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kernel.cfa @ 4479890

ADTast-experimentalenumpthread-emulationqualifiedEnum

Last change on this file since 4479890 was 4479890, checked in by Thierry Delisle <tdelisle@…>, 2 years ago
Implemented helping for io drain based on timestamps.
Property mode set to `100644`
File size: 28.8 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	#pragma GCC diagnostic push
22	#pragma GCC diagnostic ignored "-Waddress-of-packed-member"
23
24	//C Includes
25	#include <errno.h>
26	#include <stdio.h>
27	#include <string.h>
28	#include <signal.h>
29	#include <unistd.h>
30
31	extern "C" {
32	#include <sys/eventfd.h>
33	#include <sys/uio.h>
34	}
35
36	//CFA Includes
37	#include "kernel/private.hfa"
38	#include "preemption.hfa"
39	#include "strstream.hfa"
40	#include "device/cpu.hfa"
41	#include "io/types.hfa"
42
43	//Private includes
44	#define __CFA_INVOKE_PRIVATE__
45	#include "invoke.h"
46	#pragma GCC diagnostic pop
47
48	#if !defined(__CFA_NO_STATISTICS__)
49	#define __STATS_DEF( ...) __VA_ARGS__
50	#else
51	#define __STATS_DEF( ...)
52	#endif
53
54	//-----------------------------------------------------------------------------
55	// Some assembly required
56	#if defined( __i386 )
57	// mxcr : SSE Status and Control bits (control bits are preserved across function calls)
58	// fcw : X87 FPU control word (preserved across function calls)
59	#define __x87_store \
60	uint32_t __mxcr; \
61	uint16_t __fcw; \
62	__asm__ volatile ( \
63	"stmxcsr %0\n" \
64	"fnstcw %1\n" \
65	: "=m" (__mxcr),\
66	"=m" (__fcw) \
67	)
68
69	#define __x87_load \
70	__asm__ volatile ( \
71	"fldcw %1\n" \
72	"ldmxcsr %0\n" \
73	::"m" (__mxcr),\
74	"m" (__fcw) \
75	)
76
77	#elif defined( __x86_64 )
78	#define __x87_store \
79	uint32_t __mxcr; \
80	uint16_t __fcw; \
81	__asm__ volatile ( \
82	"stmxcsr %0\n" \
83	"fnstcw %1\n" \
84	: "=m" (__mxcr),\
85	"=m" (__fcw) \
86	)
87
88	#define __x87_load \
89	__asm__ volatile ( \
90	"fldcw %1\n" \
91	"ldmxcsr %0\n" \
92	:: "m" (__mxcr),\
93	"m" (__fcw) \
94	)
95
96	#elif defined( __arm__ )
97	#define __x87_store
98	#define __x87_load
99
100	#elif defined( __aarch64__ )
101	#define __x87_store \
102	uint32_t __fpcntl[2]; \
103	__asm__ volatile ( \
104	"mrs x9, FPCR\n" \
105	"mrs x10, FPSR\n" \
106	"stp x9, x10, %0\n" \
107	: "=m" (__fpcntl) : : "x9", "x10" \
108	)
109
110	#define __x87_load \
111	__asm__ volatile ( \
112	"ldp x9, x10, %0\n" \
113	"msr FPSR, x10\n" \
114	"msr FPCR, x9\n" \
115	: "=m" (__fpcntl) : : "x9", "x10" \
116	)
117
118	#else
119	#error unsupported hardware architecture
120	#endif
121
122	extern thread$ * mainThread;
123	extern processor * mainProcessor;
124
125	//-----------------------------------------------------------------------------
126	// Kernel Scheduling logic
127	static thread$ * __next_thread(cluster * this);
128	static thread$ * __next_thread_slow(cluster * this);
129	static thread$ * __next_thread_search(cluster * this);
130	static inline bool __must_unpark( thread$ * thrd ) __attribute((nonnull(1)));
131	static void __run_thread(processor * this, thread$ * dst);
132	static void __wake_one(cluster * cltr);
133
134	static void idle_sleep(processor * proc, io_future_t & future, iovec & iov);
135	static bool mark_idle (__cluster_proc_list & idles, processor & proc);
136	static void mark_awake(__cluster_proc_list & idles, processor & proc);
137
138	extern bool __cfa_io_drain( processor * proc ) __attribute__((nonnull (1)));
139	extern bool __cfa_io_flush( processor *, int min_comp );
140	static inline bool __maybe_io_drain( processor * );
141
142	#if defined(CFA_WITH_IO_URING_IDLE)
143	extern bool __kernel_read(processor * proc, io_future_t & future, iovec &, int fd);
144	#endif
145
146	extern void __disable_interrupts_hard();
147	extern void __enable_interrupts_hard();
148
149
150	//=============================================================================================
151	// Kernel Scheduling logic
152	//=============================================================================================
153	//Main of the processor contexts
154	void main(processorCtx_t & runner) {
155	// Because of a bug, we couldn't initialized the seed on construction
156	// Do it here
157	__cfaabi_tls.rand_seed ^= rdtscl();
158	__cfaabi_tls.ready_rng.fwd_seed = 25214903917_l64u * (rdtscl() ^ (uintptr_t)&runner);
159	__tls_rand_advance_bck();
160
161	processor * this = runner.proc;
162	verify(this);
163
164	/* paranoid */ verify( this->idle_wctx.ftr != 0p );
165	/* paranoid */ verify( this->idle_wctx.rdbuf != 0p );
166
167	// used for idle sleep when io_uring is present
168	// mark it as already fulfilled so we know if there is a pending request or not
169	this->idle_wctx.ftr->self.ptr = 1p;
170	iovec idle_iovec = { this->idle_wctx.rdbuf, sizeof(eventfd_t) };
171
172	__cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
173	#if !defined(__CFA_NO_STATISTICS__)
174	if( this->print_halts ) {
175	__cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->unique_id, this->name, (void*)this);
176	}
177	#endif
178
179	{
180	// Setup preemption data
181	preemption_scope scope = { this };
182
183	// if we need to run some special setup, now is the time to do it.
184	if(this->init.thrd) {
185	this->init.thrd->curr_cluster = this->cltr;
186	__run_thread(this, this->init.thrd);
187	}
188
189	__cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
190
191	thread$ * readyThread = 0p;
192	MAIN_LOOP:
193	for() {
194	// Check if there is pending io
195	__maybe_io_drain( this );
196
197	// Try to get the next thread
198	readyThread = __next_thread( this->cltr );
199
200	if( !readyThread ) {
201	__IO_STATS__(true, io.flush.idle++; )
202	__cfa_io_flush( this, 0 );
203
204	readyThread = __next_thread( this->cltr );
205	}
206
207	if( !readyThread ) for(5) {
208	__IO_STATS__(true, io.flush.idle++; )
209
210	readyThread = __next_thread_slow( this->cltr );
211
212	if( readyThread ) break;
213
214	__cfa_io_flush( this, 0 );
215	}
216
217	HALT:
218	if( !readyThread ) {
219	// Don't block if we are done
220	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
221
222	// Push self to idle stack
223	if(!mark_idle(this->cltr->procs, * this)) continue MAIN_LOOP;
224
225	// Confirm the ready-queue is empty
226	readyThread = __next_thread_search( this->cltr );
227	if( readyThread ) {
228	// A thread was found, cancel the halt
229	mark_awake(this->cltr->procs, * this);
230
231	__STATS__(true, ready.sleep.cancels++; )
232
233	// continue the mai loop
234	break HALT;
235	}
236
237	idle_sleep( this, *this->idle_wctx.ftr, idle_iovec );
238
239	// We were woken up, remove self from idle
240	mark_awake(this->cltr->procs, * this);
241
242	// DON'T just proceed, start looking again
243	continue MAIN_LOOP;
244	}
245
246	/* paranoid */ verify( readyThread );
247
248	// Reset io dirty bit
249	this->io.dirty = false;
250
251	// We found a thread run it
252	__run_thread(this, readyThread);
253
254	// Are we done?
255	if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
256
257	if(__atomic_load_n(&this->io.pending, __ATOMIC_RELAXED) && !__atomic_load_n(&this->io.dirty, __ATOMIC_RELAXED)) {
258	__IO_STATS__(true, io.flush.dirty++; )
259	__cfa_io_flush( this, 0 );
260	}
261	}
262
263	__cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
264	}
265
266	post( this->terminated );
267
268	if(this == mainProcessor) {
269	// HACK : the coroutine context switch expects this_thread to be set
270	// and it make sense for it to be set in all other cases except here
271	// fake it
272	__cfaabi_tls.this_thread = mainThread;
273	}
274
275	__cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
276	}
277
278	static int * __volatile_errno() __attribute__((noinline));
279	static int * __volatile_errno() { asm(""); return &errno; }
280
281	// KERNEL ONLY
282	// runThread runs a thread by context switching
283	// from the processor coroutine to the target thread
284	static void __run_thread(processor * this, thread$ * thrd_dst) {
285	/* paranoid */ verify( ! __preemption_enabled() );
286	/* paranoid */ verifyf( thrd_dst->state == Ready \|\| thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
287	/* paranoid */ verifyf( thrd_dst->link.next == 0p, "Expected null got %p", thrd_dst->link.next );
288	__builtin_prefetch( thrd_dst->context.SP );
289
290	__cfadbg_print_safe(runtime_core, "Kernel : core %p running thread %p (%s)\n", this, thrd_dst, thrd_dst->self_cor.name);
291
292	coroutine$ * proc_cor = get_coroutine(this->runner);
293
294	// set state of processor coroutine to inactive
295	verify(proc_cor->state == Active);
296	proc_cor->state = Blocked;
297
298	// Actually run the thread
299	RUNNING: while(true) {
300	thrd_dst->preempted = __NO_PREEMPTION;
301	thrd_dst->state = Active;
302
303	// Update global state
304	kernelTLS().this_thread = thrd_dst;
305
306	/* paranoid */ verify( ! __preemption_enabled() );
307	/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
308	/* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
309	/* paranoid */ verify( thrd_dst->context.SP );
310	/* paranoid */ verify( thrd_dst->state != Halted );
311	/* 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
312	/* 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
313	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
314
315
316
317	// set context switch to the thread that the processor is executing
318	__cfactx_switch( &proc_cor->context, &thrd_dst->context );
319	// when __cfactx_switch returns we are back in the processor coroutine
320
321
322
323	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
324	/* 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 );
325	/* 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 );
326	/* paranoid */ verify( thrd_dst->context.SP );
327	/* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
328	/* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
329	/* paranoid */ verify( ! __preemption_enabled() );
330
331	// Reset global state
332	kernelTLS().this_thread = 0p;
333
334	// We just finished running a thread, there are a few things that could have happened.
335	// 1 - Regular case : the thread has blocked and now one has scheduled it yet.
336	// 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
337	// 4 - Preempted
338	// In case 1, we may have won a race so we can't write to the state again.
339	// In case 2, we lost the race so we now own the thread.
340
341	if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
342	// The thread was preempted, reschedule it and reset the flag
343	schedule_thread$( thrd_dst, UNPARK_LOCAL );
344	break RUNNING;
345	}
346
347	if(unlikely(thrd_dst->state == Halting)) {
348	// The thread has halted, it should never be scheduled/run again
349	// finish the thread
350	__thread_finish( thrd_dst );
351	break RUNNING;
352	}
353
354	/* paranoid */ verify( thrd_dst->state == Active );
355	thrd_dst->state = Blocked;
356
357	// set state of processor coroutine to active and the thread to inactive
358	int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
359	switch(old_ticket) {
360	case TICKET_RUNNING:
361	// This is case 1, the regular case, nothing more is needed
362	break RUNNING;
363	case TICKET_UNBLOCK:
364	__STATS__(true, ready.threads.threads++; )
365	// This is case 2, the racy case, someone tried to run this thread before it finished blocking
366	// In this case, just run it again.
367	continue RUNNING;
368	default:
369	// This makes no sense, something is wrong abort
370	abort();
371	}
372	}
373
374	// Just before returning to the processor, set the processor coroutine to active
375	proc_cor->state = Active;
376
377	__cfadbg_print_safe(runtime_core, "Kernel : core %p finished running thread %p\n", this, thrd_dst);
378
379	__STATS__(true, ready.threads.threads--; )
380
381	/* paranoid */ verify( ! __preemption_enabled() );
382	}
383
384	// KERNEL_ONLY
385	void returnToKernel() {
386	/* paranoid */ verify( ! __preemption_enabled() );
387	coroutine$ * proc_cor = get_coroutine(kernelTLS().this_processor->runner);
388	thread$ * thrd_src = kernelTLS().this_thread;
389
390	__STATS_DEF( thrd_src->last_proc = kernelTLS().this_processor; )
391
392	// Run the thread on this processor
393	{
394	int local_errno = *__volatile_errno();
395	#if defined( __i386 ) \|\| defined( __x86_64 )
396	__x87_store;
397	#endif
398	/* paranoid */ verify( proc_cor->context.SP );
399	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
400	__cfactx_switch( &thrd_src->context, &proc_cor->context );
401	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
402	#if defined( __i386 ) \|\| defined( __x86_64 )
403	__x87_load;
404	#endif
405	*__volatile_errno() = local_errno;
406	}
407
408	#if !defined(__CFA_NO_STATISTICS__)
409	/* paranoid */ verify( thrd_src->last_proc != 0p );
410	if(thrd_src->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 ) \|\| thrd_src->corctx_flag, "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) \|\| thrd_src->corctx_flag, "ERROR : Returning thread$ %p has been corrupted.\n StackPointer too large.\n", thrd_src );
418	}
419
420	//-----------------------------------------------------------------------------
421	// Scheduler routines
422	// KERNEL ONLY
423	static void __schedule_thread( thread$ * thrd, unpark_hint hint ) {
424	/* paranoid */ verify( ! __preemption_enabled() );
425	/* paranoid */ verify( ready_schedule_islocked());
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	if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
439
440	// Dereference the thread now because once we push it, there is not guaranteed it's still valid.
441	struct cluster * cl = thrd->curr_cluster;
442	__STATS_DEF(bool outside = hint == UNPARK_LOCAL && thrd->last_proc && thrd->last_proc != kernelTLS().this_processor; )
443
444	// push the thread to the cluster ready-queue
445	push( cl, thrd, hint );
446
447	// variable thrd is no longer safe to use
448	thrd = 0xdeaddeaddeaddeadp;
449
450	// wake the cluster using the save variable.
451	__wake_one( cl );
452
453	#if !defined(__CFA_NO_STATISTICS__)
454	if( kernelTLS().this_stats ) {
455	__tls_stats()->ready.threads.threads++;
456	if(outside) {
457	__tls_stats()->ready.threads.extunpark++;
458	}
459	}
460	else {
461	__atomic_fetch_add(&cl->stats->ready.threads.threads, 1, __ATOMIC_RELAXED);
462	__atomic_fetch_add(&cl->stats->ready.threads.extunpark, 1, __ATOMIC_RELAXED);
463	}
464	#endif
465
466	/* paranoid */ verify( ready_schedule_islocked());
467	/* paranoid */ verify( ! __preemption_enabled() );
468	}
469
470	void schedule_thread$( thread$ * thrd, unpark_hint hint ) {
471	ready_schedule_lock();
472	__schedule_thread( thrd, hint );
473	ready_schedule_unlock();
474	}
475
476	// KERNEL ONLY
477	static inline thread$ * __next_thread(cluster * this) with( *this ) {
478	/* paranoid */ verify( ! __preemption_enabled() );
479
480	ready_schedule_lock();
481	thread$ * thrd = pop_fast( this );
482	ready_schedule_unlock();
483
484	/* paranoid */ verify( ! __preemption_enabled() );
485	return thrd;
486	}
487
488	// KERNEL ONLY
489	static inline thread$ * __next_thread_slow(cluster * this) with( *this ) {
490	/* paranoid */ verify( ! __preemption_enabled() );
491
492	ready_schedule_lock();
493	thread$ * thrd = pop_slow( this );
494	ready_schedule_unlock();
495
496	/* paranoid */ verify( ! __preemption_enabled() );
497	return thrd;
498	}
499
500	// KERNEL ONLY
501	static inline thread$ * __next_thread_search(cluster * this) with( *this ) {
502	/* paranoid */ verify( ! __preemption_enabled() );
503
504	ready_schedule_lock();
505	thread$ * thrd = pop_search( this );
506	ready_schedule_unlock();
507
508	/* paranoid */ verify( ! __preemption_enabled() );
509	return thrd;
510	}
511
512	static inline bool __must_unpark( thread$ * thrd ) {
513	int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
514	switch(old_ticket) {
515	case TICKET_RUNNING:
516	// Wake won the race, the thread will reschedule/rerun itself
517	return false;
518	case TICKET_BLOCKED:
519	/* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
520	/* paranoid */ verify( thrd->state == Blocked );
521	return true;
522	default:
523	// This makes no sense, something is wrong abort
524	abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
525	}
526	}
527
528	void __kernel_unpark( thread$ * thrd, unpark_hint hint ) {
529	/* paranoid */ verify( ! __preemption_enabled() );
530	/* paranoid */ verify( ready_schedule_islocked());
531
532	if( !thrd ) return;
533
534	if(__must_unpark(thrd)) {
535	// Wake lost the race,
536	__schedule_thread( thrd, hint );
537	}
538
539	/* paranoid */ verify( ready_schedule_islocked());
540	/* paranoid */ verify( ! __preemption_enabled() );
541	}
542
543	void unpark( thread$ * thrd, unpark_hint hint ) {
544	if( !thrd ) return;
545
546	if(__must_unpark(thrd)) {
547	disable_interrupts();
548	// Wake lost the race,
549	schedule_thread$( thrd, hint );
550	enable_interrupts(false);
551	}
552	}
553
554	void park( void ) {
555	__disable_interrupts_checked();
556	/* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
557	returnToKernel();
558	__enable_interrupts_checked();
559
560	}
561
562	extern "C" {
563	// Leave the thread monitor
564	// last routine called by a thread.
565	// Should never return
566	void __cfactx_thrd_leave() {
567	thread$ * thrd = active_thread();
568	monitor$ * this = &thrd->self_mon;
569
570	// Lock the monitor now
571	lock( this->lock __cfaabi_dbg_ctx2 );
572
573	disable_interrupts();
574
575	/* paranoid */ verify( ! __preemption_enabled() );
576	/* paranoid */ verify( thrd->state == Active );
577	/* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
578	/* paranoid */ verify( kernelTLS().this_thread == thrd );
579	/* paranoid */ verify( thrd->context.SP );
580	/* 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 );
581	/* 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 );
582
583	thrd->state = Halting;
584	if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
585	if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
586	if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
587
588	// Leave the thread
589	returnToKernel();
590
591	// Control flow should never reach here!
592	abort();
593	}
594	}
595
596	// KERNEL ONLY
597	bool force_yield( __Preemption_Reason reason ) {
598	__disable_interrupts_checked();
599	thread$ * thrd = kernelTLS().this_thread;
600	/* paranoid */ verify(thrd->state == Active);
601
602	// SKULLDUGGERY: It is possible that we are preempting this thread just before
603	// it was going to park itself. If that is the case and it is already using the
604	// intrusive fields then we can't use them to preempt the thread
605	// If that is the case, abandon the preemption.
606	bool preempted = false;
607	if(thrd->link.next == 0p) {
608	preempted = true;
609	thrd->preempted = reason;
610	returnToKernel();
611	}
612	__enable_interrupts_checked( false );
613	return preempted;
614	}
615
616	//=============================================================================================
617	// Kernel Idle Sleep
618	//=============================================================================================
619	// Wake a thread from the front if there are any
620	static void __wake_one(cluster * this) {
621	eventfd_t val;
622
623	/* paranoid */ verify( ! __preemption_enabled() );
624	/* paranoid */ verify( ready_schedule_islocked() );
625
626	// Check if there is a sleeping processor
627	struct __fd_waitctx * fdp = __atomic_load_n(&this->procs.fdw, __ATOMIC_SEQ_CST);
628
629	// If no one is sleeping: we are done
630	if( fdp == 0p ) return;
631
632	int fd = 1;
633	if( __atomic_load_n(&fdp->sem, __ATOMIC_SEQ_CST) != 1 ) {
634	fd = __atomic_exchange_n(&fdp->sem, 1, __ATOMIC_RELAXED);
635	}
636
637	switch(fd) {
638	case 0:
639	// If the processor isn't ready to sleep then the exchange will already wake it up
640	#if !defined(__CFA_NO_STATISTICS__)
641	if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.early++;
642	} else { __atomic_fetch_add(&this->stats->ready.sleep.early, 1, __ATOMIC_RELAXED); }
643	#endif
644	break;
645	case 1:
646	// If someone else already said they will wake them: we are done
647	#if !defined(__CFA_NO_STATISTICS__)
648	if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.seen++;
649	} else { __atomic_fetch_add(&this->stats->ready.sleep.seen, 1, __ATOMIC_RELAXED); }
650	#endif
651	break;
652	default:
653	// If the processor was ready to sleep, we need to wake it up with an actual write
654	val = 1;
655	eventfd_write( fd, val );
656
657	#if !defined(__CFA_NO_STATISTICS__)
658	if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.wakes++;
659	} else { __atomic_fetch_add(&this->stats->ready.sleep.wakes, 1, __ATOMIC_RELAXED); }
660	#endif
661	break;
662	}
663
664	/* paranoid */ verify( ready_schedule_islocked() );
665	/* paranoid */ verify( ! __preemption_enabled() );
666
667	return;
668	}
669
670	// Unconditionnaly wake a thread
671	void __wake_proc(processor * this) {
672	/* paranoid */ verify( ! __preemption_enabled() );
673
674	__cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
675
676	this->idle_wctx.sem = 1;
677
678	eventfd_t val;
679	val = 1;
680	eventfd_write( this->idle_wctx.evfd, val );
681
682	/* paranoid */ verify( ! __preemption_enabled() );
683	}
684
685	static void idle_sleep(processor * this, io_future_t & future, iovec & iov) {
686	// Tell everyone we are ready to go do sleep
687	for() {
688	int expected = this->idle_wctx.sem;
689
690	// Someone already told us to wake-up! No time for a nap.
691	if(expected == 1) { return; }
692
693	// Try to mark that we are going to sleep
694	if(__atomic_compare_exchange_n(&this->idle_wctx.sem, &expected, this->idle_wctx.evfd, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) ) {
695	// Every one agreed, taking a nap
696	break;
697	}
698	}
699
700
701	#if !defined(CFA_WITH_IO_URING_IDLE)
702	#if !defined(__CFA_NO_STATISTICS__)
703	if(this->print_halts) {
704	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->unique_id, rdtscl());
705	}
706	#endif
707
708	__cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle_fd);
709
710	{
711	eventfd_t val;
712	ssize_t ret = read( this->idle_wctx.evfd, &val, sizeof(val) );
713	if(ret < 0) {
714	switch((int)errno) {
715	case EAGAIN:
716	#if EAGAIN != EWOULDBLOCK
717	case EWOULDBLOCK:
718	#endif
719	case EINTR:
720	// No need to do anything special here, just assume it's a legitimate wake-up
721	break;
722	default:
723	abort( "KERNEL : internal error, read failure on idle eventfd, error(%d) %s.", (int)errno, strerror( (int)errno ) );
724	}
725	}
726	}
727
728	#if !defined(__CFA_NO_STATISTICS__)
729	if(this->print_halts) {
730	__cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->unique_id, rdtscl());
731	}
732	#endif
733	#else
734	// Do we already have a pending read
735	if(available(future)) {
736	// There is no pending read, we need to add one
737	reset(future);
738
739	__kernel_read(this, future, iov, this->idle_wctx.evfd );
740	}
741
742	__cfa_io_flush( this, 1 );
743	#endif
744	}
745
746	static bool mark_idle(__cluster_proc_list & this, processor & proc) {
747	__STATS__(true, ready.sleep.halts++; )
748
749	proc.idle_wctx.sem = 0;
750
751	/* paranoid */ verify( ! __preemption_enabled() );
752	if(!try_lock( this )) return false;
753	this.idle++;
754	/* paranoid */ verify( this.idle <= this.total );
755	remove(proc);
756	insert_first(this.idles, proc);
757
758	__atomic_store_n(&this.fdw, &proc.idle_wctx, __ATOMIC_SEQ_CST);
759	unlock( this );
760	/* paranoid */ verify( ! __preemption_enabled() );
761
762	return true;
763	}
764
765	static void mark_awake(__cluster_proc_list & this, processor & proc) {
766	/* paranoid */ verify( ! __preemption_enabled() );
767	lock( this );
768	this.idle--;
769	/* paranoid */ verify( this.idle >= 0 );
770	remove(proc);
771	insert_last(this.actives, proc);
772
773	{
774	struct __fd_waitctx * wctx = 0;
775	if(!this.idles`isEmpty) wctx = &this.idles`first.idle_wctx;
776	__atomic_store_n(&this.fdw, wctx, __ATOMIC_SEQ_CST);
777	}
778
779	unlock( this );
780	/* paranoid */ verify( ! __preemption_enabled() );
781	}
782
783	//=============================================================================================
784	// Unexpected Terminating logic
785	//=============================================================================================
786	void __kernel_abort_msg( char * abort_text, int abort_text_size ) {
787	thread$ * thrd = __cfaabi_tls.this_thread;
788
789	if(thrd) {
790	int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
791	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
792
793	if ( &thrd->self_cor != thrd->curr_cor ) {
794	len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
795	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
796	}
797	else {
798	__cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
799	}
800	}
801	else {
802	int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
803	__cfaabi_bits_write( STDERR_FILENO, abort_text, len );
804	}
805	}
806
807	int __kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
808	return get_coroutine(__cfaabi_tls.this_thread) == get_coroutine(mainThread) ? 4 : 2;
809	}
810
811	static __spinlock_t kernel_debug_lock;
812
813	extern "C" {
814	void __cfaabi_bits_acquire() {
815	lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
816	}
817
818	void __cfaabi_bits_release() {
819	unlock( kernel_debug_lock );
820	}
821	}
822
823	//=============================================================================================
824	// Kernel Utilities
825	//=============================================================================================
826	#if defined(CFA_HAVE_LINUX_IO_URING_H)
827	#include "io/types.hfa"
828	#endif
829
830	static inline bool __maybe_io_drain( processor * proc ) {
831	/* paranoid */ verify( proc );
832	bool ret = false;
833	#if defined(CFA_HAVE_LINUX_IO_URING_H)
834	__cfadbg_print_safe(runtime_core, "Kernel : core %p checking io for ring %d\n", proc, proc->io.ctx->fd);
835
836	// Check if we should drain the queue
837	$io_context * ctx = proc->io.ctx;
838	unsigned head = *ctx->cq.head;
839	unsigned tail = *ctx->cq.tail;
840	if(head == tail) return false;
841	ready_schedule_lock();
842	ret = __cfa_io_drain( proc );
843	ready_schedule_unlock();
844	#endif
845	return ret;
846	}
847
848	//-----------------------------------------------------------------------------
849	// Debug
850	__cfaabi_dbg_debug_do(
851	extern "C" {
852	void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
853	this.prev_name = prev_name;
854	this.prev_thrd = kernelTLS().this_thread;
855	}
856	}
857	)
858
859	//-----------------------------------------------------------------------------
860	// Debug
861	bool threading_enabled(void) __attribute__((const)) {
862	return true;
863	}
864
865	//-----------------------------------------------------------------------------
866	// Statistics
867	#if !defined(__CFA_NO_STATISTICS__)
868	void print_halts( processor & this ) {
869	this.print_halts = true;
870	}
871
872	static void crawl_list( cluster * cltr, dlist(processor) & list, unsigned count ) {
873	/* paranoid */ verify( cltr->stats );
874
875	processor * it = &list`first;
876	for(unsigned i = 0; i < count; i++) {
877	/* paranoid */ verifyf( it, "Unexpected null iterator, at index %u of %u\n", i, count);
878	/* paranoid */ verify( it->local_data->this_stats );
879	// __print_stats( it->local_data->this_stats, cltr->print_stats, "Processor", it->name, (void*)it );
880	__tally_stats( cltr->stats, it->local_data->this_stats );
881	it = &(*it)`next;
882	}
883	}
884
885	void crawl_cluster_stats( cluster & this ) {
886	// Stop the world, otherwise stats could get really messed-up
887	// this doesn't solve all problems but does solve many
888	// so it's probably good enough
889	disable_interrupts();
890	uint_fast32_t last_size = ready_mutate_lock();
891
892	crawl_list(&this, this.procs.actives, this.procs.total - this.procs.idle);
893	crawl_list(&this, this.procs.idles , this.procs.idle );
894
895	// Unlock the RWlock
896	ready_mutate_unlock( last_size );
897	enable_interrupts();
898	}
899
900
901	void print_stats_now( cluster & this, int flags ) {
902	crawl_cluster_stats( this );
903	__print_stats( this.stats, this.print_stats, "Cluster", this.name, (void*)&this );
904	}
905	#endif
906	// Local Variables: //
907	// mode: c //
908	// tab-width: 4 //
909	// End: //

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