source: libcfa/src/concurrency/kernel.cfa@ e4b37a1

ADT ast-experimental enum forall-pointer-decay jacob/cs343-translation pthread-emulation qualifiedEnum
Last change on this file since e4b37a1 was c86ee4c, checked in by Thierry Delisle <tdelisle@…>, 4 years ago

Merge branch 'master' of plg.uwaterloo.ca:software/cfa/cfa-cc
  • Property mode set to 100644
File size: 29.6 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 <signal.h>
25#include <unistd.h>
26extern "C" {
27 #include <sys/eventfd.h>
28}
29
30//CFA Includes
31#include "kernel_private.hfa"
32#include "preemption.hfa"
33
34//Private includes
35#define __CFA_INVOKE_PRIVATE__
36#include "invoke.h"
37
38#if !defined(__CFA_NO_STATISTICS__)
39 #define __STATS( ...) __VA_ARGS__
40#else
41 #define __STATS( ...)
42#endif
43
44//-----------------------------------------------------------------------------
45// Some assembly required
46#if defined( __i386 )
47 // mxcr : SSE Status and Control bits (control bits are preserved across function calls)
48 // fcw : X87 FPU control word (preserved across function calls)
49 #define __x87_store \
50 uint32_t __mxcr; \
51 uint16_t __fcw; \
52 __asm__ volatile ( \
53 "stmxcsr %0\n" \
54 "fnstcw %1\n" \
55 : "=m" (__mxcr),\
56 "=m" (__fcw) \
57 )
58
59 #define __x87_load \
60 __asm__ volatile ( \
61 "fldcw %1\n" \
62 "ldmxcsr %0\n" \
63 ::"m" (__mxcr),\
64 "m" (__fcw) \
65 )
66
67#elif defined( __x86_64 )
68 #define __x87_store \
69 uint32_t __mxcr; \
70 uint16_t __fcw; \
71 __asm__ volatile ( \
72 "stmxcsr %0\n" \
73 "fnstcw %1\n" \
74 : "=m" (__mxcr),\
75 "=m" (__fcw) \
76 )
77
78 #define __x87_load \
79 __asm__ volatile ( \
80 "fldcw %1\n" \
81 "ldmxcsr %0\n" \
82 :: "m" (__mxcr),\
83 "m" (__fcw) \
84 )
85
86#elif defined( __arm__ )
87 #define __x87_store
88 #define __x87_load
89
90#elif defined( __aarch64__ )
91 #define __x87_store \
92 uint32_t __fpcntl[2]; \
93 __asm__ volatile ( \
94 "mrs x9, FPCR\n" \
95 "mrs x10, FPSR\n" \
96 "stp x9, x10, %0\n" \
97 : "=m" (__fpcntl) : : "x9", "x10" \
98 )
99
100 #define __x87_load \
101 __asm__ volatile ( \
102 "ldp x9, x10, %0\n" \
103 "msr FPSR, x10\n" \
104 "msr FPCR, x9\n" \
105 : "=m" (__fpcntl) : : "x9", "x10" \
106 )
107
108#else
109 #error unsupported hardware architecture
110#endif
111
112extern thread$ * mainThread;
113extern processor * mainProcessor;
114
115//-----------------------------------------------------------------------------
116// Kernel Scheduling logic
117static thread$ * __next_thread(cluster * this);
118static thread$ * __next_thread_slow(cluster * this);
119static inline bool __must_unpark( thread$ * thrd ) __attribute((nonnull(1)));
120static void __run_thread(processor * this, thread$ * dst);
121static void __wake_one(cluster * cltr);
122
123static void mark_idle (__cluster_proc_list & idles, processor & proc);
124static void mark_awake(__cluster_proc_list & idles, processor & proc);
125static [unsigned idle, unsigned total, * processor] query_idles( & __cluster_proc_list idles );
126
127extern void __cfa_io_start( processor * );
128extern bool __cfa_io_drain( processor * );
129extern void __cfa_io_flush( processor * );
130extern void __cfa_io_stop ( processor * );
131static inline bool __maybe_io_drain( processor * );
132
133extern void __disable_interrupts_hard();
134extern void __enable_interrupts_hard();
135
136static inline void __disable_interrupts_checked() {
137 /* paranoid */ verify( __preemption_enabled() );
138 disable_interrupts();
139 /* paranoid */ verify( ! __preemption_enabled() );
140}
141
142static inline void __enable_interrupts_checked( bool poll = true ) {
143 /* paranoid */ verify( ! __preemption_enabled() );
144 enable_interrupts( poll );
145 /* paranoid */ verify( __preemption_enabled() );
146}
147
148//=============================================================================================
149// Kernel Scheduling logic
150//=============================================================================================
151//Main of the processor contexts
152void main(processorCtx_t & runner) {
153 // Because of a bug, we couldn't initialized the seed on construction
154 // Do it here
155 __cfaabi_tls.rand_seed ^= rdtscl();
156 __cfaabi_tls.ready_rng.fwd_seed = 25214903917_l64u * (rdtscl() ^ (uintptr_t)&runner);
157 __tls_rand_advance_bck();
158
159 processor * this = runner.proc;
160 verify(this);
161
162 __cfa_io_start( this );
163
164 __cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
165 #if !defined(__CFA_NO_STATISTICS__)
166 if( this->print_halts ) {
167 __cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->unique_id, this->name, (void*)this);
168 }
169 #endif
170
171 {
172 // Setup preemption data
173 preemption_scope scope = { this };
174
175 // if we need to run some special setup, now is the time to do it.
176 if(this->init.thrd) {
177 this->init.thrd->curr_cluster = this->cltr;
178 __run_thread(this, this->init.thrd);
179 }
180
181 __cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
182
183 thread$ * readyThread = 0p;
184 MAIN_LOOP:
185 for() {
186 #define OLD_MAIN 1
187 #if OLD_MAIN
188 // Check if there is pending io
189 __maybe_io_drain( this );
190
191 // Try to get the next thread
192 readyThread = __next_thread( this->cltr );
193
194 if( !readyThread ) {
195 __cfa_io_flush( this );
196 readyThread = __next_thread_slow( this->cltr );
197 }
198
199 HALT:
200 if( !readyThread ) {
201 // Don't block if we are done
202 if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
203
204 #if !defined(__CFA_NO_STATISTICS__)
205 __tls_stats()->ready.sleep.halts++;
206 #endif
207
208 // Push self to idle stack
209 mark_idle(this->cltr->procs, * this);
210
211 // Confirm the ready-queue is empty
212 readyThread = __next_thread_slow( this->cltr );
213 if( readyThread ) {
214 // A thread was found, cancel the halt
215 mark_awake(this->cltr->procs, * this);
216
217 #if !defined(__CFA_NO_STATISTICS__)
218 __tls_stats()->ready.sleep.cancels++;
219 #endif
220
221 // continue the mai loop
222 break HALT;
223 }
224
225 #if !defined(__CFA_NO_STATISTICS__)
226 if(this->print_halts) {
227 __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->unique_id, rdtscl());
228 }
229 #endif
230
231 __cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle);
232
233 __disable_interrupts_hard();
234 eventfd_t val;
235 eventfd_read( this->idle, &val );
236 __enable_interrupts_hard();
237
238 #if !defined(__CFA_NO_STATISTICS__)
239 if(this->print_halts) {
240 __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->unique_id, rdtscl());
241 }
242 #endif
243
244 // We were woken up, remove self from idle
245 mark_awake(this->cltr->procs, * this);
246
247 // DON'T just proceed, start looking again
248 continue MAIN_LOOP;
249 }
250
251 /* paranoid */ verify( readyThread );
252
253 // Reset io dirty bit
254 this->io.dirty = false;
255
256 // We found a thread run it
257 __run_thread(this, readyThread);
258
259 // Are we done?
260 if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
261
262 if(this->io.pending && !this->io.dirty) {
263 __cfa_io_flush( this );
264 }
265
266 #else
267 #warning new kernel loop
268 SEARCH: {
269 /* paranoid */ verify( ! __preemption_enabled() );
270
271 // First, lock the scheduler since we are searching for a thread
272 ready_schedule_lock();
273
274 // Try to get the next thread
275 readyThread = pop_fast( this->cltr );
276 if(readyThread) { ready_schedule_unlock(); break SEARCH; }
277
278 // If we can't find a thread, might as well flush any outstanding I/O
279 if(this->io.pending) { __cfa_io_flush( this ); }
280
281 // Spin a little on I/O, just in case
282 for(5) {
283 __maybe_io_drain( this );
284 readyThread = pop_fast( this->cltr );
285 if(readyThread) { ready_schedule_unlock(); break SEARCH; }
286 }
287
288 // no luck, try stealing a few times
289 for(5) {
290 if( __maybe_io_drain( this ) ) {
291 readyThread = pop_fast( this->cltr );
292 } else {
293 readyThread = pop_slow( this->cltr );
294 }
295 if(readyThread) { ready_schedule_unlock(); break SEARCH; }
296 }
297
298 // still no luck, search for a thread
299 readyThread = pop_search( this->cltr );
300 if(readyThread) { ready_schedule_unlock(); break SEARCH; }
301
302 // Don't block if we are done
303 if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
304
305 __STATS( __tls_stats()->ready.sleep.halts++; )
306
307 // Push self to idle stack
308 ready_schedule_unlock();
309 mark_idle(this->cltr->procs, * this);
310 ready_schedule_lock();
311
312 // Confirm the ready-queue is empty
313 __maybe_io_drain( this );
314 readyThread = pop_search( this->cltr );
315 ready_schedule_unlock();
316
317 if( readyThread ) {
318 // A thread was found, cancel the halt
319 mark_awake(this->cltr->procs, * this);
320
321 __STATS( __tls_stats()->ready.sleep.cancels++; )
322
323 // continue the main loop
324 break SEARCH;
325 }
326
327 __STATS( if(this->print_halts) __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->unique_id, rdtscl()); )
328 __cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle);
329
330 // __disable_interrupts_hard();
331 eventfd_t val;
332 eventfd_read( this->idle, &val );
333 // __enable_interrupts_hard();
334
335 __STATS( if(this->print_halts) __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->unique_id, rdtscl()); )
336
337 // We were woken up, remove self from idle
338 mark_awake(this->cltr->procs, * this);
339
340 // DON'T just proceed, start looking again
341 continue MAIN_LOOP;
342 }
343
344 RUN_THREAD:
345 /* paranoid */ verify( ! __preemption_enabled() );
346 /* paranoid */ verify( readyThread );
347
348 // Reset io dirty bit
349 this->io.dirty = false;
350
351 // We found a thread run it
352 __run_thread(this, readyThread);
353
354 // Are we done?
355 if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
356
357 if(this->io.pending && !this->io.dirty) {
358 __cfa_io_flush( this );
359 }
360
361 ready_schedule_lock();
362 __maybe_io_drain( this );
363 ready_schedule_unlock();
364 #endif
365 }
366
367 __cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
368 }
369
370 __cfa_io_stop( this );
371
372 post( this->terminated );
373
374 if(this == mainProcessor) {
375 // HACK : the coroutine context switch expects this_thread to be set
376 // and it make sense for it to be set in all other cases except here
377 // fake it
378 __cfaabi_tls.this_thread = mainThread;
379 }
380
381 __cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
382}
383
384static int * __volatile_errno() __attribute__((noinline));
385static int * __volatile_errno() { asm(""); return &errno; }
386
387// KERNEL ONLY
388// runThread runs a thread by context switching
389// from the processor coroutine to the target thread
390static void __run_thread(processor * this, thread$ * thrd_dst) {
391 /* paranoid */ verify( ! __preemption_enabled() );
392 /* paranoid */ verifyf( thrd_dst->state == Ready || thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
393 /* paranoid */ verifyf( thrd_dst->link.next == 0p, "Expected null got %p", thrd_dst->link.next );
394 __builtin_prefetch( thrd_dst->context.SP );
395
396 int curr = __kernel_getcpu();
397 if(thrd_dst->last_cpu != curr) {
398 int64_t l = thrd_dst->last_cpu;
399 int64_t c = curr;
400 int64_t v = (l << 32) | c;
401 __push_stat( __tls_stats(), v, false, "Processor", this );
402 }
403
404 thrd_dst->last_cpu = curr;
405
406 __cfadbg_print_safe(runtime_core, "Kernel : core %p running thread %p (%s)\n", this, thrd_dst, thrd_dst->self_cor.name);
407
408 coroutine$ * proc_cor = get_coroutine(this->runner);
409
410 // set state of processor coroutine to inactive
411 verify(proc_cor->state == Active);
412 proc_cor->state = Blocked;
413
414 // Actually run the thread
415 RUNNING: while(true) {
416 thrd_dst->preempted = __NO_PREEMPTION;
417 thrd_dst->state = Active;
418
419 // Update global state
420 kernelTLS().this_thread = thrd_dst;
421
422 /* paranoid */ verify( ! __preemption_enabled() );
423 /* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
424 /* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
425 /* paranoid */ verify( thrd_dst->context.SP );
426 /* paranoid */ verify( thrd_dst->state != Halted );
427 /* 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
428 /* 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
429 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
430
431
432
433 // set context switch to the thread that the processor is executing
434 __cfactx_switch( &proc_cor->context, &thrd_dst->context );
435 // when __cfactx_switch returns we are back in the processor coroutine
436
437
438
439 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
440 /* 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 );
441 /* 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 );
442 /* paranoid */ verify( thrd_dst->context.SP );
443 /* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
444 /* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
445 /* paranoid */ verify( ! __preemption_enabled() );
446
447 // Reset global state
448 kernelTLS().this_thread = 0p;
449
450 // We just finished running a thread, there are a few things that could have happened.
451 // 1 - Regular case : the thread has blocked and now one has scheduled it yet.
452 // 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
453 // 4 - Preempted
454 // In case 1, we may have won a race so we can't write to the state again.
455 // In case 2, we lost the race so we now own the thread.
456
457 if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
458 // The thread was preempted, reschedule it and reset the flag
459 schedule_thread$( thrd_dst );
460 break RUNNING;
461 }
462
463 if(unlikely(thrd_dst->state == Halting)) {
464 // The thread has halted, it should never be scheduled/run again
465 // finish the thread
466 __thread_finish( thrd_dst );
467 break RUNNING;
468 }
469
470 /* paranoid */ verify( thrd_dst->state == Active );
471 thrd_dst->state = Blocked;
472
473 // set state of processor coroutine to active and the thread to inactive
474 int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
475 switch(old_ticket) {
476 case TICKET_RUNNING:
477 // This is case 1, the regular case, nothing more is needed
478 break RUNNING;
479 case TICKET_UNBLOCK:
480 #if !defined(__CFA_NO_STATISTICS__)
481 __tls_stats()->ready.threads.threads++;
482 #endif
483 // This is case 2, the racy case, someone tried to run this thread before it finished blocking
484 // In this case, just run it again.
485 continue RUNNING;
486 default:
487 // This makes no sense, something is wrong abort
488 abort();
489 }
490 }
491
492 // Just before returning to the processor, set the processor coroutine to active
493 proc_cor->state = Active;
494
495 __cfadbg_print_safe(runtime_core, "Kernel : core %p finished running thread %p\n", this, thrd_dst);
496
497 #if !defined(__CFA_NO_STATISTICS__)
498 __tls_stats()->ready.threads.threads--;
499 #endif
500
501 /* paranoid */ verify( ! __preemption_enabled() );
502}
503
504// KERNEL_ONLY
505void returnToKernel() {
506 /* paranoid */ verify( ! __preemption_enabled() );
507 coroutine$ * proc_cor = get_coroutine(kernelTLS().this_processor->runner);
508 thread$ * thrd_src = kernelTLS().this_thread;
509
510 __STATS( thrd_src->last_proc = kernelTLS().this_processor; )
511
512 // Run the thread on this processor
513 {
514 int local_errno = *__volatile_errno();
515 #if defined( __i386 ) || defined( __x86_64 )
516 __x87_store;
517 #endif
518 /* paranoid */ verify( proc_cor->context.SP );
519 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
520 __cfactx_switch( &thrd_src->context, &proc_cor->context );
521 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
522 #if defined( __i386 ) || defined( __x86_64 )
523 __x87_load;
524 #endif
525 *__volatile_errno() = local_errno;
526 }
527
528 #if !defined(__CFA_NO_STATISTICS__)
529 /* paranoid */ verify( thrd_src->last_proc != 0p );
530 if(thrd_src->last_proc != kernelTLS().this_processor) {
531 __tls_stats()->ready.threads.migration++;
532 }
533 #endif
534
535 /* paranoid */ verify( ! __preemption_enabled() );
536 /* 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 );
537 /* 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 );
538}
539
540//-----------------------------------------------------------------------------
541// Scheduler routines
542// KERNEL ONLY
543static void __schedule_thread( thread$ * thrd ) {
544 /* paranoid */ verify( ! __preemption_enabled() );
545 /* paranoid */ verify( ready_schedule_islocked());
546 /* paranoid */ verify( thrd );
547 /* paranoid */ verify( thrd->state != Halted );
548 /* paranoid */ verify( thrd->curr_cluster );
549 /* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
550 /* paranoid */ if( thrd->state == Blocked || thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
551 "Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
552 /* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
553 "Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
554 /* paranoid */ #endif
555 /* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
556 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
557
558 const bool local = thrd->state != Start;
559 if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
560
561 // Dereference the thread now because once we push it, there is not guaranteed it's still valid.
562 struct cluster * cl = thrd->curr_cluster;
563 __STATS(bool outside = thrd->last_proc && thrd->last_proc != kernelTLS().this_processor; )
564
565 // push the thread to the cluster ready-queue
566 push( cl, thrd, local );
567
568 // variable thrd is no longer safe to use
569 thrd = 0xdeaddeaddeaddeadp;
570
571 // wake the cluster using the save variable.
572 __wake_one( cl );
573
574 #if !defined(__CFA_NO_STATISTICS__)
575 if( kernelTLS().this_stats ) {
576 __tls_stats()->ready.threads.threads++;
577 if(outside) {
578 __tls_stats()->ready.threads.extunpark++;
579 }
580 }
581 else {
582 __atomic_fetch_add(&cl->stats->ready.threads.threads, 1, __ATOMIC_RELAXED);
583 __atomic_fetch_add(&cl->stats->ready.threads.extunpark, 1, __ATOMIC_RELAXED);
584 }
585 #endif
586
587 /* paranoid */ verify( ready_schedule_islocked());
588 /* paranoid */ verify( ! __preemption_enabled() );
589}
590
591void schedule_thread$( thread$ * thrd ) {
592 ready_schedule_lock();
593 __schedule_thread( thrd );
594 ready_schedule_unlock();
595}
596
597// KERNEL ONLY
598static inline thread$ * __next_thread(cluster * this) with( *this ) {
599 /* paranoid */ verify( ! __preemption_enabled() );
600
601 ready_schedule_lock();
602 thread$ * thrd = pop_fast( this );
603 ready_schedule_unlock();
604
605 /* paranoid */ verify( ! __preemption_enabled() );
606 return thrd;
607}
608
609// KERNEL ONLY
610static inline thread$ * __next_thread_slow(cluster * this) with( *this ) {
611 /* paranoid */ verify( ! __preemption_enabled() );
612
613 ready_schedule_lock();
614 thread$ * thrd;
615 for(25) {
616 thrd = pop_slow( this );
617 if(thrd) goto RET;
618 }
619 thrd = pop_search( this );
620
621 RET:
622 ready_schedule_unlock();
623
624 /* paranoid */ verify( ! __preemption_enabled() );
625 return thrd;
626}
627
628static inline bool __must_unpark( thread$ * thrd ) {
629 int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
630 switch(old_ticket) {
631 case TICKET_RUNNING:
632 // Wake won the race, the thread will reschedule/rerun itself
633 return false;
634 case TICKET_BLOCKED:
635 /* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
636 /* paranoid */ verify( thrd->state == Blocked );
637 return true;
638 default:
639 // This makes no sense, something is wrong abort
640 abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
641 }
642}
643
644void __kernel_unpark( thread$ * thrd ) {
645 /* paranoid */ verify( ! __preemption_enabled() );
646 /* paranoid */ verify( ready_schedule_islocked());
647
648 if( !thrd ) return;
649
650 if(__must_unpark(thrd)) {
651 // Wake lost the race,
652 __schedule_thread( thrd );
653 }
654
655 /* paranoid */ verify( ready_schedule_islocked());
656 /* paranoid */ verify( ! __preemption_enabled() );
657}
658
659void unpark( thread$ * thrd ) {
660 if( !thrd ) return;
661
662 if(__must_unpark(thrd)) {
663 disable_interrupts();
664 // Wake lost the race,
665 schedule_thread$( thrd );
666 enable_interrupts(false);
667 }
668}
669
670void park( void ) {
671 __disable_interrupts_checked();
672 /* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
673 returnToKernel();
674 __enable_interrupts_checked();
675
676}
677
678extern "C" {
679 // Leave the thread monitor
680 // last routine called by a thread.
681 // Should never return
682 void __cfactx_thrd_leave() {
683 thread$ * thrd = active_thread();
684 monitor$ * this = &thrd->self_mon;
685
686 // Lock the monitor now
687 lock( this->lock __cfaabi_dbg_ctx2 );
688
689 disable_interrupts();
690
691 /* paranoid */ verify( ! __preemption_enabled() );
692 /* paranoid */ verify( thrd->state == Active );
693 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
694 /* paranoid */ verify( kernelTLS().this_thread == thrd );
695 /* paranoid */ verify( thrd->context.SP );
696 /* 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 );
697 /* 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 );
698
699 thrd->state = Halting;
700 if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
701 if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
702 if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
703
704 // Leave the thread
705 returnToKernel();
706
707 // Control flow should never reach here!
708 abort();
709 }
710}
711
712// KERNEL ONLY
713bool force_yield( __Preemption_Reason reason ) {
714 __disable_interrupts_checked();
715 thread$ * thrd = kernelTLS().this_thread;
716 /* paranoid */ verify(thrd->state == Active);
717
718 // SKULLDUGGERY: It is possible that we are preempting this thread just before
719 // it was going to park itself. If that is the case and it is already using the
720 // intrusive fields then we can't use them to preempt the thread
721 // If that is the case, abandon the preemption.
722 bool preempted = false;
723 if(thrd->link.next == 0p) {
724 preempted = true;
725 thrd->preempted = reason;
726 returnToKernel();
727 }
728 __enable_interrupts_checked( false );
729 return preempted;
730}
731
732//=============================================================================================
733// Kernel Idle Sleep
734//=============================================================================================
735// Wake a thread from the front if there are any
736static void __wake_one(cluster * this) {
737 /* paranoid */ verify( ! __preemption_enabled() );
738 /* paranoid */ verify( ready_schedule_islocked() );
739
740 // Check if there is a sleeping processor
741 processor * p;
742 unsigned idle;
743 unsigned total;
744 [idle, total, p] = query_idles(this->procs);
745
746 // If no one is sleeping, we are done
747 if( idle == 0 ) return;
748
749 // We found a processor, wake it up
750 eventfd_t val;
751 val = 1;
752 eventfd_write( p->idle, val );
753
754 #if !defined(__CFA_NO_STATISTICS__)
755 if( kernelTLS().this_stats ) {
756 __tls_stats()->ready.sleep.wakes++;
757 }
758 else {
759 __atomic_fetch_add(&this->stats->ready.sleep.wakes, 1, __ATOMIC_RELAXED);
760 }
761 #endif
762
763 /* paranoid */ verify( ready_schedule_islocked() );
764 /* paranoid */ verify( ! __preemption_enabled() );
765
766 return;
767}
768
769// Unconditionnaly wake a thread
770void __wake_proc(processor * this) {
771 __cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
772
773 __disable_interrupts_checked();
774 /* paranoid */ verify( ! __preemption_enabled() );
775 eventfd_t val;
776 val = 1;
777 eventfd_write( this->idle, val );
778 __enable_interrupts_checked();
779}
780
781static void mark_idle(__cluster_proc_list & this, processor & proc) {
782 /* paranoid */ verify( ! __preemption_enabled() );
783 lock( this );
784 this.idle++;
785 /* paranoid */ verify( this.idle <= this.total );
786 remove(proc);
787 insert_first(this.idles, proc);
788 unlock( this );
789 /* paranoid */ verify( ! __preemption_enabled() );
790}
791
792static void mark_awake(__cluster_proc_list & this, processor & proc) {
793 /* paranoid */ verify( ! __preemption_enabled() );
794 lock( this );
795 this.idle--;
796 /* paranoid */ verify( this.idle >= 0 );
797 remove(proc);
798 insert_last(this.actives, proc);
799 unlock( this );
800 /* paranoid */ verify( ! __preemption_enabled() );
801}
802
803static [unsigned idle, unsigned total, * processor] query_idles( & __cluster_proc_list this ) {
804 /* paranoid */ verify( ! __preemption_enabled() );
805 /* paranoid */ verify( ready_schedule_islocked() );
806
807 for() {
808 uint64_t l = __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST);
809 if( 1 == (l % 2) ) { Pause(); continue; }
810 unsigned idle = this.idle;
811 unsigned total = this.total;
812 processor * proc = &this.idles`first;
813 // Compiler fence is unnecessary, but gcc-8 and older incorrectly reorder code without it
814 asm volatile("": : :"memory");
815 if(l != __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST)) { Pause(); continue; }
816 return [idle, total, proc];
817 }
818
819 /* paranoid */ verify( ready_schedule_islocked() );
820 /* paranoid */ verify( ! __preemption_enabled() );
821}
822
823//=============================================================================================
824// Unexpected Terminating logic
825//=============================================================================================
826void __kernel_abort_msg( char * abort_text, int abort_text_size ) {
827 thread$ * thrd = __cfaabi_tls.this_thread;
828
829 if(thrd) {
830 int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
831 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
832
833 if ( &thrd->self_cor != thrd->curr_cor ) {
834 len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
835 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
836 }
837 else {
838 __cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
839 }
840 }
841 else {
842 int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
843 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
844 }
845}
846
847int __kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
848 return get_coroutine(__cfaabi_tls.this_thread) == get_coroutine(mainThread) ? 4 : 2;
849}
850
851static __spinlock_t kernel_debug_lock;
852
853extern "C" {
854 void __cfaabi_bits_acquire() {
855 lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
856 }
857
858 void __cfaabi_bits_release() {
859 unlock( kernel_debug_lock );
860 }
861}
862
863//=============================================================================================
864// Kernel Utilities
865//=============================================================================================
866#if defined(CFA_HAVE_LINUX_IO_URING_H)
867#include "io/types.hfa"
868#endif
869
870static inline bool __maybe_io_drain( processor * proc ) {
871 bool ret = false;
872 #if defined(CFA_HAVE_LINUX_IO_URING_H)
873 __cfadbg_print_safe(runtime_core, "Kernel : core %p checking io for ring %d\n", proc, proc->io.ctx->fd);
874
875 // Check if we should drain the queue
876 $io_context * ctx = proc->io.ctx;
877 unsigned head = *ctx->cq.head;
878 unsigned tail = *ctx->cq.tail;
879 if(head == tail) return false;
880 #if OLD_MAIN
881 ready_schedule_lock();
882 ret = __cfa_io_drain( proc );
883 ready_schedule_unlock();
884 #else
885 ret = __cfa_io_drain( proc );
886 #endif
887 #endif
888 return ret;
889}
890
891//-----------------------------------------------------------------------------
892// Debug
893__cfaabi_dbg_debug_do(
894 extern "C" {
895 void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
896 this.prev_name = prev_name;
897 this.prev_thrd = kernelTLS().this_thread;
898 }
899 }
900)
901
902//-----------------------------------------------------------------------------
903// Debug
904bool threading_enabled(void) __attribute__((const)) {
905 return true;
906}
907
908//-----------------------------------------------------------------------------
909// Statistics
910#if !defined(__CFA_NO_STATISTICS__)
911 void print_halts( processor & this ) {
912 this.print_halts = true;
913 }
914
915 static void crawl_list( cluster * cltr, dlist(processor) & list, unsigned count ) {
916 /* paranoid */ verify( cltr->stats );
917
918 processor * it = &list`first;
919 for(unsigned i = 0; i < count; i++) {
920 /* paranoid */ verifyf( it, "Unexpected null iterator, at index %u of %u\n", i, count);
921 /* paranoid */ verify( it->local_data->this_stats );
922 __tally_stats( cltr->stats, it->local_data->this_stats );
923 it = &(*it)`next;
924 }
925 }
926
927 void crawl_cluster_stats( cluster & this ) {
928 // Stop the world, otherwise stats could get really messed-up
929 // this doesn't solve all problems but does solve many
930 // so it's probably good enough
931 uint_fast32_t last_size = ready_mutate_lock();
932
933 crawl_list(&this, this.procs.actives, this.procs.total - this.procs.idle);
934 crawl_list(&this, this.procs.idles , this.procs.idle );
935
936 // Unlock the RWlock
937 ready_mutate_unlock( last_size );
938 }
939
940
941 void print_stats_now( cluster & this, int flags ) {
942 crawl_cluster_stats( this );
943 __print_stats( this.stats, this.print_stats, "Cluster", this.name, (void*)&this );
944 }
945#endif
946// Local Variables: //
947// mode: c //
948// tab-width: 4 //
949// End: //
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