From c40fd26c20e5627285f8abb10f1435bea401fa70 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Moritz=20Br=C3=BCckner?= <mail@moritz-brueckner.de>
Date: Mon, 27 Sep 2021 23:13:30 +0200
Subject: [PATCH] Fix CPU count parameter for cmft

---
 blender/arm/utils.py        | 38 ++++++++++++++++++++++++++++++++++++-
 blender/arm/write_probes.py |  5 ++++-
 2 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/blender/arm/utils.py b/blender/arm/utils.py
index 20c9c2e8..6980d710 100755
--- a/blender/arm/utils.py
+++ b/blender/arm/utils.py
@@ -130,7 +130,7 @@ def get_fp():
 def get_fp_build():
     return os.path.join(get_fp(), build_dir())
 
-def get_os():
+def get_os() -> str:
     s = platform.system()
     if s == 'Windows':
         return 'win'
@@ -1111,6 +1111,42 @@ def get_list_installed_vs_path() -> []:
         err = 'File "'+ path_file +'" not found.'
     return items, err
 
+
+def cpu_count(*, physical_only=False) -> Optional[int]:
+    """Returns the number of logical (default) or physical CPUs.
+    The result can be `None` if `os.cpu_count()` was not able to get the
+    correct count of logical CPUs.
+    """
+    if not physical_only:
+        return os.cpu_count()
+
+    _os = get_os()
+    try:
+        if _os == 'win':
+            result = subprocess.check_output(['wmic', 'cpu', 'get', 'NumberOfCores'])
+            result = result.decode('utf-8').splitlines()
+            result = int(result[2])
+            if result > 0:
+                return result
+
+        elif _os == 'linux':
+            result = subprocess.check_output("grep -P '^core id' /proc/cpuinfo | sort -u | wc -l", shell=True)
+            result = result.decode('utf-8').splitlines()
+            result = int(result[0])
+            if result > 0:
+                return result
+
+        # macOS
+        else:
+            return int(subprocess.check_output(['sysctl', '-n', 'hw.physicalcpu']))
+    except subprocess.CalledProcessError:
+        pass
+
+    # Last resort even though it can be wrong
+    log.warn("Could not retrieve count of physical CPUs, using logical CPU count instead.")
+    return os.cpu_count()
+
+
 def register(local_sdk=False):
     global use_local_sdk
     use_local_sdk = local_sdk
diff --git a/blender/arm/write_probes.py b/blender/arm/write_probes.py
index a0d1f67b..80c30a80 100644
--- a/blender/arm/write_probes.py
+++ b/blender/arm/write_probes.py
@@ -187,7 +187,10 @@ def write_probes(image_filepath: str, disable_hdr: bool, cached_num_mips: int, a
 
     wrd = bpy.data.worlds['Arm']
     use_opencl = 'true'
-    cpu_count = multiprocessing.cpu_count()
+
+    # cmft doesn't work correctly when passing the number of logical
+    # CPUs if there are more logical than physical CPUs on a machine
+    cpu_count = arm.utils.cpu_count(physical_only=True)
 
     if arm.utils.get_os() == 'win':
         cmd = [