diff --git a/tile/fiber/detail/fiber.cc b/tile/fiber/detail/fiber.cc
index accae08..25a5ae3 100644
--- a/tile/fiber/detail/fiber.cc
+++ b/tile/fiber/detail/fiber.cc
@@ -12,59 +12,42 @@ namespace tile {
 namespace fiber {
 namespace detail {
 
-#define SET_PREV_FCTX(new_fctx)                                                \
-  do {                                                                         \
-    if (PrevFiber()) {                                                         \
-      PrevFiber()->ctx_->fctx = (new_fctx);                                    \
-    }                                                                          \
-  } while (0)
-
 static thread_local Fiber *tls_current_fiber = nullptr;
 static thread_local Fiber *tls_master_fiber = nullptr;
-static thread_local Fiber *tls_prev_fiber = nullptr;
 
 constexpr std::size_t kStackSize = 128 * 1024; // 128k
 constexpr std::size_t kAlignSize = 16;
 
 struct alignas(hardware_destructive_interference_size) Fiber::FiberContext {
-  fcontext_t fctx;
   std::aligned_storage<kStackSize, kAlignSize>::type stack;
   std::function<void()> proc;
 };
 
-// static void SetPrevFiber(Fiber *fiber) noexcept { tls_prev_fiber = fiber; }
-static Fiber *PrevFiber() noexcept { return tls_prev_fiber; }
-
 void FiberEntry(fcontext_transfer_t t) {
-  SET_PREV_FCTX(t.fctx);
 
   std::function<void()> *fn = static_cast<std::function<void()> *>(t.data);
   TILE_CHECK_NE(t.data, nullptr);
   TILE_CHECK_NE(t.fctx, nullptr);
 
-  Fiber *self;
-
   try {
     // From Resume()
     t = jump_fcontext(t.fctx, nullptr);
-    self = Fiber::Current();
-    SET_PREV_FCTX(t.fctx);
+    auto self = reinterpret_cast<Fiber *>(t.data);
+    self->caller_->ctx_ = t.fctx;
 
     (*fn)();
   } catch (const std::exception &e) {
     TILE_LOG_ERROR("Exception caught in fiber: {}", e.what());
   }
-  TILE_CHECK_NE(t.fctx, nullptr);
 
-  if (self == Fiber::MasterFiber()) {
-    // TILE_LOG_INFO("FiberEntry End. Resume to {}", t.fctx);
-    jump_fcontext(t.fctx, nullptr);
+  if (GetMasterFiber() != GetCurrentFiber()) {
+    GetMasterFiber()->Resume();
   } else {
-    // TILE_LOG_INFO("FiberEntry End. Resume to {}",
-    //               Fiber::MasterFiber()->ctx_->fctx);
-    Fiber::MasterFiber()->Resume();
+    // master fiber end
+    jump_fcontext(t.fctx, GetMasterFiber());
   }
 }
+fcontext_transfer_t FiberOnTop(fcontext_transfer_t t) {}
 
 fcontext_t CreateFiber(void *stack, std::size_t stack_size,
                        std::function<void()> *fn) {
@@ -75,14 +58,11 @@ fcontext_t CreateFiber(void *stack, std::size_t stack_size,
   return jump_fcontext(fctx, fn).fctx;
 }
 
-Fiber *Fiber::Current() noexcept { return tls_current_fiber; }
-void Fiber::SetCurrent(Fiber *fiber) noexcept {
-  tls_prev_fiber = tls_current_fiber;
-  tls_current_fiber = fiber;
-}
+Fiber *GetCurrentFiber() noexcept { return tls_current_fiber; }
+void SetUpCurrentFiber(Fiber *fiber) noexcept { tls_current_fiber = fiber; }
 
-Fiber *Fiber::MasterFiber() noexcept { return tls_master_fiber; }
-void Fiber::SetMasterFiber(Fiber *fiber) noexcept { tls_master_fiber = fiber; }
+Fiber *GetMasterFiber() noexcept { return tls_master_fiber; }
+void SetUpMasterFiber(Fiber *fiber) noexcept { tls_master_fiber = fiber; }
 
 std::unique_ptr<Fiber> Fiber::Create(std::function<void()> proc) noexcept {
   return std::unique_ptr<Fiber>(new Fiber(std::move(proc)));
@@ -90,45 +70,34 @@ std::unique_ptr<Fiber> Fiber::Create(std::function<void()> proc) noexcept {
 }
 
 Fiber::Fiber(std::function<void()> proc)
-    : ctx_(object_pool::Get<FiberContext>().Leak()) {
+    : data_(object_pool::Get<FiberContext>().Leak()) {
   TILE_CHECK(proc);
 
-  ctx_->proc = std::move(proc);
-  ctx_->fctx = CreateFiber(&ctx_->stack, kStackSize, &ctx_->proc);
+  data_->proc = std::move(proc);
+  ctx_ = CreateFiber(&data_->stack, kStackSize, &data_->proc);
 }
 
 Fiber::~Fiber() {
-  if (ctx_) {
-    object_pool::Put<FiberContext>(ctx_.release());
+  if (data_) {
+    object_pool::Put<FiberContext>(data_.release());
   }
 }
 
 void Fiber::Resume() {
-  TILE_CHECK(state_ != FiberState::Suspended);
-  TILE_CHECK(state_ != FiberState::Terminated);
-  TILE_CHECK_NE(ctx_->fctx, nullptr);
+  auto caller = GetCurrentFiber();
+  TILE_CHECK_NE(caller, this, "Calling `ResumeOn()`, on self is undefined.");
 
-  auto caller = Current();
-  TILE_CHECK_NE(caller, this, "Can't `Resume()` self");
-  if (caller != Fiber::MasterFiber() && this != Fiber::MasterFiber()) {
-    caller->state_ = FiberState::Suspended;
-  } else if (caller) {
-    caller->state_ = FiberState::Ready;
-  }
+  auto t = jump_fcontext(ctx_, this);
+  caller = reinterpret_cast<Fiber *>(t.data);
+  caller->ctx_ = t.fctx;
 
-  // TILE_LOG_INFO("Resume from {} to {}", fmt::ptr(caller), fmt::ptr(this));
-  SetCurrent(this);
-  this->state_ = FiberState::Running;
-  auto caller_fctx =
-      jump_fcontext(internal::Exchange(ctx_->fctx, nullptr), nullptr).fctx;
-  if (Current() == this) {
-    // fiber terminated
-    state_ = FiberState::Terminated;
-  } else {
-    state_ = FiberState::Ready;
-  }
+  SetUpCurrentFiber(caller);
+}
 
-  // SET_PREV_FCTX(caller_fctx);
+void Fiber::ResumeOn(std::function<void()> &&cb) noexcept {
+  auto caller = GetCurrentFiber();
+  TILE_CHECK_NE(caller, this, "Calling `ResumeOn()`, on self is undefined.");
+  ontop_fcontext(ctx_, this, FiberOnTop);
 }
 
 } // namespace detail
diff --git a/tile/fiber/detail/fiber.h b/tile/fiber/detail/fiber.h
index 3ea9870..5f1b05b 100644
--- a/tile/fiber/detail/fiber.h
+++ b/tile/fiber/detail/fiber.h
@@ -18,21 +18,16 @@ namespace detail {
 
 class Scheduler;
 
+enum class FiberState {
+  Runnable,
+  Running,
+  Suspended,
+  Waiting,
+  Terminated,
+};
+
 class alignas(hardware_destructive_interference_size) Fiber {
 public:
-  enum class FiberState {
-    Runnable,
-    Running,
-    Suspended,
-    Waiting,
-    Terminated,
-  };
-
-  static Fiber *Current() noexcept;
-  static void SetCurrent(Fiber *fiber) noexcept;
-  static Fiber *MasterFiber() noexcept;
-  static void SetMasterFiber(Fiber *fiber) noexcept;
-
   static std::unique_ptr<Fiber>
   Create(std::function<void()> proc = nullptr) noexcept;
 
@@ -43,24 +38,34 @@ public:
   Fiber(Fiber &&other) noexcept = default;
   Fiber &operator=(Fiber &&other) noexcept = default;
 
-  // for `Scheduler`
   void Resume();
+  void ResumeOn(std::function<void()> &&cb) noexcept;
   void Yield();
 
 private:
   TILE_FRIEND_TEST(Fiber, Base);
   friend Scheduler;
-
-  friend void FiberEntry(struct fcontext_transfer);
   struct FiberContext;
   friend class ::tile::PoolTraits<FiberContext>;
 
+  friend void FiberEntry(struct fcontext_transfer);
+  friend struct fcontext_transfer FiberOnTop(struct fcontext_transfer);
+
   Fiber(std::function<void()> proc = nullptr);
 
 private:
-  std::unique_ptr<FiberContext> ctx_;
+  std::unique_ptr<FiberContext> data_;
   FiberState state_{FiberState::Runnable};
+  void *ctx_{nullptr};
+  Fiber *caller_{nullptr};
 };
+Fiber *GetCurrentFiber() noexcept;
+Fiber *GetMasterFiber() noexcept;
+
+void SetUpCurrentFiber(Fiber *fiber) noexcept;
+void SetUpMasterFiber(Fiber *fiber) noexcept;
+
+inline bool IsFiberContext() noexcept { return GetCurrentFiber() != nullptr; }
 
 } // namespace detail
 } // namespace fiber
diff --git a/tile/fiber/detail/fiber_test.cc b/tile/fiber/detail/fiber_test.cc
index 63ffd3e..2cf3c2d 100644
--- a/tile/fiber/detail/fiber_test.cc
+++ b/tile/fiber/detail/fiber_test.cc
@@ -18,14 +18,14 @@ TEST(Fiber, Base) {
   master_fiber = Fiber::Create([&] {
     TILE_LOG_INFO("master fiber");
     // ASSERT_EQ(cnt, 0);
-    ASSERT_EQ(Fiber::MasterFiber(), master_fiber.get());
-    ASSERT_EQ(Fiber::Current(), master_fiber.get());
+    ASSERT_EQ(GetMasterFiber(), master_fiber.get());
+    ASSERT_EQ(GetCurrentFiber(), master_fiber.get());
 
     ASSERT_EQ(cnt, 0);
     while (cnt < kMaxCnt) {
       std::unique_ptr<Fiber> worker_fiber = Fiber::Create([&] {
         while (cnt < kMaxCnt) {
-          ASSERT_EQ(Fiber::Current(), worker_fiber.get());
+          ASSERT_EQ(GetCurrentFiber(), worker_fiber.get());
           ++cnt;
           master_fiber->Resume();
         }
@@ -35,15 +35,15 @@ TEST(Fiber, Base) {
         int old = cnt;
         worker_fiber->Resume();
         ASSERT_EQ(old + 1, cnt);
-        ASSERT_EQ(Fiber::Current(), master_fiber.get());
+        ASSERT_EQ(GetCurrentFiber(), master_fiber.get());
       }
     }
 
     ASSERT_EQ(cnt, kMaxCnt);
   });
 
-  Fiber::SetMasterFiber(master_fiber.get());
-  Fiber::SetCurrent(nullptr);
+  SetUpMasterFiber(master_fiber.get());
+  SetUpCurrentFiber(nullptr);
   master_fiber->Resume();
 }
 
diff --git a/tile/fiber/detail/scheduler.h b/tile/fiber/detail/scheduler.h
index b96ab74..02c5aff 100644
--- a/tile/fiber/detail/scheduler.h
+++ b/tile/fiber/detail/scheduler.h
@@ -3,11 +3,17 @@
 
 #pragma once
 
+#include "tile/fiber/detail/fiber.h"
+
 namespace tile {
 namespace fiber {
 namespace detail {
 
-class Scheduler {};
+class Scheduler {
+public:
+  void SwitchTo(Fiber *self, Fiber *to);
+  void Yield(Fiber *self);
+};
 } // namespace detail
 } // namespace fiber
 } // namespace tile