source: libcfa/src/concurrency/kernel.cfa@ 734908c

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 734908c was 734908c, checked in by Thierry Delisle <tdelisle@…>, 5 years ago

Fudge variable in schedule_thread so it's not accidently used.
  • Property mode set to 100644
File size: 25.1 KB
Line 
1//
2// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
3//
4// The contents of this file are covered under the licence agreement in the
5// file "LICENCE" distributed with Cforall.
6//
7// kernel.c --
8//
9// Author : Thierry Delisle
10// Created On : Tue Jan 17 12:27:26 2017
11// Last Modified By : Peter A. Buhr
12// Last Modified On : Mon Aug 31 07:08:20 2020
13// Update Count : 71
14//
15
16#define __cforall_thread__
17// #define __CFA_DEBUG_PRINT_RUNTIME_CORE__
18
19//C Includes
20#include <errno.h>
21#include <stdio.h>
22#include <signal.h>
23#include <unistd.h>
24extern "C" {
25 #include <sys/eventfd.h>
26}
27
28//CFA Includes
29#include "kernel_private.hfa"
30#include "preemption.hfa"
31
32//Private includes
33#define __CFA_INVOKE_PRIVATE__
34#include "invoke.h"
35
36
37//-----------------------------------------------------------------------------
38// Some assembly required
39#if defined( __i386 )
40 // mxcr : SSE Status and Control bits (control bits are preserved across function calls)
41 // fcw : X87 FPU control word (preserved across function calls)
42 #define __x87_store \
43 uint32_t __mxcr; \
44 uint16_t __fcw; \
45 __asm__ volatile ( \
46 "stmxcsr %0\n" \
47 "fnstcw %1\n" \
48 : "=m" (__mxcr),\
49 "=m" (__fcw) \
50 )
51
52 #define __x87_load \
53 __asm__ volatile ( \
54 "fldcw %1\n" \
55 "ldmxcsr %0\n" \
56 ::"m" (__mxcr),\
57 "m" (__fcw) \
58 )
59
60#elif defined( __x86_64 )
61 #define __x87_store \
62 uint32_t __mxcr; \
63 uint16_t __fcw; \
64 __asm__ volatile ( \
65 "stmxcsr %0\n" \
66 "fnstcw %1\n" \
67 : "=m" (__mxcr),\
68 "=m" (__fcw) \
69 )
70
71 #define __x87_load \
72 __asm__ volatile ( \
73 "fldcw %1\n" \
74 "ldmxcsr %0\n" \
75 :: "m" (__mxcr),\
76 "m" (__fcw) \
77 )
78
79#elif defined( __arm__ )
80 #define __x87_store
81 #define __x87_load
82
83#elif defined( __aarch64__ )
84 #define __x87_store \
85 uint32_t __fpcntl[2]; \
86 __asm__ volatile ( \
87 "mrs x9, FPCR\n" \
88 "mrs x10, FPSR\n" \
89 "stp x9, x10, %0\n" \
90 : "=m" (__fpcntl) : : "x9", "x10" \
91 )
92
93 #define __x87_load \
94 __asm__ volatile ( \
95 "ldp x9, x10, %0\n" \
96 "msr FPSR, x10\n" \
97 "msr FPCR, x9\n" \
98 : "=m" (__fpcntl) : : "x9", "x10" \
99 )
100
101#else
102 #error unsupported hardware architecture
103#endif
104
105extern $thread * mainThread;
106extern processor * mainProcessor;
107
108//-----------------------------------------------------------------------------
109// Kernel Scheduling logic
110static $thread * __next_thread(cluster * this);
111static $thread * __next_thread_slow(cluster * this);
112static inline bool __must_unpark( $thread * thrd ) __attribute((nonnull(1)));
113static void __run_thread(processor * this, $thread * dst);
114static void __wake_one(cluster * cltr);
115
116static void mark_idle (__cluster_proc_list & idles, processor & proc);
117static void mark_awake(__cluster_proc_list & idles, processor & proc);
118static [unsigned idle, unsigned total, * processor] query_idles( & __cluster_proc_list idles );
119
120extern void __cfa_io_start( processor * );
121extern bool __cfa_io_drain( processor * );
122extern void __cfa_io_flush( processor * );
123extern void __cfa_io_stop ( processor * );
124static inline bool __maybe_io_drain( processor * );
125
126extern void __disable_interrupts_hard();
127extern void __enable_interrupts_hard();
128
129static inline void __disable_interrupts_checked() {
130 /* paranoid */ verify( __preemption_enabled() );
131 disable_interrupts();
132 /* paranoid */ verify( ! __preemption_enabled() );
133}
134
135static inline void __enable_interrupts_checked( bool poll = true ) {
136 /* paranoid */ verify( ! __preemption_enabled() );
137 enable_interrupts( poll );
138 /* paranoid */ verify( __preemption_enabled() );
139}
140
141//=============================================================================================
142// Kernel Scheduling logic
143//=============================================================================================
144//Main of the processor contexts
145void main(processorCtx_t & runner) {
146 // Because of a bug, we couldn't initialized the seed on construction
147 // Do it here
148 __cfaabi_tls.rand_seed ^= rdtscl();
149 __cfaabi_tls.ready_rng.fwd_seed = 25214903917_l64u * (rdtscl() ^ (uintptr_t)&runner);
150 __tls_rand_advance_bck();
151
152 processor * this = runner.proc;
153 verify(this);
154
155 __cfa_io_start( this );
156
157 __cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
158 #if !defined(__CFA_NO_STATISTICS__)
159 if( this->print_halts ) {
160 __cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->id, this->name, (void*)this);
161 }
162 #endif
163
164 {
165 // Setup preemption data
166 preemption_scope scope = { this };
167
168 #if !defined(__CFA_NO_STATISTICS__)
169 unsigned long long last_tally = rdtscl();
170 #endif
171
172 // if we need to run some special setup, now is the time to do it.
173 if(this->init.thrd) {
174 this->init.thrd->curr_cluster = this->cltr;
175 __run_thread(this, this->init.thrd);
176 }
177
178 __cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
179
180 $thread * readyThread = 0p;
181 MAIN_LOOP:
182 for() {
183 // Check if there is pending io
184 __maybe_io_drain( this );
185
186 // Try to get the next thread
187 readyThread = __next_thread( this->cltr );
188
189 if( !readyThread ) {
190 __cfa_io_flush( this );
191 readyThread = __next_thread_slow( this->cltr );
192 }
193
194 HALT:
195 if( !readyThread ) {
196 // Don't block if we are done
197 if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
198
199 #if !defined(__CFA_NO_STATISTICS__)
200 __tls_stats()->ready.sleep.halts++;
201 #endif
202
203 // Push self to idle stack
204 mark_idle(this->cltr->procs, * this);
205
206 // Confirm the ready-queue is empty
207 readyThread = __next_thread_slow( this->cltr );
208 if( readyThread ) {
209 // A thread was found, cancel the halt
210 mark_awake(this->cltr->procs, * this);
211
212 #if !defined(__CFA_NO_STATISTICS__)
213 __tls_stats()->ready.sleep.cancels++;
214 #endif
215
216 // continue the mai loop
217 break HALT;
218 }
219
220 #if !defined(__CFA_NO_STATISTICS__)
221 if(this->print_halts) {
222 __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->id, rdtscl());
223 }
224 #endif
225
226 __cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle);
227
228 __disable_interrupts_hard();
229 eventfd_t val;
230 eventfd_read( this->idle, &val );
231 __enable_interrupts_hard();
232
233 #if !defined(__CFA_NO_STATISTICS__)
234 if(this->print_halts) {
235 __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->id, rdtscl());
236 }
237 #endif
238
239 // We were woken up, remove self from idle
240 mark_awake(this->cltr->procs, * this);
241
242 // DON'T just proceed, start looking again
243 continue MAIN_LOOP;
244 }
245
246 /* paranoid */ verify( readyThread );
247
248 // Reset io dirty bit
249 this->io.dirty = false;
250
251 // We found a thread run it
252 __run_thread(this, readyThread);
253
254 // Are we done?
255 if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
256
257 #if !defined(__CFA_NO_STATISTICS__)
258 unsigned long long curr = rdtscl();
259 if(curr > (last_tally + 500000000)) {
260 __tally_stats(this->cltr->stats, __cfaabi_tls.this_stats);
261 last_tally = curr;
262 }
263 #endif
264
265 if(this->io.pending && !this->io.dirty) {
266 __cfa_io_flush( this );
267 }
268 }
269
270 __cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
271 }
272
273 __cfa_io_stop( this );
274
275 post( this->terminated );
276
277
278 if(this == mainProcessor) {
279 // HACK : the coroutine context switch expects this_thread to be set
280 // and it make sense for it to be set in all other cases except here
281 // fake it
282 __cfaabi_tls.this_thread = mainThread;
283 }
284
285 __cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
286}
287
288static int * __volatile_errno() __attribute__((noinline));
289static int * __volatile_errno() { asm(""); return &errno; }
290
291// KERNEL ONLY
292// runThread runs a thread by context switching
293// from the processor coroutine to the target thread
294static void __run_thread(processor * this, $thread * thrd_dst) {
295 /* paranoid */ verify( ! __preemption_enabled() );
296 /* paranoid */ verifyf( thrd_dst->state == Ready || thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
297 /* paranoid */ verifyf( thrd_dst->link.next == 0p, "Expected null got %p", thrd_dst->link.next );
298 __builtin_prefetch( thrd_dst->context.SP );
299
300 __cfadbg_print_safe(runtime_core, "Kernel : core %p running thread %p (%s)\n", this, thrd_dst, thrd_dst->self_cor.name);
301
302 $coroutine * proc_cor = get_coroutine(this->runner);
303
304 // set state of processor coroutine to inactive
305 verify(proc_cor->state == Active);
306 proc_cor->state = Blocked;
307
308 // Actually run the thread
309 RUNNING: while(true) {
310 thrd_dst->preempted = __NO_PREEMPTION;
311 thrd_dst->state = Active;
312
313 // Update global state
314 kernelTLS().this_thread = thrd_dst;
315
316 /* paranoid */ verify( ! __preemption_enabled() );
317 /* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
318 /* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
319 /* paranoid */ verify( thrd_dst->context.SP );
320 /* paranoid */ verify( thrd_dst->state != Halted );
321 /* 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
322 /* 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
323 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
324
325
326
327 // set context switch to the thread that the processor is executing
328 __cfactx_switch( &proc_cor->context, &thrd_dst->context );
329 // when __cfactx_switch returns we are back in the processor coroutine
330
331 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
332 /* 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 );
333 /* 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 );
334 /* paranoid */ verify( thrd_dst->context.SP );
335 /* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
336 /* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
337 /* paranoid */ verify( ! __preemption_enabled() );
338
339 // Reset global state
340 kernelTLS().this_thread = 0p;
341
342 // We just finished running a thread, there are a few things that could have happened.
343 // 1 - Regular case : the thread has blocked and now one has scheduled it yet.
344 // 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
345 // 4 - Preempted
346 // In case 1, we may have won a race so we can't write to the state again.
347 // In case 2, we lost the race so we now own the thread.
348
349 if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
350 // The thread was preempted, reschedule it and reset the flag
351 __schedule_thread( thrd_dst );
352 break RUNNING;
353 }
354
355 if(unlikely(thrd_dst->state == Halting)) {
356 // The thread has halted, it should never be scheduled/run again
357 // finish the thread
358 __thread_finish( thrd_dst );
359 break RUNNING;
360 }
361
362 /* paranoid */ verify( thrd_dst->state == Active );
363 thrd_dst->state = Blocked;
364
365 // set state of processor coroutine to active and the thread to inactive
366 int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
367 switch(old_ticket) {
368 case TICKET_RUNNING:
369 // This is case 1, the regular case, nothing more is needed
370 break RUNNING;
371 case TICKET_UNBLOCK:
372 #if !defined(__CFA_NO_STATISTICS__)
373 __tls_stats()->ready.threads.threads++;
374 __push_stat( __tls_stats(), __tls_stats()->ready.threads.threads, false, "Processor", this );
375 #endif
376 // This is case 2, the racy case, someone tried to run this thread before it finished blocking
377 // In this case, just run it again.
378 continue RUNNING;
379 default:
380 // This makes no sense, something is wrong abort
381 abort();
382 }
383 }
384
385 // Just before returning to the processor, set the processor coroutine to active
386 proc_cor->state = Active;
387
388 __cfadbg_print_safe(runtime_core, "Kernel : core %p finished running thread %p\n", this, thrd_dst);
389
390 #if !defined(__CFA_NO_STATISTICS__)
391 __tls_stats()->ready.threads.threads--;
392 __push_stat( __tls_stats(), __tls_stats()->ready.threads.threads, false, "Processor", this );
393 #endif
394
395 /* paranoid */ verify( ! __preemption_enabled() );
396}
397
398// KERNEL_ONLY
399void returnToKernel() {
400 /* paranoid */ verify( ! __preemption_enabled() );
401 $coroutine * proc_cor = get_coroutine(kernelTLS().this_processor->runner);
402 $thread * thrd_src = kernelTLS().this_thread;
403
404 #if !defined(__CFA_NO_STATISTICS__)
405 struct processor * last_proc = kernelTLS().this_processor;
406 #endif
407
408 // Run the thread on this processor
409 {
410 int local_errno = *__volatile_errno();
411 #if defined( __i386 ) || defined( __x86_64 )
412 __x87_store;
413 #endif
414 /* paranoid */ verify( proc_cor->context.SP );
415 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
416 __cfactx_switch( &thrd_src->context, &proc_cor->context );
417 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
418 #if defined( __i386 ) || defined( __x86_64 )
419 __x87_load;
420 #endif
421 *__volatile_errno() = local_errno;
422 }
423
424 #if !defined(__CFA_NO_STATISTICS__)
425 if(last_proc != kernelTLS().this_processor) {
426 __tls_stats()->ready.threads.migration++;
427 }
428 #endif
429
430 /* paranoid */ verify( ! __preemption_enabled() );
431 /* 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 );
432 /* 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 );
433}
434
435//-----------------------------------------------------------------------------
436// Scheduler routines
437// KERNEL ONLY
438void __schedule_thread( $thread * thrd ) {
439 /* paranoid */ verify( ! __preemption_enabled() );
440 /* paranoid */ verify( kernelTLS().this_proc_id );
441 /* paranoid */ verify( thrd );
442 /* paranoid */ verify( thrd->state != Halted );
443 /* paranoid */ verify( thrd->curr_cluster );
444 /* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
445 /* paranoid */ if( thrd->state == Blocked || thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
446 "Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
447 /* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
448 "Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
449 /* paranoid */ #endif
450 /* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
451 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
452
453
454 if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
455
456 // Dereference the thread now because once we push it, there is not guaranteed it's still valid.
457 struct cluster * cl = thrd->curr_cluster;
458
459 ready_schedule_lock();
460 // push the thread to the cluster ready-queue
461 push( cl, thrd );
462
463 // variable thrd is no longer safe to use
464 thrd = 0xdeaddeaddeaddeadp;
465
466 // wake the cluster using the save variable.
467 __wake_one( cl );
468 ready_schedule_unlock();
469
470 #if !defined(__CFA_NO_STATISTICS__)
471 if( kernelTLS().this_stats ) {
472 __tls_stats()->ready.threads.threads++;
473 __push_stat( __tls_stats(), __tls_stats()->ready.threads.threads, false, "Processor", kernelTLS().this_processor );
474 }
475 else {
476 __atomic_fetch_add(&cl->stats->ready.threads.threads, 1, __ATOMIC_RELAXED);
477 __push_stat( cl->stats, cl->stats->ready.threads.threads, true, "Cluster", cl );
478 }
479 #endif
480
481 /* paranoid */ verify( ! __preemption_enabled() );
482}
483
484// KERNEL ONLY
485static inline $thread * __next_thread(cluster * this) with( *this ) {
486 /* paranoid */ verify( ! __preemption_enabled() );
487 /* paranoid */ verify( kernelTLS().this_proc_id );
488
489 ready_schedule_lock();
490 $thread * thrd = pop_fast( this );
491 ready_schedule_unlock();
492
493 /* paranoid */ verify( kernelTLS().this_proc_id );
494 /* paranoid */ verify( ! __preemption_enabled() );
495 return thrd;
496}
497
498// KERNEL ONLY
499static inline $thread * __next_thread_slow(cluster * this) with( *this ) {
500 /* paranoid */ verify( ! __preemption_enabled() );
501 /* paranoid */ verify( kernelTLS().this_proc_id );
502
503 ready_schedule_lock();
504 $thread * thrd = pop_slow( this );
505 ready_schedule_unlock();
506
507 /* paranoid */ verify( kernelTLS().this_proc_id );
508 /* paranoid */ verify( ! __preemption_enabled() );
509 return thrd;
510}
511
512static inline bool __must_unpark( $thread * thrd ) {
513 int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
514 switch(old_ticket) {
515 case TICKET_RUNNING:
516 // Wake won the race, the thread will reschedule/rerun itself
517 return false;
518 case TICKET_BLOCKED:
519 /* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
520 /* paranoid */ verify( thrd->state == Blocked );
521 return true;
522 default:
523 // This makes no sense, something is wrong abort
524 abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
525 }
526}
527
528void unpark( $thread * thrd ) {
529 if( !thrd ) return;
530
531 if(__must_unpark(thrd)) {
532 disable_interrupts();
533 // Wake lost the race,
534 __schedule_thread( thrd );
535 enable_interrupts(false);
536 }
537}
538
539void park( void ) {
540 __disable_interrupts_checked();
541 /* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
542 returnToKernel();
543 __enable_interrupts_checked();
544
545}
546
547extern "C" {
548 // Leave the thread monitor
549 // last routine called by a thread.
550 // Should never return
551 void __cfactx_thrd_leave() {
552 $thread * thrd = active_thread();
553 $monitor * this = &thrd->self_mon;
554
555 // Lock the monitor now
556 lock( this->lock __cfaabi_dbg_ctx2 );
557
558 disable_interrupts();
559
560 /* paranoid */ verify( ! __preemption_enabled() );
561 /* paranoid */ verify( thrd->state == Active );
562 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
563 /* paranoid */ verify( kernelTLS().this_thread == thrd );
564 /* paranoid */ verify( thrd->context.SP );
565 /* 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 );
566 /* 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 );
567
568 thrd->state = Halting;
569 if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
570 if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
571 if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
572
573 // Leave the thread
574 returnToKernel();
575
576 // Control flow should never reach here!
577 abort();
578 }
579}
580
581// KERNEL ONLY
582bool force_yield( __Preemption_Reason reason ) {
583 __disable_interrupts_checked();
584 $thread * thrd = kernelTLS().this_thread;
585 /* paranoid */ verify(thrd->state == Active);
586
587 // SKULLDUGGERY: It is possible that we are preempting this thread just before
588 // it was going to park itself. If that is the case and it is already using the
589 // intrusive fields then we can't use them to preempt the thread
590 // If that is the case, abandon the preemption.
591 bool preempted = false;
592 if(thrd->link.next == 0p) {
593 preempted = true;
594 thrd->preempted = reason;
595 returnToKernel();
596 }
597 __enable_interrupts_checked( false );
598 return preempted;
599}
600
601//=============================================================================================
602// Kernel Idle Sleep
603//=============================================================================================
604// Wake a thread from the front if there are any
605static void __wake_one(cluster * this) {
606 /* paranoid */ verify( ! __preemption_enabled() );
607 /* paranoid */ verify( ready_schedule_islocked() );
608
609 // Check if there is a sleeping processor
610 processor * p;
611 unsigned idle;
612 unsigned total;
613 [idle, total, p] = query_idles(this->procs);
614
615 // If no one is sleeping, we are done
616 if( idle == 0 ) return;
617
618 // We found a processor, wake it up
619 eventfd_t val;
620 val = 1;
621 eventfd_write( p->idle, val );
622
623 #if !defined(__CFA_NO_STATISTICS__)
624 if( kernelTLS().this_stats ) {
625 __tls_stats()->ready.sleep.wakes++;
626 }
627 else {
628 __atomic_fetch_add(&this->stats->ready.sleep.wakes, 1, __ATOMIC_RELAXED);
629 }
630 #endif
631
632 /* paranoid */ verify( ready_schedule_islocked() );
633 /* paranoid */ verify( ! __preemption_enabled() );
634
635 return;
636}
637
638// Unconditionnaly wake a thread
639void __wake_proc(processor * this) {
640 __cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
641
642 __disable_interrupts_checked();
643 /* paranoid */ verify( ! __preemption_enabled() );
644 eventfd_t val;
645 val = 1;
646 eventfd_write( this->idle, val );
647 __enable_interrupts_checked();
648}
649
650static void mark_idle(__cluster_proc_list & this, processor & proc) {
651 /* paranoid */ verify( ! __preemption_enabled() );
652 lock( this );
653 this.idle++;
654 /* paranoid */ verify( this.idle <= this.total );
655 remove(proc);
656 insert_first(this.idles, proc);
657 unlock( this );
658 /* paranoid */ verify( ! __preemption_enabled() );
659}
660
661static void mark_awake(__cluster_proc_list & this, processor & proc) {
662 /* paranoid */ verify( ! __preemption_enabled() );
663 lock( this );
664 this.idle--;
665 /* paranoid */ verify( this.idle >= 0 );
666 remove(proc);
667 insert_last(this.actives, proc);
668 unlock( this );
669 /* paranoid */ verify( ! __preemption_enabled() );
670}
671
672static [unsigned idle, unsigned total, * processor] query_idles( & __cluster_proc_list this ) {
673 /* paranoid */ verify( ! __preemption_enabled() );
674 /* paranoid */ verify( ready_schedule_islocked() );
675
676 for() {
677 uint64_t l = __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST);
678 if( 1 == (l % 2) ) { Pause(); continue; }
679 unsigned idle = this.idle;
680 unsigned total = this.total;
681 processor * proc = &this.idles`first;
682 // Compiler fence is unnecessary, but gcc-8 and older incorrectly reorder code without it
683 asm volatile("": : :"memory");
684 if(l != __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST)) { Pause(); continue; }
685 return [idle, total, proc];
686 }
687
688 /* paranoid */ verify( ready_schedule_islocked() );
689 /* paranoid */ verify( ! __preemption_enabled() );
690}
691
692//=============================================================================================
693// Unexpected Terminating logic
694//=============================================================================================
695void __kernel_abort_msg( char * abort_text, int abort_text_size ) {
696 $thread * thrd = __cfaabi_tls.this_thread;
697
698 if(thrd) {
699 int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
700 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
701
702 if ( &thrd->self_cor != thrd->curr_cor ) {
703 len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
704 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
705 }
706 else {
707 __cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
708 }
709 }
710 else {
711 int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
712 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
713 }
714}
715
716int __kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
717 return get_coroutine(__cfaabi_tls.this_thread) == get_coroutine(mainThread) ? 4 : 2;
718}
719
720static __spinlock_t kernel_debug_lock;
721
722extern "C" {
723 void __cfaabi_bits_acquire() {
724 lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
725 }
726
727 void __cfaabi_bits_release() {
728 unlock( kernel_debug_lock );
729 }
730}
731
732//=============================================================================================
733// Kernel Utilities
734//=============================================================================================
735#if defined(CFA_HAVE_LINUX_IO_URING_H)
736#include "io/types.hfa"
737#endif
738
739static inline bool __maybe_io_drain( processor * proc ) {
740 #if defined(CFA_HAVE_LINUX_IO_URING_H)
741 __cfadbg_print_safe(runtime_core, "Kernel : core %p checking io for ring %d\n", proc, proc->io.ctx->fd);
742
743 // Check if we should drain the queue
744 $io_context * ctx = proc->io.ctx;
745 unsigned head = *ctx->cq.head;
746 unsigned tail = *ctx->cq.tail;
747 if(head == tail) return false;
748 return __cfa_io_drain( proc );
749 #endif
750}
751
752//-----------------------------------------------------------------------------
753// Debug
754__cfaabi_dbg_debug_do(
755 extern "C" {
756 void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
757 this.prev_name = prev_name;
758 this.prev_thrd = kernelTLS().this_thread;
759 }
760 }
761)
762
763//-----------------------------------------------------------------------------
764// Debug
765bool threading_enabled(void) __attribute__((const)) {
766 return true;
767}
768
769//-----------------------------------------------------------------------------
770// Statistics
771#if !defined(__CFA_NO_STATISTICS__)
772 void print_halts( processor & this ) {
773 this.print_halts = true;
774 }
775
776 void print_stats_now( cluster & this, int flags ) {
777 __print_stats( this.stats, this.print_stats, "Cluster", this.name, (void*)&this );
778 }
779#endif
780// Local Variables: //
781// mode: c //
782// tab-width: 4 //
783// End: //
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