X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/4d5c6aed22b8ae1c8a73cd04d8ab800322d177bf..68789b70e7a97bf748e0829eceeb4e2aca2cc490:/src/kernel/context/ContextSwapped.cpp diff --git a/src/kernel/context/ContextSwapped.cpp b/src/kernel/context/ContextSwapped.cpp index 6897767f37..b550205e99 100644 --- a/src/kernel/context/ContextSwapped.cpp +++ b/src/kernel/context/ContextSwapped.cpp @@ -1,13 +1,32 @@ -/* 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/modelchecker.h" +#include "src/internal_config.h" #include "src/kernel/context/context_private.hpp" #include "src/simix/ActorImpl.hpp" #include "src/simix/smx_private.hpp" +#include "xbt/parmap.hpp" -#include "ContextSwapped.hpp" +#include "src/kernel/context/ContextSwapped.hpp" + +#ifdef _WIN32 +#include +#include +#else +#include +#endif + +#ifdef __MINGW32__ +#define _aligned_malloc __mingw_aligned_malloc +#define _aligned_free __mingw_aligned_free +#endif /*MINGW*/ + +#if HAVE_VALGRIND_H +#include +#endif XBT_LOG_EXTERNAL_DEFAULT_CATEGORY(simix_context); @@ -15,46 +34,238 @@ namespace simgrid { namespace kernel { namespace context { -unsigned long SwappedContext::process_index_; +/* rank of the execution thread */ +thread_local uintptr_t SwappedContext::worker_id_; /* thread-specific storage for the thread id */ -SwappedContext* SwappedContext::maestro_context_ = nullptr; +SwappedContextFactory::SwappedContextFactory(std::string name) + : ContextFactory(name), parallel_(SIMIX_context_is_parallel()) +{ + parmap_ = nullptr; // will be created lazily with the right parameters if needed (ie, in parallel) + workers_context_.clear(); + workers_context_.resize(parallel_ ? SIMIX_context_get_nthreads() : 1, nullptr); +} +SwappedContextFactory::~SwappedContextFactory() +{ + delete parmap_; + parmap_ = nullptr; + workers_context_.clear(); +} -void SwappedContext::suspend() +SwappedContext::SwappedContext(std::function code, void_pfn_smxprocess_t cleanup_func, smx_actor_t process, + SwappedContextFactory* factory) + : Context(std::move(code), cleanup_func, process), factory_(factory) +{ + if (has_code()) { + if (smx_context_guard_size > 0 && not MC_is_active()) { + +#if !defined(PTH_STACKGROWTH) || (PTH_STACKGROWTH != -1) + xbt_die( + "Stack overflow protection is known to be broken on your system: you stacks grow upwards (or detection is " + "broken). " + "Please disable stack guards with --cfg=contexts:guard-size:0"); + /* Current code for stack overflow protection assumes that stacks are growing downward (PTH_STACKGROWTH == -1). + * Protected pages need to be put after the stack when PTH_STACKGROWTH == 1. */ +#endif + + size_t size = smx_context_stack_size + smx_context_guard_size; +#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; +#elif !defined(_WIN32) + if (posix_memalign(&this->stack_, xbt_pagesize, size) != 0) + xbt_die("Failed to allocate stack."); +#else + this->stack_ = _aligned_malloc(size, xbt_pagesize); +#endif + +#ifndef _WIN32 + if (mprotect(this->stack_, smx_context_guard_size, PROT_NONE) == -1) { + xbt_die( + "Failed to protect stack: %s.\n" + "If you are running a lot of actors, you may be exceeding the amount of mappings allowed per process.\n" + "On Linux systems, change this value with sudo sysctl -w vm.max_map_count=newvalue (default value: 65536)\n" + "Please see http://simgrid.gforge.inria.fr/simgrid/latest/doc/html/options.html#options_virt for more " + "info.", + strerror(errno)); + /* 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; + } else { + this->stack_ = xbt_malloc0(smx_context_stack_size); + } + +#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); +#endif + } +} + +SwappedContext::~SwappedContext() +{ + 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); + 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; + 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); +#endif + } +#endif /* not windows */ + + xbt_free(stack_); +} + +void SwappedContext::set_maestro(SwappedContext* ctx) +{ + if (factory_->threads_working_ == 0) // Don't save the soul of minions, only the one of maestro + factory_->workers_context_[0] = ctx; +} + +void* SwappedContext::get_stack() +{ + return stack_; +} + +void SwappedContext::stop() +{ + Context::stop(); + /* We must cut the actor execution using an exception to properly free the C++ RAII variables */ + throw StopRequest(); +} + +/** Maestro wants to run all ready actors */ +void SwappedContextFactory::run_all() { - /* determine the next context */ - SwappedContext* next_context; - unsigned long int i = process_index_; - process_index_++; - - if (i < simix_global->process_to_run.size()) { - /* execute the next process */ - XBT_DEBUG("Run next process"); - next_context = static_cast(simix_global->process_to_run[i]->context_); - } else { - /* all processes were run, return to maestro */ - XBT_DEBUG("No more process to run"); - next_context = static_cast(get_maestro()); + /* 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_ = 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_); + context->resume(); + }, + simix_global->process_to_run); + } else { // sequential execution + if (simix_global->process_to_run.empty()) + return; + + /* maestro is already saved in the first slot of workers_context_ */ + smx_actor_t first_actor = simix_global->process_to_run.front(); + process_index_ = 1; + /* execute the first actor; it will chain to the others when using suspend() */ + static_cast(first_actor->context_)->resume(); } - Context::set_current(next_context); - this->swap_into(next_context); } +/** 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() { - 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, SIMIX_process_yield() will call suspend(), below. + } else { // sequential execution + SwappedContext* old = static_cast(self()); + Context::set_current(this); + old->swap_into(this); + } } -void SwappedContext::run_all() +/** The actor wants to yield back to maestro, because it is blocked in a simcall (ie in SIMIX_process_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() { - 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(); + 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_); + } 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->process_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->process_to_run[i]->context_); + } 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); + } } + } // namespace context } // namespace kernel } // namespace simgrid