1 /* a fast and simple context switching library */
3 /* Copyright (c) 2009, 2010. The SimGrid Team.
4 * All rights reserved. */
6 /* This program is free software; you can redistribute it and/or modify it
7 * under the terms of the license (GNU LGPL) which comes with this package. */
13 #include "simix/context.h"
14 #include "gras_config.h"
16 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(simix_context, simix,
17 "Context switching mecanism");
19 char* smx_context_factory_name = NULL; /* factory name specified by --cfg=contexts/factory:value */
20 smx_ctx_factory_initializer_t smx_factory_initializer_to_use = NULL;
21 int smx_context_stack_size = 128 * 1024;
23 #ifdef CONTEXT_THREADS
24 __thread smx_context_t smx_current_context;
26 smx_context_t smx_current_context;
29 static int smx_parallel_contexts = 1;
30 static int smx_parallel_threshold = 1;
33 * This function is called by SIMIX_global_init() to initialize the context module.
35 void SIMIX_context_mod_init(void)
37 if (!simix_global->context_factory) {
38 /* select the context factory to use to create the contexts */
39 if (smx_factory_initializer_to_use) {
40 (*smx_factory_initializer_to_use)(&(simix_global->context_factory));
42 else { /* use the factory specified by --cfg=contexts/factory:value */
43 if (smx_context_factory_name == NULL || !strcmp(smx_context_factory_name, "ucontext")) {
45 SIMIX_ctx_sysv_factory_init(&simix_global->context_factory);
47 else if (!strcmp(smx_context_factory_name, "thread")) {
48 /* use os threads (either pthreads or windows ones) */
49 SIMIX_ctx_thread_factory_init(&simix_global->context_factory);
51 else if (!strcmp(smx_context_factory_name, "raw")) {
52 /* use raw contexts */
53 SIMIX_ctx_raw_factory_init(&simix_global->context_factory);
56 xbt_die("Invalid context factory specified");
63 * This function is call by SIMIX_clean() to finalize the context module.
65 void SIMIX_context_mod_exit(void)
67 if (simix_global->context_factory) {
68 smx_pfn_context_factory_finalize_t finalize_factory;
70 /* finalize the context factory */
71 finalize_factory = simix_global->context_factory->finalize;
72 (*finalize_factory) (&simix_global->context_factory);
74 xbt_dict_remove((xbt_dict_t) _surf_cfg_set,"contexts/factory");
78 * \brief Sets the number of parallel threads to use
79 * for the user contexts.
81 * This function should be called before initializing SIMIX.
82 * A value of 1 means no parallelism.
83 * If the value is greater than 1, the thread support must be enabled.
85 * \param nb_threads the number of threads to use
87 XBT_INLINE void SIMIX_context_set_nthreads(int nb_threads) {
89 xbt_assert(nb_threads > 0, "Invalid number of parallel threads: %d", nb_threads);
92 #ifndef CONTEXT_THREADS
93 THROWF(arg_error, 0, "No thread support for parallel context execution");
97 smx_parallel_contexts = nb_threads;
101 * \brief Returns the number of parallel threads used
102 * for the user contexts.
103 * \return the number of threads (1 means no parallelism)
105 XBT_INLINE int SIMIX_context_get_nthreads(void) {
106 return smx_parallel_contexts;
110 * \brief Returns whether some parallel threads are used
111 * for the user contexts.
112 * \return 1 if parallelism is used
114 XBT_INLINE int SIMIX_context_is_parallel(void) {
115 return smx_parallel_contexts > 1;
119 * \brief Sets the threshold above which user processes are run in parallel.
121 * If the number of threads is set to 1, there is no parallelism and this
122 * threshold has no effect.
124 * \param threshold when the number of user processes ready to run is above
125 * this threshold, they are run in parallel
127 XBT_INLINE void SIMIX_context_set_parallel_threshold(int threshold) {
128 smx_parallel_threshold = threshold;
132 * \brief Returns the threshold above which user processes are run in parallel.
134 * If the number of threads is set to 1, there is no parallelism and this
135 * threshold has no effect.
137 * \return when the number of user processes ready to run is above
138 * this threshold, they are run in parallel
140 XBT_INLINE int SIMIX_context_get_parallel_threshold(void) {
141 return smx_parallel_threshold;