Introduce per process GPU usage

src/Managers/Process.vala

@@ -25,6 +25,7 @@ public class Monitor.Process : GLib.Object {
 
     public string username = Utils.NO_DATA;
 
+
     Icon _icon;
     public Icon icon {
         get {
@@ -42,6 +43,9 @@ public class Monitor.Process : GLib.Object {
     // Contains info about io
     public ProcessIO io;
 
+    // Contains info about GPU usage
+    private ProcessDRM drm;
+
     // Contains status info
     public ProcessStatus stat;
 
@@ -61,26 +65,29 @@ public class Monitor.Process : GLib.Object {
     private uint64 cpu_last_used;
 
     // Memory usage of the process, measured in KiB.
-
     public uint64 mem_usage { get; private set; }
     public double mem_percentage { get; private set; }
 
-    private uint64 last_total;
+    public double gpu_percentage { get; private set; }
+
+    private uint64 last_total; // @TODO: Obsolete?
 
     const int HISTORY_BUFFER_SIZE = 30;
-    public Gee.ArrayList<double ? > cpu_percentage_history = new Gee.ArrayList<double ? > ();
-    public Gee.ArrayList<double ? > mem_percentage_history = new Gee.ArrayList<double ? > ();
+    public Gee.ArrayList<double ?> cpu_percentage_history = new Gee.ArrayList<double ?> ();
+    public Gee.ArrayList<double ?> mem_percentage_history = new Gee.ArrayList<double ?> ();
 
 
 
     // Construct a new process
-    public Process (int _pid) {
+    public Process (int _pid, int update_interval) {
         _icon = ProcessUtils.get_default_icon ();
 
         open_files_paths = new Gee.HashSet<string> ();
 
         last_total = 0;
 
+        drm = new ProcessDRM (_pid, update_interval);
+
         io = {};
         stat = {};
         stat.pid = _pid;
@@ -101,15 +108,18 @@ public class Monitor.Process : GLib.Object {
         exists = parse_stat () && read_cmdline ();
         get_children_pids ();
         get_usage (0, 1);
-    }
 
+        gpu_percentage = 0;
+    }
 
     // Updates the process to get latest information
     // Returns if the update was successful
     public bool update (uint64 cpu_total, uint64 cpu_last_total) {
         exists = parse_stat ();
         if (exists) {
             get_usage (cpu_total, cpu_last_total);
+            drm.update ();
+            gpu_percentage = drm.gpu_percentage;
             parse_io ();
             parse_statm ();
             get_open_files ();
@@ -280,8 +290,8 @@ public class Monitor.Process : GLib.Object {
     }
 
     /**
-     * Reads the /proc/%pid%/cmdline file and updates from the information contained therein.
-     */
+    * Reads the /proc/%pid%/cmdline file and updates from the information contained therein.
+    */
     private bool read_cmdline () {
         string ? cmdline = ProcessUtils.read_file ("/proc/%d/cmdline".printf (stat.pid));
 
@@ -301,6 +311,7 @@ public class Monitor.Process : GLib.Object {
         return true;
     }
 
+    // @TODO: Divide into get_usage_cpu and get_usage_mem and write some tests
     private void get_usage (uint64 cpu_total, uint64 cpu_last_total) {
         // Get CPU usage by process
         GTop.ProcTime proc_time;

src/Managers/ProcessDRM.vala

@@ -0,0 +1,117 @@
+/*
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ * SPDX-FileCopyrightText: 2025 elementary, Inc. (https://elementary.io)
+ */
+
+public class Monitor.ProcessDRM {
+    /** Time spent busy in nanoseconds by the render engine executing
+     * workloads from the last time it was read
+     */
+    private uint64 last_engine_render;
+    private uint64 last_engine_gfx;
+
+
+    public double gpu_percentage { get; private set; }
+
+    private int pid;
+    private int update_interval;
+
+    public ProcessDRM (int pid, int update_interval) {
+        this.pid = pid;
+        this.update_interval = update_interval;
+
+        last_engine_render = 0;
+        last_engine_gfx = 0;
+    }
+
+    public void update () {
+        string path_fdinfo = "/proc/%d/fdinfo".printf (pid);
+        string path_fd = "/proc/%d/fd".printf (pid);
+
+
+        var drm_files = new Gee.ArrayList<GLib.File ?> ();
+
+        try {
+            Dir dir = Dir.open (path_fdinfo, 0);
+            string ? name = null;
+
+            while ((name = dir.read_name ()) != null) {
+
+                // skip standard fds
+                if (name == "0" || name == "1" || name == "2") {
+                    continue;
+                }
+                string path = Path.build_filename (path_fdinfo, name);
+
+                int fd_dir_fd = Posix.open (path_fd, Posix.O_RDONLY | Posix.O_DIRECTORY);
+                if (fd_dir_fd == -1) {
+                    warning ("Cannot open file descriptor: %s", path_fd);
+                    continue;
+                }
+
+                bool is_drm = is_drm_fd (fd_dir_fd, name);
+                Posix.close (fd_dir_fd);
+
+                if (is_drm) {
+                    var drm_file = File.new_for_path (path);
+                    drm_files.add (drm_file);
+                }
+            }
+        } catch (FileError err) {
+            // prevent flooding logs with permission errors
+            if (!(err is FileError.ACCES)) {
+                warning (err.message);
+            }
+        }
+
+        foreach (var drm_file in drm_files) {
+            try {
+                var dis = new DataInputStream (drm_file.read ());
+                string ? line;
+
+                while ((line = dis.read_line ()) != null) {
+                    var splitted_line = line.split (":");
+                    switch (splitted_line[0]) {
+                    case "drm-engine-gfx":
+                        update_engine (splitted_line[1], ref last_engine_gfx);
+                        break;
+                    // for i915 there is only drm-engine-render to check
+                    case "drm-engine-render":
+                        update_engine (splitted_line[1], ref last_engine_render);
+                        break;
+                    default:
+                        // Ignore other entries
+                        break;
+                    }
+                }
+            } catch (Error err) {
+                if (!(err is FileError.ACCES)) {
+                    warning ("Can't read fdinfo: '%s' %d", err.message, err.code);
+                }
+            }
+            break;
+        }
+    }
+
+    private void update_engine (string line, ref uint64 last_engine) {
+        var engine = uint64.parse (line.strip ().split (" ")[0]);
+        if (last_engine != 0) {
+            gpu_percentage = calculate_percentage (engine, last_engine, update_interval);
+        }
+        last_engine = engine;
+    }
+
+    private static double calculate_percentage (uint64 engine, uint64 last_engine, int interval) {
+        // Since values in the files are in nanoseconds, it is also needed to convert interval to nanoseconds (10^9)
+        return 100 * ((double) (engine - last_engine)) / (interval * 1e9);
+    }
+
+    // Based on nvtop
+    // https://github.com/Syllo/nvtop/blob/4bf5db248d7aa7528f3a1ab7c94f504dff6834e4/src/extract_processinfo_fdinfo.c#L88
+    private static bool is_drm_fd (int fd_dir_fd, string name) {
+        Posix.Stat stat;
+        int ret = Posix.fstatat (fd_dir_fd, name, out stat, 0);
+        return ret == 0 && (stat.st_mode & Posix.S_IFMT) == Posix.S_IFCHR && Posix.major (stat.st_rdev) == 226;
+    }
+
+}

src/Managers/ProcessManager.vala

@@ -259,7 +259,8 @@ namespace Monitor {
          */
         private Process ? add_process (int pid, bool lazy_signal = false) {
             // create the process
-            var process = new Process (pid);
+            int update_interval = MonitorApp.settings.get_int ("update-time");
+            var process = new Process (pid, update_interval);
 
             if (!process.exists) {
                 return null;

src/Models/TreeViewModel.vala

@@ -8,8 +8,9 @@ public enum Monitor.Column {
     NAME,
     CPU,
     MEMORY,
+    GPU,
     PID,
-    CMD
+    CMD,
 }
 
 public class Monitor.TreeViewModel : Gtk.TreeStore {
@@ -25,6 +26,7 @@ public class Monitor.TreeViewModel : Gtk.TreeStore {
             typeof (string),
             typeof (double),
             typeof (int64),
+            typeof (double),
             typeof (int),
             typeof (string),
         });
@@ -79,6 +81,7 @@ public class Monitor.TreeViewModel : Gtk.TreeStore {
             set (iter,
                  Column.CPU, process.cpu_percentage,
                  Column.MEMORY, process.mem_usage,
+                 Column.GPU, process.gpu_percentage,
                  -1);
         }
     }

src/Views/ProcessView/ProcessTreeView/CPUProcessTreeView.vala

@@ -9,6 +9,7 @@ public class Monitor.CPUProcessTreeView : Gtk.TreeView {
     private Gtk.TreeViewColumn pid_column;
     private Gtk.TreeViewColumn cpu_column;
     private Gtk.TreeViewColumn memory_column;
+    private Gtk.TreeViewColumn gpu_column;
 
     public signal void process_selected (Process process);
 
@@ -58,6 +59,17 @@ public class Monitor.CPUProcessTreeView : Gtk.TreeView {
         memory_column.set_sort_column_id (Column.MEMORY);
         insert_column (memory_column, -1);
 
+        // setup gpu column
+        var gpu_cell = new Gtk.CellRendererText ();
+        gpu_cell.xalign = 0.5f;
+
+        gpu_column = new Gtk.TreeViewColumn.with_attributes (_("GPU"), gpu_cell);
+        gpu_column.expand = false;
+        gpu_column.set_cell_data_func (gpu_cell, gpu_usage_cell_layout);
+        gpu_column.alignment = 0.5f;
+        gpu_column.set_sort_column_id (Column.GPU);
+        insert_column (gpu_column, -1);
+
         // setup PID column
         var pid_cell = new Gtk.CellRendererText ();
         pid_cell.xalign = 0.5f;
@@ -142,6 +154,20 @@ public class Monitor.CPUProcessTreeView : Gtk.TreeView {
             ((Gtk.CellRendererText)cell).text = "%.1f %s".printf (memory_usage_double, units);
     }
 
+    public void gpu_usage_cell_layout (Gtk.CellLayout cell_layout, Gtk.CellRenderer cell, Gtk.TreeModel model, Gtk.TreeIter iter) {
+        // grab the value that was store in the model and convert it down to a usable format
+        Value gpu_usage_value;
+        model.get_value (iter, Column.GPU, out gpu_usage_value);
+        double gpu_usage = gpu_usage_value.get_double ();
+
+        // format the double into a string
+        if (gpu_usage < 0.0) {
+            ((Gtk.CellRendererText)cell).text = Utils.NO_DATA;
+        } else {
+            ((Gtk.CellRendererText)cell).text = "%.0f%%".printf (gpu_usage);
+        }
+    }
+
     private void pid_cell_layout (Gtk.CellLayout cell_layout, Gtk.CellRenderer cell, Gtk.TreeModel model, Gtk.TreeIter iter) {
         Value pid_value;
         model.get_value (iter, Column.PID, out pid_value);

src/meson.build

@@ -41,6 +41,7 @@ source_app_files = [
     'Managers/Process.vala',
     'Managers/ProcessStructs.vala',
     'Managers/ProcessUtils.vala',
+    'Managers/ProcessDRM.vala',
 
     # Services
     'Services/DBusServer.vala',