From 6658e9f2ff4a24cc2e074c654f8f818be1d79089 Mon Sep 17 00:00:00 2001 From: Martin Quinson Date: Sun, 6 Jan 2019 12:58:03 +0100 Subject: [PATCH] merge ParallelUContext into SwappedContext, that can now run parallel or sequential --- src/kernel/context/ContextSwapped.cpp | 131 +++++++++++++++++--------- src/kernel/context/ContextUnix.cpp | 58 +----------- src/kernel/context/ContextUnix.hpp | 11 --- 3 files changed, 86 insertions(+), 114 deletions(-) diff --git a/src/kernel/context/ContextSwapped.cpp b/src/kernel/context/ContextSwapped.cpp index 2d53c8e4cf..e5cdd662b0 100644 --- a/src/kernel/context/ContextSwapped.cpp +++ b/src/kernel/context/ContextSwapped.cpp @@ -51,42 +51,6 @@ SwappedContextFactory::~SwappedContextFactory() { SwappedContext::finalize(); } -/** 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_) { - SwappedContext::threads_working_ = 0; - - // We lazily create the parmap so that all options are actually processed when doing so. - if (SwappedContext::parmap_ == nullptr) - SwappedContext::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. - SwappedContext::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; - 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(); - } -} void SwappedContext::initialize(bool parallel) { @@ -189,11 +153,68 @@ SwappedContext::~SwappedContext() xbt_free(stack_); } -/** Maestro wants to yield back to a given actor */ +void SwappedContext::stop() +{ + Context::stop(); + throw StopRequest(); +} + +/** 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_) { + SwappedContext::threads_working_ = 0; + + // We lazily create the parmap so that all options are actually processed when doing so. + if (SwappedContext::parmap_ == nullptr) + SwappedContext::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. + SwappedContext::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; + 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(); + } +} + +/** 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() { if (factory_->parallel_) { - THROW_IMPOSSIBLE; + // Save the thread number (my body) in an os-thread-specific area + worker_id_ = 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()); + 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 // Maestro is always the calling thread of this function (ie, self() == maestro) SwappedContext* old = static_cast(self()); @@ -202,11 +223,35 @@ void SwappedContext::resume() } } -/** The actor wants to yield back to maestro */ +/** 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 (factory_->parallel_) { - THROW_IMPOSSIBLE; + // Get some more work to directly swap into the next executable actor instead of yielding back to the parmap + boost::optional next_work = 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 processes to run"); + // worker_id_ is the identity of my body, stored in thread_local when starting the scheduling round + next_context = 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; @@ -227,12 +272,6 @@ void SwappedContext::suspend() } } -void SwappedContext::stop() -{ - Context::stop(); - throw StopRequest(); -} - } // namespace context } // namespace kernel } // namespace simgrid diff --git a/src/kernel/context/ContextUnix.cpp b/src/kernel/context/ContextUnix.cpp index 15cf789a31..35316d9cac 100644 --- a/src/kernel/context/ContextUnix.cpp +++ b/src/kernel/context/ContextUnix.cpp @@ -32,10 +32,7 @@ namespace context { // UContextFactory Context* UContextFactory::create_context(std::function code, void_pfn_smxprocess_t cleanup, smx_actor_t process) { - if (parallel_) - return new_context(std::move(code), cleanup, process, this); - else - return new_context(std::move(code), cleanup, process, this); + return new_context(std::move(code), cleanup, process, this); } @@ -116,59 +113,6 @@ void UContext::swap_into(SwappedContext* to_) ASAN_FINISH_SWITCH(fake_stack, &from->asan_ctx_->asan_stack_, &from->asan_ctx_->asan_stack_size_); } -// ParallelUContext - -/** Run one particular simulated process on the current thread. - * - * Only applied to the N first elements of the parmap array, where N is the amount of worker threads in the parmap. - * See ParallelUContext::run_all for details. - */ -void ParallelUContext::resume() -{ - // Save the thread number (my body) in an os-thread-specific area - worker_id_ = 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()); - 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. -} - -/** Yield - * - * This function is called when a simulated process wants to yield back to the maestro in a blocking 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 ParallelUContext::suspend() -{ - // Get some more work to directly swap into the next executable actor instead of yielding back to the parmap - boost::optional next_work = 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 processes to run"); - // worker_id_ is the identity of my body, stored in thread_local when starting the scheduling round - next_context = 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); -} XBT_PRIVATE ContextFactory* sysv_factory() { diff --git a/src/kernel/context/ContextUnix.hpp b/src/kernel/context/ContextUnix.hpp index d1aeff2e28..00c4832144 100644 --- a/src/kernel/context/ContextUnix.hpp +++ b/src/kernel/context/ContextUnix.hpp @@ -46,17 +46,6 @@ private: static void make_ctx(ucontext_t* ucp, void (*func)(int, int), UContext* arg); }; -class ParallelUContext : public UContext { -public: - ParallelUContext(std::function code, void_pfn_smxprocess_t cleanup_func, smx_actor_t process, - SwappedContextFactory* factory) - : UContext(std::move(code), cleanup_func, process, factory) - { - } - void suspend() override; - void resume() override; -}; - class UContextFactory : public SwappedContextFactory { public: UContextFactory() : SwappedContextFactory("UContextFactory") {} -- 2.20.1