[PATCH] drm/i915: Add special execution time measurements for pipe evasion section

Stanislav Lisovskiy stanislav.lisovskiy at intel.com
Mon Aug 7 10:02:48 UTC 2023


We are getting "pipe evasion exceeded 250 us" on constant basis for different
platforms for many years. Current tracing instrumentation, shows us only
aggregate execution times for the functions in evasion section, however we are
only and particularly interested in those _only_ once this timing is exceeded,
average timing measurements or those which happen when we don't exceed that
250 us threshold are not informative at all.
This patch attemmpts to add a special debug print instrumentation, that prints
all the execution time measurements of functions participating in vblank evasion
only once it is exceeded and remain silent otherwise.
It shouldn't also add much overhead because all it does is just calling ktime_get
before and after function call.

Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>
---
 .../gpu/drm/i915/display/intel_atomic_plane.c | 22 +++++---
 drivers/gpu/drm/i915/display/intel_crtc.c     |  5 ++
 drivers/gpu/drm/i915/display/intel_display.c  | 51 +++++++++++++++----
 drivers/gpu/drm/i915/display/intel_display.h  | 49 ++++++++++++++++++
 4 files changed, 111 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_atomic_plane.c b/drivers/gpu/drm/i915/display/intel_atomic_plane.c
index 60a492e186ab8..72abca8321a62 100644
--- a/drivers/gpu/drm/i915/display/intel_atomic_plane.c
+++ b/drivers/gpu/drm/i915/display/intel_atomic_plane.c
@@ -841,19 +841,27 @@ static void skl_crtc_planes_update_arm(struct intel_atomic_state *state,
 	memcpy(ddb_y, old_crtc_state->wm.skl.plane_ddb_y,
 	       sizeof(old_crtc_state->wm.skl.plane_ddb_y));
 
-	while ((plane = skl_next_plane_to_commit(state, crtc, ddb, ddb_y, &update_mask))) {
-		struct intel_plane_state *new_plane_state =
-			intel_atomic_get_new_plane_state(state, plane);
+	while (1) {
+		struct intel_plane_state *new_plane_state;
+
+		TIME_MEASURE_FUNC_WRAP(SKL_NEXT_PLANE_TO_COMMIT, pipe_evasion,
+				       plane = skl_next_plane_to_commit(state, crtc, ddb, ddb_y, &update_mask));
+
+		if (!plane)
+			break;
+
+		new_plane_state = intel_atomic_get_new_plane_state(state, plane);
 
 		/*
 		 * TODO: for mailbox updates intel_plane_update_noarm()
 		 * would have to be called here as well.
 		 */
 		if (new_plane_state->uapi.visible ||
-		    new_plane_state->planar_slave)
-			intel_plane_update_arm(plane, new_crtc_state, new_plane_state);
-		else
-			intel_plane_disable_arm(plane, new_crtc_state);
+		    new_plane_state->planar_slave) {
+			TIME_MEASURE_FUNC_WRAP(INTEL_UPDATE_PLANE, pipe_evasion, intel_plane_update_arm(plane, new_crtc_state, new_plane_state));
+		} else {
+			TIME_MEASURE_FUNC_WRAP(INTEL_DISABLE_PLANE, pipe_evasion, intel_plane_disable_arm(plane, new_crtc_state));
+		}
 	}
 }
 
diff --git a/drivers/gpu/drm/i915/display/intel_crtc.c b/drivers/gpu/drm/i915/display/intel_crtc.c
index 182c6dd64f47c..7bad7c8544b7e 100644
--- a/drivers/gpu/drm/i915/display/intel_crtc.c
+++ b/drivers/gpu/drm/i915/display/intel_crtc.c
@@ -617,11 +617,16 @@ static void dbg_vblank_evade(struct intel_crtc *crtc, ktime_t end)
 		crtc->debug.vbl.max = delta;
 
 	if (delta > 1000 * VBLANK_EVASION_TIME_US) {
+		struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
+
 		drm_dbg_kms(crtc->base.dev,
 			    "Atomic update on pipe (%c) took %lld us, max time under evasion is %u us\n",
 			    pipe_name(crtc->pipe),
 			    div_u64(delta, 1000),
 			    VBLANK_EVASION_TIME_US);
+
+		print_time_measure_table(dev_priv, pipe_evasion, PIPE_EVASION_ENUM_MAX);
+
 		crtc->debug.vbl.over++;
 	}
 }
diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 43cba98f77531..b35dc3704725d 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -6486,6 +6486,30 @@ static void intel_pipe_fastset(const struct intel_crtc_state *old_crtc_state,
 					       &new_crtc_state->dp_m_n);
 }
 
+TIME_MEASURE_FUNC_TABLE_START(pipe_evasion)
+	TIME_MEASURE_FUNC(INTEL_COLOR_COMMIT_ARM, "intel_color_commit_arm"),
+	TIME_MEASURE_FUNC(BDW_SET_PIPE_MISC, "bdw_set_pipe_misc"),
+	TIME_MEASURE_FUNC(INTEL_PIPE_FASTSET, "intel_pipe_fastset"),
+	TIME_MEASURE_FUNC(INTEL_PSR_PROGRAM_TRANS_MAN_TRK_CTL, "intel_psr_program_trans_maxn_trk_ctl"),
+	TIME_MEASURE_FUNC(INTEL_ATOMIC_UPDATE_WATERMARKS, "intel_atomic_update_watermarks"),
+	TIME_MEASURE_FUNC(SKL_DETACH_SCALERS, "skl_detach_scalers"),
+	TIME_MEASURE_FUNC(SKL_NEXT_PLANE_TO_COMMIT, "skl_next_plane_to_commit"),
+	TIME_MEASURE_FUNC(INTEL_UPDATE_PLANE, "intel_update_plane"),
+	TIME_MEASURE_FUNC(INTEL_DISABLE_PLANE, "intel_disable_plane"),
+TIME_MEASURE_FUNC_TABLE_END
+
+void print_time_measure_table(struct drm_i915_private *dev_priv,
+			      struct time_measure_func *table, int num_entries)
+{
+	int i;
+	for (i = 0; i < num_entries; i++)
+	{
+		drm_dbg_kms(&dev_priv->drm,
+			    "Function %s took %lld us\n",
+			    table[i].name, ktime_us_delta(table[i].end, table[i].start));
+	}
+}
+
 static void commit_pipe_pre_planes(struct intel_atomic_state *state,
 				   struct intel_crtc *crtc)
 {
@@ -6501,19 +6525,27 @@ static void commit_pipe_pre_planes(struct intel_atomic_state *state,
 	 * CRTC was enabled.
 	 */
 	if (!modeset) {
-		if (intel_crtc_needs_color_update(new_crtc_state))
-			intel_color_commit_arm(new_crtc_state);
+		if (intel_crtc_needs_color_update(new_crtc_state)) {
+			TIME_MEASURE_FUNC_WRAP(INTEL_COLOR_COMMIT_ARM,
+				pipe_evasion, intel_color_commit_arm(new_crtc_state));
+		}
 
-		if (DISPLAY_VER(dev_priv) >= 9 || IS_BROADWELL(dev_priv))
-			bdw_set_pipe_misc(new_crtc_state);
+		if (DISPLAY_VER(dev_priv) >= 9 || IS_BROADWELL(dev_priv)) {
+			TIME_MEASURE_FUNC_WRAP(BDW_SET_PIPE_MISC,
+				pipe_evasion, bdw_set_pipe_misc(new_crtc_state));
+		}
 
-		if (intel_crtc_needs_fastset(new_crtc_state))
-			intel_pipe_fastset(old_crtc_state, new_crtc_state);
+		if (intel_crtc_needs_fastset(new_crtc_state)) {
+			TIME_MEASURE_FUNC_WRAP(INTEL_PIPE_FASTSET,
+				pipe_evasion, intel_pipe_fastset(old_crtc_state, new_crtc_state));
+		}
 	}
 
-	intel_psr2_program_trans_man_trk_ctl(new_crtc_state);
+	TIME_MEASURE_FUNC_WRAP(INTEL_PSR_PROGRAM_TRANS_MAN_TRK_CTL,
+		pipe_evasion, intel_psr2_program_trans_man_trk_ctl(new_crtc_state));
 
-	intel_atomic_update_watermarks(state, crtc);
+	TIME_MEASURE_FUNC_WRAP(INTEL_ATOMIC_UPDATE_WATERMARKS,
+		pipe_evasion, intel_atomic_update_watermarks(state, crtc));
 }
 
 static void commit_pipe_post_planes(struct intel_atomic_state *state,
@@ -6530,7 +6562,8 @@ static void commit_pipe_post_planes(struct intel_atomic_state *state,
 	 */
 	if (DISPLAY_VER(dev_priv) >= 9 &&
 	    !intel_crtc_needs_modeset(new_crtc_state))
-		skl_detach_scalers(new_crtc_state);
+		TIME_MEASURE_FUNC_WRAP(SKL_DETACH_SCALERS,
+			pipe_evasion, skl_detach_scalers(new_crtc_state));
 }
 
 static void intel_enable_crtc(struct intel_atomic_state *state,
diff --git a/drivers/gpu/drm/i915/display/intel_display.h b/drivers/gpu/drm/i915/display/intel_display.h
index 49ac8473b988b..31bd34e2f253c 100644
--- a/drivers/gpu/drm/i915/display/intel_display.h
+++ b/drivers/gpu/drm/i915/display/intel_display.h
@@ -531,8 +531,57 @@ enum drm_mode_status intel_mode_valid(struct drm_device *dev,
 int intel_atomic_commit(struct drm_device *dev, struct drm_atomic_state *_state,
 			bool nonblock);
 
+
+struct time_measure_func
+{
+	int id;
+	const char *name;
+	ktime_t start;
+	ktime_t end;
+};
+
+#define TIME_MEASURE_ENUM_START(enum_name) \
+			enum enum_name {
+#define TIME_MEASURE_ENUM_END };
+
+#define TIME_MEASURE_FUNC_TABLE_START(table_name) \
+			struct time_measure_func table_name[] = {
+
+#define TIME_MEASURE_FUNC_TABLE_DECLARE(table_name) \
+			extern struct time_measure_func table_name[];
+
+#define TIME_MEASURE_FUNC(_id, _name) \
+			{ .id = _id, .name = _name }
+
+#define TIME_MEASURE_FUNC_TABLE_END };
+
+#define TIME_MEASURE_FUNC_WRAP(id, table_name, func_call) \
+	{ \
+		table_name[id].start = ktime_get(); \
+		func_call; \
+		table_name[id].end = ktime_get(); \
+	}
+
+TIME_MEASURE_ENUM_START(pipe_evasion_enum)
+	INTEL_COLOR_COMMIT_ARM,
+	BDW_SET_PIPE_MISC,
+	INTEL_PIPE_FASTSET,
+	INTEL_PSR_PROGRAM_TRANS_MAN_TRK_CTL,
+	INTEL_ATOMIC_UPDATE_WATERMARKS,
+	SKL_DETACH_SCALERS,
+	SKL_NEXT_PLANE_TO_COMMIT,
+	INTEL_UPDATE_PLANE,
+	INTEL_DISABLE_PLANE,
+	PIPE_EVASION_ENUM_MAX
+TIME_MEASURE_ENUM_END
+
+TIME_MEASURE_FUNC_TABLE_DECLARE(pipe_evasion);
+
 void intel_hpd_poll_fini(struct drm_i915_private *i915);
 
+void print_time_measure_table(struct drm_i915_private *i915,
+			      struct time_measure_func *table, int num_entries);
+
 /* modesetting asserts */
 void assert_transcoder(struct drm_i915_private *dev_priv,
 		       enum transcoder cpu_transcoder, bool state);
-- 
2.37.3



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