diff --git a/src/agent.c b/src/agent.c
index 4174e0f..ebfa05e 100644
--- a/src/agent.c
+++ b/src/agent.c
@@ -26,10 +26,14 @@ static struct termios ttystate_backup;
 uv_tty_t agent_stdout_tty;
 uv_tty_t agent_stdin_tty;
 static int64_t pending_send = 0;  //记录待转发的字节，用于tty 流控
+int max_suggested_size = 10240;
 void agent_read_stdin(uv_stream_t *stream, ssize_t nread, const uv_buf_t *buf);
 
 static void alloc_buffer(uv_handle_t *handle, size_t suggested_size,
                          uv_buf_t *buf) {
+  if (suggested_size > max_suggested_size) {
+    suggested_size = max_suggested_size;
+  }
   buf->base = (char *)malloc(suggested_size);
   buf->len = suggested_size;
 }
@@ -137,20 +141,19 @@ void agent_read_stdin(uv_stream_t *stream, ssize_t nread, const uv_buf_t *buf) {
     }
 
     static char *data = NULL;
-    // TODO 动态大小
     if (data == NULL) {
-      data = (char *)malloc(9999);
+      data = (char *)malloc(2 * max_suggested_size);
     }
     static int data_size = 0;
-    CHECK(nread < 9999, "nread<9999");
+    CHECK(nread < max_suggested_size, "nread<2*max_suggested_size");
     memcpy(data + data_size, buf->base, nread);
     data_size += nread;
-    CHECK(data_size < 9999, "data_size>=9999");
+    CHECK(data_size < max_suggested_size, "data_size>=max_suggested_size");
 
     int used_data_size = process_stdin(data, data_size);
     int unused_data_size = data_size - used_data_size;
     if (unused_data_size > 0) {
-      CHECK(unused_data_size < 9999, "erorr");
+      CHECK(unused_data_size < max_suggested_size, "erorr");
       memmove(data, data + used_data_size, unused_data_size);
     }
     data_size = unused_data_size;
diff --git a/src/entry.c b/src/entry.c
index 8a312a0..99dca29 100644
--- a/src/entry.c
+++ b/src/entry.c
@@ -93,8 +93,8 @@ int main(int argc, const char *argv[]) {
 #endif
 
   log_set_quiet(true);
-  char *verbose_env_str = getenv("VERBOSE");
-  if (getenv("VERBOSE") != NULL) {
+  char *verbose_env_str = getenv("TERMTUNNEL_VERBOSE");
+  if (verbose_env_str != NULL) {
     int verbose_level = atoi(verbose_env_str);
     if (verbose_level < 0 || verbose_level > 9) {
       verbose_level = 0;
diff --git a/src/fileexchange.c b/src/fileexchange.c
index d3ca4d1..0578ecf 100644
--- a/src/fileexchange.c
+++ b/src/fileexchange.c
@@ -148,16 +148,6 @@ static int file_send_request(path_exchange_t *pe) {
   return 0;
 }
 
-#if 0
-// from libuv
-void exchange_notify_handler(uv_async_t *handle)
-{
-    log_info("exchange_notify_handler\n");
-    //comm_write_packet_to_cli(COMMAND_TTY_PING, NULL, 0);
-    return;
-}
-#endif 0
-
 int file_send_start(char *src_path, char *dst_path) {
   path_exchange_t *pe = (path_exchange_t *)malloc(sizeof(path_exchange_t));
   strcpy(pe->src_path, src_path);
diff --git a/src/pipe.c b/src/pipe.c
index 586e436..3b0155c 100644
--- a/src/pipe.c
+++ b/src/pipe.c
@@ -362,11 +362,10 @@ static void common_read_tty(uv_stream_t *stream, ssize_t nread,
     }
     fsm_append_input(global_fsm_context, buf->base, nread);
     fsm_run(global_fsm_context);
-    // TODO:可能因为单frame过大导致2000不够用
-    char *dst = (char *)malloc(2000);
+    char *dst = (char *)malloc(5 * VIR_MTU);
     int sz = 0;
     while (true) {
-      sz = fsm_pop_output(global_fsm_context, dst, 2000);
+      sz = fsm_pop_output(global_fsm_context, dst, 5 * VIR_MTU);
       if (sz > 0) {
         server_handle_green_packet(dst, sz);
       } else {
diff --git a/src/pty.c b/src/pty.c
index 54b78ef..a811772 100644
--- a/src/pty.c
+++ b/src/pty.c
@@ -47,10 +47,8 @@ int get_pty_fd() { return pty_fd; }
 
 static int do_exec(const char *name, int ptypt, char **argv, int argc) {
   struct winsize ttysize;
-  if (ioctl(myself_fd, TIOCGWINSZ, &ttysize) == 0) {
-    // pass
-    // sleep(5);
-  } else {
+  if (ioctl(myself_fd, TIOCGWINSZ, &ttysize) != 0) {
+    // fallback
     ttysize.ws_col = 20;
     ttysize.ws_row = 20;
     ttysize.ws_xpixel = 0;
@@ -69,15 +67,15 @@ static int do_exec(const char *name, int ptypt, char **argv, int argc) {
   int slavept = open(name, O_RDWR);
 
   if (slavept < 0) {
-    printf("open slave error\n");
+    fprintf(stderr, "open slave error\n");
     exit(EXIT_FAILURE);
   }
 
   ioctl(slavept, TIOCSWINSZ, &ttysize);
+
   close(0);
   close(1);
   close(2);
-
   dup2(slavept, 0);
   dup2(slavept, 1);
   dup2(slavept, 2);
@@ -85,15 +83,14 @@ static int do_exec(const char *name, int ptypt, char **argv, int argc) {
   close(slavept);
   close(pty_fd);
 
-  int fdlimit = (int)sysconf(_SC_OPEN_MAX);
+  int32_t fdlimit = (int32_t)sysconf(_SC_OPEN_MAX);
   for (int i = STDERR_FILENO + 1; i < fdlimit; i++) {
     close(i);
   }
-
-  execvp(new_argv[0], new_argv);  //不会传递环境变量
+  //unsetenv("TERMTUNNEL_VERBOSE");
+  execvp(new_argv[0], new_argv);
   fprintf(stderr, "%s: %s\n", new_argv[0], strerror(errno));
   exit(EXIT_FAILURE);
-  // printf("kkk2k\n");
   return 0;
 }
 
diff --git a/src/utils.c b/src/utils.c
index 564c9e7..00789ad 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -60,19 +60,16 @@ void *memdup(const void *src, size_t n) {
 bool stdin_is_raw() { return _stdin_is_raw; }
 
 int writen(int fd, void *buf, int n) {
-  int nwrite, left = n;
+  int nwrite = 0;
+  int left = n;
   while (left > 0) {
     if ((nwrite = write(fd, buf, left)) == -1) {
       if (errno == EINTR || errno == EAGAIN) {
         continue;
       }
     } else {
-      if (nwrite == n) {
-        return 0;
-      } else {
         left -= nwrite;
         buf += nwrite;
-      }
     }
   }
   return n;