Updated getDefaultThreadCount() to better represent other vendor posi…

…tions on SMT for gaming
GPUOpen-LibrariesAndSDKs · Sep 27, 2017 · 49a6e73 · 49a6e73
1 parent 48177af
commit 49a6e73
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Showing 2 changed files with 32 additions and 11 deletions.
diff --git a/windows/ThreadCount-Win7.cpp b/windows/ThreadCount-Win7.cpp
@@ -1,4 +1,6 @@
-// GetLogicalProcessorInformationEx requires Win7
+// This advice is specific to AMD processors and is not general guidance for all processor manufacturers.
+//
+// GetLogicalProcessorInformationEx requires Win7 or later
 // based on https://msdn.microsoft.com/en-us/library/windows/desktop/dd405488(v=vs.85).aspx
 
 #include <stdio.h>
@@ -61,15 +63,23 @@ int getCpuidFamily() {
 	return displayFamily;
 }
 
+// This advice is specific to AMD processors and is
+// not general guidance for all processor
+// manufacturers. Remember to profile!
 DWORD getDefaultThreadCount() {
 	DWORD cores, logical;
 	getProcessorCount(cores, logical);
-	DWORD count = cores;
+	DWORD count = logical;
 	char vendor[13];
 	getCpuidVendor(vendor);
-	if ((0 == strcmp(vendor, "AuthenticAMD")) && (0x15 == getCpuidFamily())) {
-		// AMD "Bulldozer" family microarchitecture
-		count = logical;
+	if (0 == strcmp(vendor, "AuthenticAMD")) {
+		if (0x15 == getCpuidFamily()) {
+			// AMD "Bulldozer" family microarchitecture
+			count = logical;
+		}
+		else {
+			count = cores;
+		}
 	}
 	return count;
 }
@@ -96,4 +106,4 @@ int main(int argc, char* argv[]) {
 	printf("Default Thread Count: %u\n", getDefaultThreadCount());
 
 	return 0;
-}
+}
diff --git a/windows/ThreadCount-WinXP.cpp b/windows/ThreadCount-WinXP.cpp
@@ -1,3 +1,6 @@
+// This advice is specific to AMD processors and is not general guidance for all processor manufacturers.
+//
+// GetLogicalProcessorInformation requires WinXP or later
 // based on https://msdn.microsoft.com/en-us/library/windows/desktop/ms683194(v=vs.85).aspx
 
 #include <intrin.h>
@@ -58,15 +61,23 @@ int getCpuidFamily() {
 	return displayFamily;
 }
 
+// This advice is specific to AMD processors and is
+// not general guidance for all processor
+// manufacturers. Remember to profile!
 DWORD getDefaultThreadCount() {
 	DWORD cores, logical;
 	getProcessorCount(cores, logical);
-	DWORD count = cores;
+	DWORD count = logical;
 	char vendor[13];
 	getCpuidVendor(vendor);
-	if ((0 == strcmp(vendor, "AuthenticAMD")) && (0x15 == getCpuidFamily())) {
-		// AMD "Bulldozer" family microarchitecture
-		count = logical;
+	if (0 == strcmp(vendor, "AuthenticAMD")) {
+		if (0x15 == getCpuidFamily()) {
+			// AMD "Bulldozer" family microarchitecture
+			count = logical;
+		}
+		else {
+			count = cores;
+		}
 	}
 	return count;
 }
@@ -93,4 +104,4 @@ int main(int argc, char* argv[]) {
 	printf("Default Thread Count: %u\n", getDefaultThreadCount());
 
 	return 0;
-}
+}