source: libcfa/src/concurrency/kernel.cfa@ 7dd98b6

ADT ast-experimental enum forall-pointer-decay pthread-emulation qualifiedEnum
Last change on this file since 7dd98b6 was c33c2af, checked in by Thierry Delisle <tdelisle@…>, 4 years ago

Made some of the schedule locking more fine grain.
  • Property mode set to 100644
File size: 30.5 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 void mark_idle (__cluster_proc_list & idles, processor & proc);
127static void mark_awake(__cluster_proc_list & idles, processor & proc);
128static [unsigned idle, unsigned total, * processor] query_idles( & __cluster_proc_list idles );
129
130extern void __cfa_io_start( processor * );
131extern bool __cfa_io_drain( processor * );
132extern void __cfa_io_flush( processor * );
133extern void __cfa_io_stop ( processor * );
134static inline bool __maybe_io_drain( processor * );
135
136extern void __disable_interrupts_hard();
137extern void __enable_interrupts_hard();
138
139static inline void __disable_interrupts_checked() {
140 /* paranoid */ verify( __preemption_enabled() );
141 disable_interrupts();
142 /* paranoid */ verify( ! __preemption_enabled() );
143}
144
145static inline void __enable_interrupts_checked( bool poll = true ) {
146 /* paranoid */ verify( ! __preemption_enabled() );
147 enable_interrupts( poll );
148 /* paranoid */ verify( __preemption_enabled() );
149}
150
151//=============================================================================================
152// Kernel Scheduling logic
153//=============================================================================================
154//Main of the processor contexts
155void main(processorCtx_t & runner) {
156 // Because of a bug, we couldn't initialized the seed on construction
157 // Do it here
158 __cfaabi_tls.rand_seed ^= rdtscl();
159 __cfaabi_tls.ready_rng.fwd_seed = 25214903917_l64u * (rdtscl() ^ (uintptr_t)&runner);
160 __tls_rand_advance_bck();
161
162 processor * this = runner.proc;
163 verify(this);
164
165 __cfa_io_start( this );
166
167 __cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
168 #if !defined(__CFA_NO_STATISTICS__)
169 if( this->print_halts ) {
170 __cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->unique_id, this->name, (void*)this);
171 }
172 #endif
173
174 {
175 // Setup preemption data
176 preemption_scope scope = { this };
177
178 // if we need to run some special setup, now is the time to do it.
179 if(this->init.thrd) {
180 this->init.thrd->curr_cluster = this->cltr;
181 __run_thread(this, this->init.thrd);
182 }
183
184 __cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
185
186 thread$ * readyThread = 0p;
187 MAIN_LOOP:
188 for() {
189 #define OLD_MAIN 1
190 #if OLD_MAIN
191 // Check if there is pending io
192 __maybe_io_drain( this );
193
194 // Try to get the next thread
195 readyThread = __next_thread( this->cltr );
196
197 if( !readyThread ) {
198 ready_schedule_lock();
199 __cfa_io_flush( this );
200 ready_schedule_unlock();
201
202 readyThread = __next_thread_slow( this->cltr );
203 }
204
205 HALT:
206 if( !readyThread ) {
207 // Don't block if we are done
208 if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
209
210 #if !defined(__CFA_NO_STATISTICS__)
211 __tls_stats()->ready.sleep.halts++;
212 #endif
213
214 // Push self to idle stack
215 mark_idle(this->cltr->procs, * this);
216
217 // Confirm the ready-queue is empty
218 readyThread = __next_thread_slow( this->cltr );
219 if( readyThread ) {
220 // A thread was found, cancel the halt
221 mark_awake(this->cltr->procs, * this);
222
223 #if !defined(__CFA_NO_STATISTICS__)
224 __tls_stats()->ready.sleep.cancels++;
225 #endif
226
227 // continue the mai loop
228 break HALT;
229 }
230
231 #if !defined(__CFA_NO_STATISTICS__)
232 if(this->print_halts) {
233 __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->unique_id, rdtscl());
234 }
235 #endif
236
237 __cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle);
238
239 {
240 eventfd_t val;
241 ssize_t ret = read( this->idle, &val, sizeof(val) );
242 if(ret < 0) {
243 switch((int)errno) {
244 case EAGAIN:
245 #if EAGAIN != EWOULDBLOCK
246 case EWOULDBLOCK:
247 #endif
248 case EINTR:
249 // No need to do anything special here, just assume it's a legitimate wake-up
250 break;
251 default:
252 abort( "KERNEL : internal error, read failure on idle eventfd, error(%d) %s.", (int)errno, strerror( (int)errno ) );
253 }
254 }
255 }
256
257 #if !defined(__CFA_NO_STATISTICS__)
258 if(this->print_halts) {
259 __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->unique_id, rdtscl());
260 }
261 #endif
262
263 // We were woken up, remove self from idle
264 mark_awake(this->cltr->procs, * this);
265
266 // DON'T just proceed, start looking again
267 continue MAIN_LOOP;
268 }
269
270 /* paranoid */ verify( readyThread );
271
272 // Reset io dirty bit
273 this->io.dirty = false;
274
275 // We found a thread run it
276 __run_thread(this, readyThread);
277
278 // Are we done?
279 if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
280
281 if(this->io.pending && !this->io.dirty) {
282 ready_schedule_lock();
283 __cfa_io_flush( this );
284 ready_schedule_unlock();
285 }
286
287 #else
288 #warning new kernel loop
289 SEARCH: {
290 /* paranoid */ verify( ! __preemption_enabled() );
291
292 // First, lock the scheduler since we are searching for a thread
293 ready_schedule_lock();
294
295 // Try to get the next thread
296 readyThread = pop_fast( this->cltr );
297 if(readyThread) { ready_schedule_unlock(); break SEARCH; }
298
299 // If we can't find a thread, might as well flush any outstanding I/O
300 if(this->io.pending) { __cfa_io_flush( this ); }
301
302 // Spin a little on I/O, just in case
303 for(5) {
304 __maybe_io_drain( this );
305 readyThread = pop_fast( this->cltr );
306 if(readyThread) { ready_schedule_unlock(); break SEARCH; }
307 }
308
309 // no luck, try stealing a few times
310 for(5) {
311 if( __maybe_io_drain( this ) ) {
312 readyThread = pop_fast( this->cltr );
313 } else {
314 readyThread = pop_slow( this->cltr );
315 }
316 if(readyThread) { ready_schedule_unlock(); break SEARCH; }
317 }
318
319 // still no luck, search for a thread
320 readyThread = pop_search( this->cltr );
321 if(readyThread) { ready_schedule_unlock(); break SEARCH; }
322
323 // Don't block if we are done
324 if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) {
325 ready_schedule_unlock();
326 break MAIN_LOOP;
327 }
328
329 __STATS( __tls_stats()->ready.sleep.halts++; )
330
331 // Push self to idle stack
332 ready_schedule_unlock();
333 mark_idle(this->cltr->procs, * this);
334 ready_schedule_lock();
335
336 // Confirm the ready-queue is empty
337 __maybe_io_drain( this );
338 readyThread = pop_search( this->cltr );
339 ready_schedule_unlock();
340
341 if( readyThread ) {
342 // A thread was found, cancel the halt
343 mark_awake(this->cltr->procs, * this);
344
345 __STATS( __tls_stats()->ready.sleep.cancels++; )
346
347 // continue the main loop
348 break SEARCH;
349 }
350
351 __STATS( if(this->print_halts) __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->unique_id, rdtscl()); )
352 __cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle);
353
354 {
355 eventfd_t val;
356 ssize_t ret = read( this->idle, &val, sizeof(val) );
357 if(ret < 0) {
358 switch((int)errno) {
359 case EAGAIN:
360 #if EAGAIN != EWOULDBLOCK
361 case EWOULDBLOCK:
362 #endif
363 case EINTR:
364 // No need to do anything special here, just assume it's a legitimate wake-up
365 break;
366 default:
367 abort( "KERNEL : internal error, read failure on idle eventfd, error(%d) %s.", (int)errno, strerror( (int)errno ) );
368 }
369 }
370 }
371
372 __STATS( if(this->print_halts) __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->unique_id, rdtscl()); )
373
374 // We were woken up, remove self from idle
375 mark_awake(this->cltr->procs, * this);
376
377 // DON'T just proceed, start looking again
378 continue MAIN_LOOP;
379 }
380
381 RUN_THREAD:
382 /* paranoid */ verify( ! __preemption_enabled() );
383 /* paranoid */ verify( readyThread );
384
385 // Reset io dirty bit
386 this->io.dirty = false;
387
388 // We found a thread run it
389 __run_thread(this, readyThread);
390
391 // Are we done?
392 if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
393
394 if(this->io.pending && !this->io.dirty) {
395 __cfa_io_flush( this );
396 }
397
398 ready_schedule_lock();
399 __maybe_io_drain( this );
400 ready_schedule_unlock();
401 #endif
402 }
403
404 __cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
405 }
406
407 __cfa_io_stop( this );
408
409 post( this->terminated );
410
411 if(this == mainProcessor) {
412 // HACK : the coroutine context switch expects this_thread to be set
413 // and it make sense for it to be set in all other cases except here
414 // fake it
415 __cfaabi_tls.this_thread = mainThread;
416 }
417
418 __cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
419}
420
421static int * __volatile_errno() __attribute__((noinline));
422static int * __volatile_errno() { asm(""); return &errno; }
423
424// KERNEL ONLY
425// runThread runs a thread by context switching
426// from the processor coroutine to the target thread
427static void __run_thread(processor * this, thread$ * thrd_dst) {
428 /* paranoid */ verify( ! __preemption_enabled() );
429 /* paranoid */ verifyf( thrd_dst->state == Ready || thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
430 /* paranoid */ verifyf( thrd_dst->link.next == 0p, "Expected null got %p", thrd_dst->link.next );
431 __builtin_prefetch( thrd_dst->context.SP );
432
433 __cfadbg_print_safe(runtime_core, "Kernel : core %p running thread %p (%s)\n", this, thrd_dst, thrd_dst->self_cor.name);
434
435 coroutine$ * proc_cor = get_coroutine(this->runner);
436
437 // set state of processor coroutine to inactive
438 verify(proc_cor->state == Active);
439 proc_cor->state = Blocked;
440
441 // Actually run the thread
442 RUNNING: while(true) {
443 thrd_dst->preempted = __NO_PREEMPTION;
444 thrd_dst->state = Active;
445
446 // Update global state
447 kernelTLS().this_thread = thrd_dst;
448
449 /* paranoid */ verify( ! __preemption_enabled() );
450 /* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
451 /* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
452 /* paranoid */ verify( thrd_dst->context.SP );
453 /* paranoid */ verify( thrd_dst->state != Halted );
454 /* 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
455 /* 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
456 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
457
458
459
460 // set context switch to the thread that the processor is executing
461 __cfactx_switch( &proc_cor->context, &thrd_dst->context );
462 // when __cfactx_switch returns we are back in the processor coroutine
463
464
465
466 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
467 /* 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 );
468 /* 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 );
469 /* paranoid */ verify( thrd_dst->context.SP );
470 /* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
471 /* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
472 /* paranoid */ verify( ! __preemption_enabled() );
473
474 // Reset global state
475 kernelTLS().this_thread = 0p;
476
477 // We just finished running a thread, there are a few things that could have happened.
478 // 1 - Regular case : the thread has blocked and now one has scheduled it yet.
479 // 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
480 // 4 - Preempted
481 // In case 1, we may have won a race so we can't write to the state again.
482 // In case 2, we lost the race so we now own the thread.
483
484 if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
485 // The thread was preempted, reschedule it and reset the flag
486 schedule_thread$( thrd_dst, UNPARK_LOCAL );
487 break RUNNING;
488 }
489
490 if(unlikely(thrd_dst->state == Halting)) {
491 // The thread has halted, it should never be scheduled/run again
492 // finish the thread
493 __thread_finish( thrd_dst );
494 break RUNNING;
495 }
496
497 /* paranoid */ verify( thrd_dst->state == Active );
498 thrd_dst->state = Blocked;
499
500 // set state of processor coroutine to active and the thread to inactive
501 int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
502 switch(old_ticket) {
503 case TICKET_RUNNING:
504 // This is case 1, the regular case, nothing more is needed
505 break RUNNING;
506 case TICKET_UNBLOCK:
507 #if !defined(__CFA_NO_STATISTICS__)
508 __tls_stats()->ready.threads.threads++;
509 #endif
510 // This is case 2, the racy case, someone tried to run this thread before it finished blocking
511 // In this case, just run it again.
512 continue RUNNING;
513 default:
514 // This makes no sense, something is wrong abort
515 abort();
516 }
517 }
518
519 // Just before returning to the processor, set the processor coroutine to active
520 proc_cor->state = Active;
521
522 __cfadbg_print_safe(runtime_core, "Kernel : core %p finished running thread %p\n", this, thrd_dst);
523
524 #if !defined(__CFA_NO_STATISTICS__)
525 __tls_stats()->ready.threads.threads--;
526 #endif
527
528 /* paranoid */ verify( ! __preemption_enabled() );
529}
530
531// KERNEL_ONLY
532void returnToKernel() {
533 /* paranoid */ verify( ! __preemption_enabled() );
534 coroutine$ * proc_cor = get_coroutine(kernelTLS().this_processor->runner);
535 thread$ * thrd_src = kernelTLS().this_thread;
536
537 __STATS( thrd_src->last_proc = kernelTLS().this_processor; )
538
539 // Run the thread on this processor
540 {
541 int local_errno = *__volatile_errno();
542 #if defined( __i386 ) || defined( __x86_64 )
543 __x87_store;
544 #endif
545 /* paranoid */ verify( proc_cor->context.SP );
546 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
547 __cfactx_switch( &thrd_src->context, &proc_cor->context );
548 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
549 #if defined( __i386 ) || defined( __x86_64 )
550 __x87_load;
551 #endif
552 *__volatile_errno() = local_errno;
553 }
554
555 #if !defined(__CFA_NO_STATISTICS__)
556 /* paranoid */ verify( thrd_src->last_proc != 0p );
557 if(thrd_src->last_proc != kernelTLS().this_processor) {
558 __tls_stats()->ready.threads.migration++;
559 }
560 #endif
561
562 /* paranoid */ verify( ! __preemption_enabled() );
563 /* 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 );
564 /* 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 );
565}
566
567//-----------------------------------------------------------------------------
568// Scheduler routines
569// KERNEL ONLY
570static void __schedule_thread( thread$ * thrd, unpark_hint hint ) {
571 /* paranoid */ verify( ! __preemption_enabled() );
572 /* paranoid */ verify( ready_schedule_islocked());
573 /* paranoid */ verify( thrd );
574 /* paranoid */ verify( thrd->state != Halted );
575 /* paranoid */ verify( thrd->curr_cluster );
576 /* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
577 /* paranoid */ if( thrd->state == Blocked || thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
578 "Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
579 /* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
580 "Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
581 /* paranoid */ #endif
582 /* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
583 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
584
585 const bool local = thrd->state != Start;
586 if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
587
588 // Dereference the thread now because once we push it, there is not guaranteed it's still valid.
589 struct cluster * cl = thrd->curr_cluster;
590 __STATS(bool outside = hint == UNPARK_LOCAL && thrd->last_proc && thrd->last_proc != kernelTLS().this_processor; )
591
592 // push the thread to the cluster ready-queue
593 push( cl, thrd, hint );
594
595 // variable thrd is no longer safe to use
596 thrd = 0xdeaddeaddeaddeadp;
597
598 // wake the cluster using the save variable.
599 __wake_one( cl );
600
601 #if !defined(__CFA_NO_STATISTICS__)
602 if( kernelTLS().this_stats ) {
603 __tls_stats()->ready.threads.threads++;
604 if(outside) {
605 __tls_stats()->ready.threads.extunpark++;
606 }
607 }
608 else {
609 __atomic_fetch_add(&cl->stats->ready.threads.threads, 1, __ATOMIC_RELAXED);
610 __atomic_fetch_add(&cl->stats->ready.threads.extunpark, 1, __ATOMIC_RELAXED);
611 }
612 #endif
613
614 /* paranoid */ verify( ready_schedule_islocked());
615 /* paranoid */ verify( ! __preemption_enabled() );
616}
617
618void schedule_thread$( thread$ * thrd, unpark_hint hint ) {
619 ready_schedule_lock();
620 __schedule_thread( thrd, hint );
621 ready_schedule_unlock();
622}
623
624// KERNEL ONLY
625static inline thread$ * __next_thread(cluster * this) with( *this ) {
626 /* paranoid */ verify( ! __preemption_enabled() );
627
628 ready_schedule_lock();
629 thread$ * thrd = pop_fast( this );
630 ready_schedule_unlock();
631
632 /* paranoid */ verify( ! __preemption_enabled() );
633 return thrd;
634}
635
636// KERNEL ONLY
637static inline thread$ * __next_thread_slow(cluster * this) with( *this ) {
638 /* paranoid */ verify( ! __preemption_enabled() );
639
640 ready_schedule_lock();
641 thread$ * thrd;
642 for(25) {
643 thrd = pop_slow( this );
644 if(thrd) goto RET;
645 }
646 thrd = pop_search( this );
647
648 RET:
649 ready_schedule_unlock();
650
651 /* paranoid */ verify( ! __preemption_enabled() );
652 return thrd;
653}
654
655static inline bool __must_unpark( thread$ * thrd ) {
656 int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
657 switch(old_ticket) {
658 case TICKET_RUNNING:
659 // Wake won the race, the thread will reschedule/rerun itself
660 return false;
661 case TICKET_BLOCKED:
662 /* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
663 /* paranoid */ verify( thrd->state == Blocked );
664 return true;
665 default:
666 // This makes no sense, something is wrong abort
667 abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
668 }
669}
670
671void __kernel_unpark( thread$ * thrd, unpark_hint hint ) {
672 /* paranoid */ verify( ! __preemption_enabled() );
673 /* paranoid */ verify( ready_schedule_islocked());
674
675 if( !thrd ) return;
676
677 if(__must_unpark(thrd)) {
678 // Wake lost the race,
679 __schedule_thread( thrd, hint );
680 }
681
682 /* paranoid */ verify( ready_schedule_islocked());
683 /* paranoid */ verify( ! __preemption_enabled() );
684}
685
686void unpark( thread$ * thrd, unpark_hint hint ) {
687 if( !thrd ) return;
688
689 if(__must_unpark(thrd)) {
690 disable_interrupts();
691 // Wake lost the race,
692 schedule_thread$( thrd, hint );
693 enable_interrupts(false);
694 }
695}
696
697void park( void ) {
698 __disable_interrupts_checked();
699 /* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
700 returnToKernel();
701 __enable_interrupts_checked();
702
703}
704
705extern "C" {
706 // Leave the thread monitor
707 // last routine called by a thread.
708 // Should never return
709 void __cfactx_thrd_leave() {
710 thread$ * thrd = active_thread();
711 monitor$ * this = &thrd->self_mon;
712
713 // Lock the monitor now
714 lock( this->lock __cfaabi_dbg_ctx2 );
715
716 disable_interrupts();
717
718 /* paranoid */ verify( ! __preemption_enabled() );
719 /* paranoid */ verify( thrd->state == Active );
720 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
721 /* paranoid */ verify( kernelTLS().this_thread == thrd );
722 /* paranoid */ verify( thrd->context.SP );
723 /* 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 );
724 /* 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 );
725
726 thrd->state = Halting;
727 if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
728 if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
729 if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
730
731 // Leave the thread
732 returnToKernel();
733
734 // Control flow should never reach here!
735 abort();
736 }
737}
738
739// KERNEL ONLY
740bool force_yield( __Preemption_Reason reason ) {
741 __disable_interrupts_checked();
742 thread$ * thrd = kernelTLS().this_thread;
743 /* paranoid */ verify(thrd->state == Active);
744
745 // SKULLDUGGERY: It is possible that we are preempting this thread just before
746 // it was going to park itself. If that is the case and it is already using the
747 // intrusive fields then we can't use them to preempt the thread
748 // If that is the case, abandon the preemption.
749 bool preempted = false;
750 if(thrd->link.next == 0p) {
751 preempted = true;
752 thrd->preempted = reason;
753 returnToKernel();
754 }
755 __enable_interrupts_checked( false );
756 return preempted;
757}
758
759//=============================================================================================
760// Kernel Idle Sleep
761//=============================================================================================
762// Wake a thread from the front if there are any
763static void __wake_one(cluster * this) {
764 /* paranoid */ verify( ! __preemption_enabled() );
765 /* paranoid */ verify( ready_schedule_islocked() );
766
767 // Check if there is a sleeping processor
768 processor * p;
769 unsigned idle;
770 unsigned total;
771 [idle, total, p] = query_idles(this->procs);
772
773 // If no one is sleeping, we are done
774 if( idle == 0 ) return;
775
776 // We found a processor, wake it up
777 eventfd_t val;
778 val = 1;
779 eventfd_write( p->idle, val );
780
781 #if !defined(__CFA_NO_STATISTICS__)
782 if( kernelTLS().this_stats ) {
783 __tls_stats()->ready.sleep.wakes++;
784 }
785 else {
786 __atomic_fetch_add(&this->stats->ready.sleep.wakes, 1, __ATOMIC_RELAXED);
787 }
788 #endif
789
790 /* paranoid */ verify( ready_schedule_islocked() );
791 /* paranoid */ verify( ! __preemption_enabled() );
792
793 return;
794}
795
796// Unconditionnaly wake a thread
797void __wake_proc(processor * this) {
798 __cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
799
800 __disable_interrupts_checked();
801 /* paranoid */ verify( ! __preemption_enabled() );
802 eventfd_t val;
803 val = 1;
804 eventfd_write( this->idle, val );
805 __enable_interrupts_checked();
806}
807
808static void mark_idle(__cluster_proc_list & this, processor & proc) {
809 /* paranoid */ verify( ! __preemption_enabled() );
810 lock( this );
811 this.idle++;
812 /* paranoid */ verify( this.idle <= this.total );
813 remove(proc);
814 insert_first(this.idles, proc);
815 unlock( this );
816 /* paranoid */ verify( ! __preemption_enabled() );
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 unlock( this );
827 /* paranoid */ verify( ! __preemption_enabled() );
828}
829
830static [unsigned idle, unsigned total, * processor] query_idles( & __cluster_proc_list this ) {
831 /* paranoid */ verify( ! __preemption_enabled() );
832 /* paranoid */ verify( ready_schedule_islocked() );
833
834 for() {
835 uint64_t l = __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST);
836 if( 1 == (l % 2) ) { Pause(); continue; }
837 unsigned idle = this.idle;
838 unsigned total = this.total;
839 processor * proc = &this.idles`first;
840 // Compiler fence is unnecessary, but gcc-8 and older incorrectly reorder code without it
841 asm volatile("": : :"memory");
842 if(l != __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST)) { Pause(); continue; }
843 return [idle, total, proc];
844 }
845
846 /* paranoid */ verify( ready_schedule_islocked() );
847 /* paranoid */ verify( ! __preemption_enabled() );
848}
849
850//=============================================================================================
851// Unexpected Terminating logic
852//=============================================================================================
853void __kernel_abort_msg( char * abort_text, int abort_text_size ) {
854 thread$ * thrd = __cfaabi_tls.this_thread;
855
856 if(thrd) {
857 int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
858 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
859
860 if ( &thrd->self_cor != thrd->curr_cor ) {
861 len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
862 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
863 }
864 else {
865 __cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
866 }
867 }
868 else {
869 int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
870 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
871 }
872}
873
874int __kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
875 return get_coroutine(__cfaabi_tls.this_thread) == get_coroutine(mainThread) ? 4 : 2;
876}
877
878static __spinlock_t kernel_debug_lock;
879
880extern "C" {
881 void __cfaabi_bits_acquire() {
882 lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
883 }
884
885 void __cfaabi_bits_release() {
886 unlock( kernel_debug_lock );
887 }
888}
889
890//=============================================================================================
891// Kernel Utilities
892//=============================================================================================
893#if defined(CFA_HAVE_LINUX_IO_URING_H)
894#include "io/types.hfa"
895#endif
896
897static inline bool __maybe_io_drain( processor * proc ) {
898 bool ret = false;
899 #if defined(CFA_HAVE_LINUX_IO_URING_H)
900 __cfadbg_print_safe(runtime_core, "Kernel : core %p checking io for ring %d\n", proc, proc->io.ctx->fd);
901
902 // Check if we should drain the queue
903 $io_context * ctx = proc->io.ctx;
904 unsigned head = *ctx->cq.head;
905 unsigned tail = *ctx->cq.tail;
906 if(head == tail) return false;
907 #if OLD_MAIN
908 ready_schedule_lock();
909 ret = __cfa_io_drain( proc );
910 ready_schedule_unlock();
911 #else
912 ret = __cfa_io_drain( proc );
913 #endif
914 #endif
915 return ret;
916}
917
918//-----------------------------------------------------------------------------
919// Debug
920__cfaabi_dbg_debug_do(
921 extern "C" {
922 void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
923 this.prev_name = prev_name;
924 this.prev_thrd = kernelTLS().this_thread;
925 }
926 }
927)
928
929//-----------------------------------------------------------------------------
930// Debug
931bool threading_enabled(void) __attribute__((const)) {
932 return true;
933}
934
935//-----------------------------------------------------------------------------
936// Statistics
937#if !defined(__CFA_NO_STATISTICS__)
938 void print_halts( processor & this ) {
939 this.print_halts = true;
940 }
941
942 static void crawl_list( cluster * cltr, dlist(processor) & list, unsigned count ) {
943 /* paranoid */ verify( cltr->stats );
944
945 processor * it = &list`first;
946 for(unsigned i = 0; i < count; i++) {
947 /* paranoid */ verifyf( it, "Unexpected null iterator, at index %u of %u\n", i, count);
948 /* paranoid */ verify( it->local_data->this_stats );
949 // __print_stats( it->local_data->this_stats, cltr->print_stats, "Processor", it->name, (void*)it );
950 __tally_stats( cltr->stats, it->local_data->this_stats );
951 it = &(*it)`next;
952 }
953 }
954
955 void crawl_cluster_stats( cluster & this ) {
956 // Stop the world, otherwise stats could get really messed-up
957 // this doesn't solve all problems but does solve many
958 // so it's probably good enough
959 disable_interrupts();
960 uint_fast32_t last_size = ready_mutate_lock();
961
962 crawl_list(&this, this.procs.actives, this.procs.total - this.procs.idle);
963 crawl_list(&this, this.procs.idles , this.procs.idle );
964
965 // Unlock the RWlock
966 ready_mutate_unlock( last_size );
967 enable_interrupts();
968 }
969
970
971 void print_stats_now( cluster & this, int flags ) {
972 crawl_cluster_stats( this );
973 __print_stats( this.stats, this.print_stats, "Cluster", this.name, (void*)&this );
974 }
975#endif
976// Local Variables: //
977// mode: c //
978// tab-width: 4 //
979// End: //
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