Include other usage to estimate call size

src/core/lib/surface/call.cc

@@ -67,6 +67,9 @@
 
 #define MAX_SEND_EXTRA_METADATA_COUNT 3
 
+// Used to create arena for the first call.
+#define ESTIMATED_MDELEM_COUNT 16
+
 /* Status data for a request can come from several sources; this
    enumerates them all, and acts as a priority sorting for which
    status to return to the application - earlier entries override
@@ -323,6 +326,11 @@ static parent_call* get_parent_call(grpc_call* call) {
   return (parent_call*)gpr_atm_acq_load(&call->parent_call_atm);
 }
 
+size_t grpc_call_get_initial_size_estimate() {
+  return sizeof(grpc_call) + sizeof(batch_control) * MAX_CONCURRENT_BATCHES +
+         sizeof(grpc_linked_mdelem) * ESTIMATED_MDELEM_COUNT;
+}
+
 grpc_error* grpc_call_create(const grpc_call_create_args* args,
                              grpc_call** out_call) {
   GPR_TIMER_SCOPE("grpc_call_create", 0);
@@ -1144,9 +1152,9 @@ static int batch_slot_for_op(grpc_op_type type) {
   GPR_UNREACHABLE_CODE(return 123456789);
 }
 
-static batch_control* allocate_batch_control(grpc_call* call,
-                                             const grpc_op* ops,
-                                             size_t num_ops) {
+static batch_control* reuse_or_allocate_batch_control(grpc_call* call,
+                                                      const grpc_op* ops,
+                                                      size_t num_ops) {
   int slot = batch_slot_for_op(ops[0].op);
   batch_control** pslot = &call->active_batches[slot];
   if (*pslot == nullptr) {
@@ -1565,7 +1573,7 @@ static grpc_call_error call_start_batch(grpc_call* call, const grpc_op* ops,
     goto done;
   }
 
-  bctl = allocate_batch_control(call, ops, nops);
+  bctl = reuse_or_allocate_batch_control(call, ops, nops);
   if (bctl == nullptr) {
     return GRPC_CALL_ERROR_TOO_MANY_OPERATIONS;
   }

src/core/lib/surface/call.h

@@ -98,6 +98,11 @@ void* grpc_call_context_get(grpc_call* call, grpc_context_index elem);
 
 uint8_t grpc_call_is_client(grpc_call* call);
 
+/* Get the estimated memory size for a call BESIDES the call stack. Combined
+ * with the size of the call stack, it helps estimate the arena size for the
+ * initial call. */
+size_t grpc_call_get_initial_size_estimate();
+
 /* Return an appropriate compression algorithm for the requested compression \a
  * level in the context of \a call. */
 grpc_compression_algorithm grpc_call_compression_for_level(

src/core/lib/surface/channel.cc

@@ -112,7 +112,8 @@ grpc_channel* grpc_channel_create_with_builder(
 
   gpr_atm_no_barrier_store(
       &channel->call_size_estimate,
-      (gpr_atm)CHANNEL_STACK_FROM_CHANNEL(channel)->call_stack_size);
+      (gpr_atm)CHANNEL_STACK_FROM_CHANNEL(channel)->call_stack_size +
+          grpc_call_get_initial_size_estimate());
 
   grpc_compression_options_init(&channel->compression_options);
   for (size_t i = 0; i < args->num_args; i++) {