/* 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 <malloc.h>
+#include <windows.h>
+#else
+#include <sys/mman.h>
+#endif
+
+#ifdef __MINGW32__
+#define _aligned_malloc __mingw_aligned_malloc
+#define _aligned_free __mingw_aligned_free
+#endif /*MINGW*/
+
+#if HAVE_VALGRIND_H
+#include <valgrind/valgrind.h>
+#endif
XBT_LOG_EXTERNAL_DEFAULT_CATEGORY(simix_context);
namespace kernel {
namespace context {
-unsigned long SwappedContext::process_index_;
+/* Parallel execution */
+simgrid::xbt::Parmap<smx_actor_t>* SwappedContext::parmap_;
+std::atomic<uintptr_t> SwappedContext::threads_working_; /* number of threads that have started their work */
+thread_local uintptr_t SwappedContext::worker_id_; /* thread-specific storage for the thread id */
+std::vector<SwappedContext*> SwappedContext::workers_context_; /* space to save the worker's context in each thread */
+
+SwappedContextFactory::SwappedContextFactory(std::string name)
+ : ContextFactory(name), parallel_(SIMIX_context_is_parallel())
+{
+ SwappedContext::set_maestro(nullptr);
+ SwappedContext::initialize(parallel_);
+}
+SwappedContextFactory::~SwappedContextFactory()
+{
+ SwappedContext::finalize();
+}
+
+void SwappedContext::initialize(bool parallel)
+{
+ parmap_ = nullptr; // will be created lazily with the right parameters if needed (ie, in parallel)
+ if (parallel) {
+ workers_context_.clear();
+ workers_context_.resize(SIMIX_context_get_nthreads(), nullptr);
+ }
+}
+
+void SwappedContext::finalize()
+{
+ delete parmap_;
+ parmap_ = nullptr;
+ workers_context_.clear();
+}
SwappedContext* SwappedContext::maestro_context_ = nullptr;
-void SwappedContext::suspend()
+SwappedContext::SwappedContext(std::function<void()> 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::stop()
+{
+ Context::stop();
+ 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<SwappedContext*>(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<SwappedContext*>(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_) {
+ 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<smx_actor_t>(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<SwappedContext*>(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<SwappedContext*>(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<SwappedContext*>(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_ = 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<SwappedContext*>(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<SwappedContext*>(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<SwappedContext*>(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<smx_actor_t> 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<SwappedContext*>(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;
+ 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 process");
+ next_context = static_cast<SwappedContext*>(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<SwappedContext*>(get_maestro());
+ }
+ Context::set_current(next_context);
+ this->swap_into(next_context);
+ }
}
+
} // namespace context
} // namespace kernel
} // namespace simgrid
