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kernel.cfa @ fc72696c

ADTast-experimentalenumforall-pointer-decaypthread-emulationqualifiedEnum

Last change on this file since fc72696c was c9c1c1c, checked in by Thierry Delisle <tdelisle@…>, 3 years ago
Minor changes to kernel main loop and fixed stats.
Property mode set to `100644`
File size: 28.7 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 _GNU_SOURCE
18
19	// #define __CFA_DEBUG_PRINT_RUNTIME_CORE__
20
21	//C Includes
22	#include <errno.h>
23	#include <stdio.h>
24	#include <string.h>
25	#include <signal.h>
26	#include <unistd.h>
27	extern "C" {
28	#include <sys/eventfd.h>
29	#include <sys/uio.h>
30	}
31
32	//CFA Includes
33	#include "kernel_private.hfa"
34	#include "preemption.hfa"
35	#include "strstream.hfa"
36	#include "device/cpu.hfa"
37	#include "io/types.hfa"
38
39	//Private includes
40	#define __CFA_INVOKE_PRIVATE__
41	#include "invoke.h"
42
43	#if !defined(__CFA_NO_STATISTICS__)
44	#define __STATS_DEF( ...) __VA_ARGS__
45	#else
46	#define __STATS_DEF( ...)
47	#endif
48
49	//-----------------------------------------------------------------------------
50	// Some assembly required
51	#if defined( __i386 )
52	// mxcr : SSE Status and Control bits (control bits are preserved across function calls)
53	// fcw : X87 FPU control word (preserved across function calls)
54	#define __x87_store \
55	uint32_t __mxcr; \
56	uint16_t __fcw; \
57	__asm__ volatile ( \
58	"stmxcsr %0\n" \
59	"fnstcw %1\n" \
60	: "=m" (__mxcr),\
61	"=m" (__fcw) \
62	)
63
64	#define __x87_load \
65	__asm__ volatile ( \
66	"fldcw %1\n" \
67	"ldmxcsr %0\n" \
68	::"m" (__mxcr),\
69	"m" (__fcw) \
70	)
71
72	#elif defined( __x86_64 )
73	#define __x87_store \
74	uint32_t __mxcr; \
75	uint16_t __fcw; \
76	__asm__ volatile ( \
77	"stmxcsr %0\n" \
78	"fnstcw %1\n" \
79	: "=m" (__mxcr),\
80	"=m" (__fcw) \
81	)
82
83	#define __x87_load \
84	__asm__ volatile ( \
85	"fldcw %1\n" \
86	"ldmxcsr %0\n" \
87	:: "m" (__mxcr),\
88	"m" (__fcw) \
89	)
90
91	#elif defined( __arm__ )
92	#define __x87_store
93	#define __x87_load
94
95	#elif defined( __aarch64__ )
96	#define __x87_store \
97	uint32_t __fpcntl[2]; \
98	__asm__ volatile ( \
99	"mrs x9, FPCR\n" \
100	"mrs x10, FPSR\n" \
101	"stp x9, x10, %0\n" \
102	: "=m" (__fpcntl) : : "x9", "x10" \
103	)
104
105	#define __x87_load \
106	__asm__ volatile ( \
107	"ldp x9, x10, %0\n" \
108	"msr FPSR, x10\n" \
109	"msr FPCR, x9\n" \
110	: "=m" (__fpcntl) : : "x9", "x10" \
111	)
112
113	#else
114	#error unsupported hardware architecture
115	#endif
116
117	extern thread$ * mainThread;
118	extern processor * mainProcessor;
119
120	//-----------------------------------------------------------------------------
121	// Kernel Scheduling logic
122	static thread$ * __next_thread(cluster * this);
123	static thread$ * __next_thread_slow(cluster * this);
124	static thread$ * __next_thread_search(cluster * this);
125	static inline bool __must_unpark( thread$ * thrd ) __attribute((nonnull(1)));
126	static void __run_thread(processor * this, thread$ * dst);
127	static void __wake_one(cluster * cltr);
128
129	static void idle_sleep(processor * proc, io_future_t & future, iovec & iov);
130	static bool mark_idle (__cluster_proc_list & idles, processor & proc);
131	static void mark_awake(__cluster_proc_list & idles, processor & proc);
132
133	extern void __cfa_io_start( processor * );
134	extern bool __cfa_io_drain( processor * );
135	extern bool __cfa_io_flush( processor *, int min_comp );
136	extern void __cfa_io_stop ( processor * );
137	static inline bool __maybe_io_drain( processor * );
138
139	#if defined(CFA_WITH_IO_URING_IDLE)
140	extern bool __kernel_read(processor * proc, io_future_t & future, iovec &, int fd);
141	#endif
142
143	extern void __disable_interrupts_hard();
144	extern void __enable_interrupts_hard();
145
146
147	//=============================================================================================
148	// Kernel Scheduling logic
149	//=============================================================================================
150	//Main of the processor contexts
151	void main(processorCtx_t & runner) {
152	// Because of a bug, we couldn't initialized the seed on construction
153	// Do it here
154	__cfaabi_tls.rand_seed ^= rdtscl();
155	__cfaabi_tls.ready_rng.fwd_seed = 25214903917_l64u * (rdtscl() ^ (uintptr_t)&runner);
156	__tls_rand_advance_bck();
157
158	processor * this = runner.proc;
159	verify(this);
160
161	io_future_t future; // used for idle sleep when io_uring is present
162	future.self.ptr = 1p; // mark it as already fulfilled so we know if there is a pending request or not
163	eventfd_t idle_val;
164	iovec idle_iovec = { &idle_val, sizeof(idle_val) };
165
166	__cfa_io_start( this );
167
168	__cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
169	#if !defined(__CFA_NO_STATISTICS__)
170	if( this->print_halts ) {
171	__cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->unique_id, this->name, (void*)this);
172	}
173	#endif
174
175	{
176	// Setup preemption data
177	preemption_scope scope = { this };
178
179	// if we need to run some special setup, now is the time to do it.
180	if(this->init.thrd) {
181	this->init.thrd->curr_cluster = this->cltr;
182	__run_thread(this, this->init.thrd);
183	}
184
185	__cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
186
187	thread$ * readyThread = 0p;
188	MAIN_LOOP:
189	for() {
190	// Check if there is pending io
191	__maybe_io_drain( this );
192
193	// Try to get the next thread
194	readyThread = __next_thread( this->cltr );
195
196	if( !readyThread ) {
197	__IO_STATS__(true, io.flush.idle++; )
198	__cfa_io_flush( this, 0 );
199
200	readyThread = __next_thread( this->cltr );
201	}
202
203	if( !readyThread ) for(5) {
204	__IO_STATS__(true, io.flush.idle++; )
205
206	readyThread = __next_thread_slow( this->cltr );
207
208	if( readyThread ) break;
209
210	__cfa_io_flush( this, 0 );
211	}
212
213	HALT:
214	if( !readyThread ) {
215	// Don't block if we are done
216	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
217
218	// Push self to idle stack
219	if(!mark_idle(this->cltr->procs, * this)) continue MAIN_LOOP;
220
221	// Confirm the ready-queue is empty
222	readyThread = __next_thread_search( this->cltr );
223	if( readyThread ) {
224	// A thread was found, cancel the halt
225	mark_awake(this->cltr->procs, * this);
226
227	__STATS__(true, ready.sleep.cancels++; )
228
229	// continue the mai loop
230	break HALT;
231	}
232
233	idle_sleep( this, future, idle_iovec );
234
235	// We were woken up, remove self from idle
236	mark_awake(this->cltr->procs, * this);
237
238	// DON'T just proceed, start looking again
239	continue MAIN_LOOP;
240	}
241
242	/* paranoid */ verify( readyThread );
243
244	// Reset io dirty bit
245	this->io.dirty = false;
246
247	// We found a thread run it
248	__run_thread(this, readyThread);
249
250	// Are we done?
251	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
252
253	if(this->io.pending && !this->io.dirty) {
254	__IO_STATS__(true, io.flush.dirty++; )
255	__cfa_io_flush( this, 0 );
256	}
257	}
258
259	__cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
260	}
261
262	for(int i = 0; !available(future); i++) {
263	if(i > 1000) __cfaabi_dbg_write( "ERROR: kernel has bin spinning on a flush after exit loop.\n", 60);
264	__cfa_io_flush( this, 1 );
265	}
266
267	__cfa_io_stop( this );
268
269	post( this->terminated );
270
271	if(this == mainProcessor) {
272	// HACK : the coroutine context switch expects this_thread to be set
273	// and it make sense for it to be set in all other cases except here
274	// fake it
275	__cfaabi_tls.this_thread = mainThread;
276	}
277
278	__cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
279	}
280
281	static int * __volatile_errno() __attribute__((noinline));
282	static int * __volatile_errno() { asm(""); return &errno; }
283
284	// KERNEL ONLY
285	// runThread runs a thread by context switching
286	// from the processor coroutine to the target thread
287	static void __run_thread(processor * this, thread$ * thrd_dst) {
288	/* paranoid */ verify( ! __preemption_enabled() );
289	/* paranoid */ verifyf( thrd_dst->state == Ready \|\| thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
290	/* paranoid */ verifyf( thrd_dst->link.next == 0p, "Expected null got %p", thrd_dst->link.next );
291	__builtin_prefetch( thrd_dst->context.SP );
292
293	__cfadbg_print_safe(runtime_core, "Kernel : core %p running thread %p (%s)\n", this, thrd_dst, thrd_dst->self_cor.name);
294
295	coroutine$ * proc_cor = get_coroutine(this->runner);
296
297	// set state of processor coroutine to inactive
298	verify(proc_cor->state == Active);
299	proc_cor->state = Blocked;
300
301	// Actually run the thread
302	RUNNING: while(true) {
303	thrd_dst->preempted = __NO_PREEMPTION;
304	thrd_dst->state = Active;
305
306	// Update global state
307	kernelTLS().this_thread = thrd_dst;
308
309	/* paranoid */ verify( ! __preemption_enabled() );
310	/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
311	/* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
312	/* paranoid */ verify( thrd_dst->context.SP );
313	/* paranoid */ verify( thrd_dst->state != Halted );
314	/* 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
315	/* 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
316	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
317
318
319
320	// set context switch to the thread that the processor is executing
321	__cfactx_switch( &proc_cor->context, &thrd_dst->context );
322	// when __cfactx_switch returns we are back in the processor coroutine
323
324
325
326	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
327	/* 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 );
328	/* 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 );
329	/* paranoid */ verify( thrd_dst->context.SP );
330	/* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
331	/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
332	/* paranoid */ verify( ! __preemption_enabled() );
333
334	// Reset global state
335	kernelTLS().this_thread = 0p;
336
337	// We just finished running a thread, there are a few things that could have happened.
338	// 1 - Regular case : the thread has blocked and now one has scheduled it yet.
339	// 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
340	// 4 - Preempted
341	// In case 1, we may have won a race so we can't write to the state again.
342	// In case 2, we lost the race so we now own the thread.
343
344	if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
345	// The thread was preempted, reschedule it and reset the flag
346	schedule_thread$( thrd_dst, UNPARK_LOCAL );
347	break RUNNING;
348	}
349
350	if(unlikely(thrd_dst->state == Halting)) {
351	// The thread has halted, it should never be scheduled/run again
352	// finish the thread
353	__thread_finish( thrd_dst );
354	break RUNNING;
355	}
356
357	/* paranoid */ verify( thrd_dst->state == Active );
358	thrd_dst->state = Blocked;
359
360	// set state of processor coroutine to active and the thread to inactive
361	int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
362	switch(old_ticket) {
363	case TICKET_RUNNING:
364	// This is case 1, the regular case, nothing more is needed
365	break RUNNING;
366	case TICKET_UNBLOCK:
367	__STATS__(true, ready.threads.threads++; )
368	// This is case 2, the racy case, someone tried to run this thread before it finished blocking
369	// In this case, just run it again.
370	continue RUNNING;
371	default:
372	// This makes no sense, something is wrong abort
373	abort();
374	}
375	}
376
377	// Just before returning to the processor, set the processor coroutine to active
378	proc_cor->state = Active;
379
380	__cfadbg_print_safe(runtime_core, "Kernel : core %p finished running thread %p\n", this, thrd_dst);
381
382	__STATS__(true, ready.threads.threads--; )
383
384	/* paranoid */ verify( ! __preemption_enabled() );
385	}
386
387	// KERNEL_ONLY
388	void returnToKernel() {
389	/* paranoid */ verify( ! __preemption_enabled() );
390	coroutine$ * proc_cor = get_coroutine(kernelTLS().this_processor->runner);
391	thread$ * thrd_src = kernelTLS().this_thread;
392
393	__STATS_DEF( thrd_src->last_proc = kernelTLS().this_processor; )
394
395	// Run the thread on this processor
396	{
397	int local_errno = *__volatile_errno();
398	#if defined( __i386 ) \|\| defined( __x86_64 )
399	__x87_store;
400	#endif
401	/* paranoid */ verify( proc_cor->context.SP );
402	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
403	__cfactx_switch( &thrd_src->context, &proc_cor->context );
404	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
405	#if defined( __i386 ) \|\| defined( __x86_64 )
406	__x87_load;
407	#endif
408	*__volatile_errno() = local_errno;
409	}
410
411	#if !defined(__CFA_NO_STATISTICS__)
412	/* paranoid */ verify( thrd_src->last_proc != 0p );
413	if(thrd_src->last_proc != kernelTLS().this_processor) {
414	__tls_stats()->ready.threads.migration++;
415	}
416	#endif
417
418	/* paranoid */ verify( ! __preemption_enabled() );
419	/* 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 );
420	/* 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 );
421	}
422
423	//-----------------------------------------------------------------------------
424	// Scheduler routines
425	// KERNEL ONLY
426	static void __schedule_thread( thread$ * thrd, unpark_hint hint ) {
427	/* paranoid */ verify( ! __preemption_enabled() );
428	/* paranoid */ verify( ready_schedule_islocked());
429	/* paranoid */ verify( thrd );
430	/* paranoid */ verify( thrd->state != Halted );
431	/* paranoid */ verify( thrd->curr_cluster );
432	/* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
433	/* paranoid */ if( thrd->state == Blocked \|\| thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
434	"Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
435	/* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
436	"Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
437	/* paranoid */ #endif
438	/* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
439	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
440
441	if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
442
443	// Dereference the thread now because once we push it, there is not guaranteed it's still valid.
444	struct cluster * cl = thrd->curr_cluster;
445	__STATS_DEF(bool outside = hint == UNPARK_LOCAL && thrd->last_proc && thrd->last_proc != kernelTLS().this_processor; )
446
447	// push the thread to the cluster ready-queue
448	push( cl, thrd, hint );
449
450	// variable thrd is no longer safe to use
451	thrd = 0xdeaddeaddeaddeadp;
452
453	// wake the cluster using the save variable.
454	__wake_one( cl );
455
456	#if !defined(__CFA_NO_STATISTICS__)
457	if( kernelTLS().this_stats ) {
458	__tls_stats()->ready.threads.threads++;
459	if(outside) {
460	__tls_stats()->ready.threads.extunpark++;
461	}
462	}
463	else {
464	__atomic_fetch_add(&cl->stats->ready.threads.threads, 1, __ATOMIC_RELAXED);
465	__atomic_fetch_add(&cl->stats->ready.threads.extunpark, 1, __ATOMIC_RELAXED);
466	}
467	#endif
468
469	/* paranoid */ verify( ready_schedule_islocked());
470	/* paranoid */ verify( ! __preemption_enabled() );
471	}
472
473	void schedule_thread$( thread$ * thrd, unpark_hint hint ) {
474	ready_schedule_lock();
475	__schedule_thread( thrd, hint );
476	ready_schedule_unlock();
477	}
478
479	// KERNEL ONLY
480	static inline thread$ * __next_thread(cluster * this) with( *this ) {
481	/* paranoid */ verify( ! __preemption_enabled() );
482
483	ready_schedule_lock();
484	thread$ * thrd = pop_fast( this );
485	ready_schedule_unlock();
486
487	/* paranoid */ verify( ! __preemption_enabled() );
488	return thrd;
489	}
490
491	// KERNEL ONLY
492	static inline thread$ * __next_thread_slow(cluster * this) with( *this ) {
493	/* paranoid */ verify( ! __preemption_enabled() );
494
495	ready_schedule_lock();
496	thread$ * thrd = pop_slow( this );
497	ready_schedule_unlock();
498
499	/* paranoid */ verify( ! __preemption_enabled() );
500	return thrd;
501	}
502
503	// KERNEL ONLY
504	static inline thread$ * __next_thread_search(cluster * this) with( *this ) {
505	/* paranoid */ verify( ! __preemption_enabled() );
506
507	ready_schedule_lock();
508	thread$ * thrd = pop_search( this );
509	ready_schedule_unlock();
510
511	/* paranoid */ verify( ! __preemption_enabled() );
512	return thrd;
513	}
514
515	static inline bool __must_unpark( thread$ * thrd ) {
516	int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
517	switch(old_ticket) {
518	case TICKET_RUNNING:
519	// Wake won the race, the thread will reschedule/rerun itself
520	return false;
521	case TICKET_BLOCKED:
522	/* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
523	/* paranoid */ verify( thrd->state == Blocked );
524	return true;
525	default:
526	// This makes no sense, something is wrong abort
527	abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
528	}
529	}
530
531	void __kernel_unpark( thread$ * thrd, unpark_hint hint ) {
532	/* paranoid */ verify( ! __preemption_enabled() );
533	/* paranoid */ verify( ready_schedule_islocked());
534
535	if( !thrd ) return;
536
537	if(__must_unpark(thrd)) {
538	// Wake lost the race,
539	__schedule_thread( thrd, hint );
540	}
541
542	/* paranoid */ verify( ready_schedule_islocked());
543	/* paranoid */ verify( ! __preemption_enabled() );
544	}
545
546	void unpark( thread$ * thrd, unpark_hint hint ) {
547	if( !thrd ) return;
548
549	if(__must_unpark(thrd)) {
550	disable_interrupts();
551	// Wake lost the race,
552	schedule_thread$( thrd, hint );
553	enable_interrupts(false);
554	}
555	}
556
557	void park( void ) {
558	__disable_interrupts_checked();
559	/* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
560	returnToKernel();
561	__enable_interrupts_checked();
562
563	}
564
565	extern "C" {
566	// Leave the thread monitor
567	// last routine called by a thread.
568	// Should never return
569	void __cfactx_thrd_leave() {
570	thread$ * thrd = active_thread();
571	monitor$ * this = &thrd->self_mon;
572
573	// Lock the monitor now
574	lock( this->lock __cfaabi_dbg_ctx2 );
575
576	disable_interrupts();
577
578	/* paranoid */ verify( ! __preemption_enabled() );
579	/* paranoid */ verify( thrd->state == Active );
580	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
581	/* paranoid */ verify( kernelTLS().this_thread == thrd );
582	/* paranoid */ verify( thrd->context.SP );
583	/* 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 );
584	/* 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 );
585
586	thrd->state = Halting;
587	if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
588	if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
589	if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
590
591	// Leave the thread
592	returnToKernel();
593
594	// Control flow should never reach here!
595	abort();
596	}
597	}
598
599	// KERNEL ONLY
600	bool force_yield( __Preemption_Reason reason ) {
601	__disable_interrupts_checked();
602	thread$ * thrd = kernelTLS().this_thread;
603	/* paranoid */ verify(thrd->state == Active);
604
605	// SKULLDUGGERY: It is possible that we are preempting this thread just before
606	// it was going to park itself. If that is the case and it is already using the
607	// intrusive fields then we can't use them to preempt the thread
608	// If that is the case, abandon the preemption.
609	bool preempted = false;
610	if(thrd->link.next == 0p) {
611	preempted = true;
612	thrd->preempted = reason;
613	returnToKernel();
614	}
615	__enable_interrupts_checked( false );
616	return preempted;
617	}
618
619	//=============================================================================================
620	// Kernel Idle Sleep
621	//=============================================================================================
622	// Wake a thread from the front if there are any
623	static void __wake_one(cluster * this) {
624	eventfd_t val;
625
626	/* paranoid */ verify( ! __preemption_enabled() );
627	/* paranoid */ verify( ready_schedule_islocked() );
628
629	// Check if there is a sleeping processor
630	struct __fd_waitctx * fdp = __atomic_load_n(&this->procs.fdw, __ATOMIC_SEQ_CST);
631
632	// If no one is sleeping: we are done
633	if( fdp == 0p ) return;
634
635	int fd = 1;
636	if( __atomic_load_n(&fdp->fd, __ATOMIC_SEQ_CST) != 1 ) {
637	fd = __atomic_exchange_n(&fdp->fd, 1, __ATOMIC_RELAXED);
638	}
639
640	switch(fd) {
641	case 0:
642	// If the processor isn't ready to sleep then the exchange will already wake it up
643	#if !defined(__CFA_NO_STATISTICS__)
644	if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.early++;
645	} else { __atomic_fetch_add(&this->stats->ready.sleep.early, 1, __ATOMIC_RELAXED); }
646	#endif
647	break;
648	case 1:
649	// If someone else already said they will wake them: we are done
650	#if !defined(__CFA_NO_STATISTICS__)
651	if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.seen++;
652	} else { __atomic_fetch_add(&this->stats->ready.sleep.seen, 1, __ATOMIC_RELAXED); }
653	#endif
654	break;
655	default:
656	// If the processor was ready to sleep, we need to wake it up with an actual write
657	val = 1;
658	eventfd_write( fd, val );
659
660	#if !defined(__CFA_NO_STATISTICS__)
661	if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.wakes++;
662	} else { __atomic_fetch_add(&this->stats->ready.sleep.wakes, 1, __ATOMIC_RELAXED); }
663	#endif
664	break;
665	}
666
667	/* paranoid */ verify( ready_schedule_islocked() );
668	/* paranoid */ verify( ! __preemption_enabled() );
669
670	return;
671	}
672
673	// Unconditionnaly wake a thread
674	void __wake_proc(processor * this) {
675	/* paranoid */ verify( ! __preemption_enabled() );
676
677	__cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
678
679	this->idle_wctx.fd = 1;
680
681	eventfd_t val;
682	val = 1;
683	eventfd_write( this->idle_fd, val );
684
685	/* paranoid */ verify( ! __preemption_enabled() );
686	}
687
688	static void idle_sleep(processor * this, io_future_t & future, iovec & iov) {
689	// Tell everyone we are ready to go do sleep
690	for() {
691	int expected = this->idle_wctx.fd;
692
693	// Someone already told us to wake-up! No time for a nap.
694	if(expected == 1) { return; }
695
696	// Try to mark that we are going to sleep
697	if(__atomic_compare_exchange_n(&this->idle_wctx.fd, &expected, this->idle_fd, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) ) {
698	// Every one agreed, taking a nap
699	break;
700	}
701	}
702
703
704	#if !defined(CFA_WITH_IO_URING_IDLE)
705	#if !defined(__CFA_NO_STATISTICS__)
706	if(this->print_halts) {
707	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->unique_id, rdtscl());
708	}
709	#endif
710
711	__cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle_fd);
712
713	{
714	eventfd_t val;
715	ssize_t ret = read( this->idle_fd, &val, sizeof(val) );
716	if(ret < 0) {
717	switch((int)errno) {
718	case EAGAIN:
719	#if EAGAIN != EWOULDBLOCK
720	case EWOULDBLOCK:
721	#endif
722	case EINTR:
723	// No need to do anything special here, just assume it's a legitimate wake-up
724	break;
725	default:
726	abort( "KERNEL : internal error, read failure on idle eventfd, error(%d) %s.", (int)errno, strerror( (int)errno ) );
727	}
728	}
729	}
730
731	#if !defined(__CFA_NO_STATISTICS__)
732	if(this->print_halts) {
733	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->unique_id, rdtscl());
734	}
735	#endif
736	#else
737	// Do we already have a pending read
738	if(available(future)) {
739	// There is no pending read, we need to add one
740	reset(future);
741
742	__kernel_read(this, future, iov, this->idle_fd );
743	}
744
745	__cfa_io_flush( this, 1 );
746	#endif
747	}
748
749	static bool mark_idle(__cluster_proc_list & this, processor & proc) {
750	__STATS__(true, ready.sleep.halts++; )
751
752	proc.idle_wctx.fd = 0;
753
754	/* paranoid */ verify( ! __preemption_enabled() );
755	if(!try_lock( this )) return false;
756	this.idle++;
757	/* paranoid */ verify( this.idle <= this.total );
758	remove(proc);
759	insert_first(this.idles, proc);
760
761	__atomic_store_n(&this.fdw, &proc.idle_wctx, __ATOMIC_SEQ_CST);
762	unlock( this );
763	/* paranoid */ verify( ! __preemption_enabled() );
764
765	return true;
766	}
767
768	static void mark_awake(__cluster_proc_list & this, processor & proc) {
769	/* paranoid */ verify( ! __preemption_enabled() );
770	lock( this );
771	this.idle--;
772	/* paranoid */ verify( this.idle >= 0 );
773	remove(proc);
774	insert_last(this.actives, proc);
775
776	{
777	struct __fd_waitctx * wctx = 0;
778	if(!this.idles`isEmpty) wctx = &this.idles`first.idle_wctx;
779	__atomic_store_n(&this.fdw, wctx, __ATOMIC_SEQ_CST);
780	}
781
782	unlock( this );
783	/* paranoid */ verify( ! __preemption_enabled() );
784	}
785
786	//=============================================================================================
787	// Unexpected Terminating logic
788	//=============================================================================================
789	void __kernel_abort_msg( char * abort_text, int abort_text_size ) {
790	thread$ * thrd = __cfaabi_tls.this_thread;
791
792	if(thrd) {
793	int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
794	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
795
796	if ( &thrd->self_cor != thrd->curr_cor ) {
797	len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
798	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
799	}
800	else {
801	__cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
802	}
803	}
804	else {
805	int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
806	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
807	}
808	}
809
810	int __kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
811	return get_coroutine(__cfaabi_tls.this_thread) == get_coroutine(mainThread) ? 4 : 2;
812	}
813
814	static __spinlock_t kernel_debug_lock;
815
816	extern "C" {
817	void __cfaabi_bits_acquire() {
818	lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
819	}
820
821	void __cfaabi_bits_release() {
822	unlock( kernel_debug_lock );
823	}
824	}
825
826	//=============================================================================================
827	// Kernel Utilities
828	//=============================================================================================
829	#if defined(CFA_HAVE_LINUX_IO_URING_H)
830	#include "io/types.hfa"
831	#endif
832
833	static inline bool __maybe_io_drain( processor * proc ) {
834	bool ret = false;
835	#if defined(CFA_HAVE_LINUX_IO_URING_H)
836	__cfadbg_print_safe(runtime_core, "Kernel : core %p checking io for ring %d\n", proc, proc->io.ctx->fd);
837
838	// Check if we should drain the queue
839	$io_context * ctx = proc->io.ctx;
840	unsigned head = *ctx->cq.head;
841	unsigned tail = *ctx->cq.tail;
842	if(head == tail) return false;
843	ready_schedule_lock();
844	ret = __cfa_io_drain( proc );
845	ready_schedule_unlock();
846	#endif
847	return ret;
848	}
849
850	//-----------------------------------------------------------------------------
851	// Debug
852	__cfaabi_dbg_debug_do(
853	extern "C" {
854	void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
855	this.prev_name = prev_name;
856	this.prev_thrd = kernelTLS().this_thread;
857	}
858	}
859	)
860
861	//-----------------------------------------------------------------------------
862	// Debug
863	bool threading_enabled(void) __attribute__((const)) {
864	return true;
865	}
866
867	//-----------------------------------------------------------------------------
868	// Statistics
869	#if !defined(__CFA_NO_STATISTICS__)
870	void print_halts( processor & this ) {
871	this.print_halts = true;
872	}
873
874	static void crawl_list( cluster * cltr, dlist(processor) & list, unsigned count ) {
875	/* paranoid */ verify( cltr->stats );
876
877	processor * it = &list`first;
878	for(unsigned i = 0; i < count; i++) {
879	/* paranoid */ verifyf( it, "Unexpected null iterator, at index %u of %u\n", i, count);
880	/* paranoid */ verify( it->local_data->this_stats );
881	// __print_stats( it->local_data->this_stats, cltr->print_stats, "Processor", it->name, (void*)it );
882	__tally_stats( cltr->stats, it->local_data->this_stats );
883	it = &(*it)`next;
884	}
885	}
886
887	void crawl_cluster_stats( cluster & this ) {
888	// Stop the world, otherwise stats could get really messed-up
889	// this doesn't solve all problems but does solve many
890	// so it's probably good enough
891	disable_interrupts();
892	uint_fast32_t last_size = ready_mutate_lock();
893
894	crawl_list(&this, this.procs.actives, this.procs.total - this.procs.idle);
895	crawl_list(&this, this.procs.idles , this.procs.idle );
896
897	// Unlock the RWlock
898	ready_mutate_unlock( last_size );
899	enable_interrupts();
900	}
901
902
903	void print_stats_now( cluster & this, int flags ) {
904	crawl_cluster_stats( this );
905	__print_stats( this.stats, this.print_stats, "Cluster", this.name, (void*)&this );
906	}
907	#endif
908	// Local Variables: //
909	// mode: c //
910	// tab-width: 4 //
911	// End: //

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