Introduce perfect activation queue

15 files changed, 174 insertions, 43 deletions

diff --git a/library/cpp/actors/core/CMakeLists.darwin-x86_64.txt b/library/cpp/actors/core/CMakeLists.darwin-x86_64.txt
index c5c1629513..392a1b5ea7 100644
--- a/library/cpp/actors/core/CMakeLists.darwin-x86_64.txt
+++ b/library/cpp/actors/core/CMakeLists.darwin-x86_64.txt
@@ -77,6 +77,7 @@ target_sources(cpp-actors-core PRIVATE
   ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/monotonic.cpp
   ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/monotonic_provider.cpp
   ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/worker_context.cpp
+  ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/perfect_activation_queue.cpp
   ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/probes.cpp
   ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/process_stats.cpp
   ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/scheduler_actor.cpp
diff --git a/library/cpp/actors/core/CMakeLists.linux-aarch64.txt b/library/cpp/actors/core/CMakeLists.linux-aarch64.txt
index 23f4e3ba64..cf4e5c9440 100644
--- a/library/cpp/actors/core/CMakeLists.linux-aarch64.txt
+++ b/library/cpp/actors/core/CMakeLists.linux-aarch64.txt
@@ -78,6 +78,7 @@ target_sources(cpp-actors-core PRIVATE
   ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/monotonic.cpp
   ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/monotonic_provider.cpp
   ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/worker_context.cpp
+  ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/perfect_activation_queue.cpp
   ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/probes.cpp
   ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/process_stats.cpp
   ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/scheduler_actor.cpp
diff --git a/library/cpp/actors/core/CMakeLists.linux-x86_64.txt b/library/cpp/actors/core/CMakeLists.linux-x86_64.txt
index 23f4e3ba64..cf4e5c9440 100644
--- a/library/cpp/actors/core/CMakeLists.linux-x86_64.txt
+++ b/library/cpp/actors/core/CMakeLists.linux-x86_64.txt
@@ -78,6 +78,7 @@ target_sources(cpp-actors-core PRIVATE
   ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/monotonic.cpp
   ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/monotonic_provider.cpp
   ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/worker_context.cpp
+  ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/perfect_activation_queue.cpp
   ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/probes.cpp
   ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/process_stats.cpp
   ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/scheduler_actor.cpp
diff --git a/library/cpp/actors/core/CMakeLists.windows-x86_64.txt b/library/cpp/actors/core/CMakeLists.windows-x86_64.txt
index c5c1629513..392a1b5ea7 100644
--- a/library/cpp/actors/core/CMakeLists.windows-x86_64.txt
+++ b/library/cpp/actors/core/CMakeLists.windows-x86_64.txt
@@ -77,6 +77,7 @@ target_sources(cpp-actors-core PRIVATE
   ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/monotonic.cpp
   ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/monotonic_provider.cpp
   ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/worker_context.cpp
+  ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/perfect_activation_queue.cpp
   ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/probes.cpp
   ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/process_stats.cpp
   ${CMAKE_SOURCE_DIR}/library/cpp/actors/core/scheduler_actor.cpp
diff --git a/library/cpp/actors/core/executor_pool_base.cpp b/library/cpp/actors/core/executor_pool_base.cpp
index 10362a7a2b..c8e3c0aa71 100644
--- a/library/cpp/actors/core/executor_pool_base.cpp
+++ b/library/cpp/actors/core/executor_pool_base.cpp
@@ -71,7 +71,7 @@ namespace NActors {
     {}
 
     TExecutorPoolBase::~TExecutorPoolBase() {
-        while (Activations.Pop(0))
+        while (Activations.Pop())
             ;
     }
 
@@ -105,7 +105,7 @@ namespace NActors {
     }
 
     void TExecutorPoolBase::ScheduleActivation(ui32 activation) {
-        ScheduleActivationEx(activation, AtomicIncrement(ActivationsRevolvingCounter));
+        ScheduleActivationEx(activation, 0);
     }
 
     Y_FORCE_INLINE bool IsAllowedToCapture(IExecutorPool *self) {
@@ -121,7 +121,7 @@ namespace NActors {
             TlsThreadContext->CapturedType = TlsThreadContext->SendingType;
         }
         if (activation) {
-            ScheduleActivationEx(activation, AtomicIncrement(ActivationsRevolvingCounter));
+            ScheduleActivationEx(activation, 0);
         }
     }
 
diff --git a/library/cpp/actors/core/executor_pool_base.h b/library/cpp/actors/core/executor_pool_base.h
index e94ffdbad9..6a321e32f8 100644
--- a/library/cpp/actors/core/executor_pool_base.h
+++ b/library/cpp/actors/core/executor_pool_base.h
@@ -3,6 +3,7 @@
 #include "executor_pool.h"
 #include "executor_thread.h"
 #include "scheduler_queue.h"
+#include "perfect_activation_queue.h"
 #include <library/cpp/actors/util/affinity.h>
 #include <library/cpp/actors/util/unordered_cache.h>
 #include <library/cpp/actors/util/threadparkpad.h>
@@ -45,8 +46,7 @@ namespace NActors {
         const i16 PoolThreads;
         TIntrusivePtr<TAffinity> ThreadsAffinity;
         TAtomic Semaphore = 0;
-        TUnorderedCache<ui32, 512, 4> Activations;
-        TAtomic ActivationsRevolvingCounter = 0;
+        TPerfectActivationQueue Activations;
         volatile bool StopFlag = false;
     public:
         TExecutorPoolBase(ui32 poolId, ui32 threads, TAffinity* affinity);
diff --git a/library/cpp/actors/core/executor_pool_basic.cpp b/library/cpp/actors/core/executor_pool_basic.cpp
index b27f98487f..a607435a1a 100644
--- a/library/cpp/actors/core/executor_pool_basic.cpp
+++ b/library/cpp/actors/core/executor_pool_basic.cpp
@@ -230,7 +230,7 @@ namespace NActors {
         } while (true);
     }
 
-    ui32 TBasicExecutorPool::GetReadyActivation(TWorkerContext& wctx, ui64 revolvingCounter) {
+    ui32 TBasicExecutorPool::GetReadyActivation(TWorkerContext& wctx, ui64 /*revolvingCounter*/) {
         TWorkerId workerId = wctx.WorkerId;
         Y_VERIFY_DEBUG(workerId < PoolThreads);
 
@@ -264,7 +264,7 @@ namespace NActors {
                     }
                 }
             } else {
-                if (const ui32 activation = Activations.Pop(++revolvingCounter)) {
+                if (const ui32 activation = Activations.Pop()) {
                     if (workerId >= 0) {
                         AtomicSet(Threads[workerId].WaitingFlag, TThreadCtx::WS_RUNNING);
                     }
@@ -320,8 +320,8 @@ namespace NActors {
         }
     }
 
-    void TBasicExecutorPool::ScheduleActivationEx(ui32 activation, ui64 revolvingCounter) {
-        Activations.Push(activation, revolvingCounter);
+    void TBasicExecutorPool::ScheduleActivationEx(ui32 activation, ui64 /*revolvingCounter*/) {
+        Activations.Push(activation);
         bool needToWakeUp = false;
 
         TAtomic x = AtomicGet(Semaphore);
diff --git a/library/cpp/actors/core/executor_pool_io.cpp b/library/cpp/actors/core/executor_pool_io.cpp
index 9e1d06c9e2..52cc25bed2 100644
--- a/library/cpp/actors/core/executor_pool_io.cpp
+++ b/library/cpp/actors/core/executor_pool_io.cpp
@@ -22,11 +22,11 @@ namespace NActors {
 
     TIOExecutorPool::~TIOExecutorPool() {
         Threads.Destroy();
-        while (ThreadQueue.Pop(0))
+        while (ThreadQueue.Pop())
             ;
     }
 
-    ui32 TIOExecutorPool::GetReadyActivation(TWorkerContext& wctx, ui64 revolvingCounter) {
+    ui32 TIOExecutorPool::GetReadyActivation(TWorkerContext& wctx, ui64 /*revolvingCounter*/) {
         i16 workerId = wctx.WorkerId;
         Y_VERIFY_DEBUG(workerId < PoolThreads);
 
@@ -38,7 +38,7 @@ namespace NActors {
         const TAtomic x = AtomicDecrement(Semaphore);
         if (x < 0) {
             TThreadCtx& threadCtx = Threads[workerId];
-            ThreadQueue.Push(workerId + 1, revolvingCounter);
+            ThreadQueue.Push(workerId + 1);
             hpnow = GetCycleCountFast();
             elapsed += hpnow - hpstart;
             if (threadCtx.Pad.Park())
@@ -48,7 +48,7 @@ namespace NActors {
         }
 
         while (!RelaxedLoad(&StopFlag)) {
-            if (const ui32 activation = Activations.Pop(++revolvingCounter)) {
+            if (const ui32 activation = Activations.Pop()) {
                 hpnow = GetCycleCountFast();
                 elapsed += hpnow - hpstart;
                 wctx.AddElapsedCycles(ActorSystemIndex, elapsed);
@@ -86,12 +86,12 @@ namespace NActors {
         ScheduleQueue->Writer.Push(deadline.MicroSeconds(), ev.Release(), cookie);
     }
 
-    void TIOExecutorPool::ScheduleActivationEx(ui32 activation, ui64 revolvingWriteCounter) {
-        Activations.Push(activation, revolvingWriteCounter);
+    void TIOExecutorPool::ScheduleActivationEx(ui32 activation, ui64 /*revolvingWriteCounter*/) {
+        Activations.Push(activation);
         const TAtomic x = AtomicIncrement(Semaphore);
         if (x <= 0) {
-            for (;; ++revolvingWriteCounter) {
-                if (const ui32 x = ThreadQueue.Pop(revolvingWriteCounter)) {
+            for (;;) {
+                if (const ui32 x = ThreadQueue.Pop()) {
                     const ui32 threadIdx = x - 1;
                     Threads[threadIdx].Pad.Unpark();
                     return;
diff --git a/library/cpp/actors/core/executor_pool_io.h b/library/cpp/actors/core/executor_pool_io.h
index f3f1a11819..dc4e872df3 100644
--- a/library/cpp/actors/core/executor_pool_io.h
+++ b/library/cpp/actors/core/executor_pool_io.h
@@ -18,7 +18,7 @@ namespace NActors {
         };
 
         TArrayHolder<TThreadCtx> Threads;
-        TUnorderedCache<ui32, 512, 4> ThreadQueue;
+        TPerfectActivationQueue ThreadQueue;
 
         THolder<NSchedulerQueue::TQueueType> ScheduleQueue;
         TTicketLock ScheduleLock;
diff --git a/library/cpp/actors/core/executor_pool_united.cpp b/library/cpp/actors/core/executor_pool_united.cpp
index 2e689dec59..cdd37a4fbd 100644
--- a/library/cpp/actors/core/executor_pool_united.cpp
+++ b/library/cpp/actors/core/executor_pool_united.cpp
@@ -33,7 +33,7 @@ namespace NActors {
         TAtomic Waiters = 0; // Number of idle cpus, waiting for activations in this pool
         char Padding[64 - sizeof(TAtomic)];
 
-        TUnorderedCache<ui32, 512, 4> Activations; // MPMC-queue for mailbox activations
+        TPerfectActivationQueue Activations; // MPMC-queue for mailbox activations
         TAtomic Active = 0; // Number of mailboxes ready for execution or currently executing
         TAtomic Tokens = 0; // Pending tokens (token is required for worker to start execution, guarantees concurrency limit and activation availability)
         volatile bool StopFlag = false;
@@ -51,7 +51,7 @@ namespace NActors {
         TStackVec<TCpu*, 15> WakeOrderCpus;
 
         ~TPool() {
-            while (Activations.Pop(0)) {}
+            while (Activations.Pop()) {}
         }
 
         void Stop() {
@@ -63,8 +63,8 @@ namespace NActors {
         }
 
         // Add activation of newly scheduled mailbox. Returns generated token (unless concurrency is exceeded)
-        bool PushActivation(ui32 activation, ui64 revolvingCounter) {
-            Activations.Push(activation, revolvingCounter);
+        bool PushActivation(ui32 activation, ui64 /*revolvingCounter*/) {
+            Activations.Push(activation);
             TAtomicBase active = AtomicIncrement(Active);
             if (active <= Concurrency) { // token generated
                 AtomicIncrement(Tokens);
@@ -103,9 +103,9 @@ namespace NActors {
         }
 
         // Get activation. Requires acquired token.
-        void BeginExecution(ui32& activation, ui64 revolvingCounter) {
+        void BeginExecution(ui32& activation, ui64 /*revolvingCounter*/) {
             while (!RelaxedLoad(&StopFlag)) {
-                if (activation = Activations.Pop(++revolvingCounter)) {
+                if (activation = Activations.Pop()) {
                     return;
                 }
                 SpinLockPause();
diff --git a/library/cpp/actors/core/mailbox.cpp b/library/cpp/actors/core/mailbox.cpp
index b28fdc0771..b0d9a9802d 100644
--- a/library/cpp/actors/core/mailbox.cpp
+++ b/library/cpp/actors/core/mailbox.cpp
@@ -93,15 +93,15 @@ namespace NActors {
             }
         }
 
-        while (MailboxCacheSimple.Pop(0))
+        while (MailboxCacheSimple.Pop())
             ;
-        while (MailboxCacheRevolving.Pop(0))
+        while (MailboxCacheRevolving.Pop())
             ;
-        while (MailboxCacheHTSwap.Pop(0))
+        while (MailboxCacheHTSwap.Pop())
             ;
-        while (MailboxCacheReadAsFilled.Pop(0))
+        while (MailboxCacheReadAsFilled.Pop())
             ;
-        while (MailboxCacheTinyReadAsFilled.Pop(0))
+        while (MailboxCacheTinyReadAsFilled.Pop())
             ;
     }
 
@@ -276,11 +276,11 @@ namespace NActors {
         return x;
     }
 
-    ui32 TMailboxTable::TryAllocateMailbox(TMailboxType::EType type, ui64 revolvingCounter) {
+    ui32 TMailboxTable::TryAllocateMailbox(TMailboxType::EType type, ui64 /*revolvingCounter*/) {
         switch (type) {
             case TMailboxType::Simple:
                 do {
-                    if (ui32 ret = MailboxCacheSimple.Pop(revolvingCounter)) {
+                    if (ui32 ret = MailboxCacheSimple.Pop()) {
                         AtomicDecrement(CachedSimpleMailboxes);
                         return ret;
                     }
@@ -288,7 +288,7 @@ namespace NActors {
                 return 0;
             case TMailboxType::Revolving:
                 do {
-                    if (ui32 ret = MailboxCacheRevolving.Pop(revolvingCounter)) {
+                    if (ui32 ret = MailboxCacheRevolving.Pop()) {
                         AtomicDecrement(CachedRevolvingMailboxes);
                         return ret;
                     }
@@ -296,7 +296,7 @@ namespace NActors {
                 return 0;
             case TMailboxType::HTSwap:
                 do {
-                    if (ui32 ret = MailboxCacheHTSwap.Pop(revolvingCounter)) {
+                    if (ui32 ret = MailboxCacheHTSwap.Pop()) {
                         AtomicDecrement(CachedHTSwapMailboxes);
                         return ret;
                     }
@@ -304,7 +304,7 @@ namespace NActors {
                 return 0;
             case TMailboxType::ReadAsFilled:
                 do {
-                    if (ui32 ret = MailboxCacheReadAsFilled.Pop(revolvingCounter)) {
+                    if (ui32 ret = MailboxCacheReadAsFilled.Pop()) {
                         AtomicDecrement(CachedReadAsFilledMailboxes);
                         return ret;
                     }
@@ -312,7 +312,7 @@ namespace NActors {
                 return 0;
             case TMailboxType::TinyReadAsFilled:
                 do {
-                    if (ui32 ret = MailboxCacheTinyReadAsFilled.Pop(revolvingCounter)) {
+                    if (ui32 ret = MailboxCacheTinyReadAsFilled.Pop()) {
                         AtomicDecrement(CachedTinyReadAsFilledMailboxes);
                         return ret;
                     }
@@ -329,27 +329,27 @@ namespace NActors {
     template
     bool TMailboxTable::GenericSendTo<&IExecutorPool::SpecificScheduleActivation>(TAutoPtr<IEventHandle>& ev, IExecutorPool* executorPool);
 
-    void TMailboxTable::ReclaimMailbox(TMailboxType::EType type, ui32 hint, ui64 revolvingCounter) {
+    void TMailboxTable::ReclaimMailbox(TMailboxType::EType type, ui32 hint, ui64 /*revolvingCounter*/) {
         if (hint != 0) {
             switch (type) {
                 case TMailboxType::Simple:
-                    MailboxCacheSimple.Push(hint, revolvingCounter);
+                    MailboxCacheSimple.Push(hint);
                     AtomicIncrement(CachedSimpleMailboxes);
                     break;
                 case TMailboxType::Revolving:
-                    MailboxCacheRevolving.Push(hint, revolvingCounter);
+                    MailboxCacheRevolving.Push(hint);
                     AtomicIncrement(CachedRevolvingMailboxes);
                     break;
                 case TMailboxType::HTSwap:
-                    MailboxCacheHTSwap.Push(hint, revolvingCounter);
+                    MailboxCacheHTSwap.Push(hint);
                     AtomicIncrement(CachedHTSwapMailboxes);
                     break;
                 case TMailboxType::ReadAsFilled:
-                    MailboxCacheReadAsFilled.Push(hint, revolvingCounter);
+                    MailboxCacheReadAsFilled.Push(hint);
                     AtomicIncrement(CachedReadAsFilledMailboxes);
                     break;
                 case TMailboxType::TinyReadAsFilled:
-                    MailboxCacheTinyReadAsFilled.Push(hint, revolvingCounter);
+                    MailboxCacheTinyReadAsFilled.Push(hint);
                     AtomicIncrement(CachedTinyReadAsFilledMailboxes);
                     break;
                 default:
@@ -571,7 +571,7 @@ namespace NActors {
             ui32 bufIndex;
             for (bufIndex = 0; index != endIndex && bufIndex != bufSize; ++bufIndex, ++index)
                 buf[bufIndex] = lineIndexMask | index;
-            cache->PushBulk(buf, bufIndex, index);
+            cache->PushBulk(buf, bufIndex);
             AtomicAdd(*counter, bufIndex);
         }
 
diff --git a/library/cpp/actors/core/mailbox.h b/library/cpp/actors/core/mailbox.h
index 0f1c3abc10..27a668aa0c 100644
--- a/library/cpp/actors/core/mailbox.h
+++ b/library/cpp/actors/core/mailbox.h
@@ -5,6 +5,7 @@
 #include "executor_pool.h"
 #include "mailbox_queue_simple.h"
 #include "mailbox_queue_revolving.h"
+#include "perfect_activation_queue.h"
 #include <library/cpp/actors/util/unordered_cache.h>
 #include <library/cpp/threading/queue/mpsc_htswap.h>
 #include <library/cpp/threading/queue/mpsc_read_as_filled.h>
@@ -300,7 +301,7 @@ namespace NActors {
         TAtomic LastAllocatedLine;
         TAtomic AllocatedMailboxCount;
 
-        typedef TUnorderedCache<ui32, 512, 4> TMailboxCache;
+        using TMailboxCache = TPerfectActivationQueue;
         TMailboxCache MailboxCacheSimple;
         TAtomic CachedSimpleMailboxes;
         TMailboxCache MailboxCacheRevolving;
diff --git a/library/cpp/actors/core/perfect_activation_queue.cpp b/library/cpp/actors/core/perfect_activation_queue.cpp
new file mode 100644
index 0000000000..d1975b5a47
--- /dev/null
+++ b/library/cpp/actors/core/perfect_activation_queue.cpp
@@ -0,0 +1,95 @@
+#include "perfect_activation_queue.h"
+
+#include <util/string/builder.h>
+
+namespace NActors {
+
+    static constexpr ui32 SizeBits = 20;
+    static constexpr ui32 SizeItems = 1 << SizeBits;
+    static constexpr ui32 SizeMask = SizeItems - 1;
+
+    // index conversion: CCCCCCCCCBBBBBAAA is converted to CCCCCCCCCAAABBBBB
+    static constexpr ui32 StripeSizeBitsA = 4; // makes a cacheline of 64 bytes
+    static constexpr ui32 StripeSizeBitsB = 4;
+
+    static void *AllocateItems(size_t size, size_t alignment) {
+#if defined(_win_)
+        return _aligned_malloc(size, alignment);
+#else
+        return aligned_alloc(alignment, size);
+#endif
+    }
+
+    TPerfectActivationQueue::TPerfectActivationQueue()
+        : QueueData(static_cast<TItem*>(AllocateItems(SizeItems * sizeof(TItem), 4096)))
+    {
+        Y_VERIFY(QueueData);
+        memset(QueueData, 0, SizeItems * sizeof(TItem));
+    }
+
+    TPerfectActivationQueue::~TPerfectActivationQueue() {
+        free(QueueData);
+    }
+
+    void TPerfectActivationQueue::Push(ui32 value) {
+        Y_VERIFY(value && value != Max<ui32>());
+        for (;;) {
+            const ui64 writeIndex = WriteIndex++;
+            TItem *ptr = QueueData + ConvertIndex(writeIndex & SizeMask);
+            const TItem cell = __atomic_exchange_n(ptr, value, __ATOMIC_SEQ_CST);
+
+            if (!cell) { // cell was free
+                return;
+            } else if (cell == Max<ui32>()) { // cell was forbidden
+                __atomic_store_n(ptr, 0, __ATOMIC_SEQ_CST);
+            } else {
+                Y_FAIL();
+            }
+        }
+    }
+
+    ui32 TPerfectActivationQueue::Pop() {
+        for (;;) {
+            const ui64 readIndex = ReadIndex++;
+            TItem *ptr = QueueData + ConvertIndex(readIndex & SizeMask);
+            TItem cell = __atomic_exchange_n(ptr, 0, __ATOMIC_SEQ_CST);
+            if (cell) {
+                Y_VERIFY(cell < Max<ui32>());
+                return cell;
+            }
+
+            // value is either not yet written, or this is a free cell -- forbid this cell for now
+            for (ui32 i = 0; i < 10; ++i) {
+                _mm_pause();
+            }
+
+            cell = __atomic_exchange_n(ptr, Max<ui32>(), __ATOMIC_SEQ_CST);
+            if (cell) {
+                Y_VERIFY(cell < Max<ui32>());
+                __atomic_store_n(ptr, 0, __ATOMIC_SEQ_CST);
+            } else if (ReadIndex < WriteIndex) {
+                continue; // give it another try, it was just a race
+            }
+
+            return cell;
+        }
+    }
+
+    void TPerfectActivationQueue::PushBulk(ui32 *values, size_t count) {
+        while (count--) {
+            Push(*values++);
+        }
+    }
+
+    ui32 TPerfectActivationQueue::ConvertIndex(ui32 index) {
+        constexpr ui32 maskA = (1 << StripeSizeBitsA) - 1;
+        const ui32 a = index & maskA;
+
+        constexpr ui32 maskB = (1 << StripeSizeBitsB) - 1;
+        const ui32 b = index >> StripeSizeBitsA & maskB;
+
+        const ui32 other = index >> StripeSizeBitsA + StripeSizeBitsB;
+        return other << StripeSizeBitsA + StripeSizeBitsB | a << StripeSizeBitsB | b;
+    }
+
+}
diff --git a/library/cpp/actors/core/perfect_activation_queue.h b/library/cpp/actors/core/perfect_activation_queue.h
new file mode 100644
index 0000000000..79e08c27d6
--- /dev/null
+++ b/library/cpp/actors/core/perfect_activation_queue.h
@@ -0,0 +1,29 @@
+#pragma once
+
+#include "defs.h"
+
+namespace NActors {
+
+    class TPerfectActivationQueue {
+        using TItem = ui32;
+
+        alignas(64) std::atomic_uint64_t ReadIndex = 0;
+        alignas(64) std::atomic_uint64_t WriteIndex = 0;
+
+        TItem *QueueData;
+
+    public:
+        static constexpr ui32 Concurrency = 1;
+
+    public:
+        TPerfectActivationQueue();
+        ~TPerfectActivationQueue();
+        void Push(ui32 value);
+        ui32 Pop();
+        void PushBulk(ui32 *values, size_t count);
+
+    private:
+        static ui32 ConvertIndex(ui32 index);
+    };
+
+} // NActors
diff --git a/library/cpp/actors/core/ya.make b/library/cpp/actors/core/ya.make
index 649effd22f..0eb021d871 100644
--- a/library/cpp/actors/core/ya.make
+++ b/library/cpp/actors/core/ya.make
@@ -85,6 +85,8 @@ SRCS(
     monotonic_provider.h
     worker_context.cpp
     worker_context.h
+    perfect_activation_queue.cpp
+    perfect_activation_queue.h
     probes.cpp
     probes.h
     process_stats.cpp