/* global_state.cpp -*-C++-*- * ************************************************************************* * * Copyright (C) 2009-2016, Intel Corporation * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * Neither the name of Intel Corporation nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. 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Changes only submitted to the * GNU compiler collection or posted to the git repository at * https://bitbucket.org/intelcilkruntime/intel-cilk-runtime.git are * not tracked. * * We welcome your contributions to this open source project. Thank you * for your assistance in helping us improve Cilk Plus. **************************************************************************/ #include "global_state.h" #include "os.h" #include "bug.h" #include "metacall_impl.h" #include "stats.h" #include "cilk/cilk_api.h" #include "cilk_malloc.h" #include "record-replay.h" #include // For max() #include #include #include #include #ifdef _WIN32 # include #endif // TBD: There is a race when multiple threads try to initialize the // user_settable_values?? // // Set to true if the user settable values portion of the global state // singleton is initialized, even if the rest of the singleton is not // initialized. int cilkg_user_settable_values_initialized = false; namespace { // Single copy of the global state. Zero-filled until // cilkg_get_user_settable_values() is called and partially-zero-filled until // cilkg_init_global_state() is called. The first field is filled in with // the size of a void* for the debugger and must be valid before initialization static global_state_t global_state_singleton = { sizeof(void *), // addr_size GLOBAL_STATE_VERSION, // structure version }; // Variables that need to export C-style names extern "C" { // Pointer to the global state singleton. global_state_t *cilkg_singleton_ptr = NULL; // __cilkrts_global_state is exported and referenced by the debugger. // The debugger expects it to be valid when the module loads. // CILK_EXPORT_DATA global_state_t *__cilkrts_global_state = &global_state_singleton; } // Returns true if 'a' and 'b' are equal null-terminated strings inline bool strmatch(const char* a, const char* b) { return 0 == std::strcmp(a, b); } // Returns the integer value represented by the null-terminated, decimal string // at 's'. inline long to_long(const char* s) { char *end; errno = 0; return std::strtol(s, &end, 10); } #ifdef _WIN32 // Returns true if 'a' and 'b' are equal null-terminated wide-char strings inline bool strmatch(const wchar_t* a, const wchar_t* b) { return 0 == wcscmp(a, b); } // Returns true if the multi-byte character string at 'a' represents the same // character sequence as the wide-character string at 'b'. The behavior is // undefined if 'a' contains more than 30 multi-byte characters. bool strmatch(const char* a, const wchar_t* b) { // Convert 'a' to wide-characters, then compare. wchar_t wa[31]; std::size_t count; errno_t err = mbstowcs_s(&count, wa, a, 30); CILK_ASSERT(0 == err); if (err) return false; return strmatch(wa, b); } // Returns true if the wide-character string at 'a' represents the same // character sequence as the multi-byte character string at 'b'. The behavior // id undefined if 'b' contains more than 30 multi-byte characters. inline bool strmatch(const wchar_t* a, const char* b) { return strmatch(b, a); } // Returns the integer value represented by the null-terminated wide-char // string at 's'. inline long to_long(const wchar_t* s) { wchar_t *end; errno = 0; return wcstol(s, &end, 0); } #endif // Check if Cilkscreen or other sequential ptool wants to force reducers. bool always_force_reduce() { // Metacall *looks* like a no-op. volatile needed to keep compiler from // optimizing away variable. volatile char not_force_reduce = '\377'; __cilkrts_metacall(METACALL_TOOL_SYSTEM, HYPER_ZERO_IF_FORCE_REDUCE, const_cast(¬_force_reduce)); return ! not_force_reduce; } // Stores the boolean value represented by the null-terminated string at 'val' // into the integer object at 'out'. Returns '__CILKRTS_SET_PARAM_SUCCESS' if // 'val' is "true", "false", "0" or "1" and '__CILKRTS_SET_PARAM_INVALID' // otherwise. template int store_bool(INT_T *out, const CHAR_T *val) { static const char* const s_zero = "0"; static const char* const s_one = "1"; static const char* const s_true = "true"; static const char* const s_false = "false"; if (val == 0) return __CILKRTS_SET_PARAM_INVALID; if (strmatch(s_false, val) || strmatch(s_zero, val)) { *out = 0; return __CILKRTS_SET_PARAM_SUCCESS; } if (strmatch(s_true, val) || strmatch(s_one, val)) { *out = 1; return __CILKRTS_SET_PARAM_SUCCESS; } return __CILKRTS_SET_PARAM_INVALID; } // Stores the integer value represented by the null-terminated string at 'val' // into the integer object at 'out', restricting the result to the range 'min' // to 'max', inclusive. Returns '__CILKRTS_SET_PARAM_SUCCESS' if the conversion // succeeds and is in range, '__CILKRTS_SET_PARAM_XRANGE' if the conversion // succeeds but is out of range, and '__CILKRTS_SET_PARAM_INVALID' otherwise. In // the case of any error, '*out' is unchanged. template int store_int(INT_T *out, const CHAR_T *val, INT_T min, INT_T max) { errno = 0; long val_as_long = to_long(val); if (val_as_long == 0 && errno != 0) return __CILKRTS_SET_PARAM_INVALID; if (val_as_long < min || val_as_long == LONG_MIN) return __CILKRTS_SET_PARAM_XRANGE; else if (val_as_long > max || val_as_long == LONG_MAX) return __CILKRTS_SET_PARAM_XRANGE; *out = val_as_long; return __CILKRTS_SET_PARAM_SUCCESS; } // Implementaton of cilkg_set_param templatized on character type. // Windows will instantiate with both char and wchar_t. // Note that g must have its user settable values set, but need not be fully // initialized. template int set_param_imp(global_state_t* g, const CHAR_T* param, const CHAR_T* value) { static const char* const s_force_reduce = "force reduce"; static const char* const s_nworkers = "nworkers"; static const char* const s_max_user_workers = "max user workers"; static const char* const s_local_stacks = "local stacks"; static const char* const s_shared_stacks = "shared stacks"; static const char* const s_nstacks = "nstacks"; static const char* const s_stack_size = "stack size"; // We must have a parameter and a value if (0 == param) return __CILKRTS_SET_PARAM_INVALID; if (0 == value) return __CILKRTS_SET_PARAM_INVALID; if (strmatch(param, s_force_reduce)) { // Sets whether we force a reduce operation at every sync. Useful for // debugging reducers. Off by default. Overridden by Cilkscreen // // Documented in cilk_api_.h if (always_force_reduce()) // Force reduce is set by cilkscreen. User cannot change it. return __CILKRTS_SET_PARAM_LATE; return store_bool(&g->force_reduce, value); } else if (strmatch(param, s_nworkers)) { // Set the total number of workers. Overrides count of cores we get // from the OS and the setting of the CILK_NWORKERS environment // variable. Setting to 0 indicates that the default worker count // should be used. // // Documented in cilk_api_.h if (cilkg_singleton_ptr) return __CILKRTS_SET_PARAM_LATE; // Fetch the number of cores. There must be at last 1, since we're // executing on *something*, aren't we!? int hardware_cpu_count = __cilkrts_hardware_cpu_count(); CILK_ASSERT(hardware_cpu_count > 0); int max_cpu_count = 16 * hardware_cpu_count; if (__cilkrts_running_under_sequential_ptool()) { hardware_cpu_count = 1; max_cpu_count = 1; } // Allow a value of 0, which means "set to hardware thread count". int ret = store_int(&g->P, value, 0, max_cpu_count); if (0 == g->P) g->P = hardware_cpu_count; return ret; } else if (strmatch(param, s_max_user_workers)) { // ** UNDOCUMENTED ** // // Sets the number of slots allocated for user worker threads int hardware_cpu_count = __cilkrts_hardware_cpu_count(); CILK_ASSERT (hardware_cpu_count > 0); return store_int(&g->max_user_workers, value, 1, 16 * hardware_cpu_count); } else if (strmatch(param, s_local_stacks)) { // ** UNDOCUMENTED ** // // Number of stacks we'll hold in the per-worker stack cache. Maximum // value is 42. See __cilkrts_make_global_state for details. return store_int(&g->fiber_pool_size, value, 0, 42); } else if (strmatch(param, s_shared_stacks)) { // ** UNDOCUMENTED ** // // Maximum number of stacks we'll hold in the global stack // cache. Maximum value is 42. See __cilkrts_make_global_state for // details. return store_int(&g->global_fiber_pool_size, value, 0, 42); } else if (strmatch(param, s_nstacks)) { // Sets the maximum number of stacks permitted at one time. If the // runtime reaches this maximum, it will cease to allocate stacks and // the app will lose parallelism. 0 means unlimited. Default is // unlimited. Minimum is twice the number of worker threads, though // that cannot be tested at this time. // // Undocumented at this time, though there are plans to expose it. // The current implentation is for Linux debugging only and is not // robust enough for users. if (cilkg_singleton_ptr) return __CILKRTS_SET_PARAM_LATE; return store_int(&g->max_stacks, value, 0, INT_MAX); } else if (strmatch(param, s_stack_size)) { // ** UNDOCUMENTED ** // // Sets the size (in bytes) of the stacks that Cilk creates. // Can only be set before the runtime starts. if (cilkg_singleton_ptr) return __CILKRTS_SET_PARAM_LATE; // Maximum value that can be parsed is MAX_INT (32-bit). int ret = store_int(&g->stack_size, value, 0, INT_MAX); // Process the value the user set (or 0 if the user didn't set // anything) into something nice for the current OS. This // processing is done immediately and stored into // g->stack_size so that a call to get stack size will return // the value that the runtime will actually use. g->stack_size = cilkos_validate_stack_size(g->stack_size); return ret; } // If got here, then didn't match any of the strings return __CILKRTS_SET_PARAM_UNIMP; } inline int calc_max_user_workers(global_state_t *g) { // If it's been set by the user, give back what we got if (g->max_user_workers > 0) return g->max_user_workers; // Calculate it return std::max(3, g->P * 2); } } // end unnamed namespace __CILKRTS_BEGIN_EXTERN_C /** * @brief Returns the global state object. If called for the first time, * initializes the user-settable values in the global state, but does not * initialize the rest of the structure. */ global_state_t* cilkg_get_user_settable_values() { // Environment variable value. More than big enough for a 64-bit signed // integer. char envstr[24]; // Abbreviating &global_state_singleton as g is not only shorter, it also // facilitates grepping for the string "g->", which appears ubiquitously // in the runtime code. global_state_t* g = &global_state_singleton; // TBD: We need synchronization around this loop to prevent // multiple threads from initializing this data. if (! cilkg_user_settable_values_initialized) { size_t len; // Preserve stealing disabled since it may have been set by the // debugger int stealing_disabled = g->stealing_disabled; // All fields will be zero until set. In particular std::memset(g, 0, sizeof(global_state_t)); // Fetch the number of cores. There must be at last 1, since we're // executing on *something*, aren't we!? int hardware_cpu_count = __cilkrts_hardware_cpu_count(); CILK_ASSERT(hardware_cpu_count > 0); bool under_ptool = __cilkrts_running_under_sequential_ptool(); if (under_ptool) hardware_cpu_count = 1; g->stealing_disabled = stealing_disabled; g->under_ptool = under_ptool; g->force_reduce = 0; // Default Off g->P = hardware_cpu_count; // Defaults to hardware CPU count g->max_user_workers = 0; // 0 unless set by user g->fiber_pool_size = 7; // Arbitrary default g->global_fiber_pool_size = 3 * 3* g->P; // Arbitrary default // 3*P was the default size of the worker array (including // space for extra user workers). This parameter was chosen // to match previous versions of the runtime. if (4 == sizeof(void *)) g->max_stacks = 1200; // Only 1GB on 32-bit machines else g->max_stacks = 2400; // 2GB on 64-bit machines // If we have 2400 1MB stacks, that is 2 gb. If we reach this // limit on a single-socket machine, we may have other // problems. Is 2400 too small for large multicore machines? // TBD(jsukha, 11/27/2012): I set this limit on stacks to be a // value independent of P. When running on a Xeon Phi with // small values of P, I recall seeing a few microbenchmarks // (e.g., fib) where a limit of 10*P seemed to be // unnecessarily slowing things down. // // That being said, the code has changed sufficiently that // this observation may no longer be true. // // Note: in general, the worst-case number of stacks required // for a Cilk computation with spawn depth "d" on P workers is // O(Pd). Code with unbalanced recursion may run into issues // with this stack usage. g->max_steal_failures = 128; // TBD: depend on max_workers? g->stack_size = 0; // 0 unless set by the user // Assume no record or replay log for now g->record_replay_file_name = NULL; g->record_or_replay = RECORD_REPLAY_NONE; // set by user if (always_force_reduce()) g->force_reduce = true; else if (cilkos_getenv(envstr, sizeof(envstr), "CILK_FORCE_REDUCE")) store_bool(&g->force_reduce, envstr); if (under_ptool) g->P = 1; // Ignore environment variable if under cilkscreen else if (cilkos_getenv(envstr, sizeof(envstr), "CILK_NWORKERS")) // Set P to environment variable, but limit to no less than 1 // and no more than 16 times the number of hardware threads. store_int(&g->P, envstr, 1, 16 * hardware_cpu_count); if (cilkos_getenv(envstr, sizeof(envstr), "CILK_MAX_USER_WORKERS")) // Set max_user_workers to environment variable, but limit to no // less than 1 and no more 16 times the number of hardware // threads. If not specified, defaults (somewhat arbitrarily) to // the larger of 3 and twice the number of hardware threads. store_int(&g->max_user_workers, envstr, 1, 16*hardware_cpu_count); if (cilkos_getenv(envstr, sizeof(envstr), "CILK_STEAL_FAILURES")) // Set the number of times a worker should fail to steal before // it looks to see whether it should suspend itself. store_int(&g->max_steal_failures, envstr, 1, INT_MAX); // Compute the total number of workers to allocate. Subtract one from // nworkers and user workers so that the first user worker isn't // factored in twice. // // total_workers must be computed now to support __cilkrts_get_total_workers g->total_workers = g->P + calc_max_user_workers(g) - 1; #ifdef CILK_RECORD_REPLAY // RecordReplay: See if we've been asked to replay a log len = cilkos_getenv(envstr, 0, "CILK_REPLAY_LOG"); if (len > 0) { len += 1; // Allow for trailing NUL g->record_or_replay = REPLAY_LOG; g->record_replay_file_name = (char *)__cilkrts_malloc(len); cilkos_getenv(g->record_replay_file_name, len, "CILK_REPLAY_LOG"); } // RecordReplay: See if we've been asked to record a log len = cilkos_getenv(envstr, 0, "CILK_RECORD_LOG"); if (len > 0) { if (RECORD_REPLAY_NONE != g->record_or_replay) cilkos_warning("CILK_RECORD_LOG ignored since CILK_REPLAY_LOG is defined.\n"); else { len += 1; // Allow for trailing NUL g->record_or_replay = RECORD_LOG; g->record_replay_file_name = (char *)__cilkrts_malloc(len); cilkos_getenv(g->record_replay_file_name, len, "CILK_RECORD_LOG"); } } #endif cilkg_user_settable_values_initialized = true; } return g; } int cilkg_calc_total_workers() { global_state_t* g = cilkg_get_user_settable_values(); // Compute the total number of workers to allocate. Subtract one from // nworkers and user workers so that the first user worker isn't // factored in twice. return g->P + calc_max_user_workers(g) - 1; } // Should be called while holding the global lock. global_state_t* cilkg_init_global_state() { if (cilkg_singleton_ptr) return cilkg_singleton_ptr; // Get partially-initialized global state. global_state_t* g = cilkg_get_user_settable_values(); if (g->max_stacks > 0) { // nstacks is currently honored on non-Windows systems only. // Set an upper bound on the number of stacks that are allocated. If // nstacks is set, each worker gets up to one stack in its cache so that // no one worker can hog all of the free stacks and keep work from being // stolen by the other workers. // nstacks corresponds to the number of stacks that will be allocated by // the runtime apart from the initial stack created for each thread by // the system. Therefore, if a user asks for n stacks, and there are // p workers created, the total number of stacks is actually n + p. // This feature is primarily for MIC which has flat memory // instead of virtual addresses and tends to run out really quickly. // It is not implemented for Windows and it's non-intuitive // interaction with the local stack cache is specifically to help out // MIC. // About max_stacks / P stacks, except we require at least 1 // per pool. if (((int)g->max_stacks / g->P) < g->fiber_pool_size) g->fiber_pool_size = g->max_stacks / g->P; if (g->fiber_pool_size <= 0) { g->fiber_pool_size = 1; } if ((int)g->max_stacks < g->P) g->max_stacks = g->P; g->global_fiber_pool_size = g->P * (g->fiber_pool_size+1); } // Number of bytes/address - validation for debugger integration g->addr_size = sizeof(void *); __cilkrts_init_stats(&g->stats); __cilkrts_frame_malloc_global_init(g); g->Q = 0; g->total_workers = cilkg_calc_total_workers(); g->system_workers = g->P - 1; // system_workers is here for the debugger. g->work_done = 0; g->workers_running = 0; g->ltqsize = 1024; /* FIXME */ g->stack_size = cilkos_validate_stack_size(g->stack_size); g->failure_to_allocate_stack = 0; return g; } void cilkg_publish_global_state(global_state_t* g) { // TBD: which one of these needs to be executed first? I say // cilkg_singleton_ptr needs to be set last, with a mfence in // between, since it is the flag that cilkg_is_published_is // checking for. __cilkrts_global_state = g; __cilkrts_fence(); cilkg_singleton_ptr = g; } void cilkg_deinit_global_state() { cilkg_singleton_ptr = NULL; // The pointer to the global state needs to remain valid for the // debugger. Thus, we can't clear the following pointer. // __cilkrts_global_state = NULL; // We also don't reset the global state, so that if we resume // execution after ending Cilk, user set variables (e.g., # of // workers) remains valid. } int cilkg_is_published(void) { return NULL != cilkg_singleton_ptr; } int cilkg_set_param(const char* param, const char* value) { return set_param_imp(cilkg_get_user_settable_values(), param, value); } #ifdef _WIN32 int cilkg_set_param_w(const wchar_t* param, const wchar_t* value) { return set_param_imp(cilkg_get_user_settable_values(), param, value); } #endif extern "C++" { // C++ scheduler function (that may throw exceptions) typedef void cpp_scheduler_t(__cilkrts_worker *w); } void __cilkrts_run_scheduler_with_exceptions(__cilkrts_worker *w) { global_state_t* g = cilkg_get_global_state(); CILK_ASSERT(g->scheduler); cpp_scheduler_t* scheduler = (cpp_scheduler_t*) g->scheduler; try { scheduler(w); } catch (...) { __cilkrts_bug("Exception escaped Cilk context"); } } __CILKRTS_END_EXTERN_C /* End global_state.cpp */