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kernel.cfa @ 04a8a54

ADTast-experimentalenumforall-pointer-decaypthread-emulationqualifiedEnum

Last change on this file since 04a8a54 was d3605f8, checked in by Thierry Delisle <tdelisle@…>, 2 years ago
Reworked io_uring idle sleep to work with either read or readv depending on what's available.
Property mode set to `100644`
File size: 30.9 KB

Line
1	//
2	// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
3	//
4	// The contents of this file are covered under the licence agreement in the
5	// file "LICENCE" distributed with Cforall.
6	//
7	// kernel.c --
8	//
9	// Author : Thierry Delisle
10	// Created On : Tue Jan 17 12:27:26 2017
11	// Last Modified By : Peter A. Buhr
12	// Last Modified On : Mon Aug 31 07:08:20 2020
13	// Update Count : 71
14	//
15
16	#define __cforall_thread__
17	#define _GNU_SOURCE
18
19	// #define __CFA_DEBUG_PRINT_RUNTIME_CORE__
20
21	//C Includes
22	#include <errno.h>
23	#include <stdio.h>
24	#include <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( ...) __VA_ARGS__
45	#else
46	#define __STATS( ...)
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 inline bool __must_unpark( thread$ * thrd ) __attribute((nonnull(1)));
125	static void __run_thread(processor * this, thread$ * dst);
126	static void __wake_one(cluster * cltr);
127
128	static void idle_sleep(processor * proc, io_future_t & future, iovec & iov);
129	static bool mark_idle (__cluster_proc_list & idles, processor & proc);
130	static void mark_awake(__cluster_proc_list & idles, processor & proc);
131
132	extern void __cfa_io_start( processor * );
133	extern bool __cfa_io_drain( processor * );
134	extern bool __cfa_io_flush( processor *, int min_comp );
135	extern void __cfa_io_stop ( processor * );
136	static inline bool __maybe_io_drain( processor * );
137
138	#if defined(CFA_WITH_IO_URING_IDLE)
139	extern bool __kernel_read(processor * proc, io_future_t & future, iovec &, int fd);
140	#endif
141
142	extern void __disable_interrupts_hard();
143	extern void __enable_interrupts_hard();
144
145	static inline void __disable_interrupts_checked() {
146	/* paranoid */ verify( __preemption_enabled() );
147	disable_interrupts();
148	/* paranoid */ verify( ! __preemption_enabled() );
149	}
150
151	static inline void __enable_interrupts_checked( bool poll = true ) {
152	/* paranoid */ verify( ! __preemption_enabled() );
153	enable_interrupts( poll );
154	/* paranoid */ verify( __preemption_enabled() );
155	}
156
157
158	//=============================================================================================
159	// Kernel Scheduling logic
160	//=============================================================================================
161	//Main of the processor contexts
162	void main(processorCtx_t & runner) {
163	// Because of a bug, we couldn't initialized the seed on construction
164	// Do it here
165	__cfaabi_tls.rand_seed ^= rdtscl();
166	__cfaabi_tls.ready_rng.fwd_seed = 25214903917_l64u * (rdtscl() ^ (uintptr_t)&runner);
167	__tls_rand_advance_bck();
168
169	processor * this = runner.proc;
170	verify(this);
171
172	io_future_t future; // used for idle sleep when io_uring is present
173	future.self.ptr = 1p; // mark it as already fulfilled so we know if there is a pending request or not
174	eventfd_t idle_val;
175	iovec idle_iovec = { &idle_val, sizeof(idle_val) };
176
177	__cfa_io_start( this );
178
179	__cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
180	#if !defined(__CFA_NO_STATISTICS__)
181	if( this->print_halts ) {
182	__cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->unique_id, this->name, (void*)this);
183	}
184	#endif
185
186	{
187	// Setup preemption data
188	preemption_scope scope = { this };
189
190	// if we need to run some special setup, now is the time to do it.
191	if(this->init.thrd) {
192	this->init.thrd->curr_cluster = this->cltr;
193	__run_thread(this, this->init.thrd);
194	}
195
196	__cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
197
198	thread$ * readyThread = 0p;
199	MAIN_LOOP:
200	for() {
201	#define OLD_MAIN 1
202	#if OLD_MAIN
203	// Check if there is pending io
204	__maybe_io_drain( this );
205
206	// Try to get the next thread
207	readyThread = __next_thread( this->cltr );
208
209	if( !readyThread ) {
210	__cfa_io_flush( this, 0 );
211
212	readyThread = __next_thread_slow( this->cltr );
213	}
214
215	HALT:
216	if( !readyThread ) {
217	// Don't block if we are done
218	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
219
220	#if !defined(__CFA_NO_STATISTICS__)
221	__tls_stats()->ready.sleep.halts++;
222	#endif
223
224	// Push self to idle stack
225	if(!mark_idle(this->cltr->procs, * this)) continue MAIN_LOOP;
226
227	// Confirm the ready-queue is empty
228	readyThread = __next_thread_slow( this->cltr );
229	if( readyThread ) {
230	// A thread was found, cancel the halt
231	mark_awake(this->cltr->procs, * this);
232
233	#if !defined(__CFA_NO_STATISTICS__)
234	__tls_stats()->ready.sleep.cancels++;
235	#endif
236
237	// continue the mai loop
238	break HALT;
239	}
240
241	idle_sleep( this, future, idle_iovec );
242
243	// We were woken up, remove self from idle
244	mark_awake(this->cltr->procs, * this);
245
246	// DON'T just proceed, start looking again
247	continue MAIN_LOOP;
248	}
249
250	/* paranoid */ verify( readyThread );
251
252	// Reset io dirty bit
253	this->io.dirty = false;
254
255	// We found a thread run it
256	__run_thread(this, readyThread);
257
258	// Are we done?
259	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
260
261	if(this->io.pending && !this->io.dirty) {
262	__cfa_io_flush( this, 0 );
263	}
264
265	#else
266	#warning new kernel loop
267	SEARCH: {
268	/* paranoid */ verify( ! __preemption_enabled() );
269
270	// First, lock the scheduler since we are searching for a thread
271	ready_schedule_lock();
272
273	// Try to get the next thread
274	readyThread = pop_fast( this->cltr );
275	if(readyThread) { ready_schedule_unlock(); break SEARCH; }
276
277	// If we can't find a thread, might as well flush any outstanding I/O
278	if(this->io.pending) { __cfa_io_flush( this, 0 ); }
279
280	// Spin a little on I/O, just in case
281	for(5) {
282	__maybe_io_drain( this );
283	readyThread = pop_fast( this->cltr );
284	if(readyThread) { ready_schedule_unlock(); break SEARCH; }
285	}
286
287	// no luck, try stealing a few times
288	for(5) {
289	if( __maybe_io_drain( this ) ) {
290	readyThread = pop_fast( this->cltr );
291	} else {
292	readyThread = pop_slow( this->cltr );
293	}
294	if(readyThread) { ready_schedule_unlock(); break SEARCH; }
295	}
296
297	// still no luck, search for a thread
298	readyThread = pop_search( this->cltr );
299	if(readyThread) { ready_schedule_unlock(); break SEARCH; }
300
301	// Don't block if we are done
302	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) {
303	ready_schedule_unlock();
304	break MAIN_LOOP;
305	}
306
307	__STATS( __tls_stats()->ready.sleep.halts++; )
308
309	// Push self to idle stack
310	ready_schedule_unlock();
311	if(!mark_idle(this->cltr->procs, * this)) goto SEARCH;
312	ready_schedule_lock();
313
314	// Confirm the ready-queue is empty
315	__maybe_io_drain( this );
316	readyThread = pop_search( this->cltr );
317	ready_schedule_unlock();
318
319	if( readyThread ) {
320	// A thread was found, cancel the halt
321	mark_awake(this->cltr->procs, * this);
322
323	__STATS( __tls_stats()->ready.sleep.cancels++; )
324
325	// continue the main loop
326	break SEARCH;
327	}
328
329	__STATS( if(this->print_halts) __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->unique_id, rdtscl()); )
330	__cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle_fd);
331
332	{
333	eventfd_t val;
334	ssize_t ret = read( this->idle_fd, &val, sizeof(val) );
335	if(ret < 0) {
336	switch((int)errno) {
337	case EAGAIN:
338	#if EAGAIN != EWOULDBLOCK
339	case EWOULDBLOCK:
340	#endif
341	case EINTR:
342	// No need to do anything special here, just assume it's a legitimate wake-up
343	break;
344	default:
345	abort( "KERNEL : internal error, read failure on idle eventfd, error(%d) %s.", (int)errno, strerror( (int)errno ) );
346	}
347	}
348	}
349
350	__STATS( if(this->print_halts) __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->unique_id, rdtscl()); )
351
352	// We were woken up, remove self from idle
353	mark_awake(this->cltr->procs, * this);
354
355	// DON'T just proceed, start looking again
356	continue MAIN_LOOP;
357	}
358
359	RUN_THREAD:
360	/* paranoid */ verify( ! __preemption_enabled() );
361	/* paranoid */ verify( readyThread );
362
363	// Reset io dirty bit
364	this->io.dirty = false;
365
366	// We found a thread run it
367	__run_thread(this, readyThread);
368
369	// Are we done?
370	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
371
372	if(this->io.pending && !this->io.dirty) {
373	__cfa_io_flush( this, 0 );
374	}
375
376	ready_schedule_lock();
377	__maybe_io_drain( this );
378	ready_schedule_unlock();
379	#endif
380	}
381
382	__cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
383	}
384
385	for(int i = 0; !available(future); i++) {
386	if(i > 1000) __cfaabi_dbg_write( "ERROR: kernel has bin spinning on a flush after exit loop.\n", 60);
387	__cfa_io_flush( this, 1 );
388	}
389
390	__cfa_io_stop( this );
391
392	post( this->terminated );
393
394	if(this == mainProcessor) {
395	// HACK : the coroutine context switch expects this_thread to be set
396	// and it make sense for it to be set in all other cases except here
397	// fake it
398	__cfaabi_tls.this_thread = mainThread;
399	}
400
401	__cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
402	}
403
404	static int * __volatile_errno() __attribute__((noinline));
405	static int * __volatile_errno() { asm(""); return &errno; }
406
407	// KERNEL ONLY
408	// runThread runs a thread by context switching
409	// from the processor coroutine to the target thread
410	static void __run_thread(processor * this, thread$ * thrd_dst) {
411	/* paranoid */ verify( ! __preemption_enabled() );
412	/* paranoid */ verifyf( thrd_dst->state == Ready \|\| thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
413	/* paranoid */ verifyf( thrd_dst->link.next == 0p, "Expected null got %p", thrd_dst->link.next );
414	__builtin_prefetch( thrd_dst->context.SP );
415
416	__cfadbg_print_safe(runtime_core, "Kernel : core %p running thread %p (%s)\n", this, thrd_dst, thrd_dst->self_cor.name);
417
418	coroutine$ * proc_cor = get_coroutine(this->runner);
419
420	// set state of processor coroutine to inactive
421	verify(proc_cor->state == Active);
422	proc_cor->state = Blocked;
423
424	// Actually run the thread
425	RUNNING: while(true) {
426	thrd_dst->preempted = __NO_PREEMPTION;
427	thrd_dst->state = Active;
428
429	// Update global state
430	kernelTLS().this_thread = thrd_dst;
431
432	/* paranoid */ verify( ! __preemption_enabled() );
433	/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
434	/* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
435	/* paranoid */ verify( thrd_dst->context.SP );
436	/* paranoid */ verify( thrd_dst->state != Halted );
437	/* 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
438	/* 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
439	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
440
441
442
443	// set context switch to the thread that the processor is executing
444	__cfactx_switch( &proc_cor->context, &thrd_dst->context );
445	// when __cfactx_switch returns we are back in the processor coroutine
446
447
448
449	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
450	/* 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 );
451	/* 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 );
452	/* paranoid */ verify( thrd_dst->context.SP );
453	/* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
454	/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
455	/* paranoid */ verify( ! __preemption_enabled() );
456
457	// Reset global state
458	kernelTLS().this_thread = 0p;
459
460	// We just finished running a thread, there are a few things that could have happened.
461	// 1 - Regular case : the thread has blocked and now one has scheduled it yet.
462	// 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
463	// 4 - Preempted
464	// In case 1, we may have won a race so we can't write to the state again.
465	// In case 2, we lost the race so we now own the thread.
466
467	if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
468	// The thread was preempted, reschedule it and reset the flag
469	schedule_thread$( thrd_dst, UNPARK_LOCAL );
470	break RUNNING;
471	}
472
473	if(unlikely(thrd_dst->state == Halting)) {
474	// The thread has halted, it should never be scheduled/run again
475	// finish the thread
476	__thread_finish( thrd_dst );
477	break RUNNING;
478	}
479
480	/* paranoid */ verify( thrd_dst->state == Active );
481	thrd_dst->state = Blocked;
482
483	// set state of processor coroutine to active and the thread to inactive
484	int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
485	switch(old_ticket) {
486	case TICKET_RUNNING:
487	// This is case 1, the regular case, nothing more is needed
488	break RUNNING;
489	case TICKET_UNBLOCK:
490	#if !defined(__CFA_NO_STATISTICS__)
491	__tls_stats()->ready.threads.threads++;
492	#endif
493	// This is case 2, the racy case, someone tried to run this thread before it finished blocking
494	// In this case, just run it again.
495	continue RUNNING;
496	default:
497	// This makes no sense, something is wrong abort
498	abort();
499	}
500	}
501
502	// Just before returning to the processor, set the processor coroutine to active
503	proc_cor->state = Active;
504
505	__cfadbg_print_safe(runtime_core, "Kernel : core %p finished running thread %p\n", this, thrd_dst);
506
507	#if !defined(__CFA_NO_STATISTICS__)
508	__tls_stats()->ready.threads.threads--;
509	#endif
510
511	/* paranoid */ verify( ! __preemption_enabled() );
512	}
513
514	// KERNEL_ONLY
515	void returnToKernel() {
516	/* paranoid */ verify( ! __preemption_enabled() );
517	coroutine$ * proc_cor = get_coroutine(kernelTLS().this_processor->runner);
518	thread$ * thrd_src = kernelTLS().this_thread;
519
520	__STATS( thrd_src->last_proc = kernelTLS().this_processor; )
521
522	// Run the thread on this processor
523	{
524	int local_errno = *__volatile_errno();
525	#if defined( __i386 ) \|\| defined( __x86_64 )
526	__x87_store;
527	#endif
528	/* paranoid */ verify( proc_cor->context.SP );
529	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
530	__cfactx_switch( &thrd_src->context, &proc_cor->context );
531	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
532	#if defined( __i386 ) \|\| defined( __x86_64 )
533	__x87_load;
534	#endif
535	*__volatile_errno() = local_errno;
536	}
537
538	#if !defined(__CFA_NO_STATISTICS__)
539	/* paranoid */ verify( thrd_src->last_proc != 0p );
540	if(thrd_src->last_proc != kernelTLS().this_processor) {
541	__tls_stats()->ready.threads.migration++;
542	}
543	#endif
544
545	/* paranoid */ verify( ! __preemption_enabled() );
546	/* 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 );
547	/* 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 );
548	}
549
550	//-----------------------------------------------------------------------------
551	// Scheduler routines
552	// KERNEL ONLY
553	static void __schedule_thread( thread$ * thrd, unpark_hint hint ) {
554	/* paranoid */ verify( ! __preemption_enabled() );
555	/* paranoid */ verify( ready_schedule_islocked());
556	/* paranoid */ verify( thrd );
557	/* paranoid */ verify( thrd->state != Halted );
558	/* paranoid */ verify( thrd->curr_cluster );
559	/* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
560	/* paranoid */ if( thrd->state == Blocked \|\| thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
561	"Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
562	/* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
563	"Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
564	/* paranoid */ #endif
565	/* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
566	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
567
568	const bool local = thrd->state != Start;
569	if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
570
571	// Dereference the thread now because once we push it, there is not guaranteed it's still valid.
572	struct cluster * cl = thrd->curr_cluster;
573	__STATS(bool outside = hint == UNPARK_LOCAL && thrd->last_proc && thrd->last_proc != kernelTLS().this_processor; )
574
575	// push the thread to the cluster ready-queue
576	push( cl, thrd, hint );
577
578	// variable thrd is no longer safe to use
579	thrd = 0xdeaddeaddeaddeadp;
580
581	// wake the cluster using the save variable.
582	__wake_one( cl );
583
584	#if !defined(__CFA_NO_STATISTICS__)
585	if( kernelTLS().this_stats ) {
586	__tls_stats()->ready.threads.threads++;
587	if(outside) {
588	__tls_stats()->ready.threads.extunpark++;
589	}
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	}
595	#endif
596
597	/* paranoid */ verify( ready_schedule_islocked());
598	/* paranoid */ verify( ! __preemption_enabled() );
599	}
600
601	void schedule_thread$( thread$ * thrd, unpark_hint hint ) {
602	ready_schedule_lock();
603	__schedule_thread( thrd, hint );
604	ready_schedule_unlock();
605	}
606
607	// KERNEL ONLY
608	static inline thread$ * __next_thread(cluster * this) with( *this ) {
609	/* paranoid */ verify( ! __preemption_enabled() );
610
611	ready_schedule_lock();
612	thread$ * thrd = pop_fast( this );
613	ready_schedule_unlock();
614
615	/* paranoid */ verify( ! __preemption_enabled() );
616	return thrd;
617	}
618
619	// KERNEL ONLY
620	static inline thread$ * __next_thread_slow(cluster * this) with( *this ) {
621	/* paranoid */ verify( ! __preemption_enabled() );
622
623	ready_schedule_lock();
624	thread$ * thrd;
625	for(25) {
626	thrd = pop_slow( this );
627	if(thrd) goto RET;
628	}
629	thrd = pop_search( this );
630
631	RET:
632	ready_schedule_unlock();
633
634	/* paranoid */ verify( ! __preemption_enabled() );
635	return thrd;
636	}
637
638	static inline bool __must_unpark( thread$ * thrd ) {
639	int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
640	switch(old_ticket) {
641	case TICKET_RUNNING:
642	// Wake won the race, the thread will reschedule/rerun itself
643	return false;
644	case TICKET_BLOCKED:
645	/* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
646	/* paranoid */ verify( thrd->state == Blocked );
647	return true;
648	default:
649	// This makes no sense, something is wrong abort
650	abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
651	}
652	}
653
654	void __kernel_unpark( thread$ * thrd, unpark_hint hint ) {
655	/* paranoid */ verify( ! __preemption_enabled() );
656	/* paranoid */ verify( ready_schedule_islocked());
657
658	if( !thrd ) return;
659
660	if(__must_unpark(thrd)) {
661	// Wake lost the race,
662	__schedule_thread( thrd, hint );
663	}
664
665	/* paranoid */ verify( ready_schedule_islocked());
666	/* paranoid */ verify( ! __preemption_enabled() );
667	}
668
669	void unpark( thread$ * thrd, unpark_hint hint ) {
670	if( !thrd ) return;
671
672	if(__must_unpark(thrd)) {
673	disable_interrupts();
674	// Wake lost the race,
675	schedule_thread$( thrd, hint );
676	enable_interrupts(false);
677	}
678	}
679
680	void park( void ) {
681	__disable_interrupts_checked();
682	/* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
683	returnToKernel();
684	__enable_interrupts_checked();
685
686	}
687
688	extern "C" {
689	// Leave the thread monitor
690	// last routine called by a thread.
691	// Should never return
692	void __cfactx_thrd_leave() {
693	thread$ * thrd = active_thread();
694	monitor$ * this = &thrd->self_mon;
695
696	// Lock the monitor now
697	lock( this->lock __cfaabi_dbg_ctx2 );
698
699	disable_interrupts();
700
701	/* paranoid */ verify( ! __preemption_enabled() );
702	/* paranoid */ verify( thrd->state == Active );
703	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
704	/* paranoid */ verify( kernelTLS().this_thread == thrd );
705	/* paranoid */ verify( thrd->context.SP );
706	/* 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 );
707	/* 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 );
708
709	thrd->state = Halting;
710	if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
711	if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
712	if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
713
714	// Leave the thread
715	returnToKernel();
716
717	// Control flow should never reach here!
718	abort();
719	}
720	}
721
722	// KERNEL ONLY
723	bool force_yield( __Preemption_Reason reason ) {
724	__disable_interrupts_checked();
725	thread$ * thrd = kernelTLS().this_thread;
726	/* paranoid */ verify(thrd->state == Active);
727
728	// SKULLDUGGERY: It is possible that we are preempting this thread just before
729	// it was going to park itself. If that is the case and it is already using the
730	// intrusive fields then we can't use them to preempt the thread
731	// If that is the case, abandon the preemption.
732	bool preempted = false;
733	if(thrd->link.next == 0p) {
734	preempted = true;
735	thrd->preempted = reason;
736	returnToKernel();
737	}
738	__enable_interrupts_checked( false );
739	return preempted;
740	}
741
742	//=============================================================================================
743	// Kernel Idle Sleep
744	//=============================================================================================
745	// Wake a thread from the front if there are any
746	static void __wake_one(cluster * this) {
747	/* paranoid */ verify( ! __preemption_enabled() );
748	/* paranoid */ verify( ready_schedule_islocked() );
749
750	// Check if there is a sleeping processor
751	int fd = __atomic_load_n(&this->procs.fd, __ATOMIC_SEQ_CST);
752
753	// If no one is sleeping, we are done
754	if( fd == 0 ) return;
755
756	// We found a processor, wake it up
757	eventfd_t val;
758	val = 1;
759	eventfd_write( fd, val );
760
761	#if !defined(__CFA_NO_STATISTICS__)
762	if( kernelTLS().this_stats ) {
763	__tls_stats()->ready.sleep.wakes++;
764	}
765	else {
766	__atomic_fetch_add(&this->stats->ready.sleep.wakes, 1, __ATOMIC_RELAXED);
767	}
768	#endif
769
770	/* paranoid */ verify( ready_schedule_islocked() );
771	/* paranoid */ verify( ! __preemption_enabled() );
772
773	return;
774	}
775
776	// Unconditionnaly wake a thread
777	void __wake_proc(processor * this) {
778	__cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
779
780	__disable_interrupts_checked();
781	/* paranoid */ verify( ! __preemption_enabled() );
782	eventfd_t val;
783	val = 1;
784	eventfd_write( this->idle_fd, val );
785	__enable_interrupts_checked();
786	}
787
788	static void idle_sleep(processor * this, io_future_t & future, iovec & iov) {
789	#if !defined(CFA_WITH_IO_URING_IDLE)
790	#if !defined(__CFA_NO_STATISTICS__)
791	if(this->print_halts) {
792	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->unique_id, rdtscl());
793	}
794	#endif
795
796	__cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle_fd);
797
798	{
799	eventfd_t val;
800	ssize_t ret = read( this->idle_fd, &val, sizeof(val) );
801	if(ret < 0) {
802	switch((int)errno) {
803	case EAGAIN:
804	#if EAGAIN != EWOULDBLOCK
805	case EWOULDBLOCK:
806	#endif
807	case EINTR:
808	// No need to do anything special here, just assume it's a legitimate wake-up
809	break;
810	default:
811	abort( "KERNEL : internal error, read failure on idle eventfd, error(%d) %s.", (int)errno, strerror( (int)errno ) );
812	}
813	}
814	}
815
816	#if !defined(__CFA_NO_STATISTICS__)
817	if(this->print_halts) {
818	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->unique_id, rdtscl());
819	}
820	#endif
821	#else
822	// Do we already have a pending read
823	if(available(future)) {
824	// There is no pending read, we need to add one
825	reset(future);
826
827	__kernel_read(this, future, iov, this->idle_fd );
828	}
829
830	__cfa_io_flush( this, 1 );
831	#endif
832	}
833
834	static bool mark_idle(__cluster_proc_list & this, processor & proc) {
835	/* paranoid */ verify( ! __preemption_enabled() );
836	if(!try_lock( this )) return false;
837	this.idle++;
838	/* paranoid */ verify( this.idle <= this.total );
839	remove(proc);
840	insert_first(this.idles, proc);
841
842	__atomic_store_n(&this.fd, proc.idle_fd, __ATOMIC_SEQ_CST);
843	unlock( this );
844	/* paranoid */ verify( ! __preemption_enabled() );
845
846	return true;
847	}
848
849	static void mark_awake(__cluster_proc_list & this, processor & proc) {
850	/* paranoid */ verify( ! __preemption_enabled() );
851	lock( this );
852	this.idle--;
853	/* paranoid */ verify( this.idle >= 0 );
854	remove(proc);
855	insert_last(this.actives, proc);
856
857	{
858	int fd = 0;
859	if(!this.idles`isEmpty) fd = this.idles`first.idle_fd;
860	__atomic_store_n(&this.fd, fd, __ATOMIC_SEQ_CST);
861	}
862
863	unlock( this );
864	/* paranoid */ verify( ! __preemption_enabled() );
865	}
866
867	//=============================================================================================
868	// Unexpected Terminating logic
869	//=============================================================================================
870	void __kernel_abort_msg( char * abort_text, int abort_text_size ) {
871	thread$ * thrd = __cfaabi_tls.this_thread;
872
873	if(thrd) {
874	int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
875	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
876
877	if ( &thrd->self_cor != thrd->curr_cor ) {
878	len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
879	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
880	}
881	else {
882	__cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
883	}
884	}
885	else {
886	int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
887	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
888	}
889	}
890
891	int __kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
892	return get_coroutine(__cfaabi_tls.this_thread) == get_coroutine(mainThread) ? 4 : 2;
893	}
894
895	static __spinlock_t kernel_debug_lock;
896
897	extern "C" {
898	void __cfaabi_bits_acquire() {
899	lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
900	}
901
902	void __cfaabi_bits_release() {
903	unlock( kernel_debug_lock );
904	}
905	}
906
907	//=============================================================================================
908	// Kernel Utilities
909	//=============================================================================================
910	#if defined(CFA_HAVE_LINUX_IO_URING_H)
911	#include "io/types.hfa"
912	#endif
913
914	static inline bool __maybe_io_drain( processor * proc ) {
915	bool ret = false;
916	#if defined(CFA_HAVE_LINUX_IO_URING_H)
917	__cfadbg_print_safe(runtime_core, "Kernel : core %p checking io for ring %d\n", proc, proc->io.ctx->fd);
918
919	// Check if we should drain the queue
920	$io_context * ctx = proc->io.ctx;
921	unsigned head = *ctx->cq.head;
922	unsigned tail = *ctx->cq.tail;
923	if(head == tail) return false;
924	#if OLD_MAIN
925	ready_schedule_lock();
926	ret = __cfa_io_drain( proc );
927	ready_schedule_unlock();
928	#else
929	ret = __cfa_io_drain( proc );
930	#endif
931	#endif
932	return ret;
933	}
934
935	//-----------------------------------------------------------------------------
936	// Debug
937	__cfaabi_dbg_debug_do(
938	extern "C" {
939	void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
940	this.prev_name = prev_name;
941	this.prev_thrd = kernelTLS().this_thread;
942	}
943	}
944	)
945
946	//-----------------------------------------------------------------------------
947	// Debug
948	bool threading_enabled(void) __attribute__((const)) {
949	return true;
950	}
951
952	//-----------------------------------------------------------------------------
953	// Statistics
954	#if !defined(__CFA_NO_STATISTICS__)
955	void print_halts( processor & this ) {
956	this.print_halts = true;
957	}
958
959	static void crawl_list( cluster * cltr, dlist(processor) & list, unsigned count ) {
960	/* paranoid */ verify( cltr->stats );
961
962	processor * it = &list`first;
963	for(unsigned i = 0; i < count; i++) {
964	/* paranoid */ verifyf( it, "Unexpected null iterator, at index %u of %u\n", i, count);
965	/* paranoid */ verify( it->local_data->this_stats );
966	// __print_stats( it->local_data->this_stats, cltr->print_stats, "Processor", it->name, (void*)it );
967	__tally_stats( cltr->stats, it->local_data->this_stats );
968	it = &(*it)`next;
969	}
970	}
971
972	void crawl_cluster_stats( cluster & this ) {
973	// Stop the world, otherwise stats could get really messed-up
974	// this doesn't solve all problems but does solve many
975	// so it's probably good enough
976	disable_interrupts();
977	uint_fast32_t last_size = ready_mutate_lock();
978
979	crawl_list(&this, this.procs.actives, this.procs.total - this.procs.idle);
980	crawl_list(&this, this.procs.idles , this.procs.idle );
981
982	// Unlock the RWlock
983	ready_mutate_unlock( last_size );
984	enable_interrupts();
985	}
986
987
988	void print_stats_now( cluster & this, int flags ) {
989	crawl_cluster_stats( this );
990	__print_stats( this.stats, this.print_stats, "Cluster", this.name, (void*)&this );
991	}
992	#endif
993	// Local Variables: //
994	// mode: c //
995	// tab-width: 4 //
996	// End: //

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