Use system-level values for Windows virtual memory

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

@@ -610,20 +610,25 @@ psutil_proc_memory_uss(PyObject *self, PyObject *args) {
  */
 static PyObject *
 psutil_virtual_mem(PyObject *self, PyObject *args) {
-    MEMORYSTATUSEX memInfo;
-    memInfo.dwLength = sizeof(MEMORYSTATUSEX);
+    unsigned long long totalPhys, availPhys, totalSys, availSys, pageSize;
+    PERFORMANCE_INFORMATION perfInfo;
 
-    if (! GlobalMemoryStatusEx(&memInfo)) {
+    if (! GetPerformanceInfo(&perfInfo, sizeof(PERFORMANCE_INFORMATION))) {
         PyErr_SetFromWindowsErr(0);
         return NULL;
     }
-    return Py_BuildValue("(LLLLLL)",
-                         memInfo.ullTotalPhys,      // total
-                         memInfo.ullAvailPhys,      // avail
-                         memInfo.ullTotalPageFile,  // total page file
-                         memInfo.ullAvailPageFile,  // avail page file
-                         memInfo.ullTotalVirtual,   // total virtual
-                         memInfo.ullAvailVirtual);  // avail virtual
+    // 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);
 }
 
 

psutil/_pswindows.py

@@ -229,7 +229,7 @@ def getpagesize():
 def virtual_memory():
     """System virtual memory as a namedtuple."""
     mem = cext.virtual_mem()
-    totphys, availphys, totpagef, availpagef, totvirt, freevirt = mem
+    totphys, availphys, totsys, availsys = mem
     #
     total = totphys
     avail = availphys
@@ -248,8 +248,8 @@ def swap_memory():
     total_system = mem[2]
     free_system = mem[3]
 
-    # Despite the name PageFile refers to total system memory here
-    # thus physical memory values need to be subtracted 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