Windows: get swap usage from the pagefile(s)

psutil/_psutil_windows.c

@@ -1596,6 +1596,7 @@ PsutilMethods[] = {
     {"cpu_times", psutil_cpu_times, METH_VARARGS},
     {"disk_io_counters", psutil_disk_io_counters, METH_VARARGS},
     {"disk_partitions", psutil_disk_partitions, METH_VARARGS},
+    {"disk_swaps", psutil_disk_swaps, METH_VARARGS},
     {"disk_usage", psutil_disk_usage, METH_VARARGS},
     {"getloadavg", (PyCFunction)psutil_get_loadavg, METH_VARARGS},
     {"getpagesize", psutil_getpagesize, METH_VARARGS},

psutil/_pswindows.py

@@ -241,18 +241,13 @@ def virtual_memory():
 
 def swap_memory():
     """Swap system memory as a (total, used, free, sin, sout) tuple."""
-    mem = cext.virtual_mem()
-
-    total_phys = mem[0]
-    free_phys = mem[1]
-    total_system = mem[2]
-    free_system = mem[3]
-
-    # 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
+    total = used = 0
+    pagefiles = cext.disk_swaps()
+    for pf in pagefiles:
+        path, total_size, total_in_use, peak_usage = pf
+        total += total_size
+        used += total_in_use
+    free = total - used
     percent = usage_percent(used, total, round_=1)
     return _common.sswap(total, used, free, percent, 0, 0)
 

psutil/arch/windows/disk.c

@@ -359,6 +359,89 @@ psutil_disk_partitions(PyObject *self, PyObject *args) {
 }
 
 
+/*
+ * Return information about the disk page files as a list.
+ * A page file is basically the same thing as a swap partition.
+ */
+PyObject *
+psutil_disk_swaps(PyObject *self, PyObject *args) {
+    NTSTATUS status;
+    PVOID buffer = NULL;
+    ULONG bufferSize = 0x200;
+    PSYSTEM_PAGEFILE_INFORMATION pInfo;
+    PyObject *py_tuple = NULL;
+    PyObject *py_path = NULL;
+    PyObject *py_retlist = PyList_New(0);
+
+    if (! py_retlist)
+        return NULL;
+
+    // Enumerate page files.
+    buffer = MALLOC_ZERO(bufferSize);
+    while ((status = NtQuerySystemInformation(
+        SystemPageFileInformation,
+        buffer,
+        bufferSize,
+        NULL)) == STATUS_INFO_LENGTH_MISMATCH)
+    {
+        FREE(buffer);
+        bufferSize *= 2;
+        buffer = MALLOC_ZERO(bufferSize);
+    }
+
+    if (! NT_SUCCESS(status)) {
+        psutil_SetFromNTStatusErr(status, "NtQuerySystemInformation");
+        goto error;
+    }
+
+    // Traverse the resulting struct.
+    // A TotalSize of 0 is used to indicate that there are no pagefiles.
+    pInfo = (SYSTEM_PAGEFILE_INFORMATION *)buffer;
+    if (pInfo->TotalSize != 0) {
+        while (TRUE) {
+            // construct python list
+            py_path = PyUnicode_FromWideChar(
+                pInfo->PageFileName.Buffer,
+                wcslen(pInfo->PageFileName.Buffer));
+            if (! py_path)
+                goto error;
+
+            py_tuple = Py_BuildValue(
+                "Okkk",
+                py_path,
+                pInfo->TotalSize * PSUTIL_SYSTEM_INFO.dwPageSize,
+                pInfo->TotalInUse * PSUTIL_SYSTEM_INFO.dwPageSize,
+                pInfo->PeakUsage * PSUTIL_SYSTEM_INFO.dwPageSize
+            );
+            if (!py_tuple)
+                goto error;
+            if (PyList_Append(py_retlist, py_tuple))
+                goto error;
+            Py_CLEAR(py_tuple);
+            Py_CLEAR(py_path);
+
+            // end of list
+            if (pInfo->NextEntryOffset == 0)
+                break;
+            // set pointer to the next pInfo struct
+            pInfo = (SYSTEM_PAGEFILE_INFORMATION *) \
+                ((BYTE *)pInfo + pInfo->NextEntryOffset);
+        }
+    }
+
+    FREE(buffer);
+    return py_retlist;
+
+error:
+    if (buffer != NULL)
+        FREE(buffer);
+    Py_XDECREF(py_tuple);
+    Py_XDECREF(py_path);
+    Py_DECREF(py_retlist);
+    return NULL;
+}
+
+
 /*
  Accept a filename's drive in native  format like "\Device\HarddiskVolume1\"
  and return the corresponding drive letter (e.g. "C:\\").

psutil/arch/windows/disk.h

@@ -8,5 +8,6 @@
 
 PyObject *psutil_disk_io_counters(PyObject *self, PyObject *args);
 PyObject *psutil_disk_partitions(PyObject *self, PyObject *args);
+PyObject *psutil_disk_swaps(PyObject *self, PyObject *args);
 PyObject *psutil_disk_usage(PyObject *self, PyObject *args);
 PyObject *psutil_QueryDosDevice(PyObject *self, PyObject *args);

psutil/arch/windows/ntextapi.h

@@ -41,6 +41,8 @@ typedef LONG NTSTATUS;
 #define ProcessWow64Information 26
 #undef  SystemProcessIdInformation
 #define SystemProcessIdInformation 88
+#undef  SystemPageFileInformation
+#define SystemPageFileInformation 18
 
 // process suspend() / resume()
 typedef enum _KTHREAD_STATE {
@@ -448,6 +450,15 @@ typedef struct _SYSTEM_PROCESS_ID_INFORMATION {
     UNICODE_STRING ImageName;
 } SYSTEM_PROCESS_ID_INFORMATION, *PSYSTEM_PROCESS_ID_INFORMATION;
 
+// disk_swaps()
+typedef struct _SYSTEM_PAGEFILE_INFORMATION {
+    ULONG NextEntryOffset;
+    ULONG TotalSize;
+    ULONG TotalInUse;
+    ULONG PeakUsage;
+    UNICODE_STRING PageFileName;
+} SYSTEM_PAGEFILE_INFORMATION, *PSYSTEM_PAGEFILE_INFORMATION;
+
 // ====================================================================
 // PEB structs for cmdline(), cwd(), environ()
 // ====================================================================

psutil/tests/test_windows.py

@@ -162,6 +162,11 @@ def test_free_phymem(self):
             int(w.AvailableBytes), psutil.virtual_memory().free,
             delta=TOLERANCE_SYS_MEM)
 
+    def test_percent_swapmem(self):
+        w = wmi.WMI().Win32_PerfRawData_PerfOS_PagingFile()[0]
+        percent = int(w.PercentUsage) * 100 / int(w.PercentUsage_Base)
+        self.assertEqual(int(percent), int(psutil.swap_memory().percent))
+
     # @unittest.skipIf(wmi is None, "wmi module is not installed")
     # def test__UPTIME(self):
     #     # _UPTIME constant is not public but it is used internally