source: libcfa/src/concurrency/kernel.cfa@ 2b96031

ADT arm-eh ast-experimental enum forall-pointer-decay jacob/cs343-translation new-ast-unique-expr pthread-emulation qualifiedEnum
Last change on this file since 2b96031 was c993b15, checked in by Thierry Delisle <tdelisle@…>, 4 years ago

Changed RW lock to avoid hitting the global array on schedule.
  • Property mode set to 100644
File size: 29.4 KB
Line 
1//
2// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
3//
4// The contents of this file are covered under the licence agreement in the
5// file "LICENCE" distributed with Cforall.
6//
7// kernel.c --
8//
9// Author : Thierry Delisle
10// Created On : Tue Jan 17 12:27:26 2017
11// Last Modified By : Peter A. Buhr
12// Last Modified On : Mon Aug 31 07:08:20 2020
13// Update Count : 71
14//
15
16#define __cforall_thread__
17// #define __CFA_DEBUG_PRINT_RUNTIME_CORE__
18
19//C Includes
20#include <errno.h>
21#include <stdio.h>
22#include <signal.h>
23#include <unistd.h>
24extern "C" {
25 #include <sys/eventfd.h>
26}
27
28//CFA Includes
29#include "kernel_private.hfa"
30#include "preemption.hfa"
31
32//Private includes
33#define __CFA_INVOKE_PRIVATE__
34#include "invoke.h"
35
36#if !defined(__CFA_NO_STATISTICS__)
37 #define __STATS( ...) __VA_ARGS__
38#else
39 #define __STATS( ...)
40#endif
41
42//-----------------------------------------------------------------------------
43// Some assembly required
44#if defined( __i386 )
45 // mxcr : SSE Status and Control bits (control bits are preserved across function calls)
46 // fcw : X87 FPU control word (preserved across function calls)
47 #define __x87_store \
48 uint32_t __mxcr; \
49 uint16_t __fcw; \
50 __asm__ volatile ( \
51 "stmxcsr %0\n" \
52 "fnstcw %1\n" \
53 : "=m" (__mxcr),\
54 "=m" (__fcw) \
55 )
56
57 #define __x87_load \
58 __asm__ volatile ( \
59 "fldcw %1\n" \
60 "ldmxcsr %0\n" \
61 ::"m" (__mxcr),\
62 "m" (__fcw) \
63 )
64
65#elif defined( __x86_64 )
66 #define __x87_store \
67 uint32_t __mxcr; \
68 uint16_t __fcw; \
69 __asm__ volatile ( \
70 "stmxcsr %0\n" \
71 "fnstcw %1\n" \
72 : "=m" (__mxcr),\
73 "=m" (__fcw) \
74 )
75
76 #define __x87_load \
77 __asm__ volatile ( \
78 "fldcw %1\n" \
79 "ldmxcsr %0\n" \
80 :: "m" (__mxcr),\
81 "m" (__fcw) \
82 )
83
84#elif defined( __arm__ )
85 #define __x87_store
86 #define __x87_load
87
88#elif defined( __aarch64__ )
89 #define __x87_store \
90 uint32_t __fpcntl[2]; \
91 __asm__ volatile ( \
92 "mrs x9, FPCR\n" \
93 "mrs x10, FPSR\n" \
94 "stp x9, x10, %0\n" \
95 : "=m" (__fpcntl) : : "x9", "x10" \
96 )
97
98 #define __x87_load \
99 __asm__ volatile ( \
100 "ldp x9, x10, %0\n" \
101 "msr FPSR, x10\n" \
102 "msr FPCR, x9\n" \
103 : "=m" (__fpcntl) : : "x9", "x10" \
104 )
105
106#else
107 #error unsupported hardware architecture
108#endif
109
110extern $thread * mainThread;
111extern processor * mainProcessor;
112
113//-----------------------------------------------------------------------------
114// Kernel Scheduling logic
115static $thread * __next_thread(cluster * this);
116static $thread * __next_thread_slow(cluster * this);
117static inline bool __must_unpark( $thread * thrd ) __attribute((nonnull(1)));
118static void __run_thread(processor * this, $thread * dst);
119static void __wake_one(cluster * cltr);
120
121static void mark_idle (__cluster_proc_list & idles, processor & proc);
122static void mark_awake(__cluster_proc_list & idles, processor & proc);
123static [unsigned idle, unsigned total, * processor] query_idles( & __cluster_proc_list idles );
124
125extern void __cfa_io_start( processor * );
126extern bool __cfa_io_drain( processor * );
127extern void __cfa_io_flush( processor * );
128extern void __cfa_io_stop ( processor * );
129static inline bool __maybe_io_drain( processor * );
130
131extern void __disable_interrupts_hard();
132extern void __enable_interrupts_hard();
133
134static inline void __disable_interrupts_checked() {
135 /* paranoid */ verify( __preemption_enabled() );
136 disable_interrupts();
137 /* paranoid */ verify( ! __preemption_enabled() );
138}
139
140static inline void __enable_interrupts_checked( bool poll = true ) {
141 /* paranoid */ verify( ! __preemption_enabled() );
142 enable_interrupts( poll );
143 /* paranoid */ verify( __preemption_enabled() );
144}
145
146//=============================================================================================
147// Kernel Scheduling logic
148//=============================================================================================
149//Main of the processor contexts
150void main(processorCtx_t & runner) {
151 // Because of a bug, we couldn't initialized the seed on construction
152 // Do it here
153 __cfaabi_tls.rand_seed ^= rdtscl();
154 __cfaabi_tls.ready_rng.fwd_seed = 25214903917_l64u * (rdtscl() ^ (uintptr_t)&runner);
155 __tls_rand_advance_bck();
156
157 processor * this = runner.proc;
158 verify(this);
159
160 __cfa_io_start( this );
161
162 __cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
163 #if !defined(__CFA_NO_STATISTICS__)
164 if( this->print_halts ) {
165 __cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->unique_id, this->name, (void*)this);
166 }
167 #endif
168
169 {
170 // Setup preemption data
171 preemption_scope scope = { this };
172
173 __STATS( unsigned long long last_tally = rdtscl(); )
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 // Check if there is pending io
187 __maybe_io_drain( this );
188
189 // Try to get the next thread
190 readyThread = __next_thread( this->cltr );
191
192 if( !readyThread ) {
193 __cfa_io_flush( this );
194 readyThread = __next_thread_slow( this->cltr );
195 }
196
197 HALT:
198 if( !readyThread ) {
199 // Don't block if we are done
200 if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
201
202 #if !defined(__CFA_NO_STATISTICS__)
203 __tls_stats()->ready.sleep.halts++;
204 #endif
205
206 // Push self to idle stack
207 mark_idle(this->cltr->procs, * this);
208
209 // Confirm the ready-queue is empty
210 readyThread = __next_thread_slow( this->cltr );
211 if( readyThread ) {
212 // A thread was found, cancel the halt
213 mark_awake(this->cltr->procs, * this);
214
215 #if !defined(__CFA_NO_STATISTICS__)
216 __tls_stats()->ready.sleep.cancels++;
217 #endif
218
219 // continue the mai loop
220 break HALT;
221 }
222
223 #if !defined(__CFA_NO_STATISTICS__)
224 if(this->print_halts) {
225 __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->unique_id, rdtscl());
226 }
227 #endif
228
229 __cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle);
230
231 __disable_interrupts_hard();
232 eventfd_t val;
233 eventfd_read( this->idle, &val );
234 __enable_interrupts_hard();
235
236 #if !defined(__CFA_NO_STATISTICS__)
237 if(this->print_halts) {
238 __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->unique_id, rdtscl());
239 }
240 #endif
241
242 // We were woken up, remove self from idle
243 mark_awake(this->cltr->procs, * this);
244
245 // DON'T just proceed, start looking again
246 continue MAIN_LOOP;
247 }
248
249 /* paranoid */ verify( readyThread );
250
251 // Reset io dirty bit
252 this->io.dirty = false;
253
254 // We found a thread run it
255 __run_thread(this, readyThread);
256
257 // Are we done?
258 if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
259
260 #if !defined(__CFA_NO_STATISTICS__)
261 unsigned long long curr = rdtscl();
262 if(curr > (last_tally + 500000000)) {
263 __tally_stats(this->cltr->stats, __cfaabi_tls.this_stats);
264 last_tally = curr;
265 }
266 #endif
267
268 if(this->io.pending && !this->io.dirty) {
269 __cfa_io_flush( this );
270 }
271
272 // SEARCH: {
273 // /* paranoid */ verify( ! __preemption_enabled() );
274 // /* paranoid */ verify( kernelTLS().this_proc_id );
275
276 // // First, lock the scheduler since we are searching for a thread
277
278 // // Try to get the next thread
279 // ready_schedule_lock();
280 // readyThread = pop_fast( this->cltr );
281 // ready_schedule_unlock();
282 // if(readyThread) { break SEARCH; }
283
284 // // If we can't find a thread, might as well flush any outstanding I/O
285 // if(this->io.pending) { __cfa_io_flush( this ); }
286
287 // // Spin a little on I/O, just in case
288 // for(25) {
289 // __maybe_io_drain( this );
290 // ready_schedule_lock();
291 // readyThread = pop_fast( this->cltr );
292 // ready_schedule_unlock();
293 // if(readyThread) { break SEARCH; }
294 // }
295
296 // // no luck, try stealing a few times
297 // for(25) {
298 // if( __maybe_io_drain( this ) ) {
299 // ready_schedule_lock();
300 // readyThread = pop_fast( this->cltr );
301 // } else {
302 // ready_schedule_lock();
303 // readyThread = pop_slow( this->cltr );
304 // }
305 // ready_schedule_unlock();
306 // if(readyThread) { break SEARCH; }
307 // }
308
309 // // still no luck, search for a thread
310 // ready_schedule_lock();
311 // readyThread = pop_search( this->cltr );
312 // ready_schedule_unlock();
313 // if(readyThread) { break SEARCH; }
314
315 // // Don't block if we are done
316 // if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
317
318 // __STATS( __tls_stats()->ready.sleep.halts++; )
319
320 // // Push self to idle stack
321 // mark_idle(this->cltr->procs, * this);
322
323 // // Confirm the ready-queue is empty
324 // __maybe_io_drain( this );
325 // ready_schedule_lock();
326 // readyThread = pop_search( this->cltr );
327 // ready_schedule_unlock();
328
329 // if( readyThread ) {
330 // // A thread was found, cancel the halt
331 // mark_awake(this->cltr->procs, * this);
332
333 // __STATS( __tls_stats()->ready.sleep.cancels++; )
334
335 // // continue the main loop
336 // break SEARCH;
337 // }
338
339 // __STATS( if(this->print_halts) __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->id, rdtscl()); )
340 // __cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle);
341
342 // // __disable_interrupts_hard();
343 // eventfd_t val;
344 // eventfd_read( this->idle, &val );
345 // // __enable_interrupts_hard();
346
347 // __STATS( if(this->print_halts) __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->id, rdtscl()); )
348
349 // // We were woken up, remove self from idle
350 // mark_awake(this->cltr->procs, * this);
351
352 // // DON'T just proceed, start looking again
353 // continue MAIN_LOOP;
354 // }
355
356 // RUN_THREAD:
357 // /* paranoid */ verify( kernelTLS().this_proc_id );
358 // /* paranoid */ verify( ! __preemption_enabled() );
359 // /* paranoid */ verify( readyThread );
360
361 // // Reset io dirty bit
362 // this->io.dirty = false;
363
364 // // We found a thread run it
365 // __run_thread(this, readyThread);
366
367 // // Are we done?
368 // if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
369
370 // #if !defined(__CFA_NO_STATISTICS__)
371 // unsigned long long curr = rdtscl();
372 // if(curr > (last_tally + 500000000)) {
373 // __tally_stats(this->cltr->stats, __cfaabi_tls.this_stats);
374 // last_tally = curr;
375 // }
376 // #endif
377
378 // if(this->io.pending && !this->io.dirty) {
379 // __cfa_io_flush( this );
380 // }
381
382 // // Check if there is pending io
383 // __maybe_io_drain( this );
384 }
385
386 __cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
387 }
388
389 __cfa_io_stop( this );
390
391 post( this->terminated );
392
393 if(this == mainProcessor) {
394 // HACK : the coroutine context switch expects this_thread to be set
395 // and it make sense for it to be set in all other cases except here
396 // fake it
397 __cfaabi_tls.this_thread = mainThread;
398 }
399
400 __cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
401}
402
403static int * __volatile_errno() __attribute__((noinline));
404static int * __volatile_errno() { asm(""); return &errno; }
405
406// KERNEL ONLY
407// runThread runs a thread by context switching
408// from the processor coroutine to the target thread
409static void __run_thread(processor * this, $thread * thrd_dst) {
410 /* paranoid */ verify( ! __preemption_enabled() );
411 /* paranoid */ verifyf( thrd_dst->state == Ready || thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
412 /* paranoid */ verifyf( thrd_dst->link.next == 0p, "Expected null got %p", thrd_dst->link.next );
413 __builtin_prefetch( thrd_dst->context.SP );
414
415 __cfadbg_print_safe(runtime_core, "Kernel : core %p running thread %p (%s)\n", this, thrd_dst, thrd_dst->self_cor.name);
416
417 $coroutine * proc_cor = get_coroutine(this->runner);
418
419 // set state of processor coroutine to inactive
420 verify(proc_cor->state == Active);
421 proc_cor->state = Blocked;
422
423 // Actually run the thread
424 RUNNING: while(true) {
425 thrd_dst->preempted = __NO_PREEMPTION;
426 thrd_dst->state = Active;
427
428 // Update global state
429 kernelTLS().this_thread = thrd_dst;
430
431 /* paranoid */ verify( ! __preemption_enabled() );
432 /* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
433 /* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
434 /* paranoid */ verify( thrd_dst->context.SP );
435 /* paranoid */ verify( thrd_dst->state != Halted );
436 /* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) < ((uintptr_t)__get_stack(thrd_dst->curr_cor)->base ) || thrd_dst->curr_cor == proc_cor, "ERROR : Destination $thread %p has been corrupted.\n StackPointer too small.\n", thrd_dst ); // add escape condition if we are setting up the processor
437 /* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) > ((uintptr_t)__get_stack(thrd_dst->curr_cor)->limit) || thrd_dst->curr_cor == proc_cor, "ERROR : Destination $thread %p has been corrupted.\n StackPointer too large.\n", thrd_dst ); // add escape condition if we are setting up the processor
438 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
439
440
441
442 // set context switch to the thread that the processor is executing
443 __cfactx_switch( &proc_cor->context, &thrd_dst->context );
444 // when __cfactx_switch returns we are back in the processor coroutine
445
446 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
447 /* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) > ((uintptr_t)__get_stack(thrd_dst->curr_cor)->limit), "ERROR : Destination $thread %p has been corrupted.\n StackPointer too large.\n", thrd_dst );
448 /* paranoid */ verifyf( ((uintptr_t)thrd_dst->context.SP) < ((uintptr_t)__get_stack(thrd_dst->curr_cor)->base ), "ERROR : Destination $thread %p has been corrupted.\n StackPointer too small.\n", thrd_dst );
449 /* paranoid */ verify( thrd_dst->context.SP );
450 /* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
451 /* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
452 /* paranoid */ verify( ! __preemption_enabled() );
453
454 // Reset global state
455 kernelTLS().this_thread = 0p;
456
457 // We just finished running a thread, there are a few things that could have happened.
458 // 1 - Regular case : the thread has blocked and now one has scheduled it yet.
459 // 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
460 // 4 - Preempted
461 // In case 1, we may have won a race so we can't write to the state again.
462 // In case 2, we lost the race so we now own the thread.
463
464 if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
465 // The thread was preempted, reschedule it and reset the flag
466 schedule_thread$( thrd_dst );
467 break RUNNING;
468 }
469
470 if(unlikely(thrd_dst->state == Halting)) {
471 // The thread has halted, it should never be scheduled/run again
472 // finish the thread
473 __thread_finish( thrd_dst );
474 break RUNNING;
475 }
476
477 /* paranoid */ verify( thrd_dst->state == Active );
478 thrd_dst->state = Blocked;
479
480 // set state of processor coroutine to active and the thread to inactive
481 int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
482 switch(old_ticket) {
483 case TICKET_RUNNING:
484 // This is case 1, the regular case, nothing more is needed
485 break RUNNING;
486 case TICKET_UNBLOCK:
487 #if !defined(__CFA_NO_STATISTICS__)
488 __tls_stats()->ready.threads.threads++;
489 __push_stat( __tls_stats(), __tls_stats()->ready.threads.threads, false, "Processor", this );
490 #endif
491 // This is case 2, the racy case, someone tried to run this thread before it finished blocking
492 // In this case, just run it again.
493 continue RUNNING;
494 default:
495 // This makes no sense, something is wrong abort
496 abort();
497 }
498 }
499
500 // Just before returning to the processor, set the processor coroutine to active
501 proc_cor->state = Active;
502
503 __cfadbg_print_safe(runtime_core, "Kernel : core %p finished running thread %p\n", this, thrd_dst);
504
505 #if !defined(__CFA_NO_STATISTICS__)
506 __tls_stats()->ready.threads.threads--;
507 __push_stat( __tls_stats(), __tls_stats()->ready.threads.threads, false, "Processor", this );
508 #endif
509
510 /* paranoid */ verify( ! __preemption_enabled() );
511}
512
513// KERNEL_ONLY
514void returnToKernel() {
515 /* paranoid */ verify( ! __preemption_enabled() );
516 $coroutine * proc_cor = get_coroutine(kernelTLS().this_processor->runner);
517 $thread * thrd_src = kernelTLS().this_thread;
518
519 __STATS( thrd_src->last_proc = kernelTLS().this_processor; )
520
521 // Run the thread on this processor
522 {
523 int local_errno = *__volatile_errno();
524 #if defined( __i386 ) || defined( __x86_64 )
525 __x87_store;
526 #endif
527 /* paranoid */ verify( proc_cor->context.SP );
528 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
529 __cfactx_switch( &thrd_src->context, &proc_cor->context );
530 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
531 #if defined( __i386 ) || defined( __x86_64 )
532 __x87_load;
533 #endif
534 *__volatile_errno() = local_errno;
535 }
536
537 #if !defined(__CFA_NO_STATISTICS__)
538 /* paranoid */ verify( thrd_src->last_proc != 0p );
539 if(thrd_src->last_proc != kernelTLS().this_processor) {
540 __tls_stats()->ready.threads.migration++;
541 }
542 #endif
543
544 /* paranoid */ verify( ! __preemption_enabled() );
545 /* paranoid */ verifyf( ((uintptr_t)thrd_src->context.SP) < ((uintptr_t)__get_stack(thrd_src->curr_cor)->base ), "ERROR : Returning $thread %p has been corrupted.\n StackPointer too small.\n", thrd_src );
546 /* paranoid */ verifyf( ((uintptr_t)thrd_src->context.SP) > ((uintptr_t)__get_stack(thrd_src->curr_cor)->limit), "ERROR : Returning $thread %p has been corrupted.\n StackPointer too large.\n", thrd_src );
547}
548
549//-----------------------------------------------------------------------------
550// Scheduler routines
551// KERNEL ONLY
552static void __schedule_thread( $thread * thrd ) {
553 /* paranoid */ verify( ! __preemption_enabled() );
554 /* paranoid */ verify( ready_schedule_islocked());
555 /* paranoid */ verify( thrd );
556 /* paranoid */ verify( thrd->state != Halted );
557 /* paranoid */ verify( thrd->curr_cluster );
558 /* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
559 /* paranoid */ if( thrd->state == Blocked || thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
560 "Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
561 /* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
562 "Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
563 /* paranoid */ #endif
564 /* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
565 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
566
567
568 if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
569
570 // Dereference the thread now because once we push it, there is not guaranteed it's still valid.
571 struct cluster * cl = thrd->curr_cluster;
572 __STATS(bool outside = thrd->last_proc && thrd->last_proc != kernelTLS().this_processor; )
573
574 // push the thread to the cluster ready-queue
575 push( cl, thrd );
576
577 // variable thrd is no longer safe to use
578 thrd = 0xdeaddeaddeaddeadp;
579
580 // wake the cluster using the save variable.
581 __wake_one( cl );
582
583 #if !defined(__CFA_NO_STATISTICS__)
584 if( kernelTLS().this_stats ) {
585 __tls_stats()->ready.threads.threads++;
586 if(outside) {
587 __tls_stats()->ready.threads.extunpark++;
588 }
589 __push_stat( __tls_stats(), __tls_stats()->ready.threads.threads, false, "Processor", kernelTLS().this_processor );
590 }
591 else {
592 __atomic_fetch_add(&cl->stats->ready.threads.threads, 1, __ATOMIC_RELAXED);
593 __atomic_fetch_add(&cl->stats->ready.threads.extunpark, 1, __ATOMIC_RELAXED);
594 __push_stat( cl->stats, cl->stats->ready.threads.threads, true, "Cluster", cl );
595 }
596 #endif
597
598 /* paranoid */ verify( ready_schedule_islocked());
599 /* paranoid */ verify( ! __preemption_enabled() );
600}
601
602void schedule_thread$( $thread * thrd ) {
603 ready_schedule_lock();
604 __schedule_thread( thrd );
605 ready_schedule_unlock();
606}
607
608// KERNEL ONLY
609static inline $thread * __next_thread(cluster * this) with( *this ) {
610 /* paranoid */ verify( ! __preemption_enabled() );
611
612 ready_schedule_lock();
613 $thread * thrd = pop_fast( this );
614 ready_schedule_unlock();
615
616 /* paranoid */ verify( ! __preemption_enabled() );
617 return thrd;
618}
619
620// KERNEL ONLY
621static inline $thread * __next_thread_slow(cluster * this) with( *this ) {
622 /* paranoid */ verify( ! __preemption_enabled() );
623
624 ready_schedule_lock();
625 $thread * thrd;
626 for(25) {
627 thrd = pop_slow( this );
628 if(thrd) goto RET;
629 }
630 thrd = pop_search( this );
631
632 RET:
633 ready_schedule_unlock();
634
635 /* paranoid */ verify( ! __preemption_enabled() );
636 return thrd;
637}
638
639static inline bool __must_unpark( $thread * thrd ) {
640 int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
641 switch(old_ticket) {
642 case TICKET_RUNNING:
643 // Wake won the race, the thread will reschedule/rerun itself
644 return false;
645 case TICKET_BLOCKED:
646 /* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
647 /* paranoid */ verify( thrd->state == Blocked );
648 return true;
649 default:
650 // This makes no sense, something is wrong abort
651 abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
652 }
653}
654
655void __kernel_unpark( $thread * thrd ) {
656 /* paranoid */ verify( ! __preemption_enabled() );
657 /* paranoid */ verify( ready_schedule_islocked());
658
659 if( !thrd ) return;
660
661 if(__must_unpark(thrd)) {
662 // Wake lost the race,
663 __schedule_thread( thrd );
664 }
665
666 /* paranoid */ verify( ready_schedule_islocked());
667 /* paranoid */ verify( ! __preemption_enabled() );
668}
669
670void unpark( $thread * thrd ) {
671 if( !thrd ) return;
672
673 if(__must_unpark(thrd)) {
674 disable_interrupts();
675 // Wake lost the race,
676 schedule_thread$( thrd );
677 enable_interrupts(false);
678 }
679}
680
681void park( void ) {
682 __disable_interrupts_checked();
683 /* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
684 returnToKernel();
685 __enable_interrupts_checked();
686
687}
688
689extern "C" {
690 // Leave the thread monitor
691 // last routine called by a thread.
692 // Should never return
693 void __cfactx_thrd_leave() {
694 $thread * thrd = active_thread();
695 $monitor * this = &thrd->self_mon;
696
697 // Lock the monitor now
698 lock( this->lock __cfaabi_dbg_ctx2 );
699
700 disable_interrupts();
701
702 /* paranoid */ verify( ! __preemption_enabled() );
703 /* paranoid */ verify( thrd->state == Active );
704 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
705 /* paranoid */ verify( kernelTLS().this_thread == thrd );
706 /* paranoid */ verify( thrd->context.SP );
707 /* 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 );
708 /* 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 );
709
710 thrd->state = Halting;
711 if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
712 if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
713 if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
714
715 // Leave the thread
716 returnToKernel();
717
718 // Control flow should never reach here!
719 abort();
720 }
721}
722
723// KERNEL ONLY
724bool force_yield( __Preemption_Reason reason ) {
725 __disable_interrupts_checked();
726 $thread * thrd = kernelTLS().this_thread;
727 /* paranoid */ verify(thrd->state == Active);
728
729 // SKULLDUGGERY: It is possible that we are preempting this thread just before
730 // it was going to park itself. If that is the case and it is already using the
731 // intrusive fields then we can't use them to preempt the thread
732 // If that is the case, abandon the preemption.
733 bool preempted = false;
734 if(thrd->link.next == 0p) {
735 preempted = true;
736 thrd->preempted = reason;
737 returnToKernel();
738 }
739 __enable_interrupts_checked( false );
740 return preempted;
741}
742
743//=============================================================================================
744// Kernel Idle Sleep
745//=============================================================================================
746// Wake a thread from the front if there are any
747static void __wake_one(cluster * this) {
748 /* paranoid */ verify( ! __preemption_enabled() );
749 /* paranoid */ verify( ready_schedule_islocked() );
750
751 // Check if there is a sleeping processor
752 processor * p;
753 unsigned idle;
754 unsigned total;
755 [idle, total, p] = query_idles(this->procs);
756
757 // If no one is sleeping, we are done
758 if( idle == 0 ) return;
759
760 // We found a processor, wake it up
761 eventfd_t val;
762 val = 1;
763 eventfd_write( p->idle, val );
764
765 #if !defined(__CFA_NO_STATISTICS__)
766 if( kernelTLS().this_stats ) {
767 __tls_stats()->ready.sleep.wakes++;
768 }
769 else {
770 __atomic_fetch_add(&this->stats->ready.sleep.wakes, 1, __ATOMIC_RELAXED);
771 }
772 #endif
773
774 /* paranoid */ verify( ready_schedule_islocked() );
775 /* paranoid */ verify( ! __preemption_enabled() );
776
777 return;
778}
779
780// Unconditionnaly wake a thread
781void __wake_proc(processor * this) {
782 __cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
783
784 __disable_interrupts_checked();
785 /* paranoid */ verify( ! __preemption_enabled() );
786 eventfd_t val;
787 val = 1;
788 eventfd_write( this->idle, val );
789 __enable_interrupts_checked();
790}
791
792static void mark_idle(__cluster_proc_list & this, processor & proc) {
793 /* paranoid */ verify( ! __preemption_enabled() );
794 lock( this );
795 this.idle++;
796 /* paranoid */ verify( this.idle <= this.total );
797 remove(proc);
798 insert_first(this.idles, proc);
799 unlock( this );
800 /* paranoid */ verify( ! __preemption_enabled() );
801}
802
803static void mark_awake(__cluster_proc_list & this, processor & proc) {
804 /* paranoid */ verify( ! __preemption_enabled() );
805 lock( this );
806 this.idle--;
807 /* paranoid */ verify( this.idle >= 0 );
808 remove(proc);
809 insert_last(this.actives, proc);
810 unlock( this );
811 /* paranoid */ verify( ! __preemption_enabled() );
812}
813
814static [unsigned idle, unsigned total, * processor] query_idles( & __cluster_proc_list this ) {
815 /* paranoid */ verify( ! __preemption_enabled() );
816 /* paranoid */ verify( ready_schedule_islocked() );
817
818 for() {
819 uint64_t l = __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST);
820 if( 1 == (l % 2) ) { Pause(); continue; }
821 unsigned idle = this.idle;
822 unsigned total = this.total;
823 processor * proc = &this.idles`first;
824 // Compiler fence is unnecessary, but gcc-8 and older incorrectly reorder code without it
825 asm volatile("": : :"memory");
826 if(l != __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST)) { Pause(); continue; }
827 return [idle, total, proc];
828 }
829
830 /* paranoid */ verify( ready_schedule_islocked() );
831 /* paranoid */ verify( ! __preemption_enabled() );
832}
833
834//=============================================================================================
835// Unexpected Terminating logic
836//=============================================================================================
837void __kernel_abort_msg( char * abort_text, int abort_text_size ) {
838 $thread * thrd = __cfaabi_tls.this_thread;
839
840 if(thrd) {
841 int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
842 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
843
844 if ( &thrd->self_cor != thrd->curr_cor ) {
845 len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
846 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
847 }
848 else {
849 __cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
850 }
851 }
852 else {
853 int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
854 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
855 }
856}
857
858int __kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
859 return get_coroutine(__cfaabi_tls.this_thread) == get_coroutine(mainThread) ? 4 : 2;
860}
861
862static __spinlock_t kernel_debug_lock;
863
864extern "C" {
865 void __cfaabi_bits_acquire() {
866 lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
867 }
868
869 void __cfaabi_bits_release() {
870 unlock( kernel_debug_lock );
871 }
872}
873
874//=============================================================================================
875// Kernel Utilities
876//=============================================================================================
877#if defined(CFA_HAVE_LINUX_IO_URING_H)
878#include "io/types.hfa"
879#endif
880
881static inline bool __maybe_io_drain( processor * proc ) {
882 bool ret = false;
883 #if defined(CFA_HAVE_LINUX_IO_URING_H)
884 __cfadbg_print_safe(runtime_core, "Kernel : core %p checking io for ring %d\n", proc, proc->io.ctx->fd);
885
886 // Check if we should drain the queue
887 $io_context * ctx = proc->io.ctx;
888 unsigned head = *ctx->cq.head;
889 unsigned tail = *ctx->cq.tail;
890 if(head == tail) return false;
891 ready_schedule_lock();
892 ret = __cfa_io_drain( proc );
893 ready_schedule_unlock();
894 #endif
895 return ret;
896}
897
898//-----------------------------------------------------------------------------
899// Debug
900__cfaabi_dbg_debug_do(
901 extern "C" {
902 void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
903 this.prev_name = prev_name;
904 this.prev_thrd = kernelTLS().this_thread;
905 }
906 }
907)
908
909//-----------------------------------------------------------------------------
910// Debug
911bool threading_enabled(void) __attribute__((const)) {
912 return true;
913}
914
915//-----------------------------------------------------------------------------
916// Statistics
917#if !defined(__CFA_NO_STATISTICS__)
918 void print_halts( processor & this ) {
919 this.print_halts = true;
920 }
921
922 void print_stats_now( cluster & this, int flags ) {
923 __print_stats( this.stats, this.print_stats, "Cluster", this.name, (void*)&this );
924 }
925#endif
926// Local Variables: //
927// mode: c //
928// tab-width: 4 //
929// End: //
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