diff --git a/trunk/src/app/srs_app_recv_thread.cpp b/trunk/src/app/srs_app_recv_thread.cpp
index 04abe5e2b..16ef3bc1e 100644
--- a/trunk/src/app/srs_app_recv_thread.cpp
+++ b/trunk/src/app/srs_app_recv_thread.cpp
@@ -42,6 +42,9 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 #define SRS_MR_SMALL_BYTES 64
 // the percent of buffer to set as small bytes
 #define SRS_MR_SMALL_PERCENT 100
+// set the socket buffer to specified KB.
+// the underlayer api will set to 2*SRS_MR_SOCKET_BUFFER KB.
+#define SRS_MR_SOCKET_BUFFER 32
 
 ISrsMessageHandler::ISrsMessageHandler()
 {
@@ -296,14 +299,16 @@ void SrsPublishRecvThread::on_thread_start()
     // we donot set the auto response to false,
     // for the main thread never send message.
 
-    // 128KB recv buffer.
-    int nb_rbuf = 128 * 1024;
+    // socket recv buffer.
+    int nb_rbuf = SRS_MR_SOCKET_BUFFER * 1024;
     socklen_t sock_buf_size = sizeof(int);
     if (setsockopt(mr_fd, SOL_SOCKET, SO_RCVBUF, &nb_rbuf, sock_buf_size) < 0) {
         srs_warn("set sock SO_RCVBUF=%d failed.", nb_rbuf);
     }
     getsockopt(mr_fd, SOL_SOCKET, SO_RCVBUF, &nb_rbuf, &sock_buf_size);
 
+    srs_trace("set socket buffer to %d, actual %d KB", SRS_MR_SOCKET_BUFFER, nb_rbuf / 1024);
+
     // enable the merge read
     // @see https://github.com/winlinvip/simple-rtmp-server/issues/241
     rtmp->set_merge_read(true, nb_rbuf, this);
diff --git a/trunk/src/rtmp/srs_protocol_buffer.cpp b/trunk/src/rtmp/srs_protocol_buffer.cpp
index cf17aa1d2..f78f6b49f 100644
--- a/trunk/src/rtmp/srs_protocol_buffer.cpp
+++ b/trunk/src/rtmp/srs_protocol_buffer.cpp
@@ -33,7 +33,7 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 // 32KB=32768
 // 64KB=65536
 // @see https://github.com/winlinvip/simple-rtmp-server/issues/241
-#define SOCKET_READ_SIZE 4096
+#define SOCKET_READ_SIZE 65536
 // the max buffer for user space socket buffer.
 #define SOCKET_MAX_BUF 65536
 
@@ -136,6 +136,10 @@ void SrsBuffer::set_merge_read(bool v, int max_buffer, IMergeReadHandler* handle
     if (v && buffer_size != nb_buffer) {
         reset_buffer(buffer_size);
     }
+
+    if (_handler) {
+        _handler->on_buffer_change(nb_buffer);
+    }
 }
 
 void SrsBuffer::on_chunk_size(int32_t chunk_size)
@@ -145,6 +149,10 @@ void SrsBuffer::on_chunk_size(int32_t chunk_size)
     }
 
     reset_buffer(chunk_size);
+
+    if (_handler) {
+        _handler->on_buffer_change(nb_buffer);
+    }
 }
 
 int SrsBuffer::buffer_size()
@@ -158,8 +166,4 @@ void SrsBuffer::reset_buffer(int size)
 
     nb_buffer = size;
     buffer = new char[nb_buffer];
-
-    if (_handler) {
-        _handler->on_buffer_change(nb_buffer);
-    }
 }