Formatting, credits, change log

Signed-off-by: Daniel Widdis <widdis@gmail.com>

CREDITS

@@ -801,3 +801,7 @@ I: 2135
 
 N: Daniel Li
 I: 2150
+
+N: Daniel Widdis
+W: https://github.com/dbwiddis
+I: 2077

HISTORY.rst

@@ -1,5 +1,15 @@
 *Bug tracker at https://github.com/giampaolo/psutil/issues*
 
+5.9.4 (IN DEVELOPMENT)
+======================
+
+XXXX-XX-XX
+
+**Bug fixes**
+
+- 2077_, [Windows]: Use system-level values for `virtual_memory()`. (patch by
+  Daniel Widdis)
+
 5.9.3
 =====
 

psutil/_psutil_windows.c

@@ -612,21 +612,23 @@ static PyObject *
 psutil_virtual_mem(PyObject *self, PyObject *args) {
     unsigned long long totalPhys, availPhys, totalSys, availSys, pageSize;
     PERFORMANCE_INFORMATION perfInfo;
+
     if (! GetPerformanceInfo(&perfInfo, sizeof(PERFORMANCE_INFORMATION))) {
         PyErr_SetFromWindowsErr(0);
         return NULL;
     }
-    // values are size_t, widen to long long
+    // values are size_t, widen (if needed) to long long
     pageSize = perfInfo.PageSize;
     totalPhys = perfInfo.PhysicalTotal * pageSize;
     availPhys = perfInfo.PhysicalAvailable * pageSize;
     totalSys = perfInfo.CommitLimit * pageSize;
     availSys = totalSys - perfInfo.CommitTotal * pageSize;
-    return Py_BuildValue("(LLLL)",
-                         totalPhys,
-                         availPhys,
-                         totalSys,
-                         availSys);
+    return Py_BuildValue(
+        "(LLLL)",
+        totalPhys,
+        availPhys,
+        totalSys,
+        availSys);
 }
 
 

psutil/_pswindows.py

@@ -248,7 +248,8 @@ def swap_memory():
     total_system = mem[2]
     free_system = mem[3]
 
-    # physical memory values need to be substracted to get swap values
+    # system memory (commit total/limit) is the sum of physical and swap
+    # thus physical memory values need to be substracted to get swap values
     total = total_system - total_phys
     free = min(total, free_system - free_phys)
     used = total - free