smx_ctx_sysv_suspend_parallel(context);
}
-static void smx_ctx_sysv_suspend_parallel(smx_context_t context)
-{
+/* This function is called by maestro at the beginning of a scheduling round to get all working threads executing some stuff
+ * It is much easier to understand what happens if you see the working threads as bodies that swap their soul for the
+ * ones of the simulated processes that must run.
+ */
+static void smx_ctx_sysv_runall_parallel(void) {
+#ifdef CONTEXT_THREADS
+ sysv_threads_working = 0;
+ // parmap_apply ensures that every working thread get an index in the process_to_run array (through an atomic fetch_and_add),
+ // and runs the smx_ctx_sysv_resume_parallel function on that index
+ xbt_parmap_apply(sysv_parmap, (void_f_pvoid_t) smx_ctx_sysv_resume_parallel,
+ simix_global->process_to_run);
+#else
+ xbt_die("You asked for a parallel execution, but you don't have any threads.");
+#endif
+}
+
+/* This function is in charge of running one particular simulated process on the current thread */
+static void smx_ctx_sysv_resume_parallel(smx_process_t simulated_process_to_run) {
+#ifdef CONTEXT_THREADS
+ unsigned long worker_id = __sync_fetch_and_add(&sysv_threads_working, 1); // what is my containing body?
+ xbt_os_thread_set_specific(sysv_worker_id_key, (void*) worker_id); // Store the number of my containing body in os-thread-specific area
+ smx_ctx_sysv_t worker_context = (smx_ctx_sysv_t)SIMIX_context_self(); // get my current soul
+ sysv_workers_context[worker_id] = worker_context; // write down that this soul is hosted in that body (for now)
+ ucontext_t* worker_stack = &worker_context->uc; // retrieves the system-level info that fuels this soul
+
+ smx_context_t context = simulated_process_to_run->context; // That's the first soul that I should become
+ SIMIX_context_set_current(context); // write in simix that I switched my soul
+ swapcontext(worker_stack, &((smx_ctx_sysv_t) context)->uc); // actually do that using the relevant syscall
+ // No body runs that soul anymore at this point. Instead the current body took the soul of simulated process
+ // The simulated process wakes back after the call to "SIMIX_context_suspend(self->context);" within smx_process.c::SIMIX_process_yield()
+
+ // From now on, the simulated processes will change their soul with the next soul to execute (in suspend_parallel, below).
+ // When nobody is to be executed in this scheduling round, the last simulated process will take back the initial soul of the current working thread
+#endif
+}
+
+/* This function is called when a simulated process wants to yield back to the maestro in a blocking simcall.
+ * This naturally occurs within SIMIX_context_suspend(self->context), called from SIMIX_process_yield()
+ * Actually, it does not really yield back to maestro, but into the next process that must be executed.
+ * If no one is to be executed, then it yields to the initial soul that was in this working thread (that was saved in resume_parallel).
+ */
+static void smx_ctx_sysv_suspend_parallel(smx_context_t context) {
#ifdef CONTEXT_THREADS
/* determine the next context */
- smx_process_t next_work = xbt_parmap_next(sysv_parmap);
+ smx_process_t next_work = xbt_parmap_next(sysv_parmap); // get the next soul to embody now
smx_context_t next_context;
- ucontext_t* next_stack;
+ ucontext_t* next_stack; // will contain the next soul to run, either simulated or initial minion's one
- if (next_work != NULL) {
- /* there is a next process to resume */
+ if (next_work != NULL) { // there is a next soul to embody (ie, a next process to resume)
XBT_DEBUG("Run next process");
next_context = next_work->context;
- next_stack = &((smx_ctx_sysv_t) next_context)->uc;
}
else {
/* all processes were run, go to the barrier */
XBT_DEBUG("No more processes to run");
- unsigned long worker_id =
+ unsigned long worker_id = // Get back the identity of my body that was stored when starting the scheduling round
(unsigned long) xbt_os_thread_get_specific(sysv_worker_id_key);
- next_context = (smx_context_t)sysv_workers_context[worker_id];
- next_stack = &((smx_ctx_sysv_t)next_context)->uc;
+ next_context = (smx_context_t)sysv_workers_context[worker_id]; // deduce the initial soul of that body
+ // When given that soul, the body will wait for the next scheduling round
}
- SIMIX_context_set_current(next_context);
- swapcontext(&((smx_ctx_sysv_t) context)->uc, next_stack);
-#endif
-}
-
-static void smx_ctx_sysv_resume_parallel(smx_process_t first_process)
-{
-#ifdef CONTEXT_THREADS
- unsigned long worker_id = __sync_fetch_and_add(&sysv_threads_working, 1);
- xbt_os_thread_set_specific(sysv_worker_id_key, (void*) worker_id);
- smx_ctx_sysv_t worker_context = (smx_ctx_sysv_t)SIMIX_context_self();
- sysv_workers_context[worker_id] = worker_context;
- ucontext_t* worker_stack = &worker_context->uc;
+ next_stack = &((smx_ctx_sysv_t)next_context)->uc;
- smx_context_t context = first_process->context;
- SIMIX_context_set_current(context);
- swapcontext(worker_stack, &((smx_ctx_sysv_t) context)->uc);
-#endif
-}
-
-static void smx_ctx_sysv_runall_parallel(void)
-{
-#ifdef CONTEXT_THREADS
- sysv_threads_working = 0;
- xbt_parmap_apply(sysv_parmap, (void_f_pvoid_t) smx_ctx_sysv_resume_parallel,
- simix_global->process_to_run);
+ SIMIX_context_set_current(next_context);
+ swapcontext(&((smx_ctx_sysv_t) context)->uc, next_stack); // get that next soul
#endif
}
