backend/native: Use high priority contexts for secondary GPUs

Ensure the context requests EGL_CONTEXT_PRIORITY_HIGH_IMG, and
that we use cogl_egl_create_context() to ensure that is honored.

https://gitlab.gnome.org/GNOME/mutter/merge_requests/923

.gitlab-ci/Dockerfile

@@ -16,7 +16,7 @@ RUN dnf -y update && dnf -y upgrade && \
     dnf builddep -y mutter && \
 
     # Until Fedora catches up with new build-deps
-    dnf install -y 'pkgconfig(graphene-gobject-1.0)' 'pkgconfig(sysprof-capture-3)' && \
+    dnf install -y 'pkgconfig(graphene-gobject-1.0)' 'pkgconfig(sysprof-capture-3)' 'pkgconfig(libcap-ng)' && \
 
     # For running unit tests
     dnf install -y xorg-x11-server-Xvfb mesa-dri-drivers dbus dbus-x11 '*/xvfb-run' gdm-lib accountsservice-libs gnome-control-center && \

cogl/cogl/cogl-egl.h

@@ -79,6 +79,15 @@ G_BEGIN_DECLS
 EGLDisplay
 cogl_egl_context_get_egl_display (CoglContext *context);
 
+gboolean cogl_egl_init_thread (void);
+
+EGLContext
+cogl_egl_create_context (EGLDisplay     display,
+                         EGLConfig      config,
+                         EGLContext     shared_context,
+                         const EGLint  *attrib_list,
+                         GError       **error);
+
 G_END_DECLS
 
 /* The gobject introspection scanner seems to parse public headers in

cogl/cogl/winsys/cogl-winsys-egl.c

@@ -110,6 +110,21 @@ static const CoglFeatureData winsys_feature_data[] =
 #include "winsys/cogl-winsys-egl-feature-functions.h"
   };
 
+static GMainContext *egl_thread_context = NULL;
+
+typedef struct _CreateEGLContextData
+{
+  EGLDisplay display;
+  EGLConfig config;
+  EGLContext shared_context;
+  const EGLint *attrib_list;
+  EGLContext context;
+  GError *error;
+  GMutex mutex;
+  GCond cond;
+  gboolean finished;
+} CreateEGLContextData;
+
 static GCallback
 _cogl_winsys_renderer_get_proc_address (CoglRenderer *renderer,
                                         const char *name,
@@ -386,16 +401,14 @@ try_create_context (CoglDisplay *display,
 
   attribs[i++] = EGL_NONE;
 
-  egl_display->egl_context = eglCreateContext (edpy,
-                                               config,
-                                               EGL_NO_CONTEXT,
-                                               attribs);
+  egl_display->egl_context = cogl_egl_create_context (edpy,
+                                                      config,
+                                                      EGL_NO_CONTEXT,
+                                                      attribs,
+                                                      error);
 
   if (egl_display->egl_context == EGL_NO_CONTEXT)
-    {
-      error_message = "Unable to create a suitable EGL context";
-      goto fail;
-    }
+    goto err;
 
   if (egl_renderer->private_features &
       COGL_EGL_WINSYS_FEATURE_CONTEXT_PRIORITY)
@@ -965,3 +978,206 @@ cogl_egl_context_get_egl_display (CoglContext *context)
 
   return egl_renderer->edpy;
 }
+
+static gpointer
+init_egl_context_thread (gpointer data)
+{
+  GMainContext *main_context = data;
+  GMainLoop *main_loop = g_main_loop_new (main_context, FALSE);
+
+  g_main_loop_run (main_loop);
+  return NULL;
+}
+
+gboolean
+cogl_egl_init_thread (void)
+{
+  g_autoptr (GMainContext) main_context = NULL;
+  g_autoptr (GThread) thread = NULL;
+  g_autoptr (GError) error = NULL;
+
+  if (egl_thread_context != NULL)
+    return TRUE;
+
+  main_context = g_main_context_new ();
+  thread = g_thread_try_new ("EGL context generator thread",
+                             init_egl_context_thread,
+                             main_context, &error);
+  if (!thread)
+    {
+      g_warning ("Failed to create EGL Context generator thread: %s",
+                 error->message);
+
+      return FALSE;
+    }
+
+  egl_thread_context = g_steal_pointer (&main_context);
+
+  return TRUE;
+}
+
+static CreateEGLContextData *
+create_egl_context_data_new (EGLDisplay    display,
+                             EGLConfig     config,
+                             EGLContext    shared_context,
+                             const EGLint *attrib_list)
+{
+  CreateEGLContextData *data;
+
+  data = g_new0 (CreateEGLContextData, 1);
+  data->display = display;
+  data->config = config;
+  data->shared_context = shared_context;
+  data->attrib_list = attrib_list;
+  data->context = EGL_NO_CONTEXT;
+  g_mutex_init (&data->mutex);
+  g_cond_init (&data->cond);
+
+  return data;
+}
+
+static const char *
+get_egl_error_str (EGLint error_number)
+{
+  switch (error_number)
+    {
+    case EGL_SUCCESS:
+      return "The last function succeeded without error.";
+      break;
+    case EGL_NOT_INITIALIZED:
+      return "EGL is not initialized, or could not be initialized, for the specified EGL display connection.";
+      break;
+    case EGL_BAD_ACCESS:
+      return "EGL cannot access a requested resource (for example a context is bound in another thread).";
+      break;
+    case EGL_BAD_ALLOC:
+      return "EGL failed to allocate resources for the requested operation.";
+      break;
+    case EGL_BAD_ATTRIBUTE:
+      return "An unrecognized attribute or attribute value was passed in the attribute list.";
+      break;
+    case EGL_BAD_CONTEXT:
+      return "An EGLContext argument does not name a valid EGL rendering context.";
+      break;
+    case EGL_BAD_CONFIG:
+      return "An EGLConfig argument does not name a valid EGL frame buffer configuration.";
+      break;
+    case EGL_BAD_CURRENT_SURFACE:
+      return "The current surface of the calling thread is a window, pixel buffer or pixmap that is no longer valid.";
+      break;
+    case EGL_BAD_DISPLAY:
+      return "An EGLDisplay argument does not name a valid EGL display connection.";
+      break;
+    case EGL_BAD_SURFACE:
+      return "An EGLSurface argument does not name a valid surface (window, pixel buffer or pixmap) configured for GL rendering.";
+      break;
+    case EGL_BAD_MATCH:
+      return "Arguments are inconsistent (for example, a valid context requires buffers not supplied by a valid surface).";
+      break;
+    case EGL_BAD_PARAMETER:
+      return "One or more argument values are invalid.";
+      break;
+    case EGL_BAD_NATIVE_PIXMAP:
+      return "A NativePixmapType argument does not refer to a valid native pixmap.";
+      break;
+    case EGL_BAD_NATIVE_WINDOW:
+      return "A NativeWindowType argument does not refer to a valid native window.";
+      break;
+    case EGL_CONTEXT_LOST:
+      return "A power management event has occurred. The application must destroy all contexts and reinitialise OpenGL ES state and objects to continue rendering. ";
+      break;
+    case EGL_BAD_STREAM_KHR:
+      return "An EGLStreamKHR argument does not name a valid EGL stream.";
+      break;
+    case EGL_BAD_STATE_KHR:
+      return "An EGLStreamKHR argument is not in a valid state";
+      break;
+    case EGL_BAD_DEVICE_EXT:
+      return "An EGLDeviceEXT argument does not name a valid EGL device.";
+      break;
+    case EGL_BAD_OUTPUT_LAYER_EXT:
+      return "An EGLOutputLayerEXT argument does not name a valid EGL output layer.";
+    default:
+      return "Unknown error";
+      break;
+    }
+}
+
+static void
+set_egl_error (GError **error)
+{
+  EGLint error_number;
+  const char *error_str;
+
+  if (!error)
+    return;
+
+  error_number = eglGetError ();
+  error_str = get_egl_error_str (error_number);
+  g_set_error_literal (error, COGL_WINSYS_ERROR,
+                       COGL_WINSYS_ERROR_CREATE_CONTEXT,
+                       error_str);
+}
+
+/* Executed in the EGL context generator thread */
+static gboolean
+create_context_in_thread (gpointer user_data)
+{
+  CreateEGLContextData *data = user_data;
+
+  g_mutex_lock (&data->mutex);
+  data->context = eglCreateContext (data->display,
+                                    data->config,
+                                    data->shared_context,
+                                    data->attrib_list);
+  if (data->context == EGL_NO_CONTEXT)
+    set_egl_error (&data->error);
+
+  data->finished = TRUE;
+  g_cond_signal (&data->cond);
+  g_mutex_unlock (&data->mutex);
+
+  return G_SOURCE_REMOVE;
+}
+
+EGLContext
+cogl_egl_create_context (EGLDisplay     display,
+                         EGLConfig      config,
+                         EGLContext     shared_context,
+                         const EGLint  *attrib_list,
+                         GError       **error)
+{
+  CreateEGLContextData *data;
+  EGLContext context;
+  GSource *source;
+
+  if (!cogl_egl_init_thread ())
+    {
+      g_set_error_literal (error, COGL_WINSYS_ERROR,
+                           COGL_WINSYS_ERROR_CREATE_CONTEXT,
+                           "EGL thread initialization failed");
+      return EGL_NO_CONTEXT;
+    }
+
+  data = create_egl_context_data_new (display, config,
+                                      shared_context, attrib_list);
+  g_mutex_lock (&data->mutex);
+
+  source = g_idle_source_new ();
+  g_source_set_callback (source, create_context_in_thread,
+                         data, NULL);
+  g_source_attach (source, egl_thread_context);
+  g_source_unref (source);
+
+  while (!data->finished)
+    g_cond_wait (&data->cond, &data->mutex);
+
+  context = data->context;
+  if (data->error)
+    g_propagate_error (error, data->error);
+
+  g_mutex_unlock (&data->mutex);
+  g_free (data);
+
+  return context;
+}

config.h.meson

@@ -67,3 +67,6 @@
 /* Either <sys/random.h> or <linux/random.h> */
 #mesondefine HAVE_SYS_RANDOM
 #mesondefine HAVE_LINUX_RANDOM
+
+/* Defined if libcap-ng is available */
+#mesondefine HAVE_LIBCAPNG

data/org.gnome.mutter.gschema.xml.in

@@ -120,10 +120,6 @@
                                         framebuffers instead of window content,
                                         to manage HiDPI monitors. Does not
                                         require a restart.
-        • “rt-scheduler”              — makes mutter request a low priority
-                                        real-time scheduling. The executable
-                                        or user must have CAP_SYS_NICE.
-                                        Requires a restart.
         • “autostart-xwayland”        — initializes Xwayland lazily if there are
                                         X11 clients. Requires restart.
       </description>

meson.build

@@ -36,6 +36,7 @@ libstartup_notification_req = '>= 0.7'
 libcanberra_req = '>= 0.26'
 libwacom_req = '>= 0.13'
 atk_req = '>= 2.5.3'
+libcapng_req = '>= 0.7.9'
 
 # optional version requirements
 udev_req = '>= 228'
@@ -127,6 +128,7 @@ xau_dep = dependency('xau')
 ice_dep = dependency('ice')
 atk_dep = dependency('atk', version: atk_req)
 libcanberra_dep = dependency('libcanberra', version: libcanberra_req)
+libcapng_dep = dependency('libcap-ng', required: get_option('libcapng'))
 
 # For now always require X11 support
 have_x11 = true
@@ -258,6 +260,7 @@ have_core_tests = false
 have_cogl_tests = false
 have_clutter_tests = false
 have_installed_tests = false
+have_libcapng = libcapng_dep.found()
 
 if have_tests
   have_core_tests = get_option('core_tests')
@@ -364,6 +367,7 @@ cdata.set('HAVE_SM', have_sm)
 cdata.set('HAVE_STARTUP_NOTIFICATION', have_startup_notification)
 cdata.set('HAVE_INTROSPECTION', have_introspection)
 cdata.set('HAVE_PROFILER', have_profiler)
+cdata.set('HAVE_LIBCAPNG', have_libcapng)
 
 xkb_base = xkeyboard_config_dep.get_pkgconfig_variable('xkb_base')
 cdata.set_quoted('XKB_BASE', xkb_base)
@@ -445,6 +449,7 @@ output = [
   '        Startup notification..... ' + have_startup_notification.to_string(),
   '        Introspection............ ' + have_introspection.to_string(),
   '        Profiler................. ' + have_profiler.to_string(),
+  '        libcap-ng................ ' + have_libcapng.to_string(),
   '',
   '    Tests:',
   '',

meson_options.txt

@@ -152,3 +152,9 @@ option('xwayland_grab_default_access_rules',
   value: 'gnome-boxes,remote-viewer,virt-viewer,virt-manager,vinagre,vncviewer,Xephyr',
   description: 'Comma delimited list of applications ressources or class allowed to issue X11 grabs in Xwayland'
 )
+
+option('libcapng',
+  type: 'feature',
+  value: 'auto',
+  description: 'Enable libcap-ng support'
+)

src/backends/meta-egl.c

@@ -35,6 +35,7 @@
 #include "backends/meta-backend-private.h"
 #include "backends/meta-egl.h"
 #include "backends/meta-egl-ext.h"
+#include "cogl/cogl-egl.h"
 #include "meta/util.h"
 
 struct _MetaEgl
@@ -506,16 +507,9 @@ meta_egl_create_context (MetaEgl      *egl,
                          const EGLint *attrib_list,
                          GError      **error)
 {
-  EGLContext context;
-
-  context = eglCreateContext (display, config, share_context, attrib_list);
-  if (context == EGL_NO_CONTEXT)
-    {
-      set_egl_error (error);
-      return EGL_NO_CONTEXT;
-    }
-
-  return context;
+  return cogl_egl_create_context (display, config,
+                                  share_context, attrib_list,
+                                  error);
 }
 
 gboolean

src/backends/meta-settings-private.h

@@ -33,8 +33,7 @@ typedef enum _MetaExperimentalFeature
   META_EXPERIMENTAL_FEATURE_NONE = 0,
   META_EXPERIMENTAL_FEATURE_SCALE_MONITOR_FRAMEBUFFER = (1 << 0),
   META_EXPERIMENTAL_FEATURE_KMS_MODIFIERS  = (1 << 1),
-  META_EXPERIMENTAL_FEATURE_RT_SCHEDULER = (1 << 2),
-  META_EXPERIMENTAL_FEATURE_AUTOSTART_XWAYLAND  = (1 << 3),
+  META_EXPERIMENTAL_FEATURE_AUTOSTART_XWAYLAND  = (1 << 2),
 } MetaExperimentalFeature;
 
 #define META_TYPE_SETTINGS (meta_settings_get_type ())

src/backends/meta-settings.c

@@ -264,8 +264,6 @@ experimental_features_handler (GVariant *features_variant,
         features |= META_EXPERIMENTAL_FEATURE_SCALE_MONITOR_FRAMEBUFFER;
       else if (g_str_equal (feature, "kms-modifiers"))
         features |= META_EXPERIMENTAL_FEATURE_KMS_MODIFIERS;
-      else if (g_str_equal (feature, "rt-scheduler"))
-        features |= META_EXPERIMENTAL_FEATURE_RT_SCHEDULER;
       else if (g_str_equal (feature, "autostart-xwayland"))
         features |= META_EXPERIMENTAL_FEATURE_AUTOSTART_XWAYLAND;
       else

src/backends/native/meta-backend-native.c

@@ -341,7 +341,6 @@ static void
 meta_backend_native_post_init (MetaBackend *backend)
 {
   ClutterDeviceManager *manager = clutter_device_manager_get_default ();
-  MetaSettings *settings = meta_backend_get_settings (backend);
 
   META_BACKEND_CLASS (meta_backend_native_parent_class)->post_init (backend);
 
@@ -349,20 +348,6 @@ meta_backend_native_post_init (MetaBackend *backend)
                                                              NULL, NULL);
   meta_device_manager_native_set_relative_motion_filter (manager, relative_motion_filter,
                                                          meta_backend_get_monitor_manager (backend));
-
-  if (meta_settings_is_experimental_feature_enabled (settings,
-                                                     META_EXPERIMENTAL_FEATURE_RT_SCHEDULER))
-    {
-      int retval;
-      struct sched_param sp = {
-        .sched_priority = sched_get_priority_min (SCHED_RR)
-      };
-
-      retval = sched_setscheduler (0, SCHED_RR | SCHED_RESET_ON_FORK, &sp);
-
-      if (retval != 0)
-        g_warning ("Failed to set RT scheduler: %m");
-    }
 }
 
 static MetaMonitorManager *

src/backends/native/meta-renderer-native.c

@@ -3509,6 +3509,7 @@ create_secondary_egl_context (MetaEgl   *egl,
 {
   EGLint attributes[] = {
     EGL_CONTEXT_CLIENT_VERSION, 3,
+    EGL_CONTEXT_PRIORITY_LEVEL_IMG, EGL_CONTEXT_PRIORITY_HIGH_IMG,
     EGL_NONE
   };
 

src/core/main.c

@@ -66,6 +66,10 @@
 #include <girepository.h>
 #endif
 
+#ifdef HAVE_LIBCAPNG
+#include <cap-ng.h>
+#endif
+
 #if defined(HAVE_NATIVE_BACKEND) && defined(HAVE_WAYLAND)
 #include <systemd/sd-login.h>
 #endif /* HAVE_WAYLAND && HAVE_NATIVE_BACKEND */
@@ -522,6 +526,22 @@ meta_override_compositor_configuration (MetaCompositorType compositor_type,
   _backend_gtype_override = backend_gtype;
 }
 
+#ifdef HAVE_NATIVE_BACKEND
+static void
+meta_set_scheduler (void)
+{
+  int retval;
+  struct sched_param sp = {
+    .sched_priority = sched_get_priority_min (SCHED_RR)
+  };
+
+  retval = sched_setscheduler (0, SCHED_RR | SCHED_RESET_ON_FORK, &sp);
+
+  if (retval != 0)
+    g_warning ("Failed to set RT scheduler: %m");
+}
+#endif /* HAVE_NATIVE_BACKEND */
+
 /**
  * meta_init: (skip)
  *
@@ -553,8 +573,6 @@ meta_init (void)
                 g_strerror (errno));
 #endif
 
-  g_unix_signal_add (SIGTERM, on_sigterm, NULL);
-
   if (g_getenv ("MUTTER_VERBOSE"))
     meta_set_verbose (TRUE);
   if (g_getenv ("MUTTER_DEBUG"))
@@ -575,6 +593,21 @@ meta_init (void)
     meta_set_is_wayland_compositor (TRUE);
 #endif
 
+#ifdef HAVE_NATIVE_BACKEND
+  if (backend_gtype == META_TYPE_BACKEND_NATIVE)
+    {
+      meta_set_scheduler ();
+      cogl_egl_init_thread ();
+    }
+#endif
+
+#ifdef HAVE_LIBCAPNG
+  capng_clear (CAPNG_SELECT_BOTH);
+  capng_apply (CAPNG_SELECT_BOTH);
+#endif
+
+  g_unix_signal_add (SIGTERM, on_sigterm, NULL);
+
   if (g_get_home_dir ())
     if (chdir (g_get_home_dir ()) < 0)
       meta_warning ("Could not change to home directory %s.\n",

src/meson.build

@@ -18,6 +18,7 @@ mutter_pkg_deps = [
   glib_dep,
   gsettings_desktop_schemas_dep,
   gtk3_dep,
+  libcapng_dep,
   pango_dep,
 ]