/* a fast and simple context switching library */
-/* Copyright (c) 2009, 2010. The SimGrid Team.
+/* Copyright (c) 2009 - 2011. The SimGrid Team.
* All rights reserved. */
/* This program is free software; you can redistribute it and/or modify it
#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(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;
-smx_context_t smx_current_context;
+
+#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;
/**
* This function is called by SIMIX_global_init() to initialize the context module.
if (!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));
+ 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 || !strcmp(smx_context_factory_name, "ucontext")) {
+
+ 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_raw_factory_init(&simix_global->context_factory);
}
else {
- xbt_die("Invalid context factory specified");
+ 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
+ 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
}
/**
/* 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");
}
+
+/**
+ * \brief Returns whether some parallel threads are used
+ * for the user contexts.
+ * \return 1 if parallelism is used
+ */
+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);
+
+ if (nb_threads > 1) {
+#ifndef CONTEXT_THREADS
+ THROWF(arg_error, 0, "The thread factory cannot be run in parallel");
+#endif
+ }
+
+ smx_parallel_contexts = nb_threads;
+}
+
+/**
+ * \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;
+}
+
+/**
+ * \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;
+}
+
+/**
+ * \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) {
+ e_xbt_parmap_mode_t mode = XBT_PARMAP_FUTEX;
+ const char* mode_name = xbt_cfg_get_string(_surf_cfg_set, "contexts/synchro");
+ if (!strcmp(mode_name, "posix")) {
+ mode = XBT_PARMAP_POSIX;
+ }
+ else if (!strcmp(mode_name, "futex")) {
+ mode = XBT_PARMAP_FUTEX;
+ }
+ else if (!strcmp(mode_name, "busy_wait")) {
+ mode = XBT_PARMAP_BUSY_WAIT;
+ }
+ else {
+ XBT_WARN("Command line setting of the parallel synchronization mode should "
+ "be one of \"posix\", \"futex\" or \"busy_wait\"");
+ }
+ return mode;
+}
+
+/**
+ * \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) {
+ if (mode == XBT_PARMAP_POSIX) {
+ xbt_cfg_set_string(_surf_cfg_set, "contexts/synchro", "posix");
+ }
+ else if (mode == XBT_PARMAP_FUTEX) {
+ xbt_cfg_set_string(_surf_cfg_set, "contexts/synchro", "futex");
+ }
+ else if (XBT_PARMAP_BUSY_WAIT) {
+ xbt_cfg_set_string(_surf_cfg_set, "contexts/synchro", "busy_wait");
+ }
+ else {
+ XBT_WARN("Command line setting of the parallel synchronization mode should "
+ "be one of \"posix\", \"futex\" or \"busy_wait\"");
+ }
+}
+
+/**
+ * \brief Returns the current context of this thread.
+ * \return the current context of this thread
+ */
+XBT_INLINE smx_context_t SIMIX_context_get_current(void)
+{
+ if (SIMIX_context_is_parallel()) {
+#ifdef HAVE_THREAD_LOCAL_STORAGE
+ return smx_current_context_parallel;
+#else
+ 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
+ xbt_os_thread_set_specific(smx_current_context_key, context);
+#endif
+ }
+ else {
+ smx_current_context_serial = context;
+ }
+}
+
