X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/4d5c6aed22b8ae1c8a73cd04d8ab800322d177bf..7dd253f0ff4dda733dd0f7c924a25df4b777f0d0:/src/kernel/context/ContextSwapped.cpp diff --git a/src/kernel/context/ContextSwapped.cpp b/src/kernel/context/ContextSwapped.cpp index 6897767f37..e2ca4165ff 100644 --- a/src/kernel/context/ContextSwapped.cpp +++ b/src/kernel/context/ContextSwapped.cpp @@ -1,13 +1,33 @@ -/* 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/actor/ActorImpl.hpp" #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 +35,223 @@ namespace simgrid { namespace kernel { namespace context { -unsigned long SwappedContext::process_index_; +/* thread-specific storage for the worker's context */ +thread_local SwappedContext* SwappedContext::worker_context_ = nullptr; -SwappedContext* SwappedContext::maestro_context_ = nullptr; +SwappedContext::SwappedContext(std::function&& code, smx_actor_t actor, SwappedContextFactory* factory) + : Context(std::move(code), actor), factory_(factory) +{ + // Save maestro (=context created first) in preparation for run_all + if (not SIMIX_context_is_parallel() && factory->maestro_context_ == nullptr) + factory->maestro_context_ = this; -void SwappedContext::suspend() + if (has_code()) { + xbt_assert((smx_context_stack_size & 0xf) == 0, "smx_context_stack_size should be multiple of 16"); + 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. */ + 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) + void* alloc; + if (posix_memalign(&alloc, xbt_pagesize, size) != 0) + xbt_die("Failed to allocate stack."); + this->stack_ = static_cast(alloc); +#else + this->stack_ = static_cast(_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 " + "https://simgrid.org/doc/latest/Configuring_SimGrid.html#configuring-the-user-code-virtualization for more " + "information.", + strerror(errno)); + /* This is fatal. We are going to fail at some point when we try reusing this. */ + } +#endif + this->stack_ = this->stack_ + smx_context_guard_size; + } else { + this->stack_ = static_cast(xbt_malloc0(smx_context_stack_size)); + } + +#if PTH_STACKGROWTH == -1 + ASAN_ONLY(this->asan_stack_ = this->stack_ + smx_context_stack_size); +#else + ASAN_ONLY(this->asan_stack_ = this->stack_); +#endif +#if HAVE_VALGRIND_H + if (RUNNING_ON_VALGRIND) + this->valgrind_stack_id_ = VALGRIND_STACK_REGISTER(this->stack_, this->stack_ + smx_context_stack_size); +#endif + } +} + +SwappedContext::~SwappedContext() { - /* 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()); + if (stack_ == nullptr) // maestro has no extra stack + return; + +#if HAVE_VALGRIND_H + if (RUNNING_ON_VALGRIND) + VALGRIND_STACK_DEREGISTER(valgrind_stack_id_); +#endif + +#ifndef _WIN32 + if (smx_context_guard_size > 0 && not MC_is_active()) { + 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_ = reinterpret_cast(stack_)[-1]; +#endif } - Context::set_current(next_context); - this->swap_into(next_context); +#endif /* not windows */ + + xbt_free(stack_); +} + +unsigned char* 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 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 (SIMIX_context_is_parallel()) { + // 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_ */ + const actor::ActorImpl* 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() { - SwappedContext* old = static_cast(self()); - Context::set_current(this); - old->swap_into(this); + if (SIMIX_context_is_parallel()) { + // Save my current soul (either maestro, or one of the minions) in a thread-specific area + worker_context_ = static_cast(self()); + // 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); + } } -void SwappedContext::run_all() +/** 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() { - 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 (SIMIX_context_is_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_context_ is my own soul, stored in thread_local when starting the scheduling round + next_context = worker_context_; + // 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_->maestro_context_; + } + Context::set_current(next_context); + this->swap_into(next_context); + } } + } // namespace context } // namespace kernel } // namespace simgrid