1 /* Copyright (c) 2009-2015. The SimGrid Team.
2 * All rights reserved. */
4 /* This program is free software; you can redistribute it and/or modify it
5 * under the terms of the license (GNU LGPL) which comes with this package. */
7 /** \file RawContext.cpp
8 * Fast context switching inspired from SystemV ucontexts.
10 * In contrast to System V context, it does not touch the signal mask
11 * which avoids making a system call (at least on Linux).
19 #include "src/internal_config.h"
22 #include "xbt/parmap.h"
23 #include "xbt/dynar.h"
25 #include "smx_private.h"
26 #include "smx_private.hpp"
29 XBT_LOG_EXTERNAL_DEFAULT_CATEGORY(simix_context);
31 // ***** Class definitions
37 class RawContextFactory;
39 class RawContext : public Context {
41 void* stack_ = nullptr;
42 /** pointer to top the stack stack */
43 void* stack_top_ = nullptr;
45 friend class RawContextFactory;
46 RawContext(std::function<void()> code,
47 void_pfn_smxprocess_t cleanup_func,
48 smx_process_t process);
51 static void wrapper(void* arg);
53 void suspend() override;
56 void suspend_serial();
57 void suspend_parallel();
59 void resume_parallel();
62 class RawContextFactory : public ContextFactory {
66 RawContext* create_context(std::function<void()> code,
67 void_pfn_smxprocess_t, smx_process_t process) override;
68 void run_all() override;
70 void run_all_adaptative();
71 void run_all_serial();
72 void run_all_parallel();
75 ContextFactory* raw_factory()
77 XBT_VERB("Using raw contexts. Because the glibc is just not good enough for us.");
78 return new RawContextFactory();
84 // ***** Loads of static stuff
86 #if HAVE_THREAD_CONTEXTS
87 static xbt_parmap_t raw_parmap;
88 static simgrid::simix::RawContext** raw_workers_context; /* space to save the worker context in each thread */
89 static uintptr_t raw_threads_working; /* number of threads that have started their work */
90 static xbt_os_thread_key_t raw_worker_id_key; /* thread-specific storage for the thread id */
92 static unsigned long raw_process_index = 0; /* index of the next process to run in the
93 * list of runnable processes */
94 static simgrid::simix::RawContext* raw_maestro_context;
96 static bool raw_context_parallel = false;
98 // ***** Raw context routines
100 typedef void (*rawctx_entry_point_t)(void *);
102 typedef void* raw_stack_t;
103 extern "C" raw_stack_t raw_makecontext(void* malloced_stack, int stack_size,
104 rawctx_entry_point_t entry_point, void* arg);
105 extern "C" void raw_swapcontext(raw_stack_t* old, raw_stack_t new_context);
107 // TODO, we should handle FP, MMX and the x87 control-word (for x86 and x86_64)
109 #if SIMGRID_PROCESSOR_x86_64
111 #if defined(__APPLE__)
113 ".globl _raw_makecontext\n"
114 "_raw_makecontext:\n"
115 #elif defined(_WIN32)
117 ".globl raw_makecontext\n"
121 ".globl raw_makecontext\n"
122 ".type raw_makecontext,@function\n"
123 "raw_makecontext:\n"/* Calling convention sets the arguments in rdi, rsi, rdx and rcx, respectively */
125 " mov %rdi,%rax\n" /* stack */
126 " add %rsi,%rax\n" /* size */
127 " andq $-16, %rax\n" /* align stack */
128 " movq $0, -8(%rax)\n" /* @return for func */
129 " mov %rdx,-16(%rax)\n" /* func */
130 " mov %rcx,-24(%rax)\n" /* arg/rdi */
131 " movq $0, -32(%rax)\n" /* rsi */
132 " movq $0, -40(%rax)\n" /* rdx */
133 " movq $0, -48(%rax)\n" /* rcx */
134 " movq $0, -56(%rax)\n" /* r8 */
135 " movq $0, -64(%rax)\n" /* r9 */
136 " movq $0, -72(%rax)\n" /* rbp */
137 " movq $0, -80(%rax)\n" /* rbx */
138 " movq $0, -88(%rax)\n" /* r12 */
139 " movq $0, -96(%rax)\n" /* r13 */
140 " movq $0, -104(%rax)\n" /* r14 */
141 " movq $0, -112(%rax)\n" /* r15 */
147 #if defined(__APPLE__)
149 ".globl _raw_swapcontext\n"
150 "_raw_swapcontext:\n"
151 #elif defined(_WIN32)
153 ".globl raw_swapcontext\n"
157 ".globl raw_swapcontext\n"
158 ".type raw_swapcontext,@function\n"
159 "raw_swapcontext:\n" /* Calling convention sets the arguments in rdi and rsi, respectively */
173 " mov %rsp,(%rdi)\n" /* old */
174 " mov %rsi,%rsp\n" /* new */
189 #elif SIMGRID_PROCESSOR_i686
191 #if defined(__APPLE__) || defined(_WIN32)
193 ".globl _raw_makecontext\n"
194 "_raw_makecontext:\n"
197 ".globl raw_makecontext\n"
198 ".type raw_makecontext,@function\n"
201 " movl 4(%esp),%eax\n" /* stack */
202 " addl 8(%esp),%eax\n" /* size */
203 " andl $-16, %eax\n" /* align stack */
204 " movl 12(%esp),%ecx\n" /* func */
205 " movl 16(%esp),%edx\n" /* arg */
206 " movl %edx, -4(%eax)\n"
207 " movl $0, -8(%eax)\n" /* @return for func */
208 " movl %ecx,-12(%eax)\n"
209 " movl $0, -16(%eax)\n" /* ebp */
210 " movl $0, -20(%eax)\n" /* ebx */
211 " movl $0, -24(%eax)\n" /* esi */
212 " movl $0, -28(%eax)\n" /* edi */
218 #if defined(__APPLE__) || defined(_WIN32)
220 ".globl _raw_swapcontext\n"
221 "_raw_swapcontext:\n"
224 ".globl raw_swapcontext\n"
225 ".type raw_swapcontext,@function\n"
228 // Fetch the parameters:
229 " movl 4(%esp),%eax\n" /* old (raw_stack_t*) */
230 " movl 8(%esp),%edx\n" /* new (raw_stack_t) */
231 // Save registers of the current context on the stack:
236 // Save the current context (stack pointer) in *old:
237 " movl %esp,(%eax)\n"
238 // Switch to the stack of the new context:
240 // Pop the values of the new context:
245 // Return using the return address of the new context:
251 /* If you implement raw contexts for other processors, don't forget to
252 update the definition of HAVE_RAW_CONTEXTS in tools/cmake/CompleteInFiles.cmake */
254 raw_stack_t raw_makecontext(void* malloced_stack, int stack_size,
255 rawctx_entry_point_t entry_point, void* arg) {
259 void raw_swapcontext(raw_stack_t* old, raw_stack_t new_context) {
265 // ***** Method definitions
270 RawContextFactory::RawContextFactory()
271 : ContextFactory("RawContextFactory")
273 raw_context_parallel = SIMIX_context_is_parallel();
274 if (raw_context_parallel) {
275 #if HAVE_THREAD_CONTEXTS
276 int nthreads = SIMIX_context_get_nthreads();
277 xbt_os_thread_key_create(&raw_worker_id_key);
279 raw_parmap = nullptr;
280 raw_workers_context = xbt_new(RawContext*, nthreads);
281 raw_maestro_context = nullptr;
283 // TODO, if(SIMIX_context_get_parallel_threshold() > 1) => choose dynamically
287 RawContextFactory::~RawContextFactory()
289 #if HAVE_THREAD_CONTEXTS
291 xbt_parmap_destroy(raw_parmap);
292 xbt_free(raw_workers_context);
296 RawContext* RawContextFactory::create_context(std::function<void()> code,
297 void_pfn_smxprocess_t cleanup, smx_process_t process)
299 return this->new_context<RawContext>(std::move(code),
303 void RawContext::wrapper(void* arg)
305 RawContext* context = (RawContext*) arg;
310 RawContext::RawContext(std::function<void()> code,
311 void_pfn_smxprocess_t cleanup, smx_process_t process)
312 : Context(std::move(code), cleanup, process)
315 this->stack_ = SIMIX_context_stack_new();
316 this->stack_top_ = raw_makecontext(this->stack_,
317 smx_context_usable_stack_size,
321 if(process != nullptr && raw_maestro_context == nullptr)
322 raw_maestro_context = this;
325 &raw_maestro_context->stack_top_,
326 sizeof(raw_maestro_context->stack_top_));
330 RawContext::~RawContext()
332 SIMIX_context_stack_delete(this->stack_);
335 void RawContext::stop()
341 void RawContextFactory::run_all()
343 if (raw_context_parallel)
349 void RawContextFactory::run_all_serial()
351 smx_process_t first_process =
352 xbt_dynar_get_as(simix_global->process_to_run, 0, smx_process_t);
353 raw_process_index = 1;
354 static_cast<RawContext*>(first_process->context)->resume_serial();
357 void RawContextFactory::run_all_parallel()
359 #if HAVE_THREAD_CONTEXTS
360 raw_threads_working = 0;
361 if (raw_parmap == nullptr)
362 raw_parmap = xbt_parmap_new(
363 SIMIX_context_get_nthreads(), SIMIX_context_get_parallel_mode());
364 xbt_parmap_apply(raw_parmap,
366 smx_process_t process = static_cast<smx_process_t>(arg);
367 RawContext* context = static_cast<RawContext*>(process->context);
368 context->resume_parallel();
370 simix_global->process_to_run);
372 xbt_die("You asked for a parallel execution, but you don't have any threads.");
376 void RawContext::suspend()
378 if (raw_context_parallel)
379 RawContext::suspend_parallel();
381 RawContext::suspend_serial();
384 void RawContext::suspend_serial()
386 /* determine the next context */
387 RawContext* next_context = nullptr;
389 i = raw_process_index++;
390 if (i < xbt_dynar_length(simix_global->process_to_run)) {
391 /* execute the next process */
392 XBT_DEBUG("Run next process");
393 next_context = (RawContext*) xbt_dynar_get_as(
394 simix_global->process_to_run, i, smx_process_t)->context;
397 /* all processes were run, return to maestro */
398 XBT_DEBUG("No more process to run");
399 next_context = (RawContext*) raw_maestro_context;
401 SIMIX_context_set_current(next_context);
402 raw_swapcontext(&this->stack_top_, next_context->stack_top_);
405 void RawContext::suspend_parallel()
407 #if HAVE_THREAD_CONTEXTS
408 /* determine the next context */
409 smx_process_t next_work = (smx_process_t) xbt_parmap_next(raw_parmap);
410 RawContext* next_context = nullptr;
412 if (next_work != NULL) {
413 /* there is a next process to resume */
414 XBT_DEBUG("Run next process");
415 next_context = (RawContext*) next_work->context;
418 /* all processes were run, go to the barrier */
419 XBT_DEBUG("No more processes to run");
420 uintptr_t worker_id = (uintptr_t)
421 xbt_os_thread_get_specific(raw_worker_id_key);
422 next_context = (RawContext*) raw_workers_context[worker_id];
423 XBT_DEBUG("Restoring worker stack %zu (working threads = %zu)",
424 worker_id, raw_threads_working);
427 SIMIX_context_set_current(next_context);
428 raw_swapcontext(&this->stack_top_, next_context->stack_top_);
432 void RawContext::resume()
434 if (raw_context_parallel)
440 void RawContext::resume_serial()
442 SIMIX_context_set_current(this);
443 raw_swapcontext(&raw_maestro_context->stack_top_, this->stack_top_);
446 void RawContext::resume_parallel()
448 #if HAVE_THREAD_CONTEXTS
449 uintptr_t worker_id = __sync_fetch_and_add(&raw_threads_working, 1);
450 xbt_os_thread_set_specific(raw_worker_id_key, (void*) worker_id);
451 RawContext* worker_context = (RawContext*) SIMIX_context_self();
452 raw_workers_context[worker_id] = worker_context;
453 XBT_DEBUG("Saving worker stack %zu", worker_id);
454 SIMIX_context_set_current(this);
455 raw_swapcontext(&worker_context->stack_top_, this->stack_top_);
457 xbt_die("Parallel execution disabled");
461 /** @brief Resumes all processes ready to run. */
462 void RawContextFactory::run_all_adaptative()
464 unsigned long nb_processes = xbt_dynar_length(simix_global->process_to_run);
465 if (SIMIX_context_is_parallel()
466 && (unsigned long) SIMIX_context_get_parallel_threshold() < nb_processes) {
467 raw_context_parallel = true;
468 XBT_DEBUG("Runall // %lu", nb_processes);
469 this->run_all_parallel();
471 XBT_DEBUG("Runall serial %lu", nb_processes);
472 raw_context_parallel = false;
473 this->run_all_serial();