[µTVM] Add platform timer and RPCTimeEvaluator to enable AutoTVM

apps/bundle_deploy/bundle.c

@@ -123,3 +123,9 @@ tvm_crt_error_t TVMPlatformMemoryAllocate(size_t num_bytes, DLContext ctx, void*
 tvm_crt_error_t TVMPlatformMemoryFree(void* ptr, DLContext ctx) {
   return g_memory_manager->Free(g_memory_manager, ptr, ctx);
 }
+
+tvm_crt_error_t TVMPlatformTimerStart() { return kTvmErrorFunctionCallNotImplemented; }
+
+tvm_crt_error_t TVMPlatformTimerStop(double* elapsed_time_seconds) {
+  return kTvmErrorFunctionCallNotImplemented;
+}

apps/bundle_deploy/bundle_static.c

@@ -124,3 +124,9 @@ tvm_crt_error_t TVMPlatformMemoryAllocate(size_t num_bytes, DLContext ctx, void*
 tvm_crt_error_t TVMPlatformMemoryFree(void* ptr, DLContext ctx) {
   return g_memory_manager->Free(g_memory_manager, ptr, ctx);
 }
+
+tvm_crt_error_t TVMPlatformTimerStart() { return kTvmErrorFunctionCallNotImplemented; }
+
+tvm_crt_error_t TVMPlatformTimerStop(double* elapsed_time_seconds) {
+  return kTvmErrorFunctionCallNotImplemented;
+}

include/tvm/runtime/c_runtime_api.h

@@ -539,6 +539,13 @@ TVM_DLL int TVMObjectRetain(TVMObjectHandle obj);
  */
 TVM_DLL int TVMObjectFree(TVMObjectHandle obj);
 
+/*!
+ * \brief Free a TVMByteArray returned from TVMFuncCall, and associated memory.
+ * \param arr The TVMByteArray instance.
+ * \return 0 on success, -1 on failure.
+ */
+TVM_DLL int TVMByteArrayFree(TVMByteArray* arr);
+
 /*!
  * \brief Allocate a data space on device.
  * \param ctx The device context to perform operation.

include/tvm/runtime/crt/error_codes.h

@@ -44,6 +44,7 @@ typedef enum {
   kTvmErrorCategoryGenerated = 6,
   kTvmErrorCategoryGraphRuntime = 7,
   kTvmErrorCategoryFunctionCall = 8,
+  kTvmErrorCategoryTimeEvaluator = 9,
 } tvm_crt_error_category_t;
 
 typedef enum {
@@ -77,6 +78,7 @@ typedef enum {
   kTvmErrorPlatformMemoryManagerInitialized = DEFINE_TVM_CRT_ERROR(kTvmErrorCategoryPlatform, 1),
   kTvmErrorPlatformShutdown = DEFINE_TVM_CRT_ERROR(kTvmErrorCategoryPlatform, 2),
   kTvmErrorPlatformNoMemory = DEFINE_TVM_CRT_ERROR(kTvmErrorCategoryPlatform, 3),
+  kTvmErrorPlatformTimerBadState = DEFINE_TVM_CRT_ERROR(kTvmErrorCategoryPlatform, 4),
 
   // Common error codes returned from generated functions.
   kTvmErrorGeneratedInvalidStorageId = DEFINE_TVM_CRT_ERROR(kTvmErrorCategoryGenerated, 0),
@@ -91,6 +93,9 @@ typedef enum {
   kTvmErrorFunctionCallWrongArgType = DEFINE_TVM_CRT_ERROR(kTvmErrorCategoryFunctionCall, 1),
   kTvmErrorFunctionCallNotImplemented = DEFINE_TVM_CRT_ERROR(kTvmErrorCategoryFunctionCall, 2),
 
+  // Time Evaluator - times functions for use with debug runtime.
+  kTvmErrorTimeEvaluatorBadHandle = DEFINE_TVM_CRT_ERROR(kTvmErrorCategoryTimeEvaluator, 0),
+
   // System errors are always negative integers; this mask indicates presence of a system error.
   // Cast tvm_crt_error_t to a signed integer to interpret the negative error code.
   kTvmErrorSystemErrorMask = (1 << (sizeof(int) * 4 - 1)),

include/tvm/runtime/crt/platform.h

@@ -78,6 +78,25 @@ tvm_crt_error_t TVMPlatformMemoryAllocate(size_t num_bytes, DLContext ctx, void*
  * \return kTvmErrorNoError if successful; a descriptive error code otherwise.
  */
 tvm_crt_error_t TVMPlatformMemoryFree(void* ptr, DLContext ctx);
+
+/*! \brief Start a device timer.
+ *
+ * The device timer used must not be running.
+ *
+ * \return kTvmErrorNoError if successful; a descriptive error code otherwise.
+ */
+tvm_crt_error_t TVMPlatformTimerStart();
+
+/*! \brief Stop the running device timer and get the elapsed time (in microseconds).
+ *
+ * The device timer used must be running.
+ *
+ * \param elapsed_time_seconds Pointer to write elapsed time into.
+ *
+ * \return kTvmErrorNoError if successful; a descriptive error code otherwise.
+ */
+tvm_crt_error_t TVMPlatformTimerStop(double* elapsed_time_seconds);
+
 #ifdef __cplusplus
 }  // extern "C"
 #endif

python/tvm/micro/session.py

@@ -23,6 +23,7 @@
 from ..error import register_error
 from .._ffi import get_global_func
 from ..contrib import graph_runtime
+from ..contrib.debugger import debug_runtime
 from ..rpc import RPCSession
 from .transport import IoTimeoutError
 from .transport import TransportLogger

src/runtime/c_runtime_api.cc

@@ -420,6 +420,15 @@ int TVMFuncFree(TVMFunctionHandle func) {
   API_END();
 }
 
+int TVMByteArrayFree(TVMByteArray* arr) {
+  if (arr == &TVMAPIRuntimeStore::Get()->ret_bytes) {
+    return 0;  // Thread-local storage does not need explicit deleting.
+  }
+
+  delete arr;
+  return 0;
+}
+
 int TVMFuncCall(TVMFunctionHandle func, TVMValue* args, int* arg_type_codes, int num_args,
                 TVMValue* ret_val, int* ret_type_code) {
   API_BEGIN();

src/runtime/crt/common/crt_runtime_api.c

@@ -110,6 +110,9 @@ static const TVMModule* registered_modules[TVM_CRT_MAX_REGISTERED_MODULES];
 /*! \brief Passed as `module_index` to EncodeFunctionHandle. */
 static const tvm_module_index_t kGlobalFuncModuleIndex = TVM_CRT_MAX_REGISTERED_MODULES;
 
+/*! \brief Special module handle for retur values from RPCTimeEvaluator. */
+static const tvm_module_index_t kTimeEvaluatorModuleIndex = 0x7fff;
+
 static int DecodeModuleHandle(TVMModuleHandle handle, tvm_module_index_t* out_module_index) {
   tvm_module_index_t module_index;
 
@@ -185,20 +188,36 @@ static int DecodeFunctionHandle(TVMFunctionHandle handle, tvm_module_index_t* mo
       (tvm_module_index_t)(((uintptr_t)handle) >> (sizeof(tvm_function_index_t) * 8));
   unvalidated_module_index &= ~0x8000;
 
-  if (unvalidated_module_index > kGlobalFuncModuleIndex) {
-    TVMAPIErrorf("invalid module handle: index=%08x", unvalidated_module_index);
-    return -1;
-  } else if (unvalidated_module_index < kGlobalFuncModuleIndex &&
-             registered_modules[unvalidated_module_index] == NULL) {
-    TVMAPIErrorf("unregistered module: index=%08x", unvalidated_module_index);
-    return -1;
+  if (unvalidated_module_index != kTimeEvaluatorModuleIndex) {
+    if (unvalidated_module_index > kGlobalFuncModuleIndex) {
+      TVMAPIErrorf("invalid module handle: index=%08x", unvalidated_module_index);
+      return -1;
+    } else if (unvalidated_module_index < kGlobalFuncModuleIndex &&
+               registered_modules[unvalidated_module_index] == NULL) {
+      TVMAPIErrorf("unregistered module: index=%08x", unvalidated_module_index);
+      return -1;
+    }
   }
 
   *function_index = ((uint32_t)((uintptr_t)handle)) & ~0x8000;
   *module_index = unvalidated_module_index;
   return 0;
 }
 
+int TVMByteArrayFree(TVMByteArray* arr) {
+  DLContext ctx = {kDLCPU, 0};
+  int to_return = TVMPlatformMemoryFree((void*)arr->data, ctx);
+  if (to_return != 0) {
+    return to_return;
+  }
+
+  return TVMPlatformMemoryFree((void*)arr, ctx);
+}
+
+tvm_crt_error_t RunTimeEvaluator(tvm_function_index_t function_index, TVMValue* args,
+                                 int* type_codes, int num_args, TVMValue* ret_val,
+                                 int* ret_type_code);
+
 int TVMFuncCall(TVMFunctionHandle func_handle, TVMValue* arg_values, int* type_codes, int num_args,
                 TVMValue* ret_val, int* ret_type_code) {
   tvm_module_index_t module_index;
@@ -211,7 +230,10 @@ int TVMFuncCall(TVMFunctionHandle func_handle, TVMValue* arg_values, int* type_c
     return -1;
   }
 
-  if (module_index == kGlobalFuncModuleIndex) {
+  if (module_index == kTimeEvaluatorModuleIndex) {
+    return RunTimeEvaluator(function_index, arg_values, type_codes, num_args, ret_val,
+                            ret_type_code);
+  } else if (module_index == kGlobalFuncModuleIndex) {
     resource_handle = NULL;
     registry = &global_func_registry.registry;
   } else {
@@ -315,6 +337,8 @@ int TVMFuncFree(TVMFunctionHandle func) {
   return 0;
 }
 
+int RPCTimeEvaluator(TVMValue* args, int* type_codes, int num_args, TVMValue* ret_val,
+                     int* ret_type_code);
 tvm_crt_error_t TVMInitializeRuntime() {
   int idx = 0;
   tvm_crt_error_t error = kTvmErrorNoError;
@@ -351,10 +375,120 @@ tvm_crt_error_t TVMInitializeRuntime() {
     error = TVMFuncRegisterGlobal("tvm.rpc.server.ModuleGetFunction", &ModuleGetFunction, 0);
   }
 
+  if (error == kTvmErrorNoError) {
+    error = TVMFuncRegisterGlobal("runtime.RPCTimeEvaluator", &RPCTimeEvaluator, 0);
+  }
+
   if (error != kTvmErrorNoError) {
     TVMPlatformMemoryFree(registry_backing_memory, ctx);
     TVMPlatformMemoryFree(func_registry_memory, ctx);
   }
 
   return error;
 }
+
+typedef struct {
+  uint16_t function_index;
+  TVMFunctionHandle func_to_time;
+  TVMContext ctx;
+  int number;
+  int repeat;
+  int min_repeat_ms;
+} time_evaluator_state_t;
+
+static time_evaluator_state_t g_time_evaluator_state;
+
+int RPCTimeEvaluator(TVMValue* args, int* type_codes, int num_args, TVMValue* ret_val,
+                     int* ret_type_code) {
+  ret_val[0].v_handle = NULL;
+  ret_type_code[0] = kTVMNullptr;
+  if (num_args < 8) {
+    TVMAPIErrorf("not enough args");
+    return kTvmErrorFunctionCallNumArguments;
+  }
+  if (type_codes[0] != kTVMModuleHandle || type_codes[1] != kTVMStr ||
+      type_codes[2] != kTVMArgInt || type_codes[3] != kTVMArgInt || type_codes[4] != kTVMArgInt ||
+      type_codes[5] != kTVMArgInt || type_codes[6] != kTVMArgInt || type_codes[7] != kTVMStr) {
+    TVMAPIErrorf("one or more invalid arg types");
+    return kTvmErrorFunctionCallWrongArgType;
+  }
+
+  TVMModuleHandle mod = (TVMModuleHandle)args[0].v_handle;
+  const char* name = args[1].v_str;
+  g_time_evaluator_state.ctx.device_type = args[2].v_int64;
+  g_time_evaluator_state.ctx.device_id = args[3].v_int64;
+  g_time_evaluator_state.number = args[4].v_int64;
+  g_time_evaluator_state.repeat = args[5].v_int64;
+  g_time_evaluator_state.min_repeat_ms = args[6].v_int64;
+
+  int ret_code =
+      TVMModGetFunction(mod, name, /* query_imports */ 0, &g_time_evaluator_state.func_to_time);
+  if (ret_code != 0) {
+    return ret_code;
+  }
+
+  g_time_evaluator_state.function_index++;
+  ret_val[0].v_handle =
+      EncodeFunctionHandle(kTimeEvaluatorModuleIndex, g_time_evaluator_state.function_index);
+  ret_type_code[0] = kTVMPackedFuncHandle;
+  return kTvmErrorNoError;
+}
+
+tvm_crt_error_t RunTimeEvaluator(tvm_function_index_t function_index, TVMValue* args,
+                                 int* type_codes, int num_args, TVMValue* ret_val,
+                                 int* ret_type_code) {
+  if (function_index != g_time_evaluator_state.function_index) {
+    return kTvmErrorTimeEvaluatorBadHandle;
+  }
+
+  // TODO(areusch): should *really* rethink needing to return doubles
+  DLContext result_byte_ctx = {kDLCPU, 0};
+  TVMByteArray* result_byte_arr;
+  tvm_crt_error_t err =
+      TVMPlatformMemoryAllocate(sizeof(TVMByteArray), result_byte_ctx, (void*)&result_byte_arr);
+  if (err != kTvmErrorNoError) {
+    return err;
+  }
+  size_t data_size = sizeof(double) * g_time_evaluator_state.repeat;
+  err = TVMPlatformMemoryAllocate(data_size, result_byte_ctx, (void*)&result_byte_arr->data);
+  if (err != kTvmErrorNoError) {
+    return err;
+  }
+  result_byte_arr->size = data_size;
+  double min_repeat_seconds = ((double)g_time_evaluator_state.min_repeat_ms) / 1000;
+  double* iter = (double*)result_byte_arr->data;
+  for (int i = 0; i < g_time_evaluator_state.repeat; i++) {
+    double repeat_res_seconds = 0.0;
+    int exec_count = 0;
+    // do-while structure ensures we run even when `min_repeat_ms` isn't set (i.e., is 0).
+    do {
+      tvm_crt_error_t ret_code = TVMPlatformTimerStart();
+      if (ret_code != kTvmErrorNoError) {
+        return ret_code;
+      }
+
+      for (int j = 0; j < g_time_evaluator_state.number; j++) {
+        ret_code = TVMFuncCall(g_time_evaluator_state.func_to_time, args, type_codes, num_args,
+                               ret_val, ret_type_code);
+        if (ret_code != 0) {
+          return ret_code;
+        }
+      }
+      exec_count += g_time_evaluator_state.number;
+
+      double curr_res_seconds;
+      ret_code = TVMPlatformTimerStop(&curr_res_seconds);
+      if (ret_code != kTvmErrorNoError) {
+        return ret_code;
+      }
+      repeat_res_seconds += curr_res_seconds;
+    } while (repeat_res_seconds < min_repeat_seconds);
+    double mean_exec_seconds = repeat_res_seconds / exec_count;
+    *iter = mean_exec_seconds;
+    iter++;
+  }
+
+  *ret_type_code = kTVMBytes;
+  ret_val->v_handle = result_byte_arr;
+  return kTvmErrorNoError;
+}

src/runtime/crt/host/crt_config.h

@@ -43,7 +43,7 @@
 #define TVM_CRT_MAX_REGISTERED_MODULES 2
 
 /*! Size of the global function registry, in bytes. */
-#define TVM_CRT_GLOBAL_FUNC_REGISTRY_SIZE_BYTES 200
+#define TVM_CRT_GLOBAL_FUNC_REGISTRY_SIZE_BYTES 256
 
 /*! Maximum packet size, in bytes, including the length header. */
 #define TVM_CRT_MAX_PACKET_SIZE_BYTES 64000

src/runtime/crt/host/main.cc

@@ -68,29 +68,30 @@ tvm_crt_error_t TVMPlatformMemoryFree(void* ptr, DLContext ctx) {
   return memory_manager->Free(memory_manager, ptr, ctx);
 }
 
-high_resolution_clock::time_point g_utvm_start_time;
+steady_clock::time_point g_utvm_start_time;
 int g_utvm_timer_running = 0;
 
-int TVMPlatformTimerStart() {
+tvm_crt_error_t TVMPlatformTimerStart() {
   if (g_utvm_timer_running) {
     std::cerr << "timer already running" << std::endl;
-    return -1;
+    return kTvmErrorPlatformTimerBadState;
   }
-  g_utvm_start_time = high_resolution_clock::now();
+  g_utvm_start_time = std::chrono::steady_clock::now();
   g_utvm_timer_running = 1;
-  return 0;
+  return kTvmErrorNoError;
 }
 
-int TVMPlatformTimerStop(double* res_us) {
+tvm_crt_error_t TVMPlatformTimerStop(double* elapsed_time_seconds) {
   if (!g_utvm_timer_running) {
     std::cerr << "timer not running" << std::endl;
-    return -1;
+    return kTvmErrorPlatformTimerBadState;
   }
-  auto utvm_stop_time = high_resolution_clock::now();
-  duration<double, std::micro> time_span(utvm_stop_time - g_utvm_start_time);
-  *res_us = time_span.count();
+  auto utvm_stop_time = std::chrono::steady_clock::now();
+  std::chrono::microseconds time_span =
+      std::chrono::duration_cast<std::chrono::microseconds>(utvm_stop_time - g_utvm_start_time);
+  *elapsed_time_seconds = static_cast<double>(time_span.count()) / 1e6;
   g_utvm_timer_running = 0;
-  return 0;
+  return kTvmErrorNoError;
 }
 }