source: libcfa/src/concurrency/kernel.cfa@ bc4a433

ADT ast-experimental enum forall-pointer-decay pthread-emulation qualifiedEnum
Last change on this file since bc4a433 was abcae55, checked in by Thierry Delisle <tdelisle@…>, 4 years ago

Removed last_cpu (and small spacing changes)
  • Property mode set to 100644
File size: 30.1 KB
Line 
1//
2// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
3//
4// The contents of this file are covered under the licence agreement in the
5// file "LICENCE" distributed with Cforall.
6//
7// kernel.c --
8//
9// Author : Thierry Delisle
10// Created On : Tue Jan 17 12:27:26 2017
11// Last Modified By : Peter A. Buhr
12// Last Modified On : Mon Aug 31 07:08:20 2020
13// Update Count : 71
14//
15
16#define __cforall_thread__
17#define _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>
27extern "C" {
28 #include <sys/eventfd.h>
29}
30
31//CFA Includes
32#include "kernel_private.hfa"
33#include "preemption.hfa"
34#include "strstream.hfa"
35#include "device/cpu.hfa"
36
37//Private includes
38#define __CFA_INVOKE_PRIVATE__
39#include "invoke.h"
40
41#if !defined(__CFA_NO_STATISTICS__)
42 #define __STATS( ...) __VA_ARGS__
43#else
44 #define __STATS( ...)
45#endif
46
47//-----------------------------------------------------------------------------
48// Some assembly required
49#if defined( __i386 )
50 // mxcr : SSE Status and Control bits (control bits are preserved across function calls)
51 // fcw : X87 FPU control word (preserved across function calls)
52 #define __x87_store \
53 uint32_t __mxcr; \
54 uint16_t __fcw; \
55 __asm__ volatile ( \
56 "stmxcsr %0\n" \
57 "fnstcw %1\n" \
58 : "=m" (__mxcr),\
59 "=m" (__fcw) \
60 )
61
62 #define __x87_load \
63 __asm__ volatile ( \
64 "fldcw %1\n" \
65 "ldmxcsr %0\n" \
66 ::"m" (__mxcr),\
67 "m" (__fcw) \
68 )
69
70#elif defined( __x86_64 )
71 #define __x87_store \
72 uint32_t __mxcr; \
73 uint16_t __fcw; \
74 __asm__ volatile ( \
75 "stmxcsr %0\n" \
76 "fnstcw %1\n" \
77 : "=m" (__mxcr),\
78 "=m" (__fcw) \
79 )
80
81 #define __x87_load \
82 __asm__ volatile ( \
83 "fldcw %1\n" \
84 "ldmxcsr %0\n" \
85 :: "m" (__mxcr),\
86 "m" (__fcw) \
87 )
88
89#elif defined( __arm__ )
90 #define __x87_store
91 #define __x87_load
92
93#elif defined( __aarch64__ )
94 #define __x87_store \
95 uint32_t __fpcntl[2]; \
96 __asm__ volatile ( \
97 "mrs x9, FPCR\n" \
98 "mrs x10, FPSR\n" \
99 "stp x9, x10, %0\n" \
100 : "=m" (__fpcntl) : : "x9", "x10" \
101 )
102
103 #define __x87_load \
104 __asm__ volatile ( \
105 "ldp x9, x10, %0\n" \
106 "msr FPSR, x10\n" \
107 "msr FPCR, x9\n" \
108 : "=m" (__fpcntl) : : "x9", "x10" \
109 )
110
111#else
112 #error unsupported hardware architecture
113#endif
114
115extern thread$ * mainThread;
116extern processor * mainProcessor;
117
118//-----------------------------------------------------------------------------
119// Kernel Scheduling logic
120static thread$ * __next_thread(cluster * this);
121static thread$ * __next_thread_slow(cluster * this);
122static inline bool __must_unpark( thread$ * thrd ) __attribute((nonnull(1)));
123static void __run_thread(processor * this, thread$ * dst);
124static void __wake_one(cluster * cltr);
125
126static void mark_idle (__cluster_proc_list & idles, processor & proc);
127static void mark_awake(__cluster_proc_list & idles, processor & proc);
128static [unsigned idle, unsigned total, * processor] query_idles( & __cluster_proc_list idles );
129
130extern void __cfa_io_start( processor * );
131extern bool __cfa_io_drain( processor * );
132extern void __cfa_io_flush( processor * );
133extern void __cfa_io_stop ( processor * );
134static inline bool __maybe_io_drain( processor * );
135
136extern void __disable_interrupts_hard();
137extern void __enable_interrupts_hard();
138
139static inline void __disable_interrupts_checked() {
140 /* paranoid */ verify( __preemption_enabled() );
141 disable_interrupts();
142 /* paranoid */ verify( ! __preemption_enabled() );
143}
144
145static inline void __enable_interrupts_checked( bool poll = true ) {
146 /* paranoid */ verify( ! __preemption_enabled() );
147 enable_interrupts( poll );
148 /* paranoid */ verify( __preemption_enabled() );
149}
150
151//=============================================================================================
152// Kernel Scheduling logic
153//=============================================================================================
154//Main of the processor contexts
155void main(processorCtx_t & runner) {
156 // Because of a bug, we couldn't initialized the seed on construction
157 // Do it here
158 __cfaabi_tls.rand_seed ^= rdtscl();
159 __cfaabi_tls.ready_rng.fwd_seed = 25214903917_l64u * (rdtscl() ^ (uintptr_t)&runner);
160 __tls_rand_advance_bck();
161
162 processor * this = runner.proc;
163 verify(this);
164
165 __cfa_io_start( this );
166
167 __cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
168 #if !defined(__CFA_NO_STATISTICS__)
169 if( this->print_halts ) {
170 __cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->unique_id, this->name, (void*)this);
171 }
172 #endif
173
174 {
175 // Setup preemption data
176 preemption_scope scope = { this };
177
178 // if we need to run some special setup, now is the time to do it.
179 if(this->init.thrd) {
180 this->init.thrd->curr_cluster = this->cltr;
181 __run_thread(this, this->init.thrd);
182 }
183
184 __cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
185
186 thread$ * readyThread = 0p;
187 MAIN_LOOP:
188 for() {
189 #define OLD_MAIN 1
190 #if OLD_MAIN
191 // Check if there is pending io
192 __maybe_io_drain( this );
193
194 // Try to get the next thread
195 readyThread = __next_thread( this->cltr );
196
197 if( !readyThread ) {
198 __cfa_io_flush( this );
199 readyThread = __next_thread_slow( this->cltr );
200 }
201
202 HALT:
203 if( !readyThread ) {
204 // Don't block if we are done
205 if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
206
207 #if !defined(__CFA_NO_STATISTICS__)
208 __tls_stats()->ready.sleep.halts++;
209 #endif
210
211 // Push self to idle stack
212 mark_idle(this->cltr->procs, * this);
213
214 // Confirm the ready-queue is empty
215 readyThread = __next_thread_slow( this->cltr );
216 if( readyThread ) {
217 // A thread was found, cancel the halt
218 mark_awake(this->cltr->procs, * this);
219
220 #if !defined(__CFA_NO_STATISTICS__)
221 __tls_stats()->ready.sleep.cancels++;
222 #endif
223
224 // continue the mai loop
225 break HALT;
226 }
227
228 #if !defined(__CFA_NO_STATISTICS__)
229 if(this->print_halts) {
230 __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->unique_id, rdtscl());
231 }
232 #endif
233
234 __cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle);
235
236 {
237 eventfd_t val;
238 ssize_t ret = read( this->idle, &val, sizeof(val) );
239 if(ret < 0) {
240 switch((int)errno) {
241 case EAGAIN:
242 #if EAGAIN != EWOULDBLOCK
243 case EWOULDBLOCK:
244 #endif
245 case EINTR:
246 // No need to do anything special here, just assume it's a legitimate wake-up
247 break;
248 default:
249 abort( "KERNEL : internal error, read failure on idle eventfd, error(%d) %s.", (int)errno, strerror( (int)errno ) );
250 }
251 }
252 }
253
254 #if !defined(__CFA_NO_STATISTICS__)
255 if(this->print_halts) {
256 __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->unique_id, rdtscl());
257 }
258 #endif
259
260 // We were woken up, remove self from idle
261 mark_awake(this->cltr->procs, * this);
262
263 // DON'T just proceed, start looking again
264 continue MAIN_LOOP;
265 }
266
267 /* paranoid */ verify( readyThread );
268
269 // Reset io dirty bit
270 this->io.dirty = false;
271
272 // We found a thread run it
273 __run_thread(this, readyThread);
274
275 // Are we done?
276 if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
277
278 if(this->io.pending && !this->io.dirty) {
279 __cfa_io_flush( this );
280 }
281
282 #else
283 #warning new kernel loop
284 SEARCH: {
285 /* paranoid */ verify( ! __preemption_enabled() );
286
287 // First, lock the scheduler since we are searching for a thread
288 ready_schedule_lock();
289
290 // Try to get the next thread
291 readyThread = pop_fast( this->cltr );
292 if(readyThread) { ready_schedule_unlock(); break SEARCH; }
293
294 // If we can't find a thread, might as well flush any outstanding I/O
295 if(this->io.pending) { __cfa_io_flush( this ); }
296
297 // Spin a little on I/O, just in case
298 for(5) {
299 __maybe_io_drain( this );
300 readyThread = pop_fast( this->cltr );
301 if(readyThread) { ready_schedule_unlock(); break SEARCH; }
302 }
303
304 // no luck, try stealing a few times
305 for(5) {
306 if( __maybe_io_drain( this ) ) {
307 readyThread = pop_fast( this->cltr );
308 } else {
309 readyThread = pop_slow( this->cltr );
310 }
311 if(readyThread) { ready_schedule_unlock(); break SEARCH; }
312 }
313
314 // still no luck, search for a thread
315 readyThread = pop_search( this->cltr );
316 if(readyThread) { ready_schedule_unlock(); break SEARCH; }
317
318 // Don't block if we are done
319 if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
320
321 __STATS( __tls_stats()->ready.sleep.halts++; )
322
323 // Push self to idle stack
324 ready_schedule_unlock();
325 mark_idle(this->cltr->procs, * this);
326 ready_schedule_lock();
327
328 // Confirm the ready-queue is empty
329 __maybe_io_drain( this );
330 readyThread = pop_search( this->cltr );
331 ready_schedule_unlock();
332
333 if( readyThread ) {
334 // A thread was found, cancel the halt
335 mark_awake(this->cltr->procs, * this);
336
337 __STATS( __tls_stats()->ready.sleep.cancels++; )
338
339 // continue the main loop
340 break SEARCH;
341 }
342
343 __STATS( if(this->print_halts) __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->unique_id, rdtscl()); )
344 __cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle);
345
346 {
347 eventfd_t val;
348 ssize_t ret = read( this->idle, &val, sizeof(val) );
349 if(ret < 0) {
350 switch((int)errno) {
351 case EAGAIN:
352 #if EAGAIN != EWOULDBLOCK
353 case EWOULDBLOCK:
354 #endif
355 case EINTR:
356 // No need to do anything special here, just assume it's a legitimate wake-up
357 break;
358 default:
359 abort( "KERNEL : internal error, read failure on idle eventfd, error(%d) %s.", (int)errno, strerror( (int)errno ) );
360 }
361 }
362 }
363
364 __STATS( if(this->print_halts) __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->unique_id, rdtscl()); )
365
366 // We were woken up, remove self from idle
367 mark_awake(this->cltr->procs, * this);
368
369 // DON'T just proceed, start looking again
370 continue MAIN_LOOP;
371 }
372
373 RUN_THREAD:
374 /* paranoid */ verify( ! __preemption_enabled() );
375 /* paranoid */ verify( readyThread );
376
377 // Reset io dirty bit
378 this->io.dirty = false;
379
380 // We found a thread run it
381 __run_thread(this, readyThread);
382
383 // Are we done?
384 if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
385
386 if(this->io.pending && !this->io.dirty) {
387 __cfa_io_flush( this );
388 }
389
390 ready_schedule_lock();
391 __maybe_io_drain( this );
392 ready_schedule_unlock();
393 #endif
394 }
395
396 __cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
397 }
398
399 __cfa_io_stop( this );
400
401 post( this->terminated );
402
403 if(this == mainProcessor) {
404 // HACK : the coroutine context switch expects this_thread to be set
405 // and it make sense for it to be set in all other cases except here
406 // fake it
407 __cfaabi_tls.this_thread = mainThread;
408 }
409
410 __cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
411}
412
413static int * __volatile_errno() __attribute__((noinline));
414static int * __volatile_errno() { asm(""); return &errno; }
415
416// KERNEL ONLY
417// runThread runs a thread by context switching
418// from the processor coroutine to the target thread
419static void __run_thread(processor * this, thread$ * thrd_dst) {
420 /* paranoid */ verify( ! __preemption_enabled() );
421 /* paranoid */ verifyf( thrd_dst->state == Ready || thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
422 /* paranoid */ verifyf( thrd_dst->link.next == 0p, "Expected null got %p", thrd_dst->link.next );
423 __builtin_prefetch( thrd_dst->context.SP );
424
425 __cfadbg_print_safe(runtime_core, "Kernel : core %p running thread %p (%s)\n", this, thrd_dst, thrd_dst->self_cor.name);
426
427 coroutine$ * proc_cor = get_coroutine(this->runner);
428
429 // set state of processor coroutine to inactive
430 verify(proc_cor->state == Active);
431 proc_cor->state = Blocked;
432
433 // Actually run the thread
434 RUNNING: while(true) {
435 thrd_dst->preempted = __NO_PREEMPTION;
436 thrd_dst->state = Active;
437
438 // Update global state
439 kernelTLS().this_thread = thrd_dst;
440
441 /* paranoid */ verify( ! __preemption_enabled() );
442 /* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
443 /* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
444 /* paranoid */ verify( thrd_dst->context.SP );
445 /* paranoid */ verify( thrd_dst->state != Halted );
446 /* 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
447 /* 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
448 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
449
450
451
452 // set context switch to the thread that the processor is executing
453 __cfactx_switch( &proc_cor->context, &thrd_dst->context );
454 // when __cfactx_switch returns we are back in the processor coroutine
455
456
457
458 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
459 /* 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 );
460 /* 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 );
461 /* paranoid */ verify( thrd_dst->context.SP );
462 /* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
463 /* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
464 /* paranoid */ verify( ! __preemption_enabled() );
465
466 // Reset global state
467 kernelTLS().this_thread = 0p;
468
469 // We just finished running a thread, there are a few things that could have happened.
470 // 1 - Regular case : the thread has blocked and now one has scheduled it yet.
471 // 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
472 // 4 - Preempted
473 // In case 1, we may have won a race so we can't write to the state again.
474 // In case 2, we lost the race so we now own the thread.
475
476 if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
477 // The thread was preempted, reschedule it and reset the flag
478 schedule_thread$( thrd_dst );
479 break RUNNING;
480 }
481
482 if(unlikely(thrd_dst->state == Halting)) {
483 // The thread has halted, it should never be scheduled/run again
484 // finish the thread
485 __thread_finish( thrd_dst );
486 break RUNNING;
487 }
488
489 /* paranoid */ verify( thrd_dst->state == Active );
490 thrd_dst->state = Blocked;
491
492 // set state of processor coroutine to active and the thread to inactive
493 int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
494 switch(old_ticket) {
495 case TICKET_RUNNING:
496 // This is case 1, the regular case, nothing more is needed
497 break RUNNING;
498 case TICKET_UNBLOCK:
499 #if !defined(__CFA_NO_STATISTICS__)
500 __tls_stats()->ready.threads.threads++;
501 #endif
502 // This is case 2, the racy case, someone tried to run this thread before it finished blocking
503 // In this case, just run it again.
504 continue RUNNING;
505 default:
506 // This makes no sense, something is wrong abort
507 abort();
508 }
509 }
510
511 // Just before returning to the processor, set the processor coroutine to active
512 proc_cor->state = Active;
513
514 __cfadbg_print_safe(runtime_core, "Kernel : core %p finished running thread %p\n", this, thrd_dst);
515
516 #if !defined(__CFA_NO_STATISTICS__)
517 __tls_stats()->ready.threads.threads--;
518 #endif
519
520 /* paranoid */ verify( ! __preemption_enabled() );
521}
522
523// KERNEL_ONLY
524void returnToKernel() {
525 /* paranoid */ verify( ! __preemption_enabled() );
526 coroutine$ * proc_cor = get_coroutine(kernelTLS().this_processor->runner);
527 thread$ * thrd_src = kernelTLS().this_thread;
528
529 __STATS( thrd_src->last_proc = kernelTLS().this_processor; )
530
531 // Run the thread on this processor
532 {
533 int local_errno = *__volatile_errno();
534 #if defined( __i386 ) || defined( __x86_64 )
535 __x87_store;
536 #endif
537 /* paranoid */ verify( proc_cor->context.SP );
538 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
539 __cfactx_switch( &thrd_src->context, &proc_cor->context );
540 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
541 #if defined( __i386 ) || defined( __x86_64 )
542 __x87_load;
543 #endif
544 *__volatile_errno() = local_errno;
545 }
546
547 #if !defined(__CFA_NO_STATISTICS__)
548 /* paranoid */ verify( thrd_src->last_proc != 0p );
549 if(thrd_src->last_proc != kernelTLS().this_processor) {
550 __tls_stats()->ready.threads.migration++;
551 }
552 #endif
553
554 /* paranoid */ verify( ! __preemption_enabled() );
555 /* 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 );
556 /* 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 );
557}
558
559//-----------------------------------------------------------------------------
560// Scheduler routines
561// KERNEL ONLY
562static void __schedule_thread( thread$ * thrd ) {
563 /* paranoid */ verify( ! __preemption_enabled() );
564 /* paranoid */ verify( ready_schedule_islocked());
565 /* paranoid */ verify( thrd );
566 /* paranoid */ verify( thrd->state != Halted );
567 /* paranoid */ verify( thrd->curr_cluster );
568 /* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
569 /* paranoid */ if( thrd->state == Blocked || thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
570 "Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
571 /* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
572 "Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
573 /* paranoid */ #endif
574 /* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
575 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
576
577 const bool local = thrd->state != Start;
578 if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
579
580 // Dereference the thread now because once we push it, there is not guaranteed it's still valid.
581 struct cluster * cl = thrd->curr_cluster;
582 __STATS(bool outside = thrd->last_proc && thrd->last_proc != kernelTLS().this_processor; )
583
584 // push the thread to the cluster ready-queue
585 push( cl, thrd, local );
586
587 // variable thrd is no longer safe to use
588 thrd = 0xdeaddeaddeaddeadp;
589
590 // wake the cluster using the save variable.
591 __wake_one( cl );
592
593 #if !defined(__CFA_NO_STATISTICS__)
594 if( kernelTLS().this_stats ) {
595 __tls_stats()->ready.threads.threads++;
596 if(outside) {
597 __tls_stats()->ready.threads.extunpark++;
598 }
599 }
600 else {
601 __atomic_fetch_add(&cl->stats->ready.threads.threads, 1, __ATOMIC_RELAXED);
602 __atomic_fetch_add(&cl->stats->ready.threads.extunpark, 1, __ATOMIC_RELAXED);
603 }
604 #endif
605
606 /* paranoid */ verify( ready_schedule_islocked());
607 /* paranoid */ verify( ! __preemption_enabled() );
608}
609
610void schedule_thread$( thread$ * thrd ) {
611 ready_schedule_lock();
612 __schedule_thread( thrd );
613 ready_schedule_unlock();
614}
615
616// KERNEL ONLY
617static inline thread$ * __next_thread(cluster * this) with( *this ) {
618 /* paranoid */ verify( ! __preemption_enabled() );
619
620 ready_schedule_lock();
621 thread$ * thrd = pop_fast( this );
622 ready_schedule_unlock();
623
624 /* paranoid */ verify( ! __preemption_enabled() );
625 return thrd;
626}
627
628// KERNEL ONLY
629static inline thread$ * __next_thread_slow(cluster * this) with( *this ) {
630 /* paranoid */ verify( ! __preemption_enabled() );
631
632 ready_schedule_lock();
633 thread$ * thrd;
634 for(25) {
635 thrd = pop_slow( this );
636 if(thrd) goto RET;
637 }
638 thrd = pop_search( this );
639
640 RET:
641 ready_schedule_unlock();
642
643 /* paranoid */ verify( ! __preemption_enabled() );
644 return thrd;
645}
646
647static inline bool __must_unpark( thread$ * thrd ) {
648 int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
649 switch(old_ticket) {
650 case TICKET_RUNNING:
651 // Wake won the race, the thread will reschedule/rerun itself
652 return false;
653 case TICKET_BLOCKED:
654 /* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
655 /* paranoid */ verify( thrd->state == Blocked );
656 return true;
657 default:
658 // This makes no sense, something is wrong abort
659 abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
660 }
661}
662
663void __kernel_unpark( thread$ * thrd ) {
664 /* paranoid */ verify( ! __preemption_enabled() );
665 /* paranoid */ verify( ready_schedule_islocked());
666
667 if( !thrd ) return;
668
669 if(__must_unpark(thrd)) {
670 // Wake lost the race,
671 __schedule_thread( thrd );
672 }
673
674 /* paranoid */ verify( ready_schedule_islocked());
675 /* paranoid */ verify( ! __preemption_enabled() );
676}
677
678void unpark( thread$ * thrd ) {
679 if( !thrd ) return;
680
681 if(__must_unpark(thrd)) {
682 disable_interrupts();
683 // Wake lost the race,
684 schedule_thread$( thrd );
685 enable_interrupts(false);
686 }
687}
688
689void park( void ) {
690 __disable_interrupts_checked();
691 /* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
692 returnToKernel();
693 __enable_interrupts_checked();
694
695}
696
697extern "C" {
698 // Leave the thread monitor
699 // last routine called by a thread.
700 // Should never return
701 void __cfactx_thrd_leave() {
702 thread$ * thrd = active_thread();
703 monitor$ * this = &thrd->self_mon;
704
705 // Lock the monitor now
706 lock( this->lock __cfaabi_dbg_ctx2 );
707
708 disable_interrupts();
709
710 /* paranoid */ verify( ! __preemption_enabled() );
711 /* paranoid */ verify( thrd->state == Active );
712 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
713 /* paranoid */ verify( kernelTLS().this_thread == thrd );
714 /* paranoid */ verify( thrd->context.SP );
715 /* 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 );
716 /* 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 );
717
718 thrd->state = Halting;
719 if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
720 if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
721 if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
722
723 // Leave the thread
724 returnToKernel();
725
726 // Control flow should never reach here!
727 abort();
728 }
729}
730
731// KERNEL ONLY
732bool force_yield( __Preemption_Reason reason ) {
733 __disable_interrupts_checked();
734 thread$ * thrd = kernelTLS().this_thread;
735 /* paranoid */ verify(thrd->state == Active);
736
737 // SKULLDUGGERY: It is possible that we are preempting this thread just before
738 // it was going to park itself. If that is the case and it is already using the
739 // intrusive fields then we can't use them to preempt the thread
740 // If that is the case, abandon the preemption.
741 bool preempted = false;
742 if(thrd->link.next == 0p) {
743 preempted = true;
744 thrd->preempted = reason;
745 returnToKernel();
746 }
747 __enable_interrupts_checked( false );
748 return preempted;
749}
750
751//=============================================================================================
752// Kernel Idle Sleep
753//=============================================================================================
754// Wake a thread from the front if there are any
755static void __wake_one(cluster * this) {
756 /* paranoid */ verify( ! __preemption_enabled() );
757 /* paranoid */ verify( ready_schedule_islocked() );
758
759 // Check if there is a sleeping processor
760 processor * p;
761 unsigned idle;
762 unsigned total;
763 [idle, total, p] = query_idles(this->procs);
764
765 // If no one is sleeping, we are done
766 if( idle == 0 ) return;
767
768 // We found a processor, wake it up
769 eventfd_t val;
770 val = 1;
771 eventfd_write( p->idle, val );
772
773 #if !defined(__CFA_NO_STATISTICS__)
774 if( kernelTLS().this_stats ) {
775 __tls_stats()->ready.sleep.wakes++;
776 }
777 else {
778 __atomic_fetch_add(&this->stats->ready.sleep.wakes, 1, __ATOMIC_RELAXED);
779 }
780 #endif
781
782 /* paranoid */ verify( ready_schedule_islocked() );
783 /* paranoid */ verify( ! __preemption_enabled() );
784
785 return;
786}
787
788// Unconditionnaly wake a thread
789void __wake_proc(processor * this) {
790 __cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
791
792 __disable_interrupts_checked();
793 /* paranoid */ verify( ! __preemption_enabled() );
794 eventfd_t val;
795 val = 1;
796 eventfd_write( this->idle, val );
797 __enable_interrupts_checked();
798}
799
800static void mark_idle(__cluster_proc_list & this, processor & proc) {
801 /* paranoid */ verify( ! __preemption_enabled() );
802 lock( this );
803 this.idle++;
804 /* paranoid */ verify( this.idle <= this.total );
805 remove(proc);
806 insert_first(this.idles, proc);
807 unlock( this );
808 /* paranoid */ verify( ! __preemption_enabled() );
809}
810
811static void mark_awake(__cluster_proc_list & this, processor & proc) {
812 /* paranoid */ verify( ! __preemption_enabled() );
813 lock( this );
814 this.idle--;
815 /* paranoid */ verify( this.idle >= 0 );
816 remove(proc);
817 insert_last(this.actives, proc);
818 unlock( this );
819 /* paranoid */ verify( ! __preemption_enabled() );
820}
821
822static [unsigned idle, unsigned total, * processor] query_idles( & __cluster_proc_list this ) {
823 /* paranoid */ verify( ! __preemption_enabled() );
824 /* paranoid */ verify( ready_schedule_islocked() );
825
826 for() {
827 uint64_t l = __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST);
828 if( 1 == (l % 2) ) { Pause(); continue; }
829 unsigned idle = this.idle;
830 unsigned total = this.total;
831 processor * proc = &this.idles`first;
832 // Compiler fence is unnecessary, but gcc-8 and older incorrectly reorder code without it
833 asm volatile("": : :"memory");
834 if(l != __atomic_load_n(&this.lock, __ATOMIC_SEQ_CST)) { Pause(); continue; }
835 return [idle, total, proc];
836 }
837
838 /* paranoid */ verify( ready_schedule_islocked() );
839 /* paranoid */ verify( ! __preemption_enabled() );
840}
841
842//=============================================================================================
843// Unexpected Terminating logic
844//=============================================================================================
845void __kernel_abort_msg( char * abort_text, int abort_text_size ) {
846 thread$ * thrd = __cfaabi_tls.this_thread;
847
848 if(thrd) {
849 int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
850 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
851
852 if ( &thrd->self_cor != thrd->curr_cor ) {
853 len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
854 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
855 }
856 else {
857 __cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
858 }
859 }
860 else {
861 int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
862 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
863 }
864}
865
866int __kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
867 return get_coroutine(__cfaabi_tls.this_thread) == get_coroutine(mainThread) ? 4 : 2;
868}
869
870static __spinlock_t kernel_debug_lock;
871
872extern "C" {
873 void __cfaabi_bits_acquire() {
874 lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
875 }
876
877 void __cfaabi_bits_release() {
878 unlock( kernel_debug_lock );
879 }
880}
881
882//=============================================================================================
883// Kernel Utilities
884//=============================================================================================
885#if defined(CFA_HAVE_LINUX_IO_URING_H)
886#include "io/types.hfa"
887#endif
888
889static inline bool __maybe_io_drain( processor * proc ) {
890 bool ret = false;
891 #if defined(CFA_HAVE_LINUX_IO_URING_H)
892 __cfadbg_print_safe(runtime_core, "Kernel : core %p checking io for ring %d\n", proc, proc->io.ctx->fd);
893
894 // Check if we should drain the queue
895 $io_context * ctx = proc->io.ctx;
896 unsigned head = *ctx->cq.head;
897 unsigned tail = *ctx->cq.tail;
898 if(head == tail) return false;
899 #if OLD_MAIN
900 ready_schedule_lock();
901 ret = __cfa_io_drain( proc );
902 ready_schedule_unlock();
903 #else
904 ret = __cfa_io_drain( proc );
905 #endif
906 #endif
907 return ret;
908}
909
910//-----------------------------------------------------------------------------
911// Debug
912__cfaabi_dbg_debug_do(
913 extern "C" {
914 void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
915 this.prev_name = prev_name;
916 this.prev_thrd = kernelTLS().this_thread;
917 }
918 }
919)
920
921//-----------------------------------------------------------------------------
922// Debug
923bool threading_enabled(void) __attribute__((const)) {
924 return true;
925}
926
927//-----------------------------------------------------------------------------
928// Statistics
929#if !defined(__CFA_NO_STATISTICS__)
930 void print_halts( processor & this ) {
931 this.print_halts = true;
932 }
933
934 static void crawl_list( cluster * cltr, dlist(processor) & list, unsigned count ) {
935 /* paranoid */ verify( cltr->stats );
936
937 processor * it = &list`first;
938 for(unsigned i = 0; i < count; i++) {
939 /* paranoid */ verifyf( it, "Unexpected null iterator, at index %u of %u\n", i, count);
940 /* paranoid */ verify( it->local_data->this_stats );
941 __tally_stats( cltr->stats, it->local_data->this_stats );
942 it = &(*it)`next;
943 }
944 }
945
946 void crawl_cluster_stats( cluster & this ) {
947 // Stop the world, otherwise stats could get really messed-up
948 // this doesn't solve all problems but does solve many
949 // so it's probably good enough
950 uint_fast32_t last_size = ready_mutate_lock();
951
952 crawl_list(&this, this.procs.actives, this.procs.total - this.procs.idle);
953 crawl_list(&this, this.procs.idles , this.procs.idle );
954
955 // Unlock the RWlock
956 ready_mutate_unlock( last_size );
957 }
958
959
960 void print_stats_now( cluster & this, int flags ) {
961 crawl_cluster_stats( this );
962 __print_stats( this.stats, this.print_stats, "Cluster", this.name, (void*)&this );
963 }
964#endif
965// Local Variables: //
966// mode: c //
967// tab-width: 4 //
968// End: //
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