X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/e4bdd31e7ef80a47732508c06ef157692be13f94..82567f27fa74ddc2b6afa8d9b682bdde15fe3f9c:/src/kernel/context/ContextSwapped.cpp diff --git a/src/kernel/context/ContextSwapped.cpp b/src/kernel/context/ContextSwapped.cpp index 7bf07905bf..ccc04209b2 100644 --- a/src/kernel/context/ContextSwapped.cpp +++ b/src/kernel/context/ContextSwapped.cpp @@ -1,8 +1,9 @@ -/* Copyright (c) 2009-2018. The SimGrid Team. All rights reserved. */ +/* Copyright (c) 2009-2019. The SimGrid Team. All rights reserved. */ /* This program is free software; you can redistribute it and/or modify it * under the terms of the license (GNU LGPL) which comes with this package. */ +#include "simgrid/Exception.hpp" #include "simgrid/modelchecker.h" #include "src/internal_config.h" #include "src/kernel/context/context_private.hpp" @@ -34,34 +35,22 @@ namespace simgrid { namespace kernel { namespace context { -/* Sequential execution */ -unsigned long SwappedContext::process_index_; - -/* Parallel execution */ -simgrid::xbt::Parmap* SwappedContext::parmap_; -std::atomic SwappedContext::threads_working_; /* number of threads that have started their work */ +/* rank of the execution thread */ thread_local uintptr_t SwappedContext::worker_id_; /* thread-specific storage for the thread id */ -std::vector SwappedContext::workers_context_; /* space to save the worker's context in each thread */ -void SwappedContext::initialize() +SwappedContextFactory::SwappedContextFactory() : ContextFactory(), parallel_(SIMIX_context_is_parallel()) { - parmap_ = nullptr; - workers_context_.clear(); - workers_context_.resize(SIMIX_context_get_nthreads(), nullptr); + parmap_ = nullptr; // will be created lazily with the right parameters if needed (ie, in parallel) + workers_context_.resize(parallel_ ? SIMIX_context_get_nthreads() : 1, nullptr); } -void SwappedContext::finalize() +SwappedContext::SwappedContext(std::function&& code, smx_actor_t actor, SwappedContextFactory* factory) + : Context(std::move(code), actor), factory_(factory) { - delete parmap_; - parmap_ = nullptr; - workers_context_.clear(); -} + // Save maestro (=context created first) in preparation for run_all + if (not factory->parallel_ && factory_->workers_context_[0] == nullptr) + factory_->workers_context_[0] = this; -SwappedContext* SwappedContext::maestro_context_ = nullptr; - -SwappedContext::SwappedContext(std::function code, void_pfn_smxprocess_t cleanup_func, smx_actor_t process) - : Context(std::move(code), cleanup_func, process) -{ if (has_code()) { if (smx_context_guard_size > 0 && not MC_is_active()) { @@ -78,14 +67,16 @@ SwappedContext::SwappedContext(std::function code, void_pfn_smxprocess_t #if SIMGRID_HAVE_MC /* Cannot use posix_memalign when SIMGRID_HAVE_MC. Align stack by hand, and save the * pointer returned by xbt_malloc0. */ - char* alloc = (char*)xbt_malloc0(size + xbt_pagesize); - stack_ = alloc - ((uintptr_t)alloc & (xbt_pagesize - 1)) + xbt_pagesize; - *((void**)stack_ - 1) = alloc; + unsigned char* alloc = static_cast(xbt_malloc0(size + xbt_pagesize)); + stack_ = alloc - (reinterpret_cast(alloc) & (xbt_pagesize - 1)) + xbt_pagesize; + reinterpret_cast(stack_)[-1] = alloc; #elif !defined(_WIN32) - if (posix_memalign(&this->stack_, xbt_pagesize, size) != 0) + void* alloc; + if (posix_memalign(&alloc, xbt_pagesize, size) != 0) xbt_die("Failed to allocate stack."); + this->stack_ = static_cast(alloc); #else - this->stack_ = _aligned_malloc(size, xbt_pagesize); + this->stack_ = static_cast(_aligned_malloc(size, xbt_pagesize)); #endif #ifndef _WIN32 @@ -100,40 +91,44 @@ SwappedContext::SwappedContext(std::function code, void_pfn_smxprocess_t /* This is fatal. We are going to fail at some point when we try reusing this. */ } #endif - this->stack_ = (char*)this->stack_ + smx_context_guard_size; + this->stack_ = this->stack_ + smx_context_guard_size; } else { - this->stack_ = xbt_malloc0(smx_context_stack_size); + this->stack_ = static_cast(xbt_malloc0(smx_context_stack_size)); } +#if PTH_STACKGROWTH == -1 + ASAN_ONLY(this->asan_stack_ = this->stack_ + smx_context_usable_stack_size); +#else + ASAN_ONLY(this->asan_stack_ = this->stack_); +#endif #if HAVE_VALGRIND_H - unsigned int valgrind_stack_id = - VALGRIND_STACK_REGISTER(this->stack_, (char*)this->stack_ + smx_context_stack_size); - memcpy((char*)this->stack_ + smx_context_usable_stack_size, &valgrind_stack_id, sizeof valgrind_stack_id); + unsigned int valgrind_stack_id = VALGRIND_STACK_REGISTER(this->stack_, this->stack_ + smx_context_stack_size); + memcpy(this->stack_ + smx_context_usable_stack_size, &valgrind_stack_id, sizeof valgrind_stack_id); #endif } } SwappedContext::~SwappedContext() { - if (stack_ == nullptr) + if (stack_ == nullptr) // maestro has no extra stack return; #if HAVE_VALGRIND_H unsigned int valgrind_stack_id; - memcpy(&valgrind_stack_id, (char*)stack_ + smx_context_usable_stack_size, sizeof valgrind_stack_id); + memcpy(&valgrind_stack_id, stack_ + smx_context_usable_stack_size, sizeof valgrind_stack_id); VALGRIND_STACK_DEREGISTER(valgrind_stack_id); #endif #ifndef _WIN32 if (smx_context_guard_size > 0 && not MC_is_active()) { - stack_ = (char*)stack_ - smx_context_guard_size; + stack_ = stack_ - smx_context_guard_size; if (mprotect(stack_, smx_context_guard_size, PROT_READ | PROT_WRITE) == -1) { XBT_WARN("Failed to remove page protection: %s", strerror(errno)); /* try to pursue anyway */ } #if SIMGRID_HAVE_MC /* Retrieve the saved pointer. See SIMIX_context_stack_new above. */ - stack_ = *((void**)stack_ - 1); + stack_ = reinterpret_cast(stack_)[-1]; #endif } #endif /* not windows */ @@ -141,45 +136,131 @@ SwappedContext::~SwappedContext() xbt_free(stack_); } -/** Maestro wants to run all read_to_run actors */ -void SwappedContext::run_all() +unsigned char* SwappedContext::get_stack() { - if (simix_global->process_to_run.empty()) - return; - smx_actor_t first_process = simix_global->process_to_run.front(); - process_index_ = 1; - /* execute the first process */ - static_cast(first_process->context_)->resume(); + return stack_; } -/** Maestro wants to yield back to a given actor */ +void SwappedContext::stop() +{ + Context::stop(); + /* We must cut the actor execution using an exception to properly free the C++ RAII variables */ + throw ForcefulKillException(); +} + +/** Maestro wants to run all ready actors */ +void SwappedContextFactory::run_all() +{ + /* This function is called by maestro at the beginning of a scheduling round to get all working threads executing some + * stuff It is much easier to understand what happens if you see the working threads as bodies that swap their soul + * for the ones of the simulated processes that must run. + */ + if (parallel_) { + threads_working_ = 0; + + // We lazily create the parmap so that all options are actually processed when doing so. + if (parmap_ == nullptr) + parmap_.reset( + new simgrid::xbt::Parmap(SIMIX_context_get_nthreads(), SIMIX_context_get_parallel_mode())); + + // Usually, Parmap::apply() executes the provided function on all elements of the array. + // Here, the executed function does not return the control to the parmap before all the array is processed: + // - suspend() should switch back to the worker_context (either maestro or one of its minions) to return + // the control to the parmap. Instead, it uses parmap_->next() to steal another work, and does it directly. + // It only yields back to worker_context when the work array is exhausted. + // - So, resume() is only launched from the parmap for the first job of each minion. + parmap_->apply( + [](smx_actor_t process) { + SwappedContext* context = static_cast(process->context_.get()); + context->resume(); + }, + simix_global->actors_to_run); + } else { // sequential execution + if (simix_global->actors_to_run.empty()) + return; + + /* maestro is already saved in the first slot of workers_context_ */ + smx_actor_t first_actor = simix_global->actors_to_run.front(); + process_index_ = 1; + /* execute the first actor; it will chain to the others when using suspend() */ + static_cast(first_actor->context_.get())->resume(); + } +} + +/** Maestro wants to yield back to a given actor, so awake it on the current thread + * + * In parallel, it is only applied to the N first elements of the parmap array, + * where N is the amount of worker threads in the parmap. + * See SwappedContextFactory::run_all for details. + */ void SwappedContext::resume() { - // Maestro is always the calling thread of this function (ie, self() == maestro) - SwappedContext* old = static_cast(self()); - Context::set_current(this); - old->swap_into(this); + if (factory_->parallel_) { + // Save the thread number (my body) in an os-thread-specific area + worker_id_ = factory_->threads_working_.fetch_add(1, std::memory_order_relaxed); + // Save my current soul (either maestro, or one of the minions) in a permanent area + SwappedContext* worker_context = static_cast(self()); + factory_->workers_context_[worker_id_] = worker_context; + // Switch my soul and the actor's one + Context::set_current(this); + worker_context->swap_into(this); + // No body runs that soul anymore at this point, but it is stored in a safe place. + // When the executed actor will do a blocking action, ActorImpl::yield() will call suspend(), below. + } else { // sequential execution + SwappedContext* old = static_cast(self()); + Context::set_current(this); + old->swap_into(this); + } } -/** The actor wants to yield back to maestro */ +/** The actor wants to yield back to maestro, because it is blocked in a simcall (i.e., in ActorImpl::yield()) + * + * Actually, it does not really yield back to maestro, but directly into the next executable actor. + * + * This makes the parmap::apply awkward (see ParallelUContext::run_all()) because it only apply regularly + * on the few first elements of the array, but it saves a lot of context switches back to maestro, + * and directly forth to the next executable actor. + */ void SwappedContext::suspend() { - /* determine the next context */ - SwappedContext* next_context; - unsigned long int i = process_index_; - process_index_++; - - if (i < simix_global->process_to_run.size()) { - /* Actually swap into the next actor directly without transiting to maestro */ - XBT_DEBUG("Run next process"); - next_context = static_cast(simix_global->process_to_run[i]->context_); - } else { - /* all processes were run, actually return to maestro */ - XBT_DEBUG("No more process to run"); - next_context = static_cast(get_maestro()); + if (factory_->parallel_) { + // Get some more work to directly swap into the next executable actor instead of yielding back to the parmap + boost::optional next_work = factory_->parmap_->next(); + SwappedContext* next_context; + if (next_work) { + // There is a next soul to embody (ie, another executable actor) + XBT_DEBUG("Run next process"); + next_context = static_cast(next_work.get()->context_.get()); + } else { + // All actors were run, go back to the parmap context + XBT_DEBUG("No more actors to run"); + // worker_id_ is the identity of my body, stored in thread_local when starting the scheduling round + next_context = factory_->workers_context_[worker_id_]; + // When given that soul, the body will wait for the next scheduling round + } + + // Get the next soul to run, either from another actor or the initial minion's one + Context::set_current(next_context); + this->swap_into(next_context); + + } else { // sequential execution + /* determine the next context */ + SwappedContext* next_context; + unsigned long int i = factory_->process_index_; + factory_->process_index_++; + + if (i < simix_global->actors_to_run.size()) { + /* Actually swap into the next actor directly without transiting to maestro */ + XBT_DEBUG("Run next actor"); + next_context = static_cast(simix_global->actors_to_run[i]->context_.get()); + } else { + /* all processes were run, actually return to maestro */ + XBT_DEBUG("No more actors to run"); + next_context = factory_->workers_context_[0]; + } + Context::set_current(next_context); + this->swap_into(next_context); } - Context::set_current(next_context); - this->swap_into(next_context); } } // namespace context