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kernel.cfa @ b91bfde

ADTarm-ehast-experimentalenumforall-pointer-decayjacob/cs343-translationnew-ast-unique-exprpthread-emulationqualifiedEnum

Last change on this file since b91bfde was ec43cf9, checked in by Thierry Delisle <tdelisle@…>, 4 years ago
Kernel now keeps track of the how many threads each processor has contributed. This isn't useful if it is not sampled regularly but it's a first step.
Property mode set to `100644`
File size: 24.4 KB

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

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