Collect stats on why writes are initiated

src/core/ext/transport/chttp2/transport/chttp2_transport.c

@@ -144,10 +144,11 @@ static void finish_bdp_ping_locked(grpc_exec_ctx *exec_ctx, void *tp,
 
 static void cancel_pings(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
                          grpc_error *error);
-static void send_ping_locked(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
-                             grpc_chttp2_ping_type ping_type,
-                             grpc_closure *on_initiate,
-                             grpc_closure *on_complete);
+static void send_ping_locked(
+    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
+    grpc_chttp2_ping_type ping_type, grpc_closure *on_initiate,
+    grpc_closure *on_complete,
+    grpc_chttp2_initiate_write_reason initiate_write_reason);
 static void retry_initiate_ping_locked(grpc_exec_ctx *exec_ctx, void *tp,
                                        grpc_error *error);
 
@@ -346,7 +347,6 @@ static void init_transport(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
   if (is_client) {
     grpc_slice_buffer_add(&t->outbuf, grpc_slice_from_copied_string(
                                           GRPC_CHTTP2_CLIENT_CONNECT_STRING));
-    grpc_chttp2_initiate_write(exec_ctx, t, "initial_write");
   }
 
   /* configure http2 the way we like it */
@@ -578,7 +578,8 @@ static void init_transport(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
     t->keepalive_state = GRPC_CHTTP2_KEEPALIVE_STATE_DISABLED;
   }
 
-  grpc_chttp2_initiate_write(exec_ctx, t, "init");
+  grpc_chttp2_initiate_write(exec_ctx, t,
+                             GRPC_CHTTP2_INITIATE_WRITE_INITIAL_WRITE);
   post_benign_reclaimer(exec_ctx, t);
 }
 
@@ -846,13 +847,91 @@ static void set_write_state(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
   }
 }
 
+static void inc_initiate_write_reason(
+    grpc_exec_ctx *exec_ctx, grpc_chttp2_initiate_write_reason reason) {
+  switch (reason) {
+    case GRPC_CHTTP2_INITIATE_WRITE_INITIAL_WRITE:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_INITIAL_WRITE(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_START_NEW_STREAM:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_START_NEW_STREAM(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_SEND_MESSAGE:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_SEND_MESSAGE(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_SEND_INITIAL_METADATA:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_SEND_INITIAL_METADATA(
+          exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_SEND_TRAILING_METADATA:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_SEND_TRAILING_METADATA(
+          exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_RETRY_SEND_PING:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_RETRY_SEND_PING(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_CONTINUE_PINGS:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_CONTINUE_PINGS(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_GOAWAY_SENT:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_GOAWAY_SENT(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_RST_STREAM:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_RST_STREAM(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_CLOSE_FROM_API:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_CLOSE_FROM_API(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_STREAM_FLOW_CONTROL:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_STREAM_FLOW_CONTROL(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_TRANSPORT_FLOW_CONTROL:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_TRANSPORT_FLOW_CONTROL(
+          exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_SEND_SETTINGS:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_SEND_SETTINGS(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_BDP_ESTIMATOR_PING:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_BDP_ESTIMATOR_PING(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_FLOW_CONTROL_UNSTALLED_BY_SETTING:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_FLOW_CONTROL_UNSTALLED_BY_SETTING(
+          exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_FLOW_CONTROL_UNSTALLED_BY_UPDATE:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_FLOW_CONTROL_UNSTALLED_BY_UPDATE(
+          exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_APPLICATION_PING:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_APPLICATION_PING(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_KEEPALIVE_PING:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_KEEPALIVE_PING(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_TRANSPORT_FLOW_CONTROL_UNSTALLED:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_TRANSPORT_FLOW_CONTROL_UNSTALLED(
+          exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_PING_RESPONSE:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_PING_RESPONSE(exec_ctx);
+      break;
+    case GRPC_CHTTP2_INITIATE_WRITE_FORCE_RST_STREAM:
+      GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_FORCE_RST_STREAM(exec_ctx);
+      break;
+  }
+}
+
 void grpc_chttp2_initiate_write(grpc_exec_ctx *exec_ctx,
-                                grpc_chttp2_transport *t, const char *reason) {
+                                grpc_chttp2_transport *t,
+                                grpc_chttp2_initiate_write_reason reason) {
   GPR_TIMER_BEGIN("grpc_chttp2_initiate_write", 0);
 
   switch (t->write_state) {
     case GRPC_CHTTP2_WRITE_STATE_IDLE:
-      set_write_state(exec_ctx, t, GRPC_CHTTP2_WRITE_STATE_WRITING, reason);
+      inc_initiate_write_reason(exec_ctx, reason);
+      set_write_state(exec_ctx, t, GRPC_CHTTP2_WRITE_STATE_WRITING,
+                      grpc_chttp2_initiate_write_reason_string(reason));
       t->is_first_write_in_batch = true;
       GRPC_CHTTP2_REF_TRANSPORT(t, "writing");
       GRPC_CLOSURE_SCHED(
@@ -864,7 +943,7 @@ void grpc_chttp2_initiate_write(grpc_exec_ctx *exec_ctx,
       break;
     case GRPC_CHTTP2_WRITE_STATE_WRITING:
       set_write_state(exec_ctx, t, GRPC_CHTTP2_WRITE_STATE_WRITING_WITH_MORE,
-                      reason);
+                      grpc_chttp2_initiate_write_reason_string(reason));
       break;
     case GRPC_CHTTP2_WRITE_STATE_WRITING_WITH_MORE:
       break;
@@ -872,16 +951,12 @@ void grpc_chttp2_initiate_write(grpc_exec_ctx *exec_ctx,
   GPR_TIMER_END("grpc_chttp2_initiate_write", 0);
 }
 
-void grpc_chttp2_become_writable(grpc_exec_ctx *exec_ctx,
-                                 grpc_chttp2_transport *t,
-                                 grpc_chttp2_stream *s,
-                                 bool also_initiate_write, const char *reason) {
+void grpc_chttp2_mark_stream_writable(grpc_exec_ctx *exec_ctx,
+                                      grpc_chttp2_transport *t,
+                                      grpc_chttp2_stream *s) {
   if (!t->closed && grpc_chttp2_list_add_writable_stream(t, s)) {
     GRPC_CHTTP2_STREAM_REF(s, "chttp2_writing:become");
   }
-  if (also_initiate_write) {
-    grpc_chttp2_initiate_write(exec_ctx, t, reason);
-  }
 }
 
 static grpc_closure_scheduler *write_scheduler(grpc_chttp2_transport *t,
@@ -1105,7 +1180,9 @@ static void maybe_start_some_streams(grpc_exec_ctx *exec_ctx,
 
     grpc_chttp2_stream_map_add(&t->stream_map, s->id, s);
     post_destructive_reclaimer(exec_ctx, t);
-    grpc_chttp2_become_writable(exec_ctx, t, s, true, "new_stream");
+    grpc_chttp2_mark_stream_writable(exec_ctx, t, s);
+    grpc_chttp2_initiate_write(exec_ctx, t,
+                               GRPC_CHTTP2_INITIATE_WRITE_START_NEW_STREAM);
   }
   /* cancel out streams that will never be started */
   while (t->next_stream_id >= MAX_CLIENT_STREAM_ID &&
@@ -1202,7 +1279,9 @@ static void maybe_become_writable_due_to_send_msg(grpc_exec_ctx *exec_ctx,
                                                   grpc_chttp2_stream *s) {
   if (s->id != 0 && (!s->write_buffering ||
                      s->flow_controlled_buffer.length > t->write_buffer_size)) {
-    grpc_chttp2_become_writable(exec_ctx, t, s, true, "op.send_message");
+    grpc_chttp2_mark_stream_writable(exec_ctx, t, s);
+    grpc_chttp2_initiate_write(exec_ctx, t,
+                               GRPC_CHTTP2_INITIATE_WRITE_SEND_MESSAGE);
   }
 }
 
@@ -1404,14 +1483,13 @@ static void perform_stream_op_locked(grpc_exec_ctx *exec_ctx, void *stream_op,
           }
         } else {
           GPR_ASSERT(s->id != 0);
-          bool initiate_write = true;
-          if (op->send_message &&
-              (op->payload->send_message.send_message->flags &
-               GRPC_WRITE_BUFFER_HINT)) {
-            initiate_write = false;
+          grpc_chttp2_mark_stream_writable(exec_ctx, t, s);
+          if (!(op->send_message &&
+                (op->payload->send_message.send_message->flags &
+                 GRPC_WRITE_BUFFER_HINT))) {
+            grpc_chttp2_initiate_write(
+                exec_ctx, t, GRPC_CHTTP2_INITIATE_WRITE_SEND_INITIAL_METADATA);
           }
-          grpc_chttp2_become_writable(exec_ctx, t, s, initiate_write,
-                                      "op.send_initial_metadata");
         }
       } else {
         s->send_initial_metadata = NULL;
@@ -1519,8 +1597,9 @@ static void perform_stream_op_locked(grpc_exec_ctx *exec_ctx, void *stream_op,
       } else if (s->id != 0) {
         /* TODO(ctiller): check if there's flow control for any outstanding
            bytes before going writable */
-        grpc_chttp2_become_writable(exec_ctx, t, s, true,
-                                    "op.send_trailing_metadata");
+        grpc_chttp2_mark_stream_writable(exec_ctx, t, s);
+        grpc_chttp2_initiate_write(
+            exec_ctx, t, GRPC_CHTTP2_INITIATE_WRITE_SEND_TRAILING_METADATA);
       }
     }
   }
@@ -1632,15 +1711,17 @@ static void cancel_pings(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
   GRPC_ERROR_UNREF(error);
 }
 
-static void send_ping_locked(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
-                             grpc_chttp2_ping_type ping_type,
-                             grpc_closure *on_initiate, grpc_closure *on_ack) {
+static void send_ping_locked(
+    grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
+    grpc_chttp2_ping_type ping_type, grpc_closure *on_initiate,
+    grpc_closure *on_ack,
+    grpc_chttp2_initiate_write_reason initiate_write_reason) {
   grpc_chttp2_ping_queue *pq = &t->ping_queues[ping_type];
   grpc_closure_list_append(&pq->lists[GRPC_CHTTP2_PCL_INITIATE], on_initiate,
                            GRPC_ERROR_NONE);
   if (grpc_closure_list_append(&pq->lists[GRPC_CHTTP2_PCL_NEXT], on_ack,
                                GRPC_ERROR_NONE)) {
-    grpc_chttp2_initiate_write(exec_ctx, t, "send_ping");
+    grpc_chttp2_initiate_write(exec_ctx, t, initiate_write_reason);
   }
 }
 
@@ -1648,7 +1729,8 @@ static void retry_initiate_ping_locked(grpc_exec_ctx *exec_ctx, void *tp,
                                        grpc_error *error) {
   grpc_chttp2_transport *t = (grpc_chttp2_transport *)tp;
   t->ping_state.is_delayed_ping_timer_set = false;
-  grpc_chttp2_initiate_write(exec_ctx, t, "retry_send_ping");
+  grpc_chttp2_initiate_write(exec_ctx, t,
+                             GRPC_CHTTP2_INITIATE_WRITE_RETRY_SEND_PING);
 }
 
 void grpc_chttp2_ack_ping(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
@@ -1663,7 +1745,8 @@ void grpc_chttp2_ack_ping(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
   }
   GRPC_CLOSURE_LIST_SCHED(exec_ctx, &pq->lists[GRPC_CHTTP2_PCL_INFLIGHT]);
   if (!grpc_closure_list_empty(pq->lists[GRPC_CHTTP2_PCL_NEXT])) {
-    grpc_chttp2_initiate_write(exec_ctx, t, "continue_pings");
+    grpc_chttp2_initiate_write(exec_ctx, t,
+                               GRPC_CHTTP2_INITIATE_WRITE_CONTINUE_PINGS);
   }
 }
 
@@ -1676,7 +1759,8 @@ static void send_goaway(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
                         &slice, &http_error);
   grpc_chttp2_goaway_append(t->last_new_stream_id, (uint32_t)http_error,
                             grpc_slice_ref_internal(slice), &t->qbuf);
-  grpc_chttp2_initiate_write(exec_ctx, t, "goaway_sent");
+  grpc_chttp2_initiate_write(exec_ctx, t,
+                             GRPC_CHTTP2_INITIATE_WRITE_GOAWAY_SENT);
   GRPC_ERROR_UNREF(error);
 }
 
@@ -1723,7 +1807,8 @@ static void perform_transport_op_locked(grpc_exec_ctx *exec_ctx,
 
   if (op->send_ping) {
     send_ping_locked(exec_ctx, t, GRPC_CHTTP2_PING_ON_NEXT_WRITE, NULL,
-                     op->send_ping);
+                     op->send_ping,
+                     GRPC_CHTTP2_INITIATE_WRITE_APPLICATION_PING);
   }
 
   if (op->on_connectivity_state_change != NULL) {
@@ -1968,7 +2053,8 @@ void grpc_chttp2_cancel_stream(grpc_exec_ctx *exec_ctx,
       grpc_slice_buffer_add(
           &t->qbuf, grpc_chttp2_rst_stream_create(s->id, (uint32_t)http_error,
                                                   &s->stats.outgoing));
-      grpc_chttp2_initiate_write(exec_ctx, t, "rst_stream");
+      grpc_chttp2_initiate_write(exec_ctx, t,
+                                 GRPC_CHTTP2_INITIATE_WRITE_RST_STREAM);
     }
   }
   if (due_to_error != GRPC_ERROR_NONE && !s->seen_error) {
@@ -2289,7 +2375,8 @@ static void close_from_api(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
                                               &s->stats.outgoing));
 
   grpc_chttp2_mark_stream_closed(exec_ctx, t, s, 1, 1, error);
-  grpc_chttp2_initiate_write(exec_ctx, t, "close_from_api");
+  grpc_chttp2_initiate_write(exec_ctx, t,
+                             GRPC_CHTTP2_INITIATE_WRITE_CLOSE_FROM_API);
 }
 
 typedef struct {
@@ -2324,19 +2411,20 @@ void grpc_chttp2_act_on_flowctl_action(grpc_exec_ctx *exec_ctx,
     case GRPC_CHTTP2_FLOWCTL_NO_ACTION_NEEDED:
       break;
     case GRPC_CHTTP2_FLOWCTL_UPDATE_IMMEDIATELY:
-      grpc_chttp2_become_writable(exec_ctx, t, s, true,
-                                  "immediate stream flowctl");
+      grpc_chttp2_mark_stream_writable(exec_ctx, t, s);
+      grpc_chttp2_initiate_write(
+          exec_ctx, t, GRPC_CHTTP2_INITIATE_WRITE_STREAM_FLOW_CONTROL);
       break;
     case GRPC_CHTTP2_FLOWCTL_QUEUE_UPDATE:
-      grpc_chttp2_become_writable(exec_ctx, t, s, false,
-                                  "queue stream flowctl");
+      grpc_chttp2_mark_stream_writable(exec_ctx, t, s);
       break;
   }
   switch (action.send_transport_update) {
     case GRPC_CHTTP2_FLOWCTL_NO_ACTION_NEEDED:
       break;
     case GRPC_CHTTP2_FLOWCTL_UPDATE_IMMEDIATELY:
-      grpc_chttp2_initiate_write(exec_ctx, t, "immediate transport flowctl");
+      grpc_chttp2_initiate_write(
+          exec_ctx, t, GRPC_CHTTP2_INITIATE_WRITE_TRANSPORT_FLOW_CONTROL);
       break;
     // this is the same as no action b/c every time the transport enters the
     // writing path it will maybe do an update
@@ -2354,7 +2442,8 @@ void grpc_chttp2_act_on_flowctl_action(grpc_exec_ctx *exec_ctx,
                            (uint32_t)action.max_frame_size);
     }
     if (action.send_setting_update == GRPC_CHTTP2_FLOWCTL_UPDATE_IMMEDIATELY) {
-      grpc_chttp2_initiate_write(exec_ctx, t, "immediate setting update");
+      grpc_chttp2_initiate_write(exec_ctx, t,
+                                 GRPC_CHTTP2_INITIATE_WRITE_SEND_SETTINGS);
     }
   }
   if (action.need_ping) {
@@ -2362,7 +2451,8 @@ void grpc_chttp2_act_on_flowctl_action(grpc_exec_ctx *exec_ctx,
     grpc_bdp_estimator_schedule_ping(&t->flow_control.bdp_estimator);
     send_ping_locked(exec_ctx, t,
                      GRPC_CHTTP2_PING_BEFORE_TRANSPORT_WINDOW_UPDATE,
-                     &t->start_bdp_ping_locked, &t->finish_bdp_ping_locked);
+                     &t->start_bdp_ping_locked, &t->finish_bdp_ping_locked,
+                     GRPC_CHTTP2_INITIATE_WRITE_BDP_ESTIMATOR_PING);
   }
 }
 
@@ -2441,7 +2531,10 @@ static void read_action_locked(grpc_exec_ctx *exec_ctx, void *tp,
       if (t->flow_control.initial_window_update > 0) {
         grpc_chttp2_stream *s;
         while (grpc_chttp2_list_pop_stalled_by_stream(t, &s)) {
-          grpc_chttp2_become_writable(exec_ctx, t, s, true, "unstalled");
+          grpc_chttp2_mark_stream_writable(exec_ctx, t, s);
+          grpc_chttp2_initiate_write(
+              exec_ctx, t,
+              GRPC_CHTTP2_INITIATE_WRITE_FLOW_CONTROL_UNSTALLED_BY_SETTING);
         }
       }
       t->flow_control.initial_window_update = 0;
@@ -2556,7 +2649,8 @@ static void init_keepalive_ping_locked(grpc_exec_ctx *exec_ctx, void *arg,
       GRPC_CHTTP2_REF_TRANSPORT(t, "keepalive ping end");
       send_ping_locked(exec_ctx, t, GRPC_CHTTP2_PING_ON_NEXT_WRITE,
                        &t->start_keepalive_ping_locked,
-                       &t->finish_keepalive_ping_locked);
+                       &t->finish_keepalive_ping_locked,
+                       GRPC_CHTTP2_INITIATE_WRITE_KEEPALIVE_PING);
     } else {
       GRPC_CHTTP2_REF_TRANSPORT(t, "init keepalive ping");
       grpc_timer_init(
@@ -2912,8 +3006,7 @@ grpc_chttp2_incoming_byte_stream *grpc_chttp2_incoming_byte_stream_create(
     grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t, grpc_chttp2_stream *s,
     uint32_t frame_size, uint32_t flags) {
   grpc_chttp2_incoming_byte_stream *incoming_byte_stream =
-      (grpc_chttp2_incoming_byte_stream *)gpr_malloc(
-          sizeof(*incoming_byte_stream));
+      gpr_malloc(sizeof(*incoming_byte_stream));
   incoming_byte_stream->base.length = frame_size;
   incoming_byte_stream->remaining_bytes = frame_size;
   incoming_byte_stream->base.flags = flags;
@@ -3017,6 +3110,56 @@ static void destructive_reclaimer_locked(grpc_exec_ctx *exec_ctx, void *arg,
 /*******************************************************************************
  * MONITORING
  */
+
+const char *grpc_chttp2_initiate_write_reason_string(
+    grpc_chttp2_initiate_write_reason reason) {
+  switch (reason) {
+    case GRPC_CHTTP2_INITIATE_WRITE_INITIAL_WRITE:
+      return "INITIAL_WRITE";
+    case GRPC_CHTTP2_INITIATE_WRITE_START_NEW_STREAM:
+      return "START_NEW_STREAM";
+    case GRPC_CHTTP2_INITIATE_WRITE_SEND_MESSAGE:
+      return "SEND_MESSAGE";
+    case GRPC_CHTTP2_INITIATE_WRITE_SEND_INITIAL_METADATA:
+      return "SEND_INITIAL_METADATA";
+    case GRPC_CHTTP2_INITIATE_WRITE_SEND_TRAILING_METADATA:
+      return "SEND_TRAILING_METADATA";
+    case GRPC_CHTTP2_INITIATE_WRITE_RETRY_SEND_PING:
+      return "RETRY_SEND_PING";
+    case GRPC_CHTTP2_INITIATE_WRITE_CONTINUE_PINGS:
+      return "CONTINUE_PINGS";
+    case GRPC_CHTTP2_INITIATE_WRITE_GOAWAY_SENT:
+      return "GOAWAY_SENT";
+    case GRPC_CHTTP2_INITIATE_WRITE_RST_STREAM:
+      return "RST_STREAM";
+    case GRPC_CHTTP2_INITIATE_WRITE_CLOSE_FROM_API:
+      return "CLOSE_FROM_API";
+    case GRPC_CHTTP2_INITIATE_WRITE_STREAM_FLOW_CONTROL:
+      return "STREAM_FLOW_CONTROL";
+    case GRPC_CHTTP2_INITIATE_WRITE_TRANSPORT_FLOW_CONTROL:
+      return "TRANSPORT_FLOW_CONTROL";
+    case GRPC_CHTTP2_INITIATE_WRITE_SEND_SETTINGS:
+      return "SEND_SETTINGS";
+    case GRPC_CHTTP2_INITIATE_WRITE_BDP_ESTIMATOR_PING:
+      return "BDP_ESTIMATOR_PING";
+    case GRPC_CHTTP2_INITIATE_WRITE_FLOW_CONTROL_UNSTALLED_BY_SETTING:
+      return "FLOW_CONTROL_UNSTALLED_BY_SETTING";
+    case GRPC_CHTTP2_INITIATE_WRITE_FLOW_CONTROL_UNSTALLED_BY_UPDATE:
+      return "FLOW_CONTROL_UNSTALLED_BY_UPDATE";
+    case GRPC_CHTTP2_INITIATE_WRITE_APPLICATION_PING:
+      return "APPLICATION_PING";
+    case GRPC_CHTTP2_INITIATE_WRITE_KEEPALIVE_PING:
+      return "KEEPALIVE_PING";
+    case GRPC_CHTTP2_INITIATE_WRITE_TRANSPORT_FLOW_CONTROL_UNSTALLED:
+      return "TRANSPORT_FLOW_CONTROL_UNSTALLED";
+    case GRPC_CHTTP2_INITIATE_WRITE_PING_RESPONSE:
+      return "PING_RESPONSE";
+    case GRPC_CHTTP2_INITIATE_WRITE_FORCE_RST_STREAM:
+      return "FORCE_RST_STREAM";
+  }
+  GPR_UNREACHABLE_CODE(return "unknown");
+}
+
 static grpc_endpoint *chttp2_get_endpoint(grpc_exec_ctx *exec_ctx,
                                           grpc_transport *t) {
   return ((grpc_chttp2_transport *)t)->ep;

src/core/ext/transport/chttp2/transport/frame_ping.c

@@ -117,7 +117,8 @@ grpc_error *grpc_chttp2_ping_parser_parse(grpc_exec_ctx *exec_ctx, void *parser,
               t->ping_acks, t->ping_ack_capacity * sizeof(*t->ping_acks));
         }
         t->ping_acks[t->ping_ack_count++] = p->opaque_8bytes;
-        grpc_chttp2_initiate_write(exec_ctx, t, "ping response");
+        grpc_chttp2_initiate_write(exec_ctx, t,
+                                   GRPC_CHTTP2_INITIATE_WRITE_PING_RESPONSE);
       }
     }
   }

src/core/ext/transport/chttp2/transport/frame_window_update.c

@@ -99,8 +99,10 @@ grpc_error *grpc_chttp2_window_update_parser_parse(
         grpc_chttp2_flowctl_recv_stream_update(
             &t->flow_control, &s->flow_control, received_update);
         if (grpc_chttp2_list_remove_stalled_by_stream(t, s)) {
-          grpc_chttp2_become_writable(exec_ctx, t, s, true,
-                                      "stream.read_flow_control");
+          grpc_chttp2_mark_stream_writable(exec_ctx, t, s);
+          grpc_chttp2_initiate_write(
+              exec_ctx, t,
+              GRPC_CHTTP2_INITIATE_WRITE_FLOW_CONTROL_UNSTALLED_BY_UPDATE);
         }
       }
     } else {
@@ -109,7 +111,9 @@ grpc_error *grpc_chttp2_window_update_parser_parse(
                                                 received_update);
       bool is_zero = t->flow_control.remote_window <= 0;
       if (was_zero && !is_zero) {
-        grpc_chttp2_initiate_write(exec_ctx, t, "new_global_flow_control");
+        grpc_chttp2_initiate_write(
+            exec_ctx, t,
+            GRPC_CHTTP2_INITIATE_WRITE_TRANSPORT_FLOW_CONTROL_UNSTALLED);
       }
     }
   }

src/core/ext/transport/chttp2/transport/hpack_parser.c

@@ -1649,7 +1649,8 @@ static void force_client_rst_stream(grpc_exec_ctx *exec_ctx, void *sp,
     grpc_slice_buffer_add(
         &t->qbuf, grpc_chttp2_rst_stream_create(s->id, GRPC_HTTP2_NO_ERROR,
                                                 &s->stats.outgoing));
-    grpc_chttp2_initiate_write(exec_ctx, t, "force_rst_stream");
+    grpc_chttp2_initiate_write(exec_ctx, t,
+                               GRPC_CHTTP2_INITIATE_WRITE_FORCE_RST_STREAM);
     grpc_chttp2_mark_stream_closed(exec_ctx, t, s, true, true, GRPC_ERROR_NONE);
   }
   GRPC_CHTTP2_STREAM_UNREF(exec_ctx, s, "final_rst");

src/core/ext/transport/chttp2/transport/internal.h

@@ -79,6 +79,33 @@ typedef enum {
   GRPC_CHTTP2_PCL_COUNT /* must be last */
 } grpc_chttp2_ping_closure_list;
 
+typedef enum {
+  GRPC_CHTTP2_INITIATE_WRITE_INITIAL_WRITE,
+  GRPC_CHTTP2_INITIATE_WRITE_START_NEW_STREAM,
+  GRPC_CHTTP2_INITIATE_WRITE_SEND_MESSAGE,
+  GRPC_CHTTP2_INITIATE_WRITE_SEND_INITIAL_METADATA,
+  GRPC_CHTTP2_INITIATE_WRITE_SEND_TRAILING_METADATA,
+  GRPC_CHTTP2_INITIATE_WRITE_RETRY_SEND_PING,
+  GRPC_CHTTP2_INITIATE_WRITE_CONTINUE_PINGS,
+  GRPC_CHTTP2_INITIATE_WRITE_GOAWAY_SENT,
+  GRPC_CHTTP2_INITIATE_WRITE_RST_STREAM,
+  GRPC_CHTTP2_INITIATE_WRITE_CLOSE_FROM_API,
+  GRPC_CHTTP2_INITIATE_WRITE_STREAM_FLOW_CONTROL,
+  GRPC_CHTTP2_INITIATE_WRITE_TRANSPORT_FLOW_CONTROL,
+  GRPC_CHTTP2_INITIATE_WRITE_SEND_SETTINGS,
+  GRPC_CHTTP2_INITIATE_WRITE_BDP_ESTIMATOR_PING,
+  GRPC_CHTTP2_INITIATE_WRITE_FLOW_CONTROL_UNSTALLED_BY_SETTING,
+  GRPC_CHTTP2_INITIATE_WRITE_FLOW_CONTROL_UNSTALLED_BY_UPDATE,
+  GRPC_CHTTP2_INITIATE_WRITE_APPLICATION_PING,
+  GRPC_CHTTP2_INITIATE_WRITE_KEEPALIVE_PING,
+  GRPC_CHTTP2_INITIATE_WRITE_TRANSPORT_FLOW_CONTROL_UNSTALLED,
+  GRPC_CHTTP2_INITIATE_WRITE_PING_RESPONSE,
+  GRPC_CHTTP2_INITIATE_WRITE_FORCE_RST_STREAM,
+} grpc_chttp2_initiate_write_reason;
+
+const char *grpc_chttp2_initiate_write_reason_string(
+    grpc_chttp2_initiate_write_reason reason);
+
 typedef struct {
   grpc_closure_list lists[GRPC_CHTTP2_PCL_COUNT];
   uint64_t inflight_id;
@@ -599,7 +626,8 @@ struct grpc_chttp2_stream {
     The actual call chain is documented in the implementation of this function.
     */
 void grpc_chttp2_initiate_write(grpc_exec_ctx *exec_ctx,
-                                grpc_chttp2_transport *t, const char *reason);
+                                grpc_chttp2_transport *t,
+                                grpc_chttp2_initiate_write_reason reason);
 
 typedef struct {
   /** are we writing? */
@@ -851,10 +879,9 @@ void grpc_chttp2_add_ping_strike(grpc_exec_ctx *exec_ctx,
 
 /** add a ref to the stream and add it to the writable list;
     ref will be dropped in writing.c */
-void grpc_chttp2_become_writable(grpc_exec_ctx *exec_ctx,
-                                 grpc_chttp2_transport *t,
-                                 grpc_chttp2_stream *s,
-                                 bool also_initiate_write, const char *reason);
+void grpc_chttp2_mark_stream_writable(grpc_exec_ctx *exec_ctx,
+                                      grpc_chttp2_transport *t,
+                                      grpc_chttp2_stream *s);
 
 void grpc_chttp2_cancel_stream(grpc_exec_ctx *exec_ctx,
                                grpc_chttp2_transport *t, grpc_chttp2_stream *s,

src/core/ext/transport/chttp2/transport/writing.c

@@ -201,9 +201,8 @@ grpc_chttp2_begin_write_result grpc_chttp2_begin_write(
 
   if (t->flow_control.remote_window > 0) {
     while (grpc_chttp2_list_pop_stalled_by_transport(t, &s)) {
-      if (!t->closed && grpc_chttp2_list_add_writable_stream(t, s) &&
-          stream_ref_if_not_destroyed(&s->refcount->refs)) {
-        grpc_chttp2_initiate_write(exec_ctx, t, "transport.read_flow_control");
+      if (!t->closed && grpc_chttp2_list_add_writable_stream(t, s)) {
+        stream_ref_if_not_destroyed(&s->refcount->refs);
       }
     }
   }

src/core/lib/debug/stats_data.c

@@ -50,6 +50,27 @@ const char *grpc_stats_counter_name[GRPC_STATS_COUNTER_COUNT] = {
     "http2_writes_offloaded",
     "http2_writes_continued",
     "http2_partial_writes",
+    "http2_initiate_write_due_to_initial_write",
+    "http2_initiate_write_due_to_start_new_stream",
+    "http2_initiate_write_due_to_send_message",
+    "http2_initiate_write_due_to_send_initial_metadata",
+    "http2_initiate_write_due_to_send_trailing_metadata",
+    "http2_initiate_write_due_to_retry_send_ping",
+    "http2_initiate_write_due_to_continue_pings",
+    "http2_initiate_write_due_to_goaway_sent",
+    "http2_initiate_write_due_to_rst_stream",
+    "http2_initiate_write_due_to_close_from_api",
+    "http2_initiate_write_due_to_stream_flow_control",
+    "http2_initiate_write_due_to_transport_flow_control",
+    "http2_initiate_write_due_to_send_settings",
+    "http2_initiate_write_due_to_bdp_estimator_ping",
+    "http2_initiate_write_due_to_flow_control_unstalled_by_setting",
+    "http2_initiate_write_due_to_flow_control_unstalled_by_update",
+    "http2_initiate_write_due_to_application_ping",
+    "http2_initiate_write_due_to_keepalive_ping",
+    "http2_initiate_write_due_to_transport_flow_control_unstalled",
+    "http2_initiate_write_due_to_ping_response",
+    "http2_initiate_write_due_to_force_rst_stream",
     "combiner_locks_initiated",
     "combiner_locks_scheduled_items",
     "combiner_locks_scheduled_final_items",
@@ -92,6 +113,30 @@ const char *grpc_stats_counter_doc[GRPC_STATS_COUNTER_COUNT] = {
     "written",
     "Number of HTTP2 writes that were made knowing there was still more data "
     "to be written (we cap maximum write size to syscall_write)",
+    "Number of HTTP2 writes initiated due to 'initial_write'",
+    "Number of HTTP2 writes initiated due to 'start_new_stream'",
+    "Number of HTTP2 writes initiated due to 'send_message'",
+    "Number of HTTP2 writes initiated due to 'send_initial_metadata'",
+    "Number of HTTP2 writes initiated due to 'send_trailing_metadata'",
+    "Number of HTTP2 writes initiated due to 'retry_send_ping'",
+    "Number of HTTP2 writes initiated due to 'continue_pings'",
+    "Number of HTTP2 writes initiated due to 'goaway_sent'",
+    "Number of HTTP2 writes initiated due to 'rst_stream'",
+    "Number of HTTP2 writes initiated due to 'close_from_api'",
+    "Number of HTTP2 writes initiated due to 'stream_flow_control'",
+    "Number of HTTP2 writes initiated due to 'transport_flow_control'",
+    "Number of HTTP2 writes initiated due to 'send_settings'",
+    "Number of HTTP2 writes initiated due to 'bdp_estimator_ping'",
+    "Number of HTTP2 writes initiated due to "
+    "'flow_control_unstalled_by_setting'",
+    "Number of HTTP2 writes initiated due to "
+    "'flow_control_unstalled_by_update'",
+    "Number of HTTP2 writes initiated due to 'application_ping'",
+    "Number of HTTP2 writes initiated due to 'keepalive_ping'",
+    "Number of HTTP2 writes initiated due to "
+    "'transport_flow_control_unstalled'",
+    "Number of HTTP2 writes initiated due to 'ping_response'",
+    "Number of HTTP2 writes initiated due to 'force_rst_stream'",
     "Number of combiner lock entries by process (first items queued to a "
     "combiner)",
     "Number of items scheduled against combiner locks",

src/core/lib/debug/stats_data.h

@@ -52,6 +52,27 @@ typedef enum {
   GRPC_STATS_COUNTER_HTTP2_WRITES_OFFLOADED,
   GRPC_STATS_COUNTER_HTTP2_WRITES_CONTINUED,
   GRPC_STATS_COUNTER_HTTP2_PARTIAL_WRITES,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_INITIAL_WRITE,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_START_NEW_STREAM,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_SEND_MESSAGE,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_SEND_INITIAL_METADATA,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_SEND_TRAILING_METADATA,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_RETRY_SEND_PING,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_CONTINUE_PINGS,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_GOAWAY_SENT,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_RST_STREAM,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_CLOSE_FROM_API,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_STREAM_FLOW_CONTROL,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_TRANSPORT_FLOW_CONTROL,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_SEND_SETTINGS,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_BDP_ESTIMATOR_PING,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_FLOW_CONTROL_UNSTALLED_BY_SETTING,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_FLOW_CONTROL_UNSTALLED_BY_UPDATE,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_APPLICATION_PING,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_KEEPALIVE_PING,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_TRANSPORT_FLOW_CONTROL_UNSTALLED,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_PING_RESPONSE,
+  GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_FORCE_RST_STREAM,
   GRPC_STATS_COUNTER_COMBINER_LOCKS_INITIATED,
   GRPC_STATS_COUNTER_COMBINER_LOCKS_SCHEDULED_ITEMS,
   GRPC_STATS_COUNTER_COMBINER_LOCKS_SCHEDULED_FINAL_ITEMS,
@@ -169,6 +190,95 @@ typedef enum {
   GRPC_STATS_INC_COUNTER((exec_ctx), GRPC_STATS_COUNTER_HTTP2_WRITES_CONTINUED)
 #define GRPC_STATS_INC_HTTP2_PARTIAL_WRITES(exec_ctx) \
   GRPC_STATS_INC_COUNTER((exec_ctx), GRPC_STATS_COUNTER_HTTP2_PARTIAL_WRITES)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_INITIAL_WRITE(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                                  \
+      (exec_ctx),                                                          \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_INITIAL_WRITE)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_START_NEW_STREAM(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                                     \
+      (exec_ctx),                                                             \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_START_NEW_STREAM)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_SEND_MESSAGE(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                                 \
+      (exec_ctx), GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_SEND_MESSAGE)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_SEND_INITIAL_METADATA( \
+    exec_ctx)                                                             \
+  GRPC_STATS_INC_COUNTER(                                                 \
+      (exec_ctx),                                                         \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_SEND_INITIAL_METADATA)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_SEND_TRAILING_METADATA( \
+    exec_ctx)                                                              \
+  GRPC_STATS_INC_COUNTER(                                                  \
+      (exec_ctx),                                                          \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_SEND_TRAILING_METADATA)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_RETRY_SEND_PING(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                                    \
+      (exec_ctx),                                                            \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_RETRY_SEND_PING)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_CONTINUE_PINGS(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                                   \
+      (exec_ctx),                                                           \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_CONTINUE_PINGS)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_GOAWAY_SENT(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                                \
+      (exec_ctx), GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_GOAWAY_SENT)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_RST_STREAM(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                               \
+      (exec_ctx), GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_RST_STREAM)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_CLOSE_FROM_API(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                                   \
+      (exec_ctx),                                                           \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_CLOSE_FROM_API)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_STREAM_FLOW_CONTROL( \
+    exec_ctx)                                                           \
+  GRPC_STATS_INC_COUNTER(                                               \
+      (exec_ctx),                                                       \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_STREAM_FLOW_CONTROL)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_TRANSPORT_FLOW_CONTROL( \
+    exec_ctx)                                                              \
+  GRPC_STATS_INC_COUNTER(                                                  \
+      (exec_ctx),                                                          \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_TRANSPORT_FLOW_CONTROL)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_SEND_SETTINGS(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                                  \
+      (exec_ctx),                                                          \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_SEND_SETTINGS)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_BDP_ESTIMATOR_PING( \
+    exec_ctx)                                                          \
+  GRPC_STATS_INC_COUNTER(                                              \
+      (exec_ctx),                                                      \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_BDP_ESTIMATOR_PING)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_FLOW_CONTROL_UNSTALLED_BY_SETTING( \
+    exec_ctx)                                                                         \
+  GRPC_STATS_INC_COUNTER(                                                             \
+      (exec_ctx),                                                                     \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_FLOW_CONTROL_UNSTALLED_BY_SETTING)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_FLOW_CONTROL_UNSTALLED_BY_UPDATE( \
+    exec_ctx)                                                                        \
+  GRPC_STATS_INC_COUNTER(                                                            \
+      (exec_ctx),                                                                    \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_FLOW_CONTROL_UNSTALLED_BY_UPDATE)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_APPLICATION_PING(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                                     \
+      (exec_ctx),                                                             \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_APPLICATION_PING)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_KEEPALIVE_PING(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                                   \
+      (exec_ctx),                                                           \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_KEEPALIVE_PING)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_TRANSPORT_FLOW_CONTROL_UNSTALLED( \
+    exec_ctx)                                                                        \
+  GRPC_STATS_INC_COUNTER(                                                            \
+      (exec_ctx),                                                                    \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_TRANSPORT_FLOW_CONTROL_UNSTALLED)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_PING_RESPONSE(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                                  \
+      (exec_ctx),                                                          \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_PING_RESPONSE)
+#define GRPC_STATS_INC_HTTP2_INITIATE_WRITE_DUE_TO_FORCE_RST_STREAM(exec_ctx) \
+  GRPC_STATS_INC_COUNTER(                                                     \
+      (exec_ctx),                                                             \
+      GRPC_STATS_COUNTER_HTTP2_INITIATE_WRITE_DUE_TO_FORCE_RST_STREAM)
 #define GRPC_STATS_INC_COMBINER_LOCKS_INITIATED(exec_ctx) \
   GRPC_STATS_INC_COUNTER((exec_ctx),                      \
                          GRPC_STATS_COUNTER_COMBINER_LOCKS_INITIATED)

src/core/lib/debug/stats_data.yaml

@@ -117,6 +117,48 @@
 - counter: http2_partial_writes
   doc: Number of HTTP2 writes that were made knowing there was still more data
        to be written (we cap maximum write size to syscall_write)
+- counter: http2_initiate_write_due_to_initial_write
+  doc: Number of HTTP2 writes initiated due to 'initial_write'
+- counter: http2_initiate_write_due_to_start_new_stream
+  doc: Number of HTTP2 writes initiated due to 'start_new_stream'
+- counter: http2_initiate_write_due_to_send_message
+  doc: Number of HTTP2 writes initiated due to 'send_message'
+- counter: http2_initiate_write_due_to_send_initial_metadata
+  doc: Number of HTTP2 writes initiated due to 'send_initial_metadata'
+- counter: http2_initiate_write_due_to_send_trailing_metadata
+  doc: Number of HTTP2 writes initiated due to 'send_trailing_metadata'
+- counter: http2_initiate_write_due_to_retry_send_ping
+  doc: Number of HTTP2 writes initiated due to 'retry_send_ping'
+- counter: http2_initiate_write_due_to_continue_pings
+  doc: Number of HTTP2 writes initiated due to 'continue_pings'
+- counter: http2_initiate_write_due_to_goaway_sent
+  doc: Number of HTTP2 writes initiated due to 'goaway_sent'
+- counter: http2_initiate_write_due_to_rst_stream
+  doc: Number of HTTP2 writes initiated due to 'rst_stream'
+- counter: http2_initiate_write_due_to_close_from_api
+  doc: Number of HTTP2 writes initiated due to 'close_from_api'
+- counter: http2_initiate_write_due_to_stream_flow_control
+  doc: Number of HTTP2 writes initiated due to 'stream_flow_control'
+- counter: http2_initiate_write_due_to_transport_flow_control
+  doc: Number of HTTP2 writes initiated due to 'transport_flow_control'
+- counter: http2_initiate_write_due_to_send_settings
+  doc: Number of HTTP2 writes initiated due to 'send_settings'
+- counter: http2_initiate_write_due_to_bdp_estimator_ping
+  doc: Number of HTTP2 writes initiated due to 'bdp_estimator_ping'
+- counter: http2_initiate_write_due_to_flow_control_unstalled_by_setting
+  doc: Number of HTTP2 writes initiated due to 'flow_control_unstalled_by_setting'
+- counter: http2_initiate_write_due_to_flow_control_unstalled_by_update
+  doc: Number of HTTP2 writes initiated due to 'flow_control_unstalled_by_update'
+- counter: http2_initiate_write_due_to_application_ping
+  doc: Number of HTTP2 writes initiated due to 'application_ping'
+- counter: http2_initiate_write_due_to_keepalive_ping
+  doc: Number of HTTP2 writes initiated due to 'keepalive_ping'
+- counter: http2_initiate_write_due_to_transport_flow_control_unstalled
+  doc: Number of HTTP2 writes initiated due to 'transport_flow_control_unstalled'
+- counter: http2_initiate_write_due_to_ping_response
+  doc: Number of HTTP2 writes initiated due to 'ping_response'
+- counter: http2_initiate_write_due_to_force_rst_stream
+  doc: Number of HTTP2 writes initiated due to 'force_rst_stream'
 # combiner locks
 - counter: combiner_locks_initiated
   doc: Number of combiner lock entries by process

src/core/lib/debug/stats_data_bq_schema.sql

@@ -1,5 +1,9 @@
 client_calls_created_per_iteration:FLOAT,
 server_calls_created_per_iteration:FLOAT,
+cqs_created_per_iteration:FLOAT,
+client_channels_created_per_iteration:FLOAT,
+client_subchannels_created_per_iteration:FLOAT,
+server_channels_created_per_iteration:FLOAT,
 syscall_poll_per_iteration:FLOAT,
 syscall_wait_per_iteration:FLOAT,
 histogram_slow_lookups_per_iteration:FLOAT,
@@ -21,6 +25,27 @@ http2_writes_begun_per_iteration:FLOAT,
 http2_writes_offloaded_per_iteration:FLOAT,
 http2_writes_continued_per_iteration:FLOAT,
 http2_partial_writes_per_iteration:FLOAT,
+http2_initiate_write_due_to_initial_write_per_iteration:FLOAT,
+http2_initiate_write_due_to_start_new_stream_per_iteration:FLOAT,
+http2_initiate_write_due_to_send_message_per_iteration:FLOAT,
+http2_initiate_write_due_to_send_initial_metadata_per_iteration:FLOAT,
+http2_initiate_write_due_to_send_trailing_metadata_per_iteration:FLOAT,
+http2_initiate_write_due_to_retry_send_ping_per_iteration:FLOAT,
+http2_initiate_write_due_to_continue_pings_per_iteration:FLOAT,
+http2_initiate_write_due_to_goaway_sent_per_iteration:FLOAT,
+http2_initiate_write_due_to_rst_stream_per_iteration:FLOAT,
+http2_initiate_write_due_to_close_from_api_per_iteration:FLOAT,
+http2_initiate_write_due_to_stream_flow_control_per_iteration:FLOAT,
+http2_initiate_write_due_to_transport_flow_control_per_iteration:FLOAT,
+http2_initiate_write_due_to_send_settings_per_iteration:FLOAT,
+http2_initiate_write_due_to_bdp_estimator_ping_per_iteration:FLOAT,
+http2_initiate_write_due_to_flow_control_unstalled_by_setting_per_iteration:FLOAT,
+http2_initiate_write_due_to_flow_control_unstalled_by_update_per_iteration:FLOAT,
+http2_initiate_write_due_to_application_ping_per_iteration:FLOAT,
+http2_initiate_write_due_to_keepalive_ping_per_iteration:FLOAT,
+http2_initiate_write_due_to_transport_flow_control_unstalled_per_iteration:FLOAT,
+http2_initiate_write_due_to_ping_response_per_iteration:FLOAT,
+http2_initiate_write_due_to_force_rst_stream_per_iteration:FLOAT,
 combiner_locks_initiated_per_iteration:FLOAT,
 combiner_locks_scheduled_items_per_iteration:FLOAT,
 combiner_locks_scheduled_final_items_per_iteration:FLOAT,

tools/run_tests/performance/massage_qps_stats.py

@@ -22,6 +22,10 @@ def massage_qps_stats(scenario_result):
     del stats["coreStats"]
     stats["core_client_calls_created"] = massage_qps_stats_helpers.counter(core_stats, "client_calls_created")
     stats["core_server_calls_created"] = massage_qps_stats_helpers.counter(core_stats, "server_calls_created")
+    stats["core_cqs_created"] = massage_qps_stats_helpers.counter(core_stats, "cqs_created")
+    stats["core_client_channels_created"] = massage_qps_stats_helpers.counter(core_stats, "client_channels_created")
+    stats["core_client_subchannels_created"] = massage_qps_stats_helpers.counter(core_stats, "client_subchannels_created")
+    stats["core_server_channels_created"] = massage_qps_stats_helpers.counter(core_stats, "server_channels_created")
     stats["core_syscall_poll"] = massage_qps_stats_helpers.counter(core_stats, "syscall_poll")
     stats["core_syscall_wait"] = massage_qps_stats_helpers.counter(core_stats, "syscall_wait")
     stats["core_histogram_slow_lookups"] = massage_qps_stats_helpers.counter(core_stats, "histogram_slow_lookups")
@@ -43,6 +47,27 @@ def massage_qps_stats(scenario_result):
     stats["core_http2_writes_offloaded"] = massage_qps_stats_helpers.counter(core_stats, "http2_writes_offloaded")
     stats["core_http2_writes_continued"] = massage_qps_stats_helpers.counter(core_stats, "http2_writes_continued")
     stats["core_http2_partial_writes"] = massage_qps_stats_helpers.counter(core_stats, "http2_partial_writes")
+    stats["core_http2_initiate_write_due_to_initial_write"] = massage_qps_stats_helpers.counter(core_stats, "http2_initiate_write_due_to_initial_write")
+    stats["core_http2_initiate_write_due_to_start_new_stream"] = massage_qps_stats_helpers.counter(core_stats, "http2_initiate_write_due_to_start_new_stream")
+    stats["core_http2_initiate_write_due_to_send_message"] = massage_qps_stats_helpers.counter(core_stats, "http2_initiate_write_due_to_send_message")
+    stats["core_http2_initiate_write_due_to_send_initial_metadata"] = massage_qps_stats_helpers.counter(core_stats, "http2_initiate_write_due_to_send_initial_metadata")
+    stats["core_http2_initiate_write_due_to_send_trailing_metadata"] = massage_qps_stats_helpers.counter(core_stats, "http2_initiate_write_due_to_send_trailing_metadata")
+    stats["core_http2_initiate_write_due_to_retry_send_ping"] = massage_qps_stats_helpers.counter(core_stats, "http2_initiate_write_due_to_retry_send_ping")
+    stats["core_http2_initiate_write_due_to_continue_pings"] = massage_qps_stats_helpers.counter(core_stats, "http2_initiate_write_due_to_continue_pings")
+    stats["core_http2_initiate_write_due_to_goaway_sent"] = massage_qps_stats_helpers.counter(core_stats, "http2_initiate_write_due_to_goaway_sent")
+    stats["core_http2_initiate_write_due_to_rst_stream"] = massage_qps_stats_helpers.counter(core_stats, "http2_initiate_write_due_to_rst_stream")
+    stats["core_http2_initiate_write_due_to_close_from_api"] = massage_qps_stats_helpers.counter(core_stats, "http2_initiate_write_due_to_close_from_api")
+    stats["core_http2_initiate_write_due_to_stream_flow_control"] = massage_qps_stats_helpers.counter(core_stats, "http2_initiate_write_due_to_stream_flow_control")
+    stats["core_http2_initiate_write_due_to_transport_flow_control"] = massage_qps_stats_helpers.counter(core_stats, "http2_initiate_write_due_to_transport_flow_control")
+    stats["core_http2_initiate_write_due_to_send_settings"] = massage_qps_stats_helpers.counter(core_stats, "http2_initiate_write_due_to_send_settings")
+    stats["core_http2_initiate_write_due_to_bdp_estimator_ping"] = massage_qps_stats_helpers.counter(core_stats, "http2_initiate_write_due_to_bdp_estimator_ping")
+    stats["core_http2_initiate_write_due_to_flow_control_unstalled_by_setting"] = massage_qps_stats_helpers.counter(core_stats, "http2_initiate_write_due_to_flow_control_unstalled_by_setting")
+    stats["core_http2_initiate_write_due_to_flow_control_unstalled_by_update"] = massage_qps_stats_helpers.counter(core_stats, "http2_initiate_write_due_to_flow_control_unstalled_by_update")
+    stats["core_http2_initiate_write_due_to_application_ping"] = massage_qps_stats_helpers.counter(core_stats, "http2_initiate_write_due_to_application_ping")
+    stats["core_http2_initiate_write_due_to_keepalive_ping"] = massage_qps_stats_helpers.counter(core_stats, "http2_initiate_write_due_to_keepalive_ping")
+    stats["core_http2_initiate_write_due_to_transport_flow_control_unstalled"] = massage_qps_stats_helpers.counter(core_stats, "http2_initiate_write_due_to_transport_flow_control_unstalled")
+    stats["core_http2_initiate_write_due_to_ping_response"] = massage_qps_stats_helpers.counter(core_stats, "http2_initiate_write_due_to_ping_response")
+    stats["core_http2_initiate_write_due_to_force_rst_stream"] = massage_qps_stats_helpers.counter(core_stats, "http2_initiate_write_due_to_force_rst_stream")
     stats["core_combiner_locks_initiated"] = massage_qps_stats_helpers.counter(core_stats, "combiner_locks_initiated")
     stats["core_combiner_locks_scheduled_items"] = massage_qps_stats_helpers.counter(core_stats, "combiner_locks_scheduled_items")
     stats["core_combiner_locks_scheduled_final_items"] = massage_qps_stats_helpers.counter(core_stats, "combiner_locks_scheduled_final_items")

tools/run_tests/performance/scenario_result_schema.json

@@ -120,6 +120,26 @@
         "name": "core_server_calls_created", 
         "type": "INTEGER"
       }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_cqs_created", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_client_channels_created", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_client_subchannels_created", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_server_channels_created", 
+        "type": "INTEGER"
+      }, 
       {
         "mode": "NULLABLE", 
         "name": "core_syscall_poll", 
@@ -225,6 +245,111 @@
         "name": "core_http2_partial_writes", 
         "type": "INTEGER"
       }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_initial_write", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_start_new_stream", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_send_message", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_send_initial_metadata", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_send_trailing_metadata", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_retry_send_ping", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_continue_pings", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_goaway_sent", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_rst_stream", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_close_from_api", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_stream_flow_control", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_transport_flow_control", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_send_settings", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_bdp_estimator_ping", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_flow_control_unstalled_by_setting", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_flow_control_unstalled_by_update", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_application_ping", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_keepalive_ping", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_transport_flow_control_unstalled", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_ping_response", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_force_rst_stream", 
+        "type": "INTEGER"
+      }, 
       {
         "mode": "NULLABLE", 
         "name": "core_combiner_locks_initiated", 
@@ -597,6 +722,26 @@
         "name": "core_server_calls_created", 
         "type": "INTEGER"
       }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_cqs_created", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_client_channels_created", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_client_subchannels_created", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_server_channels_created", 
+        "type": "INTEGER"
+      }, 
       {
         "mode": "NULLABLE", 
         "name": "core_syscall_poll", 
@@ -702,6 +847,111 @@
         "name": "core_http2_partial_writes", 
         "type": "INTEGER"
       }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_initial_write", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_start_new_stream", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_send_message", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_send_initial_metadata", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_send_trailing_metadata", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_retry_send_ping", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_continue_pings", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_goaway_sent", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_rst_stream", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_close_from_api", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_stream_flow_control", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_transport_flow_control", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_send_settings", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_bdp_estimator_ping", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_flow_control_unstalled_by_setting", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_flow_control_unstalled_by_update", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_application_ping", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_keepalive_ping", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_transport_flow_control_unstalled", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_ping_response", 
+        "type": "INTEGER"
+      }, 
+      {
+        "mode": "NULLABLE", 
+        "name": "core_http2_initiate_write_due_to_force_rst_stream", 
+        "type": "INTEGER"
+      }, 
       {
         "mode": "NULLABLE", 
         "name": "core_combiner_locks_initiated",