source: libcfa/src/concurrency/kernel.cfa@ a892e61

ADT ast-experimental enum pthread-emulation qualifiedEnum
Last change on this file since a892e61 was c9c1c1cb, checked in by Thierry Delisle <tdelisle@…>, 4 years ago

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