Use larger block size in proto write
diff --git a/include/grpc++/impl/codegen/proto_utils.h b/include/grpc++/impl/codegen/proto_utils.h
index 6df9de4..8c0c32b 100644
--- a/include/grpc++/impl/codegen/proto_utils.h
+++ b/include/grpc++/impl/codegen/proto_utils.h
@@ -52,7 +52,7 @@
 
 class GrpcBufferWriterPeer;
 
-const int kGrpcBufferWriterMaxBufferLength = 8192;
+const int kGrpcBufferWriterMaxBufferLength = 1024 * 1024;
 
 class GrpcBufferWriter final
     : public ::grpc::protobuf::io::ZeroCopyOutputStream {