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Use logical count for everything newer than dozer #4

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Use logical count for everything newer than dozer #4

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2d54294
Use logical count for everything newer than dozer
Artoria2e5 Dec 13, 2020
c23d83d
README: Add useful links
Artoria2e5 Dec 13, 2020
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5 changes: 5 additions & 0 deletions README.md
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Expand Up @@ -11,3 +11,8 @@ These self-contained code samples show you how to correctly detect physical and
## Support and suggestions

If you spot a bug, or would like to see the samples evolve in a particular way, file an issue and we'll take a look!

## Further reading

- Ken Mitchell (2017). [CPU Core Count Detection on Windows®](https://gpuopen.com/learn/cpu-core-count-detection-windows/). *GPUOpen*.
- Ken Mitchell, Elliot Kim (2018). [AMD Ryzen™ CPU Optimization](https://gpuopen.com/wp-content/uploads/2018/05/gdc_2018_sponsored_optimizing_for_ryzen.pdf). Presented on GDC 2018.
10 changes: 6 additions & 4 deletions windows/ThreadCount-Win7.cpp
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Expand Up @@ -73,8 +73,10 @@ DWORD getDefaultThreadCount() {
char vendor[13];
getCpuidVendor(vendor);
if (0 == strcmp(vendor, "AuthenticAMD")) {
if (0x15 == getCpuidFamily()) {
// AMD "Bulldozer" family microarchitecture
if (0x15 <= getCpuidFamily()) {
// AMD "Bulldozer" family microarchitecture or newer
// Jaguar does not have SMT, and Zen SMT is no worse than Bulldozer
// MAINTAINER: remember to update if SMT ever gets bad!
count = logical;
}
else {
Expand All @@ -92,8 +94,8 @@ int main(int argc, char* argv[]) {

DWORD cores, logical;
getProcessorCount(cores, logical);
if ((0 == strcmp(vendor, "AuthenticAMD")) && (0x15 == getCpuidFamily())) {
// AMD "Bulldozer" family microarchitecture
if ((0 == strcmp(vendor, "AuthenticAMD")) && (0x15 <= getCpuidFamily())) {
// AMD "Bulldozer" family microarchitecture or newer
printf("Processor Module Count: %u\n", logical / 2);
printf("Processor Core Count: %u\n", logical);
}
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8 changes: 5 additions & 3 deletions windows/ThreadCount-WinXP.cpp
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Expand Up @@ -72,7 +72,9 @@ DWORD getDefaultThreadCount() {
getCpuidVendor(vendor);
if (0 == strcmp(vendor, "AuthenticAMD")) {
if (0x15 == getCpuidFamily()) {
// AMD "Bulldozer" family microarchitecture
// AMD "Bulldozer" family microarchitecture or newer
// Jaguar does not have SMT, and Zen SMT is no worse than Bulldozer
// MAINTAINER: remember to update if SMT ever gets bad!
count = logical;
}
else {
Expand All @@ -90,8 +92,8 @@ int main(int argc, char* argv[]) {

DWORD cores, logical;
getProcessorCount(cores, logical);
if ((0 == strcmp(vendor, "AuthenticAMD")) && (0x15 == getCpuidFamily())) {
// AMD "Bulldozer" family microarchitecture
if ((0 == strcmp(vendor, "AuthenticAMD")) && (0x15 <= getCpuidFamily())) {
// AMD "Bulldozer" family microarchitecture or newer
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okay, maybe not this..

printf("Processor Module Count: %u\n", logical / 2);
printf("Processor Core Count: %u\n", logical);
}
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