/* a fast and simple context switching library */
-/* Copyright (c) 2009, 2010. The SimGrid Team.
+/* Copyright (c) 2009-2014. The SimGrid Team.
* All rights reserved. */
/* This program is free software; you can redistribute it and/or modify it
#include "xbt/log.h"
#include "xbt/swag.h"
#include "xbt/xbt_os_thread.h"
-#include "src/simix/private.h"
-#include "simix/context.h"
-#include "gras_config.h"
+#include "smx_private.h"
+#include "simgrid/sg_config.h"
+#include "internal_config.h"
+#include "simgrid/modelchecker.h"
+
+
+#ifdef _WIN32
+#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
+
+
+
+#ifdef HAVE_VALGRIND_VALGRIND_H
+# include <valgrind/valgrind.h>
+#endif
XBT_LOG_NEW_DEFAULT_SUBCATEGORY(simix_context, simix,
- "Context switching mecanism");
+ "Context switching mechanism");
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;
-
+int smx_context_stack_size;
+int smx_context_stack_size_was_set = 0;
+int smx_context_guard_size;
+int smx_context_guard_size_was_set = 0;
#ifdef HAVE_THREAD_LOCAL_STORAGE
-__thread smx_context_t smx_current_context;
+static __thread smx_context_t smx_current_context_parallel;
#else
-smx_context_t smx_current_context; /* define it anyway, will be used in non-parallel mode */
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 = 1;
+static int smx_parallel_threshold = 2;
+static e_xbt_parmap_mode_t smx_parallel_synchronization_mode = XBT_PARMAP_DEFAULT;
/**
* This function is called by SIMIX_global_init() to initialize the context module.
*/
void SIMIX_context_mod_init(void)
{
+#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) {
/* 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) {
- /* use the default factory */
-#ifdef CONTEXT_UCONTEXT
- SIMIX_ctx_sysv_factory_init(&simix_global->context_factory);
-#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);
-#endif
}
+#ifdef CONTEXT_UCONTEXT
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);
}
+#endif
+#ifdef HAVE_RAWCTX
else if (!strcmp(smx_context_factory_name, "raw")) {
- /* use raw contexts */
- SIMIX_ctx_raw_factory_init(&simix_global->context_factory);
+ /* use raw contexts */
+ SIMIX_ctx_raw_factory_init(&simix_global->context_factory);
}
+#endif
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 contexts are disabled at compilation time on this machine -- check configure logs for details)");
+#endif
+#ifdef CONTEXT_UCONTEXT
+ XBT_ERROR(" ucontext: classical system V contexts (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
}
/**
- * This function is call by SIMIX_clean() to finalize the context module.
+ * This function is called by SIMIX_clean() to finalize the context module.
*/
void SIMIX_context_mod_exit(void)
{
/* 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");
+ xbt_dict_remove((xbt_dict_t) _sg_cfg_set,"contexts/factory");
}
-/**
- * \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) {
+void *SIMIX_context_stack_new(void)
+{
+ void *stack;
- xbt_assert(nb_threads > 0, "Invalid number of parallel threads: %d", nb_threads);
+ /* FIXME: 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. */
- if (nb_threads > 1) {
-#ifndef CONTEXT_THREADS
- THROWF(arg_error, 0, "No thread support for parallel context execution");
+ if (smx_context_guard_size > 0 && !MC_is_active()) {
+
+#if defined(_XBT_WIN32) || (PTH_STACKGROWTH != -1)
+ static int warned_once = 0;
+ if (!warned_once) {
+ XBT_WARN("Stack overflow protection is known to be broken on your system. Either you're on Windows or PTH_STACKGROWTH != -1 (current value is %d).",
+ PTH_STACKGROWTH);
+ warned_once = 1;
+ }
+#endif
+
+ size_t size = smx_context_stack_size + smx_context_guard_size;
+#ifdef HAVE_MC
+ /* Cannot use posix_memalign when HAVE_MC. Align stack by hand, and save the
+ * pointer returned by xbt_malloc0. */
+ char *alloc = xbt_malloc0(size + xbt_pagesize);
+ stack = alloc - ((uintptr_t)alloc & (xbt_pagesize - 1)) + xbt_pagesize;
+ *((void **)stack - 1) = alloc;
+#elif !defined(_XBT_WIN32)
+ if (posix_memalign(&stack, xbt_pagesize, size) != 0)
+ xbt_die("Failed to allocate stack.");
+#else
+ stack = _aligned_malloc(size, xbt_pagesize);
+#endif
+
+#ifndef _XBT_WIN32
+ if (mprotect(stack, smx_context_guard_size, PROT_NONE) == -1) {
+ XBT_WARN("Failed to protect stack: %s", strerror(errno));
+ /* That's not fatal, pursue anyway. */
+ }
#endif
+ stack = (char *)stack + smx_context_guard_size;
+ } else {
+ stack = xbt_malloc0(smx_context_stack_size);
}
- smx_parallel_contexts = nb_threads;
+#ifdef HAVE_VALGRIND_VALGRIND_H
+ unsigned int valgrind_stack_id =
+ VALGRIND_STACK_REGISTER(stack, (char *)stack + smx_context_stack_size);
+ memcpy((char *)stack + smx_context_usable_stack_size, &valgrind_stack_id,
+ sizeof valgrind_stack_id);
+#endif
+
+ return stack;
+}
+
+void SIMIX_context_stack_delete(void *stack)
+{
+ if (!stack)
+ return;
+
+#ifdef HAVE_VALGRIND_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 && !MC_is_active()) {
+ stack = (char *)stack - smx_context_guard_size;
+ if (mprotect(stack, smx_context_guard_size,
+ PROT_READ | PROT_WRITE | PROT_EXEC) == -1) {
+ XBT_WARN("Failed to remove page protection: %s", strerror(errno));
+ /* try to pursue anyway */
+ }
+#ifdef HAVE_MC
+ /* Retrieve the saved pointer. See SIMIX_context_stack_new above. */
+ stack = *((void **)stack - 1);
+#endif
+ }
+#endif
+
+ xbt_free(stack);
+}
+
+/**
+ * \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 whether some parallel threads are used
+ * \brief Sets the number of parallel threads to use
* for the user contexts.
- * \return 1 if parallelism is used
+ *
+ * This function should be called before initializing SIMIX.
+ * A value of 1 means no parallelism (1 thread only).
+ * If the value is greater than 1, the thread support must be enabled.
+ *
+ * \param nb_threads the number of threads to use
*/
-XBT_INLINE int SIMIX_context_is_parallel(void) {
- return smx_parallel_contexts > 1;
+void SIMIX_context_set_nthreads(int nb_threads) {
+ if (nb_threads<=0) {
+ nb_threads = xbt_os_get_numcores();
+ XBT_INFO("Auto-setting contexts/nthreads to %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 Sets the threshold above which user processes are run in parallel.
+ * \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.
*
- * \param threshold when the number of user processes ready to run is above
+ * \return 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;
+XBT_INLINE int SIMIX_context_get_parallel_threshold(void) {
+ return smx_parallel_threshold;
}
/**
- * \brief Returns the threshold above which user processes are run in parallel.
+ * \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.
*
- * \return when the number of user processes ready to run is above
+ * \param threshold 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;
+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) {
+ return smx_parallel_synchronization_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) {
+ smx_parallel_synchronization_mode = mode;
}
/**
*/
XBT_INLINE smx_context_t SIMIX_context_get_current(void)
{
+ if (SIMIX_context_is_parallel()) {
#ifdef HAVE_THREAD_LOCAL_STORAGE
- return smx_current_context;
+ return smx_current_context_parallel;
#else
- return xbt_os_thread_get_specific(smx_current_context_key);
+ return xbt_os_thread_get_specific(smx_current_context_key);
#endif
+ }
+ else {
+ return smx_current_context_serial;
+ }
}
/**
*/
XBT_INLINE void SIMIX_context_set_current(smx_context_t context)
{
+ if (SIMIX_context_is_parallel()) {
#ifdef HAVE_THREAD_LOCAL_STORAGE
- smx_current_context = context;
+ smx_current_context_parallel = context;
#else
- xbt_os_thread_set_specific(smx_current_context_key, context);
+ xbt_os_thread_set_specific(smx_current_context_key, context);
#endif
+ }
+ else {
+ smx_current_context_serial = context;
+ }
}
-
