source: libcfa/src/concurrency/kernel.cfa@ c6c7e6c

ADT arm-eh ast-experimental enum forall-pointer-decay jacob/cs343-translation new-ast-unique-expr pthread-emulation qualifiedEnum stuck-waitfor-destruct
Last change on this file since c6c7e6c was c6c7e6c, checked in by Thierry Delisle <tdelisle@…>, 5 years ago

Seperated semphore and scheduling logic in unpark
  • Property mode set to 100644
File size: 25.3 KB
Line 
1//
2// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
3//
4// The contents of this file are covered under the licence agreement in the
5// file "LICENCE" distributed with Cforall.
6//
7// kernel.c --
8//
9// Author : Thierry Delisle
10// Created On : Tue Jan 17 12:27:26 2017
11// Last Modified By : Peter A. Buhr
12// Last Modified On : Mon Aug 31 07:08:20 2020
13// Update Count : 71
14//
15
16#define __cforall_thread__
17// #define __CFA_DEBUG_PRINT_RUNTIME_CORE__
18
19//C Includes
20#include <errno.h>
21#include <stdio.h>
22#include <signal.h>
23#include <unistd.h>
24extern "C" {
25 #include <sys/eventfd.h>
26}
27
28//CFA Includes
29#include "kernel_private.hfa"
30#include "preemption.hfa"
31
32//Private includes
33#define __CFA_INVOKE_PRIVATE__
34#include "invoke.h"
35
36
37//-----------------------------------------------------------------------------
38// Some assembly required
39#if defined( __i386 )
40 // mxcr : SSE Status and Control bits (control bits are preserved across function calls)
41 // fcw : X87 FPU control word (preserved across function calls)
42 #define __x87_store \
43 uint32_t __mxcr; \
44 uint16_t __fcw; \
45 __asm__ volatile ( \
46 "stmxcsr %0\n" \
47 "fnstcw %1\n" \
48 : "=m" (__mxcr),\
49 "=m" (__fcw) \
50 )
51
52 #define __x87_load \
53 __asm__ volatile ( \
54 "fldcw %1\n" \
55 "ldmxcsr %0\n" \
56 ::"m" (__mxcr),\
57 "m" (__fcw) \
58 )
59
60#elif defined( __x86_64 )
61 #define __x87_store \
62 uint32_t __mxcr; \
63 uint16_t __fcw; \
64 __asm__ volatile ( \
65 "stmxcsr %0\n" \
66 "fnstcw %1\n" \
67 : "=m" (__mxcr),\
68 "=m" (__fcw) \
69 )
70
71 #define __x87_load \
72 __asm__ volatile ( \
73 "fldcw %1\n" \
74 "ldmxcsr %0\n" \
75 :: "m" (__mxcr),\
76 "m" (__fcw) \
77 )
78
79#elif defined( __arm__ )
80 #define __x87_store
81 #define __x87_load
82
83#elif defined( __aarch64__ )
84 #define __x87_store \
85 uint32_t __fpcntl[2]; \
86 __asm__ volatile ( \
87 "mrs x9, FPCR\n" \
88 "mrs x10, FPSR\n" \
89 "stp x9, x10, %0\n" \
90 : "=m" (__fpcntl) : : "x9", "x10" \
91 )
92
93 #define __x87_load \
94 __asm__ volatile ( \
95 "ldp x9, x10, %0\n" \
96 "msr FPSR, x10\n" \
97 "msr FPCR, x9\n" \
98 : "=m" (__fpcntl) : : "x9", "x10" \
99 )
100
101#else
102 #error unsupported hardware architecture
103#endif
104
105extern $thread * mainThread;
106extern processor * mainProcessor;
107
108//-----------------------------------------------------------------------------
109// Kernel Scheduling logic
110static $thread * __next_thread(cluster * this);
111static $thread * __next_thread_slow(cluster * this);
112static inline bool __must_unpark( $thread * thrd ) __attribute((nonnull(1)));
113static void __run_thread(processor * this, $thread * dst);
114static void __wake_one(cluster * cltr);
115
116static void mark_idle (__cluster_proc_list & idles, processor & proc);
117static void mark_awake(__cluster_proc_list & idles, processor & proc);
118static [unsigned idle, unsigned total, * processor] query_idles( & __cluster_proc_list idles );
119
120extern void __cfa_io_start( processor * );
121extern bool __cfa_io_drain( processor * );
122extern void __cfa_io_flush( processor * );
123extern void __cfa_io_stop ( processor * );
124static inline bool __maybe_io_drain( processor * );
125
126extern void __disable_interrupts_hard();
127extern void __enable_interrupts_hard();
128
129//=============================================================================================
130// Kernel Scheduling logic
131//=============================================================================================
132//Main of the processor contexts
133void main(processorCtx_t & runner) {
134 // Because of a bug, we couldn't initialized the seed on construction
135 // Do it here
136 __cfaabi_tls.rand_seed ^= rdtscl();
137 __cfaabi_tls.ready_rng.fwd_seed = 25214903917_l64u * (rdtscl() ^ (uintptr_t)&runner);
138 __tls_rand_advance_bck();
139
140 processor * this = runner.proc;
141 verify(this);
142
143 __cfa_io_start( this );
144
145 __cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
146 #if !defined(__CFA_NO_STATISTICS__)
147 if( this->print_halts ) {
148 __cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->id, this->name, (void*)this);
149 }
150 #endif
151
152 {
153 // Setup preemption data
154 preemption_scope scope = { this };
155
156 #if !defined(__CFA_NO_STATISTICS__)
157 unsigned long long last_tally = rdtscl();
158 #endif
159
160 // if we need to run some special setup, now is the time to do it.
161 if(this->init.thrd) {
162 this->init.thrd->curr_cluster = this->cltr;
163 __run_thread(this, this->init.thrd);
164 }
165
166 __cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
167
168 $thread * readyThread = 0p;
169 MAIN_LOOP:
170 for() {
171 // Check if there is pending io
172 __maybe_io_drain( this );
173
174 // Try to get the next thread
175 readyThread = __next_thread( this->cltr );
176
177 if( !readyThread ) {
178 __cfa_io_flush( this );
179 readyThread = __next_thread_slow( this->cltr );
180 }
181
182 HALT:
183 if( !readyThread ) {
184 // Don't block if we are done
185 if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
186
187 #if !defined(__CFA_NO_STATISTICS__)
188 __tls_stats()->ready.sleep.halts++;
189 #endif
190
191 // Push self to idle stack
192 mark_idle(this->cltr->procs, * this);
193
194 // Confirm the ready-queue is empty
195 readyThread = __next_thread_slow( this->cltr );
196 if( readyThread ) {
197 // A thread was found, cancel the halt
198 mark_awake(this->cltr->procs, * this);
199
200 #if !defined(__CFA_NO_STATISTICS__)
201 __tls_stats()->ready.sleep.cancels++;
202 #endif
203
204 // continue the mai loop
205 break HALT;
206 }
207
208 #if !defined(__CFA_NO_STATISTICS__)
209 if(this->print_halts) {
210 __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->id, rdtscl());
211 }
212 #endif
213
214 __cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle);
215
216 __disable_interrupts_hard();
217 eventfd_t val;
218 eventfd_read( this->idle, &val );
219 __enable_interrupts_hard();
220
221 #if !defined(__CFA_NO_STATISTICS__)
222 if(this->print_halts) {
223 __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->id, rdtscl());
224 }
225 #endif
226
227 // We were woken up, remove self from idle
228 mark_awake(this->cltr->procs, * this);
229
230 // DON'T just proceed, start looking again
231 continue MAIN_LOOP;
232 }
233
234 /* paranoid */ verify( readyThread );
235
236 // Reset io dirty bit
237 this->io.dirty = false;
238
239 // We found a thread run it
240 __run_thread(this, readyThread);
241
242 // Are we done?
243 if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
244
245 #if !defined(__CFA_NO_STATISTICS__)
246 unsigned long long curr = rdtscl();
247 if(curr > (last_tally + 500000000)) {
248 __tally_stats(this->cltr->stats, __cfaabi_tls.this_stats);
249 last_tally = curr;
250 }
251 #endif
252
253 if(this->io.pending && !this->io.dirty) {
254 __cfa_io_flush( this );
255 }
256 }
257
258 __cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
259 }
260
261 __cfa_io_stop( this );
262
263 post( this->terminated );
264
265
266 if(this == mainProcessor) {
267 // HACK : the coroutine context switch expects this_thread to be set
268 // and it make sense for it to be set in all other cases except here
269 // fake it
270 __cfaabi_tls.this_thread = mainThread;
271 }
272
273 __cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
274}
275
276static int * __volatile_errno() __attribute__((noinline));
277static int * __volatile_errno() { asm(""); return &errno; }
278
279// KERNEL ONLY
280// runThread runs a thread by context switching
281// from the processor coroutine to the target thread
282static void __run_thread(processor * this, $thread * thrd_dst) {
283 /* paranoid */ verify( ! __preemption_enabled() );
284 /* paranoid */ verifyf( thrd_dst->state == Ready || thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
285 /* paranoid */ verifyf( thrd_dst->link.next == 0p, "Expected null got %p", thrd_dst->link.next );
286 __builtin_prefetch( thrd_dst->context.SP );
287
288 __cfadbg_print_safe(runtime_core, "Kernel : core %p running thread %p (%s)\n", this, thrd_dst, thrd_dst->self_cor.name);
289
290 $coroutine * proc_cor = get_coroutine(this->runner);
291
292 // set state of processor coroutine to inactive
293 verify(proc_cor->state == Active);
294 proc_cor->state = Blocked;
295
296 // Actually run the thread
297 RUNNING: while(true) {
298 thrd_dst->preempted = __NO_PREEMPTION;
299 thrd_dst->state = Active;
300
301 // Update global state
302 kernelTLS().this_thread = thrd_dst;
303
304 /* paranoid */ verify( ! __preemption_enabled() );
305 /* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
306 /* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
307 /* paranoid */ verify( thrd_dst->context.SP );
308 /* paranoid */ verify( thrd_dst->state != Halted );
309 /* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) < ((uintptr_t)__get_stack(thrd_dst->curr_cor)->base ) || thrd_dst->curr_cor == proc_cor, "ERROR : Destination $thread %p has been corrupted.\n StackPointer too small.\n", thrd_dst ); // add escape condition if we are setting up the processor
310 /* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) > ((uintptr_t)__get_stack(thrd_dst->curr_cor)->limit) || thrd_dst->curr_cor == proc_cor, "ERROR : Destination $thread %p has been corrupted.\n StackPointer too large.\n", thrd_dst ); // add escape condition if we are setting up the processor
311 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
312
313
314
315 // set context switch to the thread that the processor is executing
316 __cfactx_switch( &proc_cor->context, &thrd_dst->context );
317 // when __cfactx_switch returns we are back in the processor coroutine
318
319 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
320 /* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) > ((uintptr_t)__get_stack(thrd_dst->curr_cor)->limit), "ERROR : Destination $thread %p has been corrupted.\n StackPointer too large.\n", thrd_dst );
321 /* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) < ((uintptr_t)__get_stack(thrd_dst->curr_cor)->base ), "ERROR : Destination $thread %p has been corrupted.\n StackPointer too small.\n", thrd_dst );
322 /* paranoid */ verify( thrd_dst->context.SP );
323 /* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
324 /* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
325 /* paranoid */ verify( ! __preemption_enabled() );
326
327 // Reset global state
328 kernelTLS().this_thread = 0p;
329
330 // We just finished running a thread, there are a few things that could have happened.
331 // 1 - Regular case : the thread has blocked and now one has scheduled it yet.
332 // 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
333 // 4 - Preempted
334 // In case 1, we may have won a race so we can't write to the state again.
335 // In case 2, we lost the race so we now own the thread.
336
337 if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
338 // The thread was preempted, reschedule it and reset the flag
339 __schedule_thread( thrd_dst );
340 break RUNNING;
341 }
342
343 if(unlikely(thrd_dst->state == Halting)) {
344 // The thread has halted, it should never be scheduled/run again
345 // finish the thread
346 __thread_finish( thrd_dst );
347 break RUNNING;
348 }
349
350 /* paranoid */ verify( thrd_dst->state == Active );
351 thrd_dst->state = Blocked;
352
353 // set state of processor coroutine to active and the thread to inactive
354 int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
355 switch(old_ticket) {
356 case TICKET_RUNNING:
357 // This is case 1, the regular case, nothing more is needed
358 break RUNNING;
359 case TICKET_UNBLOCK:
360 #if !defined(__CFA_NO_STATISTICS__)
361 __tls_stats()->ready.threads.threads++;
362 __push_stat( __tls_stats(), __tls_stats()->ready.threads.threads, false, "Processor", this );
363 #endif
364 // This is case 2, the racy case, someone tried to run this thread before it finished blocking
365 // In this case, just run it again.
366 continue RUNNING;
367 default:
368 // This makes no sense, something is wrong abort
369 abort();
370 }
371 }
372
373 // Just before returning to the processor, set the processor coroutine to active
374 proc_cor->state = Active;
375
376 __cfadbg_print_safe(runtime_core, "Kernel : core %p finished running thread %p\n", this, thrd_dst);
377
378 #if !defined(__CFA_NO_STATISTICS__)
379 __tls_stats()->ready.threads.threads--;
380 __push_stat( __tls_stats(), __tls_stats()->ready.threads.threads, false, "Processor", this );
381 #endif
382
383 /* paranoid */ verify( ! __preemption_enabled() );
384}
385
386// KERNEL_ONLY
387void returnToKernel() {
388 /* paranoid */ verify( ! __preemption_enabled() );
389 $coroutine * proc_cor = get_coroutine(kernelTLS().this_processor->runner);
390 $thread * thrd_src = kernelTLS().this_thread;
391
392 #if !defined(__CFA_NO_STATISTICS__)
393 struct processor * last_proc = kernelTLS().this_processor;
394 #endif
395
396 // Run the thread on this processor
397 {
398 int local_errno = *__volatile_errno();
399 #if defined( __i386 ) || defined( __x86_64 )
400 __x87_store;
401 #endif
402 /* paranoid */ verify( proc_cor->context.SP );
403 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
404 __cfactx_switch( &thrd_src->context, &proc_cor->context );
405 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
406 #if defined( __i386 ) || defined( __x86_64 )
407 __x87_load;
408 #endif
409 *__volatile_errno() = local_errno;
410 }
411
412 #if !defined(__CFA_NO_STATISTICS__)
413 if(last_proc != kernelTLS().this_processor) {
414 __tls_stats()->ready.threads.migration++;
415 }
416 #endif
417
418 /* paranoid */ verify( ! __preemption_enabled() );
419 /* paranoid */ verifyf( ((uintptr_t)thrd_src->context.SP) < ((uintptr_t)__get_stack(thrd_src->curr_cor)->base ), "ERROR : Returning $thread %p has been corrupted.\n StackPointer too small.\n", thrd_src );
420 /* paranoid */ verifyf( ((uintptr_t)thrd_src->context.SP) > ((uintptr_t)__get_stack(thrd_src->curr_cor)->limit), "ERROR : Returning $thread %p has been corrupted.\n StackPointer too large.\n", thrd_src );
421}
422
423//-----------------------------------------------------------------------------
424// Scheduler routines
425// KERNEL ONLY
426void __schedule_thread( $thread * thrd ) {
427 /* paranoid */ verify( ! __preemption_enabled() );
428 /* paranoid */ verify( kernelTLS().this_proc_id );
429 /* paranoid */ verify( thrd );
430 /* paranoid */ verify( thrd->state != Halted );
431 /* paranoid */ verify( thrd->curr_cluster );
432 /* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
433 /* paranoid */ if( thrd->state == Blocked || thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
434 "Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
435 /* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
436 "Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
437 /* paranoid */ #endif
438 /* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
439 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
440
441
442 if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
443
444 // Dereference the thread now because once we push it, there is not guaranteed it's still valid.
445 struct cluster * cl = thrd->curr_cluster;
446
447 ready_schedule_lock();
448 // push the thread to the cluster ready-queue
449 push( cl, thrd );
450
451 // variable thrd is no longer safe to use
452
453 // wake the cluster using the save variable.
454 __wake_one( cl );
455 ready_schedule_unlock();
456
457 #if !defined(__CFA_NO_STATISTICS__)
458 if( kernelTLS().this_stats ) {
459 __tls_stats()->ready.threads.threads++;
460 __push_stat( __tls_stats(), __tls_stats()->ready.threads.threads, false, "Processor", kernelTLS().this_processor );
461 }
462 else {
463 __atomic_fetch_add(&cl->stats->ready.threads.threads, 1, __ATOMIC_RELAXED);
464 __push_stat( cl->stats, cl->stats->ready.threads.threads, true, "Cluster", cl );
465 }
466 #endif
467
468 /* paranoid */ verify( ! __preemption_enabled() );
469}
470
471// KERNEL ONLY
472static inline $thread * __next_thread(cluster * this) with( *this ) {
473 /* paranoid */ verify( ! __preemption_enabled() );
474 /* paranoid */ verify( kernelTLS().this_proc_id );
475
476 ready_schedule_lock();
477 $thread * thrd = pop_fast( this );
478 ready_schedule_unlock();
479
480 /* paranoid */ verify( kernelTLS().this_proc_id );
481 /* paranoid */ verify( ! __preemption_enabled() );
482 return thrd;
483}
484
485// KERNEL ONLY
486static inline $thread * __next_thread_slow(cluster * this) with( *this ) {
487 /* paranoid */ verify( ! __preemption_enabled() );
488 /* paranoid */ verify( kernelTLS().this_proc_id );
489
490 ready_schedule_lock();
491 $thread * thrd = pop_slow( this );
492 ready_schedule_unlock();
493
494 /* paranoid */ verify( kernelTLS().this_proc_id );
495 /* paranoid */ verify( ! __preemption_enabled() );
496 return thrd;
497}
498
499static inline bool __must_unpark( $thread * thrd ) {
500 int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
501 switch(old_ticket) {
502 case TICKET_RUNNING:
503 // Wake won the race, the thread will reschedule/rerun itself
504 return false;
505 case TICKET_BLOCKED:
506 /* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
507 /* paranoid */ verify( thrd->state == Blocked );
508 return true;
509 default:
510 // This makes no sense, something is wrong abort
511 abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
512 }
513}
514
515void unpark( $thread * thrd ) {
516 if( !thrd ) return;
517
518 if(__must_unpark(thrd)) {
519 /* paranoid */ verify( publicTLS_get(this_proc_id) );
520 disable_interrupts();
521
522 /* paranoid */ verify( ! __preemption_enabled() );
523
524 // Wake lost the race,
525 __schedule_thread( thrd );
526
527 /* paranoid */ verify( ! __preemption_enabled() );
528
529 enable_interrupts_noPoll();
530 /* paranoid */ verify( publicTLS_get(this_proc_id) );
531 }
532}
533
534void park( void ) {
535 /* paranoid */ verify( __preemption_enabled() );
536 disable_interrupts();
537 /* paranoid */ verify( ! __preemption_enabled() );
538 /* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
539
540 returnToKernel();
541
542 /* paranoid */ verify( ! __preemption_enabled() );
543 enable_interrupts( __cfaabi_dbg_ctx );
544 /* paranoid */ verify( __preemption_enabled() );
545
546}
547
548extern "C" {
549 // Leave the thread monitor
550 // last routine called by a thread.
551 // Should never return
552 void __cfactx_thrd_leave() {
553 $thread * thrd = active_thread();
554 $monitor * this = &thrd->self_mon;
555
556 // Lock the monitor now
557 lock( this->lock __cfaabi_dbg_ctx2 );
558
559 disable_interrupts();
560
561 /* paranoid */ verify( ! __preemption_enabled() );
562 /* paranoid */ verify( thrd->state == Active );
563 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
564 /* paranoid */ verify( kernelTLS().this_thread == thrd );
565 /* paranoid */ verify( thrd->context.SP );
566 /* paranoid */ verifyf( ((uintptr_t)thrd->context.SP) > ((uintptr_t)__get_stack(thrd->curr_cor)->limit), "ERROR : $thread %p has been corrupted.\n StackPointer too large.\n", thrd );
567 /* paranoid */ verifyf( ((uintptr_t)thrd->context.SP) < ((uintptr_t)__get_stack(thrd->curr_cor)->base ), "ERROR : $thread %p has been corrupted.\n StackPointer too small.\n", thrd );
568
569 thrd->state = Halting;
570 if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
571 if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
572 if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
573
574 // Leave the thread
575 returnToKernel();
576
577 // Control flow should never reach here!
578 abort();
579 }
580}
581
582// KERNEL ONLY
583bool force_yield( __Preemption_Reason reason ) {
584 /* paranoid */ verify( __preemption_enabled() );
585 disable_interrupts();
586 /* paranoid */ verify( ! __preemption_enabled() );
587
588 $thread * thrd = kernelTLS().this_thread;
589 /* paranoid */ verify(thrd->state == Active);
590
591 // SKULLDUGGERY: It is possible that we are preempting this thread just before
592 // it was going to park itself. If that is the case and it is already using the
593 // intrusive fields then we can't use them to preempt the thread
594 // If that is the case, abandon the preemption.
595 bool preempted = false;
596 if(thrd->link.next == 0p) {
597 preempted = true;
598 thrd->preempted = reason;
599 returnToKernel();
600 }
601
602 /* paranoid */ verify( ! __preemption_enabled() );
603 enable_interrupts_noPoll();
604 /* paranoid */ verify( __preemption_enabled() );
605
606 return preempted;
607}
608
609//=============================================================================================
610// Kernel Idle Sleep
611//=============================================================================================
612// Wake a thread from the front if there are any
613static void __wake_one(cluster * this) {
614 /* paranoid */ verify( ! __preemption_enabled() );
615 /* paranoid */ verify( ready_schedule_islocked() );
616
617 // Check if there is a sleeping processor
618 processor * p;
619 unsigned idle;
620 unsigned total;
621 [idle, total, p] = query_idles(this->procs);
622
623 // If no one is sleeping, we are done
624 if( idle == 0 ) return;
625
626 // We found a processor, wake it up
627 eventfd_t val;
628 val = 1;
629 eventfd_write( p->idle, val );
630
631 #if !defined(__CFA_NO_STATISTICS__)
632 if( kernelTLS().this_stats ) {
633 __tls_stats()->ready.sleep.wakes++;
634 }
635 else {
636 __atomic_fetch_add(&this->stats->ready.sleep.wakes, 1, __ATOMIC_RELAXED);
637 }
638 #endif
639
640 /* paranoid */ verify( ready_schedule_islocked() );
641 /* paranoid */ verify( ! __preemption_enabled() );
642
643 return;
644}
645
646// Unconditionnaly wake a thread
647void __wake_proc(processor * this) {
648 __cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
649
650 disable_interrupts();
651 /* paranoid */ verify( ! __preemption_enabled() );
652 eventfd_t val;
653 val = 1;
654 eventfd_write( this->idle, val );
655 enable_interrupts( __cfaabi_dbg_ctx );
656}
657
658static void mark_idle(__cluster_proc_list & this, processor & proc) {
659 /* paranoid */ verify( ! __preemption_enabled() );
660 lock( this );
661 this.idle++;
662 /* paranoid */ verify( this.idle <= this.total );
663 remove(proc);
664 insert_first(this.idles, proc);
665 unlock( this );
666 /* paranoid */ verify( ! __preemption_enabled() );
667}
668
669static void mark_awake(__cluster_proc_list & this, processor & proc) {
670 /* paranoid */ verify( ! __preemption_enabled() );
671 lock( this );
672 this.idle--;
673 /* paranoid */ verify( this.idle >= 0 );
674 remove(proc);
675 insert_last(this.actives, proc);
676 unlock( this );
677 /* paranoid */ verify( ! __preemption_enabled() );
678}
679
680static [unsigned idle, unsigned total, * processor] query_idles( & __cluster_proc_list this ) {
681 /* paranoid */ verify( ! __preemption_enabled() );
682 /* paranoid */ verify( ready_schedule_islocked() );
683
684 for() {
685 uint64_t l = __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST);
686 if( 1 == (l % 2) ) { Pause(); continue; }
687 unsigned idle = this.idle;
688 unsigned total = this.total;
689 processor * proc = &this.idles`first;
690 // Compiler fence is unnecessary, but gcc-8 and older incorrectly reorder code without it
691 asm volatile("": : :"memory");
692 if(l != __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST)) { Pause(); continue; }
693 return [idle, total, proc];
694 }
695
696 /* paranoid */ verify( ready_schedule_islocked() );
697 /* paranoid */ verify( ! __preemption_enabled() );
698}
699
700//=============================================================================================
701// Unexpected Terminating logic
702//=============================================================================================
703void __kernel_abort_msg( char * abort_text, int abort_text_size ) {
704 $thread * thrd = __cfaabi_tls.this_thread;
705
706 if(thrd) {
707 int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
708 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
709
710 if ( &thrd->self_cor != thrd->curr_cor ) {
711 len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
712 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
713 }
714 else {
715 __cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
716 }
717 }
718 else {
719 int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
720 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
721 }
722}
723
724int __kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
725 return get_coroutine(__cfaabi_tls.this_thread) == get_coroutine(mainThread) ? 4 : 2;
726}
727
728static __spinlock_t kernel_debug_lock;
729
730extern "C" {
731 void __cfaabi_bits_acquire() {
732 lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
733 }
734
735 void __cfaabi_bits_release() {
736 unlock( kernel_debug_lock );
737 }
738}
739
740//=============================================================================================
741// Kernel Utilities
742//=============================================================================================
743#if defined(CFA_HAVE_LINUX_IO_URING_H)
744#include "io/types.hfa"
745#endif
746
747static inline bool __maybe_io_drain( processor * proc ) {
748 #if defined(CFA_HAVE_LINUX_IO_URING_H)
749 __cfadbg_print_safe(runtime_core, "Kernel : core %p checking io for ring %d\n", proc, proc->io.ctx->fd);
750
751 // Check if we should drain the queue
752 $io_context * ctx = proc->io.ctx;
753 unsigned head = *ctx->cq.head;
754 unsigned tail = *ctx->cq.tail;
755 if(head == tail) return false;
756 return __cfa_io_drain( proc );
757 #endif
758}
759
760//-----------------------------------------------------------------------------
761// Debug
762__cfaabi_dbg_debug_do(
763 extern "C" {
764 void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
765 this.prev_name = prev_name;
766 this.prev_thrd = kernelTLS().this_thread;
767 }
768 }
769)
770
771//-----------------------------------------------------------------------------
772// Debug
773bool threading_enabled(void) __attribute__((const)) {
774 return true;
775}
776
777//-----------------------------------------------------------------------------
778// Statistics
779#if !defined(__CFA_NO_STATISTICS__)
780 void print_halts( processor & this ) {
781 this.print_halts = true;
782 }
783
784 void print_stats_now( cluster & this, int flags ) {
785 __print_stats( this.stats, this.print_stats, "Cluster", this.name, (void*)&this );
786 }
787#endif
788// Local Variables: //
789// mode: c //
790// tab-width: 4 //
791// End: //
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