(size_t idx) {
 
-  // Use a local variable instead of a static: slower but thread-safe
+  // If OS already scheduled us on a different group than 0 then don't overwrite
+  // the choice, eventually we are one of many one-threaded processes running on
+  // some Windows NUMA hardware, for instance in fishtest. To make it simple,
+  // just check if running threads are below a threshold, in this case all this
+  // NUMA machinery is not needed.
+  if (Threads.size() < 8)
+      return;
+
+  // Use only local variables to be thread-safe
   int group = get_group(idx);
 
   if (group == -1)
       return;
 
-  GROUP_AFFINITY mask;
-  if (GetNumaNodeProcessorMaskEx(group, &mask))
-      SetThreadGroupAffinity(GetCurrentThread(), &mask, nullptr);
+  // Early exit if the needed API are not available at runtime
+  HMODULE k32 = GetModuleHandle("Kernel32.dll");
+  auto fun2 = (fun2_t)GetProcAddress(k32, "GetNumaNodeProcessorMaskEx");
+  auto fun3 = (fun3_t)GetProcAddress(k32, "SetThreadGroupAffinity");
+
+  if (!fun2 || !fun3)
+      return;
+
+  GROUP_AFFINITY affinity;
+  if (fun2(group, &affinity))
+      fun3(GetCurrentThread(), &affinity, nullptr);
 }
 
 #endif