[fiber] Don't inline context methods (+40% performance improvement!) …

…+ fix unit tests
modm-io · Sep 11, 2020 · 9b07eff · 9b07eff
1 parent 9385b49
commit 9b07eff
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Showing 11 changed files with 96 additions and 125 deletions.
diff --git a/examples/generic/fiber/main.cpp b/examples/generic/fiber/main.cpp
@@ -17,17 +17,16 @@ using namespace Board;
 using namespace std::chrono_literals;
 
 constexpr uint32_t cycles = 1000'000;
-volatile uint32_t counter = 0;
+volatile uint32_t f1counter = 0, f2counter = 0;
 
 void f1() {
-  while (++counter < cycles) {
+  while (++f1counter < cycles / 2) {
     modm::yield();
   }
 }
 
 void f2() {
-  while (++counter < cycles) {
-    asm volatile ("");
+  while (++f2counter < cycles / 2) {
     modm::yield();
   }
 }
@@ -36,8 +35,8 @@ modm::fiber::Stack<2048> stack1, stack2;
 modm::Fiber fiber1(stack1, &f1), fiber2(stack2, &f2);
 
 
-// Blue pill (M3 64MHz): Executed 1000000 in 1520841us (657530.94 yields per second)
-// Feather M0 (M0+ 48MHz): Executed 1000000 in 2190108us (456598.50 yields per second)
+// Blue pill (M3 72MHz): Executed 1000000 in 1098591us (910256.88 yields per second)
+// Feather M0 (M0+ 48MHz): Executed 1000000 in 1944692us (514220.25 yields per second)
 int main( int argc, char * argv[])
 {
   Board::initialize();

diff --git a/src/modm/processing/fiber/context.hpp b/src/modm/processing/fiber/context.hpp
@@ -25,22 +25,17 @@ struct modm_context {
 extern modm_context main_context;
 
 /* Prepares the stack to look like the "from" arg after modm_jumpcontext as run. */
-inline modm_context
+modm_context
 modm_makecontext(modm_stack_t* stack, std::size_t stack_size, void (*fn)(void), void (*end)(void));
 
 /* Switches control from the main context to the user context. */
-modm_always_inline
 void
 modm_startcontext(const modm_context &to);
 
 /* Jumps from the "from" user context to the "to" user context. */
-modm_always_inline
 void
 modm_jumpcontext(modm_context* from, const modm_context &to);
 
 /* Switches control back to the main context from the user context. */
-modm_always_inline
 void
 modm_endcontext();
-
-#include "context_impl.hpp"
diff --git a/...ssing/fiber/context_cortex_armv7_impl.hpp → ...processing/fiber/context_cortex_armv7.cpp b/...ssing/fiber/context_cortex_armv7_impl.hpp → ...processing/fiber/context_cortex_armv7.cpp
@@ -9,6 +9,7 @@
  */
 // ----------------------------------------------------------------------------
 
+#include "context.hpp"
 #include <modm/platform/device.hpp>
 #include <modm/debug/logger.hpp>
 
@@ -39,14 +40,9 @@ modm_makecontext(modm_stack_t* stack, std::size_t stack_size,
 void
 modm_startcontext(const modm_context &to)
 {
-	modm_stack_t** main_sp = &main_context.sp;
-	modm_stack_t* to_sp = to.sp;
 	asm volatile
 	(
-		"adr r3, 1f"			"\n\t" // Load address of instruction after "pop {pc}" into r3
-		"add r3, r3, #1"		"\n\t" // Stay in thumb mode
-		"push {r3}"				"\n\t" // Save instruction address to stack (to be used for PC later)
-
+		"push {lr}"		"\n\t"
 		"push {r4-r11, lr}"		"\n\t"
 
 		"mov r3, sp"			"\n\t"
@@ -57,48 +53,34 @@ modm_startcontext(const modm_context &to)
 		"orr r3, r2"			"\n\t"
 		"msr control, r3"		"\n\t"
 
-		"pop {r4-r11}"			"\n\t"
-		"pop {r3}"				"\n\t"
-		"mov lr, r3"			"\n\t"
-
+		"pop {r4-r11, lr}"			"\n\t" // LR points to the "done" function
 		"pop {pc}"				"\n\t" // Perform the jump
-		".align 2"				"\n\t"
-		"1:"					"\n\t"
 
-		/*outputs*/: [main_sp] "+r" (main_sp), [to_sp] "+r" (to_sp)
-		/*inputs*/:
-		/*clobbers*/: "r2", "r3", "memory"
+    /*outputs*/:
+    /*inputs*/: [main_sp] "r" (&main_context.sp), [to_sp] "r" (to.sp)
+    /*clobbers*/: "r2", "r3", "memory"
 	);
 }
 
 void
 modm_jumpcontext(modm_context* from, const modm_context &to)
 {
-	register modm_stack_t** from_sp asm("r0") = &from->sp;
-	register modm_stack_t* to_sp asm("r1") = to.sp;
 	asm volatile
 	(
-		"adr r3, 1f"			"\n\t" // Load address of instruction after "pop {pc}" into r3
-		"add r3, r3, #1"		"\n\t" // Stay in thumb mode
-		"push {r3}"				"\n\t" // Save instruction address to stack (to be used for PC later)
 
+		"push {lr}"		"\n\t" // Later used as PC
 		"push {r4-r11, lr}"		"\n\t"
 
 		"mov r3, sp"			"\n\t"
 		"str r3, [%[from_sp]]"	"\n\t" // Store the SP in "from"
 		"mov sp, %[to_sp]"		"\n\t" // Restore SP from "to"
 
-		"pop {r4-r11}"			"\n\t"
-		"pop {r3}"				"\n\t"
-		"mov lr, r3"			"\n\t"
-
-		"pop {pc}"				"\n\t" // Perform the jump
-		".align 2"				"\n\t"
-		"1:"					"\n\t"
+		"pop {r4-r11, lr}"			"\n\t"
+		"pop {pc}"			"\n\t" // Perform the jump
 
-		/*outputs*/: [from_sp] "+r" (from_sp), [to_sp] "+r" (to_sp)
-		/*inputs*/:
-		/*clobbers*/: "r2", "r3", "r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12", "memory"
+    /*outputs*/:
+    /*inputs*/: [from_sp] "r" (&from->sp), [to_sp] "r" (to.sp)
+    /*clobbers*/: "r3", "memory"
 	);
 }
 
@@ -112,11 +94,8 @@ modm_endcontext()
 		"bic r1, r1, r2"		"\n\t"
 		"msr control, r1"		"\n\t"
 
-		"pop {r4-r11}"			"\n\t"
-		"pop {r3}"				"\n\t"
-		"mov lr, r3"			"\n\t"
-
-		"pop {pc}"				"\n\t" // Perform the jump
+		"pop {r4-r11, lr}"			"\n\t"
+		"pop {pc}"			"\n\t" // Perform the jump
 
 		/*outputs*/:
 		/*inputs*/:

diff --git a/...ocessing/fiber/context_cortex_m0_impl.hpp → ...dm/processing/fiber/context_cortex_m0.cpp b/...ocessing/fiber/context_cortex_m0_impl.hpp → ...dm/processing/fiber/context_cortex_m0.cpp
@@ -9,6 +9,8 @@
  */
 // ----------------------------------------------------------------------------
 
+
+#include "context.hpp"
 #include <modm/platform/device.hpp>
 #include <modm/debug/logger.hpp>
 
@@ -37,13 +39,8 @@ modm_makecontext(modm_stack_t* stack, std::size_t stack_size,
 
 void
 modm_startcontext(const modm_context &to) {
-  modm_stack_t** main_sp = &main_context.sp;
-  modm_stack_t* to_sp = to.sp;
   asm volatile(
-    "adr r3, 1f\n\t" // Load address of instruction after "pop {pc}" into r3
-    "add r3, r3, #1\n\t" // Stay in thumb mode
-    "push {r3}\n\t" // Save instruction address to stack (to be used for PC later)
-
+    "push {lr}\n\t"
     "push {r4-r7, lr}\n\t"
     "mov r4, r8\n\t"
     "mov r5, r9\n\t"
@@ -67,24 +64,17 @@ modm_startcontext(const modm_context &to) {
     "pop {r4-r7}\n\t"
     "pop {r3}\n\t"
     "mov lr, r3\n\t"
-
     "pop {pc}\n\t" // Perform the jump
-    ".align 2\n\t"
-    "1:\n\t"
-    /*outputs*/: [main_sp] "+r" (main_sp), [to_sp] "+r" (to_sp)
-    /*inputs*/:
-    /*clobbers*/: "r2", "r3", "r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12", "memory");
+
+    /*outputs*/:
+    /*inputs*/: [main_sp] "r" (&main_context.sp), [to_sp] "r" (to.sp)
+    /*clobbers*/: "r2", "r3", "memory");
 }
 
 void
 modm_jumpcontext(modm_context* from, const modm_context &to) {
-  register modm_stack_t** from_sp asm("r0") = &from->sp;
-  register modm_stack_t* to_sp asm("r1") = to.sp;
   asm volatile(
-    "adr r3, 1f\n\t" // Load address of instruction after "pop {pc}" into r3
-    "add r3, r3, #1\n\t" // Stay in thumb mode
-    "push {r3}\n\t" // Save instruction address to stack (to be used for PC later)
-
+    "push {lr}\n\t"
     "push {r4-r7, lr}\n\t"
     "mov r4, r8\n\t"
     "mov r5, r9\n\t"
@@ -104,13 +94,11 @@ modm_jumpcontext(modm_context* from, const modm_context &to) {
     "pop {r4-r7}\n\t"
     "pop {r3}\n\t"
     "mov lr, r3\n\t"
-
     "pop {pc}\n\t" // Perform the jump
-    ".align 2\n\t"
-    "1:\n\t"
-    /*outputs*/: [from_sp] "+r" (from_sp), [to_sp] "+r" (to_sp)
-    /*inputs*/:
-    /*clobbers*/: "r2", "r3", "r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12", "memory");
+
+    /*outputs*/:
+    /*inputs*/: [from_sp] "r" (&from->sp), [to_sp] "r" (to.sp)
+    /*clobbers*/: "r3", "memory");
 }
 
 void
@@ -129,9 +117,9 @@ modm_endcontext() {
     "pop {r4-r7}\n\t"
     "pop {r3}\n\t"
     "mov lr, r3\n\t"
-
     "pop {pc}\n\t" // Perform the jump
+
     /*outputs*/:
     /*inputs*/:
-    /*clobbers*/: "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12", "memory");
+    /*clobbers*/: "memory");
   }
diff --git a/.../processing/fiber/context_x86_64_impl.hpp → src/modm/processing/fiber/context_x86_64.cpp b/.../processing/fiber/context_x86_64_impl.hpp → src/modm/processing/fiber/context_x86_64.cpp
@@ -9,6 +9,7 @@
  */
 // ----------------------------------------------------------------------------
 
+#include "context.hpp"
 
 modm_context
 modm_makecontext(modm_stack_t* stack, std::size_t stack_size,
@@ -20,7 +21,6 @@ modm_makecontext(modm_stack_t* stack, std::size_t stack_size,
   return {sp, stack_size};
 }
 
-modm_always_inline
 void
 modm_startcontext(const modm_context &to) {
   modm_jumpcontext(&main_context, to);
@@ -60,7 +60,6 @@ modm_jumpcontext(modm_context* from, const modm_context &to) {
     /*clobbers*/: "rax", "memory");
 }
 
-modm_always_inline
 void
 modm_endcontext() {
   modm_context dummy;

diff --git a/src/modm/processing/fiber/fiber.cpp b/src/modm/processing/fiber/fiber.cpp
@@ -19,6 +19,12 @@
 
 namespace modm {
 
+namespace fiber {
+
+Scheduler scheduler;
+
+} // namespace fiber
+
 void Fiber::dumpStack()  {
 #ifdef MODM_BOARD_HAS_LOGGER
   MODM_LOG_DEBUG
@@ -34,7 +40,7 @@ void Fiber::dumpStack()  {
 void Waitable::wait() {
   using ::modm::fiber::scheduler;
   pushWaiter(scheduler.removeCurrent());
-  yield();
+  scheduler.currentFiber()->jump(*scheduler.lastFiber()->next());
 }
 
 void Waitable::signal() {

diff --git a/src/modm/processing/fiber/fiber.hpp b/src/modm/processing/fiber/fiber.hpp
@@ -82,8 +82,7 @@ class Fiber
 
 protected:
 	inline void
-	jump(Fiber& other)
-	{ modm_jumpcontext(&ctx_, other.ctx_); }
+	jump(Fiber& other);
 
 private:
   Fiber() = default;
@@ -314,7 +313,7 @@ class Scheduler
   Fiber* current_fiber_ = nullptr;
 };
 
-static Scheduler scheduler;
+extern Scheduler scheduler;
 
 } // namespace fiber
 

diff --git a/src/modm/processing/fiber/fiber_impl.hpp b/src/modm/processing/fiber/fiber_impl.hpp
@@ -26,15 +26,9 @@ void yield()
 {
   using fiber::scheduler;
   Fiber* current = scheduler.currentFiber();
-  Fiber* next;
-  if (scheduler.last_fiber_->next() != current) {
-    next = scheduler.lastFiber()->next();
-  } else {
-    next = current->next();
-    scheduler.last_fiber_ = current;
-  }
-  if (current == next) return;
-  scheduler.current_fiber_ = next;
+  Fiber* next = current->next();
+  if (next == current) return;
+  scheduler.last_fiber_ = current;
   current->jump(*next);
 }
 
@@ -46,16 +40,23 @@ Fiber::Fiber(fiber::Stack<size>& stack, void(*f)())
 	fiber::scheduler.registerFiber(this);
 }
 
+void
+Fiber::jump(Fiber& other)
+{
+  fiber::scheduler.current_fiber_ = &other;
+  modm_jumpcontext(&ctx_, other.ctx_);
+}
+
 void Fiber::done() {
   using fiber::scheduler;
+  Fiber* current = scheduler.currentFiber();
+  Fiber* next = current->next();
   scheduler.removeCurrent();
   if (scheduler.empty()) {
-// #ifdef MODM_BOARD_HAS_LOGGER
-//   MODM_LOG_DEBUG << "Fiber::done: Returning control to main thread." << modm::endl;
-// #endif
+    scheduler.current_fiber_ = nullptr;
     modm_endcontext();
   }
-  yield();
+  current->jump(*next);
 }
 
 template<class Data_t>
@@ -80,7 +81,7 @@ Data_t Channel<Data_t>::recv() {
     wait();
   }
   // Now we are in full or ready state.
-  modm_assert(!empty(), "Channel::poll.empty", "Channel should not be empty");
+  modm_assert(!empty(), "Channel::recv.empty", "Channel should not be empty");
   Data_t result;
   if (--size_) {
     result = std::move(buffer_[size_]);
@@ -97,27 +98,27 @@ void Scheduler::registerFiber(Fiber* fiber) {
   if (last_fiber_ == nullptr) {
     fiber->next(fiber);
     last_fiber_ = fiber;
-    current_fiber_ = fiber;
     return;
   }
   runLast(fiber);
 }
 
 void Scheduler::start() {
   if (last_fiber_ == nullptr) return;
-// #ifdef MODM_BOARD_HAS_LOGGER
-//   MODM_LOG_DEBUG << "Starting scheduler with fibers [ current = " << currentFiber()
-//   << ", last = " << lastFiber()
-//   << " ] " << modm::endl;
-//   for (Fiber* fiber = currentFiber();; fiber = fiber->next()) {
-//     MODM_LOG_DEBUG
-//       << "(" << modm::hex << fiber
-//       << ") { sp: " << fiber->ctx_.sp
-//       << ", next: " << fiber->next() << " }"
-//       << modm::endl;
-//     if (fiber->next() == currentFiber()) break;
-//   }
-// #endif
+  current_fiber_ = last_fiber_->next();
+#ifdef MODM_BOARD_HAS_LOGGER
+  MODM_LOG_DEBUG << "Starting scheduler with fibers [ current = " << currentFiber()
+  << ", last = " << lastFiber()
+  << " ] " << modm::endl;
+  for (Fiber* fiber = currentFiber();; fiber = fiber->next()) {
+    MODM_LOG_DEBUG
+      << "(" << modm::hex << fiber
+      << ") { sp: " << fiber->ctx_.sp
+      << ", next: " << fiber->next() << " }"
+      << modm::endl;
+    if (fiber->next() == currentFiber()) break;
+  }
+#endif
   modm_startcontext(currentFiber()->ctx_);
 }