diff --git a/performance.xlsx b/performance.xlsx
index f5564d2..82f29d5 100644
Binary files a/performance.xlsx and b/performance.xlsx differ
diff --git a/src/ipc.cpp b/src/ipc.cpp
index c23dbcd..79d20d7 100644
--- a/src/ipc.cpp
+++ b/src/ipc.cpp
@@ -146,7 +146,7 @@ static bool send(ipc::handle_t h, void const * data, std::size_t size) {
             { que, msg_id, static_cast<int>(size) - offset - static_cast<int>(data_length) }, {}
         };
         std::memcpy(msg.data_, static_cast<byte_t const *>(data) + offset, data_length);
-        if (!que->push(msg)) return false;
+        while (!que->push(msg)) std::this_thread::yield();
     }
     // if remain > 0, this is the last message fragment
     int remain = static_cast<int>(size) - offset;
@@ -156,7 +156,7 @@ static bool send(ipc::handle_t h, void const * data, std::size_t size) {
         };
         std::memcpy(msg.data_, static_cast<byte_t const *>(data) + offset,
                                static_cast<std::size_t>(remain));
-        if (!que->push(msg)) return false;
+        while (!que->push(msg)) std::this_thread::yield();
     }
     return true;
 }
diff --git a/src/prod_cons.h b/src/prod_cons.h
index bdd8966..4acd4da 100644
--- a/src/prod_cons.h
+++ b/src/prod_cons.h
@@ -182,17 +182,12 @@ struct prod_cons_impl<wr<relat::single, relat::multi, trans::broadcast>> {
     bool push(W* wrapper, F&& f, E<DataSize>* elems) {
         auto conn_cnt = wrapper->conn_count(std::memory_order_relaxed);
         if (conn_cnt == 0) return false;
-        auto el = elems + circ::index_of(wt_.load(std::memory_order_acquire));
+        auto* el = elems + circ::index_of(wt_.load(std::memory_order_acquire));
         // check all consumers have finished reading this element
-        while (1) {
-            rc_t expected = 0;
-            if (el->rc_.compare_exchange_weak(
-                        expected, static_cast<rc_t>(conn_cnt), std::memory_order_release)) {
-                break;
-            }
-            std::this_thread::yield();
-            conn_cnt = wrapper->conn_count(); // acquire
-            if (conn_cnt == 0) return false;
+        rc_t expected = 0;
+        if (!el->rc_.compare_exchange_strong(
+                    expected, static_cast<rc_t>(conn_cnt), std::memory_order_release)) {
+            return false; // full
         }
         std::forward<F>(f)(&(el->data_));
         wt_.fetch_add(1, std::memory_order_release);
@@ -202,7 +197,7 @@ struct prod_cons_impl<wr<relat::single, relat::multi, trans::broadcast>> {
     template <typename W, typename F, template <std::size_t> class E, std::size_t DataSize>
     bool pop(W* /*wrapper*/, circ::u2_t& cur, F&& f, E<DataSize>* elems) {
         if (cur == cursor()) return false; // acquire
-        auto el = elems + circ::index_of(cur++);
+        auto* el = elems + circ::index_of(cur++);
         std::forward<F>(f)(&(el->data_));
         for (unsigned k = 0;;) {
             rc_t cur_rc = el->rc_.load(std::memory_order_acquire);
@@ -219,38 +214,89 @@ struct prod_cons_impl<wr<relat::single, relat::multi, trans::broadcast>> {
 };
 
 template <>
-struct prod_cons_impl<wr<relat::multi , relat::multi, trans::broadcast>>
-     : prod_cons_impl<wr<relat::single, relat::multi, trans::broadcast>> {
+struct prod_cons_impl<wr<relat::multi , relat::multi, trans::broadcast>> {
+
+    using rc_t   = std::uint64_t;
+    using flag_t = std::uint64_t;
+
+    enum : rc_t {
+        rc_mask = 0x00000000ffffffffull,
+        rc_incr = 0x0000000100000000ull
+    };
+
+    template <std::size_t DataSize>
+    struct elem_t {
+        byte_t data_[DataSize] {};
+        std::atomic<rc_t  > rc_   { 0 }; // read-counter
+        std::atomic<flag_t> f_ct_ { 0 }; // commit flag
+    };
 
     alignas(circ::cache_line_size) std::atomic<circ::u2_t> ct_; // commit index
 
+    circ::u2_t cursor() const noexcept {
+        return ct_.load(std::memory_order_acquire);
+    }
+
     template <typename W, typename F, template <std::size_t> class E, std::size_t DataSize>
     bool push(W* wrapper, F&& f, E<DataSize>* elems) {
-        auto conn_cnt = wrapper->conn_count(std::memory_order_relaxed);
-        if (conn_cnt == 0) return false;
-        circ::u2_t cur_ct = ct_.fetch_add(1, std::memory_order_acquire),
-                   nxt_ct = cur_ct + 1;
-        auto el = elems + circ::index_of(cur_ct);
-        // check all consumers have finished reading this element
-        while (1) {
-            rc_t expected = 0;
+        E<DataSize>* el;
+        circ::u2_t cur_ct, nxt_ct;
+        for (unsigned k = 0;;) {
+            auto cc = wrapper->conn_count(std::memory_order_relaxed);
+            if (cc == 0) {
+                return false; // no reader
+            }
+            el = elems + circ::index_of(cur_ct = ct_.load(std::memory_order_relaxed));
+            auto cur_rc = el->rc_.load(std::memory_order_acquire);
+            if (cur_rc & rc_mask) {
+                return false; // full
+            }
+            auto cur_fl = el->f_ct_.load(std::memory_order_acquire);
+            if ((cur_fl != cur_ct) && cur_fl) {
+                return false; // full
+            }
+            // (cur_rc & rc_mask) should == 0 here
             if (el->rc_.compare_exchange_weak(
-                        expected, static_cast<rc_t>(conn_cnt), std::memory_order_release)) {
+                        cur_rc, static_cast<rc_t>(cc) | ((cur_rc & ~rc_mask) + rc_incr), std::memory_order_release)) {
                 break;
             }
-            std::this_thread::yield();
-            conn_cnt = wrapper->conn_count(); // acquire
-            if (conn_cnt == 0) return false;
+            ipc::yield(k);
         }
+        // only one thread/process would touch here at one time
+        ct_.store(nxt_ct = cur_ct + 1, std::memory_order_release);
         std::forward<F>(f)(&(el->data_));
-        while (1) {
-            auto exp_wt = cur_ct;
-            if (wt_.compare_exchange_weak(exp_wt, nxt_ct, std::memory_order_release)) {
+        // set flag & try update wt
+        el->f_ct_.store(~static_cast<flag_t>(cur_ct));
+        return true;
+    }
+
+    template <typename W, typename F, template <std::size_t> class E, std::size_t DataSize, std::size_t N>
+    bool pop(W* /*wrapper*/, circ::u2_t& cur, F&& f, E<DataSize>(& elems)[N]) {
+        auto* el = elems + circ::index_of(cur);
+        auto cur_fl = el->f_ct_.load(std::memory_order_acquire);
+        if (cur_fl != ~static_cast<flag_t>(cur)) {
+            return false; // empty
+        }
+        ++cur;
+        std::forward<F>(f)(&(el->data_));
+        for (unsigned k = 0;;) {
+            auto cur_rc = el->rc_.load(std::memory_order_acquire);
+            switch (cur_rc & rc_mask) {
+            case 0:
+                el->f_ct_.store(cur + N - 1, std::memory_order_release);
+                return true;
+            case 1:
+                el->f_ct_.store(cur + N - 1, std::memory_order_release);
+                [[fallthrough]];
+            default:
+                if (el->rc_.compare_exchange_weak(
+                            cur_rc, cur_rc + rc_incr - 1, std::memory_order_release)) {
+                    return true;
+                }
                 break;
             }
-            std::this_thread::yield();
+            ipc::yield(k);
         }
-        return true;
     }
 };
 
diff --git a/src/queue.h b/src/queue.h
index c9c2eb4..82cb02c 100644
--- a/src/queue.h
+++ b/src/queue.h
@@ -81,29 +81,31 @@ public:
     }
 
     template <typename Elems>
-    std::size_t connect(Elems* elems) {
-        if (elems == nullptr) return invalid_value;
+    auto connect(Elems* elems)
+     -> std::tuple<bool, decltype(std::declval<Elems>().cursor())> {
+        if (elems == nullptr) return {};
         if (connected_) {
-            // if it's already connected, just return an error count
-            return invalid_value;
+            // if it's already connected, just return false
+            return {};
         }
         connected_ = true;
-        auto ret = elems->connect();
+        elems->connect();
+        auto ret = std::make_tuple(true, elems->cursor());
         cc_waiter_.broadcast();
         return ret;
     }
 
     template <typename Elems>
-    std::size_t disconnect(Elems* elems) {
-        if (elems == nullptr) return invalid_value;
+    bool disconnect(Elems* elems) {
+        if (elems == nullptr) return false;
         if (!connected_) {
-            // if it's already disconnected, just return an error count
-            return invalid_value;
+            // if it's already disconnected, just return false
+            return false;
         }
         connected_ = false;
-        auto ret = elems->disconnect();
+        elems->disconnect();
         cc_waiter_.broadcast();
-        return ret;
+        return true;
     }
 
     template <typename Elems>
@@ -155,11 +157,16 @@ public:
         return elems_;
     }
 
-    std::size_t connect() {
-        return base_t::connect(elems_);
+    bool connect() {
+        auto tp = base_t::connect(elems_);
+        if (std::get<0>(tp)) {
+            cursor_ = std::get<1>(tp);
+            return true;
+        }
+        return false;
     }
 
-    std::size_t disconnect() {
+    bool disconnect() {
         return base_t::disconnect(elems_);
     }
 
@@ -186,9 +193,6 @@ public:
             base_t::close(old);
         }
         else base_t::open(elems_, name);
-        if (elems_ != nullptr) {
-            cursor_ = elems_->cursor();
-        }
         return old;
     }
 
diff --git a/test/test_circ.cpp b/test/test_circ.cpp
index 9f60ee5..63e87d3 100644
--- a/test/test_circ.cpp
+++ b/test/test_circ.cpp
@@ -183,12 +183,12 @@ struct test_cq<ipc::queue<T...>> {
 
     cn_t* connect() {
         cn_t* queue = new cn_t { ca_ };
-        [&] { QVERIFY(queue->connect() != ipc::invalid_value); } ();
+        [&] { QVERIFY(queue->connect()); } ();
         return queue;
     }
 
     void disconnect(cn_t* queue) {
-        QVERIFY(queue->disconnect() != ipc::invalid_value);
+        QVERIFY(queue->disconnect());
         QVERIFY(queue->detach() != nullptr);
         delete queue;
     }
@@ -241,7 +241,7 @@ private slots:
 
 #include "test_circ.moc"
 
-constexpr int LoopCount = 1000000;
+constexpr int LoopCount = 10000000;
 //constexpr int LoopCount = 1000/*0000*/;
 
 void Unit::initTestCase() {
@@ -270,6 +270,13 @@ void test_prod_cons() {
 }
 
 void Unit::test_prod_cons_1v1() {
+//    ea_t<
+//        sizeof(msg_t),
+//        pc_t<ipc::relat::multi, ipc::relat::multi, ipc::trans::broadcast>
+//    > el_arr_mmb;
+//    benchmark_prod_cons<1, 1, LoopCount, void>(&el_arr_mmb);
+//    benchmark_prod_cons<2, 1, LoopCount, void>(&el_arr_mmb);
+
     ea_t<
         sizeof(msg_t),
         pc_t<ipc::relat::single, ipc::relat::single, ipc::trans::unicast>
@@ -387,7 +394,7 @@ void Unit::test_queue() {
     queue.attach(cq);
     QVERIFY(queue.detach() != nullptr);
 
-    ipc::detail::static_for(std::make_index_sequence<8>{}, [](auto index) {
+    ipc::detail::static_for(std::make_index_sequence<16>{}, [](auto index) {
         benchmark_prod_cons<1, decltype(index)::value + 1, LoopCount>((queue_t*)nullptr);
     });
 }
diff --git a/test/test_ipc.cpp b/test/test_ipc.cpp
index 72dc0ff..6d0c544 100644
--- a/test/test_ipc.cpp
+++ b/test/test_ipc.cpp
@@ -402,7 +402,7 @@ void Unit::test_route_rtt() {
 
 void Unit::test_route_performance() {
     //return;
-    ipc::detail::static_for(std::make_index_sequence<8>{}, [](auto index) {
+    ipc::detail::static_for(std::make_index_sequence<16>{}, [](auto index) {
         test_prod_cons<ipc::route, 1, decltype(index)::value + 1, false>();
     });
     test_prod_cons<ipc::route, 1, 8>(); // test & verify
@@ -476,13 +476,13 @@ void Unit::test_channel_rtt() {
 }
 
 void Unit::test_channel_performance() {
-    ipc::detail::static_for(std::make_index_sequence<8>{}, [](auto index) {
+    ipc::detail::static_for(std::make_index_sequence<16>{}, [](auto index) {
         test_prod_cons<ipc::channel, 1, decltype(index)::value + 1, false>();
     });
-    ipc::detail::static_for(std::make_index_sequence<8>{}, [](auto index) {
+    ipc::detail::static_for(std::make_index_sequence<16>{}, [](auto index) {
         test_prod_cons<ipc::channel, decltype(index)::value + 1, 1, false>();
     });
-    ipc::detail::static_for(std::make_index_sequence<8>{}, [](auto index) {
+    ipc::detail::static_for(std::make_index_sequence<16>{}, [](auto index) {
         test_prod_cons<ipc::channel, decltype(index)::value + 1,
                                      decltype(index)::value + 1, false>();
     });