diff --git a/trunk/3rdparty/st-srs/README.md b/trunk/3rdparty/st-srs/README.md
index 60fc1a651..522d3c761 100644
--- a/trunk/3rdparty/st-srs/README.md
+++ b/trunk/3rdparty/st-srs/README.md
@@ -22,6 +22,8 @@ The branch [srs](https://github.com/ossrs/state-threads/tree/srs) will be patche
 - [x] Patch [st.osx10.14.build.patch](https://github.com/ossrs/srs/blob/2.0release/trunk/3rdparty/patches/6.st.osx10.14.build.patch), for osx 10.14 build.
 - [x] Support macro `MD_ST_NO_ASM` to disable ASM, [#8](https://github.com/ossrs/state-threads/issues/8).
 - [x] Merge patch [srs#1282](https://github.com/ossrs/srs/issues/1282#issuecomment-445539513) to support aarch64, [#9](https://github.com/ossrs/state-threads/issues/9).
+- [x] Support OSX for Apple Darwin, macOS, [#11](https://github.com/ossrs/state-threads/issues/11).
+- [x] Support sendmmsg for UDP, [#12](https://github.com/ossrs/state-threads/issues/12).
 
 ## Docs
 
@@ -85,4 +87,10 @@ Important cli options:
 1. `--track-origins=<yes|no> [default: no]`, Controls whether Memcheck tracks the origin of uninitialised values. By default, it does not, which means that although it can tell you that an uninitialised value is being used in a dangerous way, it cannot tell you where the uninitialised value came from. This often makes it difficult to track down the root problem.
 1. `--show-reachable=<yes|no> , --show-possibly-lost=<yes|no>`, to show the using memory.
 
+## Analysis
+
+1. About setjmp and longjmp, read [setjmp](https://gitee.com/winlinvip/srs-wiki/raw/master/images/st-setjmp.jpg).
+1. About the stack structure, read [stack](https://gitee.com/winlinvip/srs-wiki/raw/master/images/st-stack.jpg)
+1. About asm code comments, read [#91d530e](https://github.com/ossrs/state-threads/commit/91d530e#diff-ed9428b14ff6afda0e9ab04cc91d4445R25).
+
 Winlin 2016
diff --git a/trunk/src/app/srs_app_rtc_conn.cpp b/trunk/src/app/srs_app_rtc_conn.cpp
index 230ea2e49..5b79be9ca 100644
--- a/trunk/src/app/srs_app_rtc_conn.cpp
+++ b/trunk/src/app/srs_app_rtc_conn.cpp
@@ -2013,6 +2013,7 @@ srs_error_t SrsUdpMuxSender::cycle()
     srs_error_t err = srs_success;
 
     uint64_t nn_msgs = 0; uint64_t nn_msgs_last = 0; int nn_msgs_max = 0;
+    uint64_t nn_bytes = 0; int nn_bytes_max = 0;
     uint64_t nn_gso_msgs = 0; uint64_t nn_gso_iovs = 0; int nn_gso_msgs_max = 0; int nn_gso_iovs_max = 0;
     int nn_loop = 0; int nn_wait = 0;
     srs_utime_t time_last = srs_get_system_time();
@@ -2044,21 +2045,8 @@ srs_error_t SrsUdpMuxSender::cycle()
         cache_pos = 0;
 
         int gso_pos = 0;
+        int nn_writen = 0;
         if (pos > 0) {
-            // Collect informations for GSO.
-            if (stat_enabled) {
-                // For shared GSO cache, stat the messages.
-                // @see https://linux.die.net/man/2/sendmmsg
-                // @see https://linux.die.net/man/2/sendmsg
-                for (int i = 0; i < pos; i++) {
-                    mmsghdr* mhdr = &hotspot[i];
-
-                    int real_iovs = mhdr->msg_hdr.msg_iovlen;
-                    gso_pos++; nn_gso_msgs++; nn_gso_iovs += real_iovs;
-                    gso_iovs += real_iovs;
-                }
-            }
-
             // Send out all messages.
             // @see https://linux.die.net/man/2/sendmmsg
             // @see https://linux.die.net/man/2/sendmsg
@@ -2076,6 +2064,22 @@ srs_error_t SrsUdpMuxSender::cycle()
                     stat->perf_on_sendmmsg_packets(vlen);
                 }
             }
+
+            // Collect informations for GSO.
+            if (stat_enabled) {
+                // Stat the messages, iovs and bytes.
+                // @see https://linux.die.net/man/2/sendmmsg
+                // @see https://linux.die.net/man/2/sendmsg
+                for (int i = 0; i < pos; i++) {
+                    mmsghdr* mhdr = &hotspot[i];
+
+                    nn_writen += (int)mhdr->msg_len;
+
+                    int real_iovs = mhdr->msg_hdr.msg_iovlen;
+                    gso_pos++; nn_gso_msgs++; nn_gso_iovs += real_iovs;
+                    gso_iovs += real_iovs;
+                }
+            }
         }
 
         if (!stat_enabled) {
@@ -2085,6 +2089,8 @@ srs_error_t SrsUdpMuxSender::cycle()
         // Increase total messages.
         nn_msgs += pos + gso_iovs;
         nn_msgs_max = srs_max(pos, nn_msgs_max);
+        nn_bytes += nn_writen;
+        nn_bytes_max = srs_max(nn_bytes_max, nn_writen);
         nn_gso_msgs_max = srs_max(gso_pos, nn_gso_msgs_max);
         nn_gso_iovs_max = srs_max(gso_iovs, nn_gso_iovs_max);
 
@@ -2115,12 +2121,13 @@ srs_error_t SrsUdpMuxSender::cycle()
                 nn_cache += hdr->msg_hdr.msg_iovlen;
             }
 
-            srs_trace("-> RTC SEND #%d, sessions %d, udp %d/%d/%" PRId64 ", gso %d/%d/%" PRId64 ", iovs %d/%d/%" PRId64 ", pps %d/%d%s, cache %d/%d",
+            srs_trace("-> RTC SEND #%d, sessions %d, udp %d/%d/%" PRId64 ", gso %d/%d/%" PRId64 ", iovs %d/%d/%" PRId64 ", pps %d/%d%s, cache %d/%d, bytes %d/%" PRId64,
                 srs_netfd_fileno(lfd), (int)server->nn_sessions(), pos, nn_msgs_max, nn_msgs, gso_pos, nn_gso_msgs_max, nn_gso_msgs, gso_iovs,
-                nn_gso_iovs_max, nn_gso_iovs, pps_average, pps_last, pps_unit.c_str(), (int)hotspot.size(), nn_cache);
+                nn_gso_iovs_max, nn_gso_iovs, pps_average, pps_last, pps_unit.c_str(), (int)hotspot.size(), nn_cache, nn_bytes_max, nn_bytes);
             nn_msgs_last = nn_msgs; time_last = srs_get_system_time();
             nn_loop = nn_wait = nn_msgs_max = 0;
             nn_gso_msgs_max = 0; nn_gso_iovs_max = 0;
+            nn_bytes_max = 0;
         }
     }