diff --git a/src/adapter/driver/driver.c b/src/adapter/driver/driver.c
index 9558c63c..f4c39838 100644
--- a/src/adapter/driver/driver.c
+++ b/src/adapter/driver/driver.c
@@ -1206,8 +1206,8 @@ int neu_adapter_driver_add_tag(neu_adapter_driver_t *driver, const char *group,
 
     HASH_FIND_STR(driver->groups, group, find);
     if (find == NULL) {
-        neu_adapter_driver_add_group(driver, group, 300);
-        adapter_storage_add_group(driver->adapter.name, group, 300);
+        neu_adapter_driver_add_group(driver, group, 100);
+        adapter_storage_add_group(driver->adapter.name, group, 100);
     }
     HASH_FIND_STR(driver->groups, group, find);
     assert(find != NULL);
diff --git a/src/connection/connection.c b/src/connection/connection.c
index f8cf1f12..ac3d0b71 100644
--- a/src/connection/connection.c
+++ b/src/connection/connection.c
@@ -357,7 +357,7 @@ ssize_t neu_conn_send(neu_conn_t *conn, uint8_t *buf, ssize_t len)
                     } else {
                         struct timespec t1 = {
                             .tv_sec  = 0,
-                            .tv_nsec = 1000 * 1000 * 10,
+                            .tv_nsec = 1000 * 1000 * 20,
                         };
                         struct timespec t2 = { 0 };
                         nanosleep(&t1, &t2);
diff --git a/src/event/event_linux.c b/src/event/event_linux.c
index 70764bf8..254ddac7 100644
--- a/src/event/event_linux.c
+++ b/src/event/event_linux.c
@@ -73,14 +73,14 @@ struct neu_events {
 
     pthread_mutex_t   mtx;
     int               n_event;
-    struct event_data event_datas[256];
+    struct event_data event_datas[512];
 };
 
 static int get_free_event(neu_events_t *events)
 {
     int ret = -1;
     pthread_mutex_lock(&events->mtx);
-    for (int i = 0; i < 256; i++) {
+    for (int i = 0; i < 512; i++) {
         if (events->event_datas[i].use == false) {
             events->event_datas[i].use   = true;
             events->event_datas[i].index = i;
@@ -213,6 +213,9 @@ neu_event_timer_t *neu_event_add_timer(neu_events_t *          events,
         .it_interval.tv_nsec = timer.millisecond * 1000 * 1000,
     };
     int index = get_free_event(events);
+    if (index < 0) {
+        zlog_fatal(neuron, "no free event: %d", events->epoll_fd);
+    }
     assert(index >= 0);
 
     neu_event_timer_t *timer_ctx = &events->event_datas[index].ctx.timer;