source: libcfa/src/concurrency/kernel.cfa@ c60e5094

ADT ast-experimental enum forall-pointer-decay pthread-emulation qualifiedEnum
Last change on this file since c60e5094 was a633f6f, checked in by Thierry Delisle <tdelisle@…>, 4 years ago

Fix the new FD change.
  • Property mode set to 100644
File size: 29.9 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 _GNU_SOURCE
18
19// #define __CFA_DEBUG_PRINT_RUNTIME_CORE__
20
21//C Includes
22#include <errno.h>
23#include <stdio.h>
24#include <string.h>
25#include <signal.h>
26#include <unistd.h>
27extern "C" {
28 #include <sys/eventfd.h>
29}
30
31//CFA Includes
32#include "kernel_private.hfa"
33#include "preemption.hfa"
34#include "strstream.hfa"
35#include "device/cpu.hfa"
36
37//Private includes
38#define __CFA_INVOKE_PRIVATE__
39#include "invoke.h"
40
41#if !defined(__CFA_NO_STATISTICS__)
42 #define __STATS( ...) __VA_ARGS__
43#else
44 #define __STATS( ...)
45#endif
46
47//-----------------------------------------------------------------------------
48// Some assembly required
49#if defined( __i386 )
50 // mxcr : SSE Status and Control bits (control bits are preserved across function calls)
51 // fcw : X87 FPU control word (preserved across function calls)
52 #define __x87_store \
53 uint32_t __mxcr; \
54 uint16_t __fcw; \
55 __asm__ volatile ( \
56 "stmxcsr %0\n" \
57 "fnstcw %1\n" \
58 : "=m" (__mxcr),\
59 "=m" (__fcw) \
60 )
61
62 #define __x87_load \
63 __asm__ volatile ( \
64 "fldcw %1\n" \
65 "ldmxcsr %0\n" \
66 ::"m" (__mxcr),\
67 "m" (__fcw) \
68 )
69
70#elif defined( __x86_64 )
71 #define __x87_store \
72 uint32_t __mxcr; \
73 uint16_t __fcw; \
74 __asm__ volatile ( \
75 "stmxcsr %0\n" \
76 "fnstcw %1\n" \
77 : "=m" (__mxcr),\
78 "=m" (__fcw) \
79 )
80
81 #define __x87_load \
82 __asm__ volatile ( \
83 "fldcw %1\n" \
84 "ldmxcsr %0\n" \
85 :: "m" (__mxcr),\
86 "m" (__fcw) \
87 )
88
89#elif defined( __arm__ )
90 #define __x87_store
91 #define __x87_load
92
93#elif defined( __aarch64__ )
94 #define __x87_store \
95 uint32_t __fpcntl[2]; \
96 __asm__ volatile ( \
97 "mrs x9, FPCR\n" \
98 "mrs x10, FPSR\n" \
99 "stp x9, x10, %0\n" \
100 : "=m" (__fpcntl) : : "x9", "x10" \
101 )
102
103 #define __x87_load \
104 __asm__ volatile ( \
105 "ldp x9, x10, %0\n" \
106 "msr FPSR, x10\n" \
107 "msr FPCR, x9\n" \
108 : "=m" (__fpcntl) : : "x9", "x10" \
109 )
110
111#else
112 #error unsupported hardware architecture
113#endif
114
115extern thread$ * mainThread;
116extern processor * mainProcessor;
117
118//-----------------------------------------------------------------------------
119// Kernel Scheduling logic
120static thread$ * __next_thread(cluster * this);
121static thread$ * __next_thread_slow(cluster * this);
122static inline bool __must_unpark( thread$ * thrd ) __attribute((nonnull(1)));
123static void __run_thread(processor * this, thread$ * dst);
124static void __wake_one(cluster * cltr);
125
126static bool mark_idle (__cluster_proc_list & idles, processor & proc);
127static void mark_awake(__cluster_proc_list & idles, processor & proc);
128
129extern void __cfa_io_start( processor * );
130extern bool __cfa_io_drain( processor * );
131extern void __cfa_io_flush( processor * );
132extern void __cfa_io_stop ( processor * );
133static inline bool __maybe_io_drain( processor * );
134
135extern void __disable_interrupts_hard();
136extern void __enable_interrupts_hard();
137
138static inline void __disable_interrupts_checked() {
139 /* paranoid */ verify( __preemption_enabled() );
140 disable_interrupts();
141 /* paranoid */ verify( ! __preemption_enabled() );
142}
143
144static inline void __enable_interrupts_checked( bool poll = true ) {
145 /* paranoid */ verify( ! __preemption_enabled() );
146 enable_interrupts( poll );
147 /* paranoid */ verify( __preemption_enabled() );
148}
149
150//=============================================================================================
151// Kernel Scheduling logic
152//=============================================================================================
153//Main of the processor contexts
154void main(processorCtx_t & runner) {
155 // Because of a bug, we couldn't initialized the seed on construction
156 // Do it here
157 __cfaabi_tls.rand_seed ^= rdtscl();
158 __cfaabi_tls.ready_rng.fwd_seed = 25214903917_l64u * (rdtscl() ^ (uintptr_t)&runner);
159 __tls_rand_advance_bck();
160
161 processor * this = runner.proc;
162 verify(this);
163
164 __cfa_io_start( this );
165
166 __cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
167 #if !defined(__CFA_NO_STATISTICS__)
168 if( this->print_halts ) {
169 __cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->unique_id, this->name, (void*)this);
170 }
171 #endif
172
173 {
174 // Setup preemption data
175 preemption_scope scope = { this };
176
177 // if we need to run some special setup, now is the time to do it.
178 if(this->init.thrd) {
179 this->init.thrd->curr_cluster = this->cltr;
180 __run_thread(this, this->init.thrd);
181 }
182
183 __cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
184
185 thread$ * readyThread = 0p;
186 MAIN_LOOP:
187 for() {
188 #define OLD_MAIN 1
189 #if OLD_MAIN
190 // Check if there is pending io
191 __maybe_io_drain( this );
192
193 // Try to get the next thread
194 readyThread = __next_thread( this->cltr );
195
196 if( !readyThread ) {
197 ready_schedule_lock();
198 __cfa_io_flush( this );
199 ready_schedule_unlock();
200
201 readyThread = __next_thread_slow( this->cltr );
202 }
203
204 HALT:
205 if( !readyThread ) {
206 // Don't block if we are done
207 if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
208
209 #if !defined(__CFA_NO_STATISTICS__)
210 __tls_stats()->ready.sleep.halts++;
211 #endif
212
213 // Push self to idle stack
214 if(!mark_idle(this->cltr->procs, * this)) continue MAIN_LOOP;
215
216 // Confirm the ready-queue is empty
217 readyThread = __next_thread_slow( this->cltr );
218 if( readyThread ) {
219 // A thread was found, cancel the halt
220 mark_awake(this->cltr->procs, * this);
221
222 #if !defined(__CFA_NO_STATISTICS__)
223 __tls_stats()->ready.sleep.cancels++;
224 #endif
225
226 // continue the mai loop
227 break HALT;
228 }
229
230 #if !defined(__CFA_NO_STATISTICS__)
231 if(this->print_halts) {
232 __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->unique_id, rdtscl());
233 }
234 #endif
235
236 __cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle);
237
238 {
239 eventfd_t val;
240 ssize_t ret = read( this->idle, &val, sizeof(val) );
241 if(ret < 0) {
242 switch((int)errno) {
243 case EAGAIN:
244 #if EAGAIN != EWOULDBLOCK
245 case EWOULDBLOCK:
246 #endif
247 case EINTR:
248 // No need to do anything special here, just assume it's a legitimate wake-up
249 break;
250 default:
251 abort( "KERNEL : internal error, read failure on idle eventfd, error(%d) %s.", (int)errno, strerror( (int)errno ) );
252 }
253 }
254 }
255
256 #if !defined(__CFA_NO_STATISTICS__)
257 if(this->print_halts) {
258 __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->unique_id, rdtscl());
259 }
260 #endif
261
262 // We were woken up, remove self from idle
263 mark_awake(this->cltr->procs, * this);
264
265 // DON'T just proceed, start looking again
266 continue MAIN_LOOP;
267 }
268
269 /* paranoid */ verify( readyThread );
270
271 // Reset io dirty bit
272 this->io.dirty = false;
273
274 // We found a thread run it
275 __run_thread(this, readyThread);
276
277 // Are we done?
278 if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
279
280 if(this->io.pending && !this->io.dirty) {
281 ready_schedule_lock();
282 __cfa_io_flush( this );
283 ready_schedule_unlock();
284 }
285
286 #else
287 #warning new kernel loop
288 SEARCH: {
289 /* paranoid */ verify( ! __preemption_enabled() );
290
291 // First, lock the scheduler since we are searching for a thread
292 ready_schedule_lock();
293
294 // Try to get the next thread
295 readyThread = pop_fast( this->cltr );
296 if(readyThread) { ready_schedule_unlock(); break SEARCH; }
297
298 // If we can't find a thread, might as well flush any outstanding I/O
299 if(this->io.pending) { __cfa_io_flush( this ); }
300
301 // Spin a little on I/O, just in case
302 for(5) {
303 __maybe_io_drain( this );
304 readyThread = pop_fast( this->cltr );
305 if(readyThread) { ready_schedule_unlock(); break SEARCH; }
306 }
307
308 // no luck, try stealing a few times
309 for(5) {
310 if( __maybe_io_drain( this ) ) {
311 readyThread = pop_fast( this->cltr );
312 } else {
313 readyThread = pop_slow( this->cltr );
314 }
315 if(readyThread) { ready_schedule_unlock(); break SEARCH; }
316 }
317
318 // still no luck, search for a thread
319 readyThread = pop_search( this->cltr );
320 if(readyThread) { ready_schedule_unlock(); break SEARCH; }
321
322 // Don't block if we are done
323 if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) {
324 ready_schedule_unlock();
325 break MAIN_LOOP;
326 }
327
328 __STATS( __tls_stats()->ready.sleep.halts++; )
329
330 // Push self to idle stack
331 ready_schedule_unlock();
332 if(!mark_idle(this->cltr->procs, * this)) goto SEARCH;
333 ready_schedule_lock();
334
335 // Confirm the ready-queue is empty
336 __maybe_io_drain( this );
337 readyThread = pop_search( this->cltr );
338 ready_schedule_unlock();
339
340 if( readyThread ) {
341 // A thread was found, cancel the halt
342 mark_awake(this->cltr->procs, * this);
343
344 __STATS( __tls_stats()->ready.sleep.cancels++; )
345
346 // continue the main loop
347 break SEARCH;
348 }
349
350 __STATS( if(this->print_halts) __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->unique_id, rdtscl()); )
351 __cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle);
352
353 {
354 eventfd_t val;
355 ssize_t ret = read( this->idle, &val, sizeof(val) );
356 if(ret < 0) {
357 switch((int)errno) {
358 case EAGAIN:
359 #if EAGAIN != EWOULDBLOCK
360 case EWOULDBLOCK:
361 #endif
362 case EINTR:
363 // No need to do anything special here, just assume it's a legitimate wake-up
364 break;
365 default:
366 abort( "KERNEL : internal error, read failure on idle eventfd, error(%d) %s.", (int)errno, strerror( (int)errno ) );
367 }
368 }
369 }
370
371 __STATS( if(this->print_halts) __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->unique_id, rdtscl()); )
372
373 // We were woken up, remove self from idle
374 mark_awake(this->cltr->procs, * this);
375
376 // DON'T just proceed, start looking again
377 continue MAIN_LOOP;
378 }
379
380 RUN_THREAD:
381 /* paranoid */ verify( ! __preemption_enabled() );
382 /* paranoid */ verify( readyThread );
383
384 // Reset io dirty bit
385 this->io.dirty = false;
386
387 // We found a thread run it
388 __run_thread(this, readyThread);
389
390 // Are we done?
391 if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
392
393 if(this->io.pending && !this->io.dirty) {
394 __cfa_io_flush( this );
395 }
396
397 ready_schedule_lock();
398 __maybe_io_drain( this );
399 ready_schedule_unlock();
400 #endif
401 }
402
403 __cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
404 }
405
406 __cfa_io_stop( this );
407
408 post( this->terminated );
409
410 if(this == mainProcessor) {
411 // HACK : the coroutine context switch expects this_thread to be set
412 // and it make sense for it to be set in all other cases except here
413 // fake it
414 __cfaabi_tls.this_thread = mainThread;
415 }
416
417 __cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
418}
419
420static int * __volatile_errno() __attribute__((noinline));
421static int * __volatile_errno() { asm(""); return &errno; }
422
423// KERNEL ONLY
424// runThread runs a thread by context switching
425// from the processor coroutine to the target thread
426static void __run_thread(processor * this, thread$ * thrd_dst) {
427 /* paranoid */ verify( ! __preemption_enabled() );
428 /* paranoid */ verifyf( thrd_dst->state == Ready || thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
429 /* paranoid */ verifyf( thrd_dst->link.next == 0p, "Expected null got %p", thrd_dst->link.next );
430 __builtin_prefetch( thrd_dst->context.SP );
431
432 __cfadbg_print_safe(runtime_core, "Kernel : core %p running thread %p (%s)\n", this, thrd_dst, thrd_dst->self_cor.name);
433
434 coroutine$ * proc_cor = get_coroutine(this->runner);
435
436 // set state of processor coroutine to inactive
437 verify(proc_cor->state == Active);
438 proc_cor->state = Blocked;
439
440 // Actually run the thread
441 RUNNING: while(true) {
442 thrd_dst->preempted = __NO_PREEMPTION;
443 thrd_dst->state = Active;
444
445 // Update global state
446 kernelTLS().this_thread = thrd_dst;
447
448 /* paranoid */ verify( ! __preemption_enabled() );
449 /* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
450 /* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
451 /* paranoid */ verify( thrd_dst->context.SP );
452 /* paranoid */ verify( thrd_dst->state != Halted );
453 /* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) < ((uintptr_t)__get_stack(thrd_dst->curr_cor)->base ) || thrd_dst->curr_cor == proc_cor || thrd_dst->corctx_flag, "ERROR : Destination thread$ %p has been corrupted.\n StackPointer too small.\n", thrd_dst ); // add escape condition if we are setting up the processor
454 /* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) > ((uintptr_t)__get_stack(thrd_dst->curr_cor)->limit) || thrd_dst->curr_cor == proc_cor || thrd_dst->corctx_flag, "ERROR : Destination thread$ %p has been corrupted.\n StackPointer too large.\n", thrd_dst ); // add escape condition if we are setting up the processor
455 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
456
457
458
459 // set context switch to the thread that the processor is executing
460 __cfactx_switch( &proc_cor->context, &thrd_dst->context );
461 // when __cfactx_switch returns we are back in the processor coroutine
462
463
464
465 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
466 /* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) > ((uintptr_t)__get_stack(thrd_dst->curr_cor)->limit) || thrd_dst->corctx_flag, "ERROR : Destination thread$ %p has been corrupted.\n StackPointer too large.\n", thrd_dst );
467 /* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) < ((uintptr_t)__get_stack(thrd_dst->curr_cor)->base ) || thrd_dst->corctx_flag, "ERROR : Destination thread$ %p has been corrupted.\n StackPointer too small.\n", thrd_dst );
468 /* paranoid */ verify( thrd_dst->context.SP );
469 /* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
470 /* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
471 /* paranoid */ verify( ! __preemption_enabled() );
472
473 // Reset global state
474 kernelTLS().this_thread = 0p;
475
476 // We just finished running a thread, there are a few things that could have happened.
477 // 1 - Regular case : the thread has blocked and now one has scheduled it yet.
478 // 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
479 // 4 - Preempted
480 // In case 1, we may have won a race so we can't write to the state again.
481 // In case 2, we lost the race so we now own the thread.
482
483 if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
484 // The thread was preempted, reschedule it and reset the flag
485 schedule_thread$( thrd_dst, UNPARK_LOCAL );
486 break RUNNING;
487 }
488
489 if(unlikely(thrd_dst->state == Halting)) {
490 // The thread has halted, it should never be scheduled/run again
491 // finish the thread
492 __thread_finish( thrd_dst );
493 break RUNNING;
494 }
495
496 /* paranoid */ verify( thrd_dst->state == Active );
497 thrd_dst->state = Blocked;
498
499 // set state of processor coroutine to active and the thread to inactive
500 int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
501 switch(old_ticket) {
502 case TICKET_RUNNING:
503 // This is case 1, the regular case, nothing more is needed
504 break RUNNING;
505 case TICKET_UNBLOCK:
506 #if !defined(__CFA_NO_STATISTICS__)
507 __tls_stats()->ready.threads.threads++;
508 #endif
509 // This is case 2, the racy case, someone tried to run this thread before it finished blocking
510 // In this case, just run it again.
511 continue RUNNING;
512 default:
513 // This makes no sense, something is wrong abort
514 abort();
515 }
516 }
517
518 // Just before returning to the processor, set the processor coroutine to active
519 proc_cor->state = Active;
520
521 __cfadbg_print_safe(runtime_core, "Kernel : core %p finished running thread %p\n", this, thrd_dst);
522
523 #if !defined(__CFA_NO_STATISTICS__)
524 __tls_stats()->ready.threads.threads--;
525 #endif
526
527 /* paranoid */ verify( ! __preemption_enabled() );
528}
529
530// KERNEL_ONLY
531void returnToKernel() {
532 /* paranoid */ verify( ! __preemption_enabled() );
533 coroutine$ * proc_cor = get_coroutine(kernelTLS().this_processor->runner);
534 thread$ * thrd_src = kernelTLS().this_thread;
535
536 __STATS( thrd_src->last_proc = kernelTLS().this_processor; )
537
538 // Run the thread on this processor
539 {
540 int local_errno = *__volatile_errno();
541 #if defined( __i386 ) || defined( __x86_64 )
542 __x87_store;
543 #endif
544 /* paranoid */ verify( proc_cor->context.SP );
545 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
546 __cfactx_switch( &thrd_src->context, &proc_cor->context );
547 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
548 #if defined( __i386 ) || defined( __x86_64 )
549 __x87_load;
550 #endif
551 *__volatile_errno() = local_errno;
552 }
553
554 #if !defined(__CFA_NO_STATISTICS__)
555 /* paranoid */ verify( thrd_src->last_proc != 0p );
556 if(thrd_src->last_proc != kernelTLS().this_processor) {
557 __tls_stats()->ready.threads.migration++;
558 }
559 #endif
560
561 /* paranoid */ verify( ! __preemption_enabled() );
562 /* paranoid */ verifyf( ((uintptr_t)thrd_src->context.SP) < ((uintptr_t)__get_stack(thrd_src->curr_cor)->base ) || thrd_src->corctx_flag, "ERROR : Returning thread$ %p has been corrupted.\n StackPointer too small.\n", thrd_src );
563 /* paranoid */ verifyf( ((uintptr_t)thrd_src->context.SP) > ((uintptr_t)__get_stack(thrd_src->curr_cor)->limit) || thrd_src->corctx_flag, "ERROR : Returning thread$ %p has been corrupted.\n StackPointer too large.\n", thrd_src );
564}
565
566//-----------------------------------------------------------------------------
567// Scheduler routines
568// KERNEL ONLY
569static void __schedule_thread( thread$ * thrd, unpark_hint hint ) {
570 /* paranoid */ verify( ! __preemption_enabled() );
571 /* paranoid */ verify( ready_schedule_islocked());
572 /* paranoid */ verify( thrd );
573 /* paranoid */ verify( thrd->state != Halted );
574 /* paranoid */ verify( thrd->curr_cluster );
575 /* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
576 /* paranoid */ if( thrd->state == Blocked || thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
577 "Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
578 /* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
579 "Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
580 /* paranoid */ #endif
581 /* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
582 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
583
584 const bool local = thrd->state != Start;
585 if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
586
587 // Dereference the thread now because once we push it, there is not guaranteed it's still valid.
588 struct cluster * cl = thrd->curr_cluster;
589 __STATS(bool outside = hint == UNPARK_LOCAL && thrd->last_proc && thrd->last_proc != kernelTLS().this_processor; )
590
591 // push the thread to the cluster ready-queue
592 push( cl, thrd, hint );
593
594 // variable thrd is no longer safe to use
595 thrd = 0xdeaddeaddeaddeadp;
596
597 // wake the cluster using the save variable.
598 __wake_one( cl );
599
600 #if !defined(__CFA_NO_STATISTICS__)
601 if( kernelTLS().this_stats ) {
602 __tls_stats()->ready.threads.threads++;
603 if(outside) {
604 __tls_stats()->ready.threads.extunpark++;
605 }
606 }
607 else {
608 __atomic_fetch_add(&cl->stats->ready.threads.threads, 1, __ATOMIC_RELAXED);
609 __atomic_fetch_add(&cl->stats->ready.threads.extunpark, 1, __ATOMIC_RELAXED);
610 }
611 #endif
612
613 /* paranoid */ verify( ready_schedule_islocked());
614 /* paranoid */ verify( ! __preemption_enabled() );
615}
616
617void schedule_thread$( thread$ * thrd, unpark_hint hint ) {
618 ready_schedule_lock();
619 __schedule_thread( thrd, hint );
620 ready_schedule_unlock();
621}
622
623// KERNEL ONLY
624static inline thread$ * __next_thread(cluster * this) with( *this ) {
625 /* paranoid */ verify( ! __preemption_enabled() );
626
627 ready_schedule_lock();
628 thread$ * thrd = pop_fast( this );
629 ready_schedule_unlock();
630
631 /* paranoid */ verify( ! __preemption_enabled() );
632 return thrd;
633}
634
635// KERNEL ONLY
636static inline thread$ * __next_thread_slow(cluster * this) with( *this ) {
637 /* paranoid */ verify( ! __preemption_enabled() );
638
639 ready_schedule_lock();
640 thread$ * thrd;
641 for(25) {
642 thrd = pop_slow( this );
643 if(thrd) goto RET;
644 }
645 thrd = pop_search( this );
646
647 RET:
648 ready_schedule_unlock();
649
650 /* paranoid */ verify( ! __preemption_enabled() );
651 return thrd;
652}
653
654static inline bool __must_unpark( thread$ * thrd ) {
655 int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
656 switch(old_ticket) {
657 case TICKET_RUNNING:
658 // Wake won the race, the thread will reschedule/rerun itself
659 return false;
660 case TICKET_BLOCKED:
661 /* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
662 /* paranoid */ verify( thrd->state == Blocked );
663 return true;
664 default:
665 // This makes no sense, something is wrong abort
666 abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
667 }
668}
669
670void __kernel_unpark( thread$ * thrd, unpark_hint hint ) {
671 /* paranoid */ verify( ! __preemption_enabled() );
672 /* paranoid */ verify( ready_schedule_islocked());
673
674 if( !thrd ) return;
675
676 if(__must_unpark(thrd)) {
677 // Wake lost the race,
678 __schedule_thread( thrd, hint );
679 }
680
681 /* paranoid */ verify( ready_schedule_islocked());
682 /* paranoid */ verify( ! __preemption_enabled() );
683}
684
685void unpark( thread$ * thrd, unpark_hint hint ) {
686 if( !thrd ) return;
687
688 if(__must_unpark(thrd)) {
689 disable_interrupts();
690 // Wake lost the race,
691 schedule_thread$( thrd, hint );
692 enable_interrupts(false);
693 }
694}
695
696void park( void ) {
697 __disable_interrupts_checked();
698 /* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
699 returnToKernel();
700 __enable_interrupts_checked();
701
702}
703
704extern "C" {
705 // Leave the thread monitor
706 // last routine called by a thread.
707 // Should never return
708 void __cfactx_thrd_leave() {
709 thread$ * thrd = active_thread();
710 monitor$ * this = &thrd->self_mon;
711
712 // Lock the monitor now
713 lock( this->lock __cfaabi_dbg_ctx2 );
714
715 disable_interrupts();
716
717 /* paranoid */ verify( ! __preemption_enabled() );
718 /* paranoid */ verify( thrd->state == Active );
719 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
720 /* paranoid */ verify( kernelTLS().this_thread == thrd );
721 /* paranoid */ verify( thrd->context.SP );
722 /* 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 );
723 /* 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 );
724
725 thrd->state = Halting;
726 if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
727 if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
728 if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
729
730 // Leave the thread
731 returnToKernel();
732
733 // Control flow should never reach here!
734 abort();
735 }
736}
737
738// KERNEL ONLY
739bool force_yield( __Preemption_Reason reason ) {
740 __disable_interrupts_checked();
741 thread$ * thrd = kernelTLS().this_thread;
742 /* paranoid */ verify(thrd->state == Active);
743
744 // SKULLDUGGERY: It is possible that we are preempting this thread just before
745 // it was going to park itself. If that is the case and it is already using the
746 // intrusive fields then we can't use them to preempt the thread
747 // If that is the case, abandon the preemption.
748 bool preempted = false;
749 if(thrd->link.next == 0p) {
750 preempted = true;
751 thrd->preempted = reason;
752 returnToKernel();
753 }
754 __enable_interrupts_checked( false );
755 return preempted;
756}
757
758//=============================================================================================
759// Kernel Idle Sleep
760//=============================================================================================
761// Wake a thread from the front if there are any
762static void __wake_one(cluster * this) {
763 /* paranoid */ verify( ! __preemption_enabled() );
764 /* paranoid */ verify( ready_schedule_islocked() );
765
766 // Check if there is a sleeping processor
767 int fd = __atomic_load_n(&this->procs.fd, __ATOMIC_SEQ_CST);
768
769 // If no one is sleeping, we are done
770 if( fd == 0 ) return;
771
772 // We found a processor, wake it up
773 eventfd_t val;
774 val = 1;
775 eventfd_write( fd, val );
776
777 #if !defined(__CFA_NO_STATISTICS__)
778 if( kernelTLS().this_stats ) {
779 __tls_stats()->ready.sleep.wakes++;
780 }
781 else {
782 __atomic_fetch_add(&this->stats->ready.sleep.wakes, 1, __ATOMIC_RELAXED);
783 }
784 #endif
785
786 /* paranoid */ verify( ready_schedule_islocked() );
787 /* paranoid */ verify( ! __preemption_enabled() );
788
789 return;
790}
791
792// Unconditionnaly wake a thread
793void __wake_proc(processor * this) {
794 __cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
795
796 __disable_interrupts_checked();
797 /* paranoid */ verify( ! __preemption_enabled() );
798 eventfd_t val;
799 val = 1;
800 eventfd_write( this->idle, val );
801 __enable_interrupts_checked();
802}
803
804static bool mark_idle(__cluster_proc_list & this, processor & proc) {
805 /* paranoid */ verify( ! __preemption_enabled() );
806 if(!try_lock( this )) return false;
807 this.idle++;
808 /* paranoid */ verify( this.idle <= this.total );
809 remove(proc);
810 insert_first(this.idles, proc);
811
812 __atomic_store_n(&this.fd, proc.idle, __ATOMIC_SEQ_CST);
813 unlock( this );
814 /* paranoid */ verify( ! __preemption_enabled() );
815
816 return true;
817}
818
819static void mark_awake(__cluster_proc_list & this, processor & proc) {
820 /* paranoid */ verify( ! __preemption_enabled() );
821 lock( this );
822 this.idle--;
823 /* paranoid */ verify( this.idle >= 0 );
824 remove(proc);
825 insert_last(this.actives, proc);
826
827 {
828 int fd = 0;
829 if(!this.idles`isEmpty) fd = this.idles`first.idle;
830 __atomic_store_n(&this.fd, fd, __ATOMIC_SEQ_CST);
831 }
832
833 unlock( this );
834 /* paranoid */ verify( ! __preemption_enabled() );
835}
836
837//=============================================================================================
838// Unexpected Terminating logic
839//=============================================================================================
840void __kernel_abort_msg( char * abort_text, int abort_text_size ) {
841 thread$ * thrd = __cfaabi_tls.this_thread;
842
843 if(thrd) {
844 int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
845 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
846
847 if ( &thrd->self_cor != thrd->curr_cor ) {
848 len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
849 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
850 }
851 else {
852 __cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
853 }
854 }
855 else {
856 int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
857 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
858 }
859}
860
861int __kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
862 return get_coroutine(__cfaabi_tls.this_thread) == get_coroutine(mainThread) ? 4 : 2;
863}
864
865static __spinlock_t kernel_debug_lock;
866
867extern "C" {
868 void __cfaabi_bits_acquire() {
869 lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
870 }
871
872 void __cfaabi_bits_release() {
873 unlock( kernel_debug_lock );
874 }
875}
876
877//=============================================================================================
878// Kernel Utilities
879//=============================================================================================
880#if defined(CFA_HAVE_LINUX_IO_URING_H)
881#include "io/types.hfa"
882#endif
883
884static inline bool __maybe_io_drain( processor * proc ) {
885 bool ret = false;
886 #if defined(CFA_HAVE_LINUX_IO_URING_H)
887 __cfadbg_print_safe(runtime_core, "Kernel : core %p checking io for ring %d\n", proc, proc->io.ctx->fd);
888
889 // Check if we should drain the queue
890 $io_context * ctx = proc->io.ctx;
891 unsigned head = *ctx->cq.head;
892 unsigned tail = *ctx->cq.tail;
893 if(head == tail) return false;
894 #if OLD_MAIN
895 ready_schedule_lock();
896 ret = __cfa_io_drain( proc );
897 ready_schedule_unlock();
898 #else
899 ret = __cfa_io_drain( proc );
900 #endif
901 #endif
902 return ret;
903}
904
905//-----------------------------------------------------------------------------
906// Debug
907__cfaabi_dbg_debug_do(
908 extern "C" {
909 void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
910 this.prev_name = prev_name;
911 this.prev_thrd = kernelTLS().this_thread;
912 }
913 }
914)
915
916//-----------------------------------------------------------------------------
917// Debug
918bool threading_enabled(void) __attribute__((const)) {
919 return true;
920}
921
922//-----------------------------------------------------------------------------
923// Statistics
924#if !defined(__CFA_NO_STATISTICS__)
925 void print_halts( processor & this ) {
926 this.print_halts = true;
927 }
928
929 static void crawl_list( cluster * cltr, dlist(processor) & list, unsigned count ) {
930 /* paranoid */ verify( cltr->stats );
931
932 processor * it = &list`first;
933 for(unsigned i = 0; i < count; i++) {
934 /* paranoid */ verifyf( it, "Unexpected null iterator, at index %u of %u\n", i, count);
935 /* paranoid */ verify( it->local_data->this_stats );
936 // __print_stats( it->local_data->this_stats, cltr->print_stats, "Processor", it->name, (void*)it );
937 __tally_stats( cltr->stats, it->local_data->this_stats );
938 it = &(*it)`next;
939 }
940 }
941
942 void crawl_cluster_stats( cluster & this ) {
943 // Stop the world, otherwise stats could get really messed-up
944 // this doesn't solve all problems but does solve many
945 // so it's probably good enough
946 disable_interrupts();
947 uint_fast32_t last_size = ready_mutate_lock();
948
949 crawl_list(&this, this.procs.actives, this.procs.total - this.procs.idle);
950 crawl_list(&this, this.procs.idles , this.procs.idle );
951
952 // Unlock the RWlock
953 ready_mutate_unlock( last_size );
954 enable_interrupts();
955 }
956
957
958 void print_stats_now( cluster & this, int flags ) {
959 crawl_cluster_stats( this );
960 __print_stats( this.stats, this.print_stats, "Cluster", this.name, (void*)&this );
961 }
962#endif
963// Local Variables: //
964// mode: c //
965// tab-width: 4 //
966// End: //
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