1 files changed, 51 insertions, 0 deletions
diff --git a/psutil/arch/windows/mem.c b/psutil/arch/windows/mem.c
index 18b535e6..24dc15ad 100644
--- a/psutil/arch/windows/mem.c
+++ b/psutil/arch/windows/mem.c
@@ -7,6 +7,7 @@
 #include <Python.h>
 #include <windows.h>
 #include <Psapi.h>
+#include <pdh.h>
 
 #include "../../_psutil_common.h"
 
@@ -41,3 +42,53 @@ psutil_virtual_mem(PyObject *self, PyObject *args) {
         totalSys,
         availSys);
 }
+
+
+// Return a float representing the percent usage of all paging files on
+// the system.
+PyObject *
+psutil_swap_percent(PyObject *self, PyObject *args) {
+    WCHAR *szCounterPath = L"\\Paging File(_Total)\\% Usage";
+    PDH_STATUS s;
+    HQUERY hQuery;
+    HCOUNTER hCounter;
+    PDH_FMT_COUNTERVALUE counterValue;
+    double percentUsage;
+
+    if ((PdhOpenQueryW(NULL, 0, &hQuery)) != ERROR_SUCCESS) {
+        PyErr_Format(PyExc_RuntimeError, "PdhOpenQueryW failed");
+        return NULL;
+    }
+
+    s = PdhAddEnglishCounterW(hQuery, szCounterPath, 0, &hCounter);
+    if (s != ERROR_SUCCESS) {
+        PdhCloseQuery(hQuery);
+        PyErr_Format(
+            PyExc_RuntimeError,
+            "PdhAddEnglishCounterW failed. Performance counters may be disabled."
+        );
+        return NULL;
+    }
+
+    s = PdhCollectQueryData(hQuery);
+    if (s != ERROR_SUCCESS) {
+        // If swap disabled this will fail.
+        psutil_debug("PdhCollectQueryData failed; assume swap percent is 0");
+        percentUsage = 0;
+    }
+    else {
+        s = PdhGetFormattedCounterValue(
+            (PDH_HCOUNTER)hCounter, PDH_FMT_DOUBLE, 0, &counterValue);
+        if (s != ERROR_SUCCESS) {
+            PdhCloseQuery(hQuery);
+            PyErr_Format(
+                PyExc_RuntimeError, "PdhGetFormattedCounterValue failed");
+            return NULL;
+        }
+        percentUsage = counterValue.doubleValue;
+    }
+
+    PdhRemoveCounter(hCounter);
+    PdhCloseQuery(hQuery);
+    return Py_BuildValue("d", percentUsage);
+}