/* a fast and simple context switching library */
-/* Copyright (c) 2004-2008 the SimGrid team. */
-/* All rights reserved. */
+/* Copyright (c) 2009, 2010. 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 "portable.h"
#include "xbt/log.h"
#include "xbt/swag.h"
-#include "private.h"
+#include "xbt/xbt_os_thread.h"
+#include "src/simix/private.h"
+#include "simix/context.h"
+#include "gras_config.h"
-XBT_LOG_NEW_DEFAULT_SUBCATEGORY(smx_context, simix, "Context switching mecanism");
+XBT_LOG_NEW_DEFAULT_SUBCATEGORY(simix_context, simix,
+ "Context switching mecanism");
+char* smx_context_factory_name = NULL; /* factory name specified by --cfg=contexts/factory:value */
+smx_ctx_factory_initializer_t smx_factory_initializer_to_use = NULL;
+int smx_context_stack_size = 128 * 1024;
-/**
- * This function is call by SIMIX_global_init() to initialize the context module.
+#ifdef HAVE_THREAD_LOCAL_STORAGE
+static __thread smx_context_t smx_current_context_parallel;
+#else
+static xbt_os_thread_key_t smx_current_context_key = 0;
+#endif
+static smx_context_t smx_current_context_serial;
+static int smx_parallel_contexts = 1;
+static int smx_parallel_threshold = 2;
+static e_xbt_parmap_mode_t smx_parallel_synchronization_mode = XBT_PARMAP_FUTEX;
+
+/**
+ * This function is called by SIMIX_global_init() to initialize the context module.
*/
void SIMIX_context_mod_init(void)
{
if (!simix_global->context_factory) {
- /* select context factory to use to create the context(depends of the macro definitions) */
-
-#ifdef CONTEXT_THREADS
- /* context switch based os thread */
- SIMIX_ctx_thread_factory_init(&simix_global->context_factory);
-#elif !defined(WIN32)
- /* context switch based ucontext */
- SIMIX_ctx_sysv_factory_init(&simix_global->context_factory);
+ /* select the context factory to use to create the contexts */
+ if (smx_factory_initializer_to_use) {
+ smx_factory_initializer_to_use(&simix_global->context_factory);
+ }
+ else { /* use the factory specified by --cfg=contexts/factory:value */
+
+ if (smx_context_factory_name == NULL) {
+ /* use the default factory */
+ #ifdef HAVE_RAWCTX
+ SIMIX_ctx_raw_factory_init(&simix_global->context_factory);
+ #elif CONTEXT_UCONTEXT
+ SIMIX_ctx_sysv_factory_init(&simix_global->context_factory);
+ #else
+ SIMIX_ctx_thread_factory_init(&simix_global->context_factory);
+ #endif
+ }
+ else if (!strcmp(smx_context_factory_name, "ucontext")) {
+ /* use ucontext */
+#ifdef CONTEXT_UCONTEXT
+ SIMIX_ctx_sysv_factory_init(&simix_global->context_factory);
+#else
+ xbt_die("The context factory 'ucontext' unavailable on your system");
+#endif
+ }
+ else if (!strcmp(smx_context_factory_name, "thread")) {
+ /* use os threads (either pthreads or windows ones) */
+ SIMIX_ctx_thread_factory_init(&simix_global->context_factory);
+ }
+ else if (!strcmp(smx_context_factory_name, "raw")) {
+ /* use raw contexts */
+ SIMIX_ctx_raw_factory_init(&simix_global->context_factory);
+ }
+ else {
+ XBT_ERROR("Invalid context factory specified. Valid factories on this machine:");
+#ifdef HAVE_RAWCTX
+ XBT_ERROR(" raw: high performance context factory implemented specifically for SimGrid");
#else
- /* context switch is not allowed on Windows */
-#error ERROR [__FILE__, line __LINE__]: no context based implementation specified.
+ XBT_ERROR(" (raw contextes are disabled at compilation time on this machine -- check configure logs for details)");
#endif
+#ifdef CONTEXT_UCONTEXT
+ XBT_ERROR(" ucontext: classical system V contextes (implemented with makecontext, swapcontext and friends)");
+#else
+ XBT_ERROR(" (ucontext is disabled at compilation time on this machine -- check configure logs for details)");
+#endif
+ XBT_ERROR(" thread: slow portability layer using system threads (pthreads on UNIX, CreateThread() on windows)");
+ xbt_die("Please use a valid factory.");
+ }
+ }
}
+
+#if defined(CONTEXT_THREADS) && !defined(HAVE_THREAD_LOCAL_STORAGE)
+ /* the __thread storage class is not available on this platform:
+ * use getspecific/setspecific instead to store the current context in each thread */
+ xbt_os_thread_key_create(&smx_current_context_key);
+#endif
}
/**
if (simix_global->context_factory) {
smx_pfn_context_factory_finalize_t finalize_factory;
- /* if there are living processes then kill them (except maestro) */
- if(simix_global->process_list != NULL)
- SIMIX_process_killall();
-
/* finalize the context factory */
finalize_factory = simix_global->context_factory->finalize;
- (*finalize_factory) (&simix_global->context_factory);
+ finalize_factory(&simix_global->context_factory);
}
+ xbt_dict_remove((xbt_dict_t) _surf_cfg_set,"contexts/factory");
}
/**
- * This function is used to change the context factory.
- * Warning: it destroy all the existing contexts
+ * \brief Returns whether some parallel threads are used
+ * for the user contexts.
+ * \return 1 if parallelism is used
*/
-int SIMIX_context_select_factory(const char *name)
-{
- /* if a factory is already instantiated (SIMIX_context_mod_init() was called) */
- if (simix_global->context_factory != NULL) {
- /* if the desired factory is different of the current factory, call SIMIX_context_mod_exit() */
- if (strcmp(simix_global->context_factory->name, name))
- SIMIX_context_mod_exit();
- else
- /* the same context factory is requested return directly */
- return 0;
- }
+XBT_INLINE int SIMIX_context_is_parallel(void) {
+ return smx_parallel_contexts > 1;
+}
+
+/**
+ * \brief Returns the number of parallel threads used
+ * for the user contexts.
+ * \return the number of threads (1 means no parallelism)
+ */
+XBT_INLINE int SIMIX_context_get_nthreads(void) {
+ return smx_parallel_contexts;
+}
+
+/**
+ * \brief Sets the number of parallel threads to use
+ * for the user contexts.
+ *
+ * This function should be called before initializing SIMIX.
+ * A value of 1 means no parallelism.
+ * If the value is greater than 1, the thread support must be enabled.
+ *
+ * \param nb_threads the number of threads to use
+ */
+XBT_INLINE void SIMIX_context_set_nthreads(int nb_threads) {
+
+ xbt_assert(nb_threads > 0, "Invalid number of parallel threads: %d", nb_threads);
- /* get the desired factory */
- SIMIX_context_init_factory_by_name(&simix_global->context_factory, name);
+ if (nb_threads > 1) {
+#ifndef CONTEXT_THREADS
+ THROWF(arg_error, 0, "No thread support for parallel context execution");
+#endif
+ }
- /* maestro process specialisation */
- simix_global->maestro_process->context = SIMIX_context_create_maestro ();
+ smx_parallel_contexts = nb_threads;
+}
- /* the current process is the process of the maestro */
- simix_global->current_process = simix_global->maestro_process;
+/**
+ * \brief Returns the threshold above which user processes are run in parallel.
+ *
+ * If the number of threads is set to 1, there is no parallelism and this
+ * threshold has no effect.
+ *
+ * \return when the number of user processes ready to run is above
+ * this threshold, they are run in parallel
+ */
+XBT_INLINE int SIMIX_context_get_parallel_threshold(void) {
+ return smx_parallel_threshold;
+}
- /* the current context doesn't want to die */
- simix_global->current_process->iwannadie = 0;
+/**
+ * \brief Sets the threshold above which user processes are run in parallel.
+ *
+ * If the number of threads is set to 1, there is no parallelism and this
+ * threshold has no effect.
+ *
+ * \param threshold when the number of user processes ready to run is above
+ * this threshold, they are run in parallel
+ */
+XBT_INLINE void SIMIX_context_set_parallel_threshold(int threshold) {
+ smx_parallel_threshold = threshold;
+}
- /* insert the current context in the list of the contexts in use */
- xbt_swag_insert(simix_global->current_process, simix_global->process_list);
+/**
+ * \brief Returns the synchronization mode used when processes are run in
+ * parallel.
+ * \return how threads are synchronized if processes are run in parallel
+ */
+XBT_INLINE e_xbt_parmap_mode_t SIMIX_context_get_parallel_mode(void) {
+ return smx_parallel_synchronization_mode;
+}
- return 0;
+/**
+ * \brief Sets the synchronization mode to use when processes are run in
+ * parallel.
+ * \param mode how to synchronize threads if processes are run in parallel
+ */
+XBT_INLINE void SIMIX_context_set_parallel_mode(e_xbt_parmap_mode_t mode) {
+ smx_parallel_synchronization_mode = mode;
}
/**
- * Initializes a context factory given by its name
+ * \brief Returns the current context of this thread.
+ * \return the current context of this thread
*/
-void SIMIX_context_init_factory_by_name(smx_context_factory_t * factory,
- const char *name)
+XBT_INLINE smx_context_t SIMIX_context_get_current(void)
{
- if (!strcmp(name, "java"))
-#ifdef HAVE_JAVA
- SIMIX_ctx_java_factory_init(factory);
-#else
- THROW0(not_found_error, 0, "Factory 'Java' does not exist: Java support was not compiled in the SimGrid library");
-#endif /* HAVE_JAVA */
-
- else if (!strcmp(name, "thread"))
-#ifdef CONTEXT_THREADS
- SIMIX_ctx_thread_factory_init(factory);
+ if (SIMIX_context_is_parallel()) {
+#ifdef HAVE_THREAD_LOCAL_STORAGE
+ return smx_current_context_parallel;
#else
- THROW0(not_found_error, 0, "Factory 'thread' does not exist: thread support was not compiled in the SimGrid library");
-#endif /* CONTEXT_THREADS */
-
- else if (!strcmp(name, "sysv"))
-#if !defined(WIN32) && !defined(CONTEXT_THREADS)
- SIMIX_ctx_sysv_factory_init(factory);
+ return xbt_os_thread_get_specific(smx_current_context_key);
+#endif
+ }
+ else {
+ return smx_current_context_serial;
+ }
+}
+
+/**
+ * \brief Sets the current context of this thread.
+ * \param context the context to set
+ */
+XBT_INLINE void SIMIX_context_set_current(smx_context_t context)
+{
+ if (SIMIX_context_is_parallel()) {
+#ifdef HAVE_THREAD_LOCAL_STORAGE
+ smx_current_context_parallel = context;
#else
- THROW0(not_found_error, 0, "Factory 'sysv' does not exist: no System V thread support under Windows");
-#endif
- else
- THROW1(not_found_error, 0, "Factory '%s' does not exist", name);
+ xbt_os_thread_set_specific(smx_current_context_key, context);
+#endif
+ }
+ else {
+ smx_current_context_serial = context;
+ }
}
+
