source: libcfa/src/concurrency/kernel.cfa@ 1553a55

ADT ast-experimental
Last change on this file since 1553a55 was a757ba1, checked in by Thierry Delisle <tdelisle@…>, 3 years ago

Removed wait-with-io_uring feature which was slow, broken and ifdefed out.
  • Property mode set to 100644
File size: 28.6 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
31extern "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
122extern thread$ * mainThread;
123extern processor * mainProcessor;
124
125//-----------------------------------------------------------------------------
126// Kernel Scheduling logic
127static thread$ * __next_thread(cluster * this);
128static thread$ * __next_thread_slow(cluster * this);
129static thread$ * __next_thread_search(cluster * this);
130static inline bool __must_unpark( thread$ * thrd ) __attribute((nonnull(1)));
131static void __run_thread(processor * this, thread$ * dst);
132static void __wake_one(cluster * cltr);
133
134static void idle_sleep(processor * proc);
135static bool mark_idle (__cluster_proc_list & idles, processor & proc);
136static void mark_awake(__cluster_proc_list & idles, processor & proc);
137
138extern bool __cfa_io_drain( processor * proc ) __attribute__((nonnull (1)));
139extern bool __cfa_io_flush( processor * ) __attribute__((nonnull (1)));
140
141
142extern void __disable_interrupts_hard();
143extern void __enable_interrupts_hard();
144
145
146//=============================================================================================
147// Kernel Scheduling logic
148//=============================================================================================
149//Main of the processor contexts
150void main(processorCtx_t & runner) {
151 // Because of a bug, we couldn't initialized the seed on construction
152 // Do it here
153 __cfaabi_tls.rand_seed ^= rdtscl();
154 __cfaabi_tls.ready_rng.fwd_seed = 25214903917_l64u * (rdtscl() ^ (uintptr_t)&runner);
155 __tls_rand_advance_bck();
156
157 processor * this = runner.proc;
158 verify(this);
159
160 __cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
161 #if !defined(__CFA_NO_STATISTICS__)
162 if( this->print_halts ) {
163 __cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->unique_id, this->name, (void*)this);
164 }
165 #endif
166
167 {
168 // Setup preemption data
169 preemption_scope scope = { this };
170
171 // if we need to run some special setup, now is the time to do it.
172 if(this->init.thrd) {
173 this->init.thrd->curr_cluster = this->cltr;
174 __run_thread(this, this->init.thrd);
175 }
176
177 __cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
178
179 thread$ * readyThread = 0p;
180 MAIN_LOOP:
181 for() {
182 // Check if there is pending io
183 __cfa_io_drain( this );
184
185 // Try to get the next thread
186 readyThread = __next_thread( this->cltr );
187
188 if( !readyThread ) {
189 // there is no point in holding submissions if we are idle
190 __IO_STATS__(true, io.flush.idle++; )
191 __cfa_io_flush( this );
192
193 // drain again in case something showed up
194 __cfa_io_drain( this );
195
196 readyThread = __next_thread( this->cltr );
197 }
198
199 if( !readyThread ) for(5) {
200 readyThread = __next_thread_slow( this->cltr );
201
202 if( readyThread ) break;
203
204 // It's unlikely we still I/O to submit, but the arbiter could
205 __IO_STATS__(true, io.flush.idle++; )
206 __cfa_io_flush( this );
207
208 // drain again in case something showed up
209 __cfa_io_drain( this );
210 }
211
212 HALT:
213 if( !readyThread ) {
214 // Don't block if we are done
215 if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
216
217 // Push self to idle stack
218 if(!mark_idle(this->cltr->procs, * this)) continue MAIN_LOOP;
219
220 // Confirm the ready-queue is empty
221 readyThread = __next_thread_search( this->cltr );
222 if( readyThread ) {
223 // A thread was found, cancel the halt
224 mark_awake(this->cltr->procs, * this);
225
226 __STATS__(true, ready.sleep.cancels++; )
227
228 // continue the mai loop
229 break HALT;
230 }
231
232 idle_sleep( this );
233
234 // We were woken up, remove self from idle
235 mark_awake(this->cltr->procs, * this);
236
237 // DON'T just proceed, start looking again
238 continue MAIN_LOOP;
239 }
240
241 /* paranoid */ verify( readyThread );
242
243 // Reset io dirty bit
244 this->io.dirty = false;
245
246 // We found a thread run it
247 __run_thread(this, readyThread);
248
249 // Are we done?
250 if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
251
252 if(__atomic_load_n(&this->io.pending, __ATOMIC_RELAXED) && !__atomic_load_n(&this->io.dirty, __ATOMIC_RELAXED)) {
253 __IO_STATS__(true, io.flush.dirty++; )
254 __cfa_io_flush( this );
255 }
256 }
257
258 __cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
259 }
260
261 post( this->terminated );
262
263 if(this == mainProcessor) {
264 // HACK : the coroutine context switch expects this_thread to be set
265 // and it make sense for it to be set in all other cases except here
266 // fake it
267 __cfaabi_tls.this_thread = mainThread;
268 }
269
270 __cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
271}
272
273static int * __volatile_errno() __attribute__((noinline));
274static int * __volatile_errno() { asm(""); return &errno; }
275
276// KERNEL ONLY
277// runThread runs a thread by context switching
278// from the processor coroutine to the target thread
279static void __run_thread(processor * this, thread$ * thrd_dst) {
280 /* paranoid */ verify( ! __preemption_enabled() );
281 /* paranoid */ verifyf( thrd_dst->state == Ready || thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
282 /* paranoid */ verifyf( thrd_dst->rdy_link.next == 0p, "Expected null got %p", thrd_dst->rdy_link.next );
283 __builtin_prefetch( thrd_dst->context.SP );
284
285 __cfadbg_print_safe(runtime_core, "Kernel : core %p running thread %p (%s)\n", this, thrd_dst, thrd_dst->self_cor.name);
286
287 coroutine$ * proc_cor = get_coroutine(this->runner);
288
289 // set state of processor coroutine to inactive
290 verify(proc_cor->state == Active);
291 proc_cor->state = Blocked;
292
293 // Actually run the thread
294 RUNNING: while(true) {
295 thrd_dst->preempted = __NO_PREEMPTION;
296
297 // Update global state
298 kernelTLS().this_thread = thrd_dst;
299
300 // Update the state after setting this_thread
301 // so that the debugger can find all active threads
302 // in tls storage
303 thrd_dst->state = Active;
304
305 /* paranoid */ verify( ! __preemption_enabled() );
306 /* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
307 /* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
308 /* paranoid */ verify( thrd_dst->context.SP );
309 /* paranoid */ verify( thrd_dst->state != Halted );
310 /* 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
311 /* 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
312 /* paranoid */ verify( __atomic_exchange_n( &thrd_dst->executing, this, __ATOMIC_SEQ_CST) == 0p );
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 */ verify( __atomic_exchange_n( &thrd_dst->executing, 0p, __ATOMIC_SEQ_CST) == this );
325 /* 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 );
326 /* 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 );
327 /* paranoid */ verify( thrd_dst->state != Halted );
328 /* paranoid */ verify( thrd_dst->context.SP );
329 /* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
330 /* paranoid */ verify( ! __preemption_enabled() );
331
332 // We just finished running a thread, there are a few things that could have happened.
333 // 1 - Regular case : the thread has blocked and now one has scheduled it yet.
334 // 2 - Racy case : the thread has blocked but someone has already tried to schedule it.
335 // 4 - Preempted
336 // In case 1, we may have won a race so we can't write to the state again.
337 // In case 2, we lost the race so we now own the thread.
338
339 if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
340 // Reset the this_thread now that we know
341 // the state isn't active anymore
342 kernelTLS().this_thread = 0p;
343
344 // The thread was preempted, reschedule it and reset the flag
345 schedule_thread$( thrd_dst, UNPARK_LOCAL );
346 break RUNNING;
347 }
348
349 if(unlikely(thrd_dst->state == Halting)) {
350 // Reset the this_thread now that we know
351 // the state isn't active anymore
352 kernelTLS().this_thread = 0p;
353
354 // The thread has halted, it should never be scheduled/run again
355 // finish the thread
356 __thread_finish( thrd_dst );
357 break RUNNING;
358 }
359
360 /* paranoid */ verify( thrd_dst->state == Active );
361 thrd_dst->state = Blocked;
362
363 // Reset the this_thread now that we know
364 // the state isn't active anymore
365 kernelTLS().this_thread = 0p;
366
367 // set state of processor coroutine to active and the thread to inactive
368 int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
369 switch(old_ticket) {
370 case TICKET_RUNNING:
371 // This is case 1, the regular case, nothing more is needed
372 break RUNNING;
373 case TICKET_UNBLOCK:
374 __STATS__(true, ready.threads.threads++; )
375 // This is case 2, the racy case, someone tried to run this thread before it finished blocking
376 // In this case, just run it again.
377 continue RUNNING;
378 default:
379 // This makes no sense, something is wrong abort
380 abort();
381 }
382 }
383
384 // Just before returning to the processor, set the processor coroutine to active
385 proc_cor->state = Active;
386
387 __cfadbg_print_safe(runtime_core, "Kernel : core %p finished running thread %p\n", this, thrd_dst);
388
389 __STATS__(true, ready.threads.threads--; )
390
391 /* paranoid */ verify( ! __preemption_enabled() );
392}
393
394// KERNEL_ONLY
395static void returnToKernel() {
396 /* paranoid */ verify( ! __preemption_enabled() );
397 coroutine$ * proc_cor = get_coroutine(kernelTLS().this_processor->runner);
398 thread$ * thrd_src = kernelTLS().this_thread;
399
400 __STATS_DEF( thrd_src->last_proc = kernelTLS().this_processor; )
401
402 // Run the thread on this processor
403 {
404 int local_errno = *__volatile_errno();
405 #if defined( __i386 ) || defined( __x86_64 )
406 __x87_store;
407 #endif
408 /* paranoid */ verify( proc_cor->context.SP );
409 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
410 __cfactx_switch( &thrd_src->context, &proc_cor->context );
411 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
412 #if defined( __i386 ) || defined( __x86_64 )
413 __x87_load;
414 #endif
415 *__volatile_errno() = local_errno;
416 }
417
418 #if !defined(__CFA_NO_STATISTICS__)
419 /* paranoid */ verify( thrd_src->last_proc != 0p );
420 if(thrd_src->last_proc != kernelTLS().this_processor) {
421 __tls_stats()->ready.threads.migration++;
422 }
423 #endif
424
425 /* paranoid */ verify( ! __preemption_enabled() );
426 /* 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 );
427 /* 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 );
428}
429
430//-----------------------------------------------------------------------------
431// Scheduler routines
432// KERNEL ONLY
433static void __schedule_thread( thread$ * thrd, unpark_hint hint ) {
434 /* paranoid */ verify( ! __preemption_enabled() );
435 /* paranoid */ verify( ready_schedule_islocked());
436 /* paranoid */ verify( thrd );
437 /* paranoid */ verify( thrd->state != Halted );
438 /* paranoid */ verify( thrd->curr_cluster );
439 /* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
440 /* paranoid */ if( thrd->state == Blocked || thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
441 "Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
442 /* paranoid */ if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
443 "Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
444 /* paranoid */ #endif
445 /* paranoid */ verifyf( thrd->rdy_link.next == 0p, "Expected null got %p", thrd->rdy_link.next );
446 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
447
448 if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
449
450 // Dereference the thread now because once we push it, there is not guaranteed it's still valid.
451 struct cluster * cl = thrd->curr_cluster;
452 __STATS_DEF(bool outside = hint == UNPARK_LOCAL && thrd->last_proc && thrd->last_proc != kernelTLS().this_processor; )
453
454 // push the thread to the cluster ready-queue
455 push( cl, thrd, hint );
456
457 // variable thrd is no longer safe to use
458 thrd = 0xdeaddeaddeaddeadp;
459
460 // wake the cluster using the save variable.
461 __wake_one( cl );
462
463 #if !defined(__CFA_NO_STATISTICS__)
464 if( kernelTLS().this_stats ) {
465 __tls_stats()->ready.threads.threads++;
466 if(outside) {
467 __tls_stats()->ready.threads.extunpark++;
468 }
469 }
470 else {
471 __atomic_fetch_add(&cl->stats->ready.threads.threads, 1, __ATOMIC_RELAXED);
472 __atomic_fetch_add(&cl->stats->ready.threads.extunpark, 1, __ATOMIC_RELAXED);
473 }
474 #endif
475
476 /* paranoid */ verify( ready_schedule_islocked());
477 /* paranoid */ verify( ! __preemption_enabled() );
478}
479
480void schedule_thread$( thread$ * thrd, unpark_hint hint ) {
481 ready_schedule_lock();
482 __schedule_thread( thrd, hint );
483 ready_schedule_unlock();
484}
485
486// KERNEL ONLY
487static inline thread$ * __next_thread(cluster * this) with( *this ) {
488 /* paranoid */ verify( ! __preemption_enabled() );
489
490 ready_schedule_lock();
491 thread$ * thrd = pop_fast( this );
492 ready_schedule_unlock();
493
494 /* paranoid */ verify( ! __preemption_enabled() );
495 return thrd;
496}
497
498// KERNEL ONLY
499static inline thread$ * __next_thread_slow(cluster * this) with( *this ) {
500 /* paranoid */ verify( ! __preemption_enabled() );
501
502 ready_schedule_lock();
503 thread$ * thrd = pop_slow( this );
504 ready_schedule_unlock();
505
506 /* paranoid */ verify( ! __preemption_enabled() );
507 return thrd;
508}
509
510// KERNEL ONLY
511static inline thread$ * __next_thread_search(cluster * this) with( *this ) {
512 /* paranoid */ verify( ! __preemption_enabled() );
513
514 ready_schedule_lock();
515 thread$ * thrd = pop_search( this );
516 ready_schedule_unlock();
517
518 /* paranoid */ verify( ! __preemption_enabled() );
519 return thrd;
520}
521
522static inline bool __must_unpark( thread$ * thrd ) {
523 int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
524 switch(old_ticket) {
525 case TICKET_RUNNING:
526 // Wake won the race, the thread will reschedule/rerun itself
527 return false;
528 case TICKET_BLOCKED:
529 /* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
530 /* paranoid */ verify( thrd->state == Blocked );
531 return true;
532 default:
533 // This makes no sense, something is wrong abort
534 abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
535 }
536}
537
538void __kernel_unpark( thread$ * thrd, unpark_hint hint ) {
539 /* paranoid */ verify( ! __preemption_enabled() );
540 /* paranoid */ verify( ready_schedule_islocked());
541
542 if( !thrd ) return;
543
544 if(__must_unpark(thrd)) {
545 // Wake lost the race,
546 __schedule_thread( thrd, hint );
547 }
548
549 /* paranoid */ verify( ready_schedule_islocked());
550 /* paranoid */ verify( ! __preemption_enabled() );
551}
552
553void unpark( thread$ * thrd, unpark_hint hint ) libcfa_public {
554 if( !thrd ) return;
555
556 if(__must_unpark(thrd)) {
557 disable_interrupts();
558 // Wake lost the race,
559 schedule_thread$( thrd, hint );
560 enable_interrupts(false);
561 }
562}
563
564void park( void ) libcfa_public {
565 __disable_interrupts_checked();
566 /* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
567 returnToKernel();
568 __enable_interrupts_checked();
569
570}
571
572extern "C" {
573 // Leave the thread monitor
574 // last routine called by a thread.
575 // Should never return
576 void __cfactx_thrd_leave() {
577 thread$ * thrd = active_thread();
578 monitor$ * this = &thrd->self_mon;
579
580 // Lock the monitor now
581 lock( this->lock __cfaabi_dbg_ctx2 );
582
583 disable_interrupts();
584
585 /* paranoid */ verify( ! __preemption_enabled() );
586 /* paranoid */ verify( thrd->state == Active );
587 /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
588 /* paranoid */ verify( kernelTLS().this_thread == thrd );
589 /* paranoid */ verify( thrd->context.SP );
590 /* 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 );
591 /* 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 );
592
593 if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
594 if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
595 if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
596
597 thrd->state = Halting;
598 thrd->ticket = TICKET_DEAD;
599
600 // Leave the thread
601 returnToKernel();
602
603 // Control flow should never reach here!
604 abort();
605 }
606}
607
608// KERNEL ONLY
609bool force_yield( __Preemption_Reason reason ) libcfa_public {
610 __disable_interrupts_checked();
611 thread$ * thrd = kernelTLS().this_thread;
612 /* paranoid */ verify(thrd->state == Active);
613
614 // SKULLDUGGERY: It is possible that we are preempting this thread just before
615 // it was going to park itself. If that is the case and it is already using the
616 // intrusive fields then we can't use them to preempt the thread
617 // If that is the case, abandon the preemption.
618 bool preempted = false;
619 if(thrd->rdy_link.next == 0p) {
620 preempted = true;
621 thrd->preempted = reason;
622 returnToKernel();
623 }
624 __enable_interrupts_checked( false );
625 return preempted;
626}
627
628//=============================================================================================
629// Kernel Idle Sleep
630//=============================================================================================
631// Wake a thread from the front if there are any
632static void __wake_one(cluster * this) {
633 eventfd_t val;
634
635 /* paranoid */ verify( ! __preemption_enabled() );
636 /* paranoid */ verify( ready_schedule_islocked() );
637
638 // Check if there is a sleeping processor
639 struct __fd_waitctx * fdp = __atomic_load_n(&this->procs.fdw, __ATOMIC_SEQ_CST);
640
641 // If no one is sleeping: we are done
642 if( fdp == 0p ) return;
643
644 int fd = 1;
645 if( __atomic_load_n(&fdp->sem, __ATOMIC_SEQ_CST) != 1 ) {
646 fd = __atomic_exchange_n(&fdp->sem, 1, __ATOMIC_RELAXED);
647 }
648
649 switch(fd) {
650 __attribute__((unused)) int ret;
651 case 0:
652 // If the processor isn't ready to sleep then the exchange will already wake it up
653 #if !defined(__CFA_NO_STATISTICS__)
654 if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.early++;
655 } else { __atomic_fetch_add(&this->stats->ready.sleep.early, 1, __ATOMIC_RELAXED); }
656 #endif
657 break;
658 case 1:
659 // If someone else already said they will wake them: we are done
660 #if !defined(__CFA_NO_STATISTICS__)
661 if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.seen++;
662 } else { __atomic_fetch_add(&this->stats->ready.sleep.seen, 1, __ATOMIC_RELAXED); }
663 #endif
664 break;
665 default:
666 // If the processor was ready to sleep, we need to wake it up with an actual write
667 val = 1;
668 ret = eventfd_write( fd, val );
669 /* paranoid */ verifyf( ret == 0, "Expected return to be 0, was %d\n", ret );
670
671 #if !defined(__CFA_NO_STATISTICS__)
672 if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.wakes++;
673 } else { __atomic_fetch_add(&this->stats->ready.sleep.wakes, 1, __ATOMIC_RELAXED); }
674 #endif
675 break;
676 }
677
678 /* paranoid */ verify( ready_schedule_islocked() );
679 /* paranoid */ verify( ! __preemption_enabled() );
680
681 return;
682}
683
684// Unconditionnaly wake a thread
685void __wake_proc(processor * this) {
686 /* paranoid */ verify( ! __preemption_enabled() );
687
688 __cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
689
690 this->idle_wctx.sem = 1;
691
692 this->idle_wctx.wake__time = rdtscl();
693
694 eventfd_t val;
695 val = 1;
696 __attribute__((unused)) int ret = eventfd_write( this->idle_wctx.evfd, val );
697
698 /* paranoid */ verifyf( ret == 0, "Expected return to be 0, was %d\n", ret );
699 /* paranoid */ verify( ! __preemption_enabled() );
700}
701
702static void idle_sleep(processor * this) {
703 /* paranoid */ verify( this->idle_wctx.evfd != 1 );
704 /* paranoid */ verify( this->idle_wctx.evfd != 2 );
705
706 // Tell everyone we are ready to go do sleep
707 for() {
708 int expected = this->idle_wctx.sem;
709
710 // Someone already told us to wake-up! No time for a nap.
711 if(expected == 1) { return; }
712
713 // Try to mark that we are going to sleep
714 if(__atomic_compare_exchange_n(&this->idle_wctx.sem, &expected, this->idle_wctx.evfd, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) ) {
715 // Every one agreed, taking a nap
716 break;
717 }
718 }
719
720
721 #if !defined(__CFA_NO_STATISTICS__)
722 if(this->print_halts) {
723 __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->unique_id, rdtscl());
724 }
725 #endif
726
727 __cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle_fd);
728
729 {
730 eventfd_t val;
731 ssize_t ret = read( this->idle_wctx.evfd, &val, sizeof(val) );
732 if(ret < 0) {
733 switch((int)errno) {
734 case EAGAIN:
735 #if EAGAIN != EWOULDBLOCK
736 case EWOULDBLOCK:
737 #endif
738 case EINTR:
739 // No need to do anything special here, just assume it's a legitimate wake-up
740 break;
741 default:
742 abort( "KERNEL : internal error, read failure on idle eventfd, error(%d) %s.", (int)errno, strerror( (int)errno ) );
743 }
744 }
745 }
746
747 #if !defined(__CFA_NO_STATISTICS__)
748 if(this->print_halts) {
749 __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->unique_id, rdtscl());
750 }
751 #endif
752}
753
754static bool mark_idle(__cluster_proc_list & this, processor & proc) {
755 __STATS__(true, ready.sleep.halts++; )
756
757 proc.idle_wctx.sem = 0;
758
759 /* paranoid */ verify( ! __preemption_enabled() );
760 if(!try_lock( this )) return false;
761 this.idle++;
762 /* paranoid */ verify( this.idle <= this.total );
763 remove(proc);
764 insert_first(this.idles, proc);
765
766 // update the pointer to the head wait context, which should now point to this proc.
767 __atomic_store_n(&this.fdw, &proc.idle_wctx, __ATOMIC_SEQ_CST);
768 unlock( this );
769 /* paranoid */ verify( ! __preemption_enabled() );
770
771 return true;
772}
773
774static void mark_awake(__cluster_proc_list & this, processor & proc) {
775 /* paranoid */ verify( ! __preemption_enabled() );
776 lock( this );
777 this.idle--;
778 /* paranoid */ verify( this.idle >= 0 );
779 remove(proc);
780 insert_last(this.actives, proc);
781
782 {
783 // update the pointer to the head wait context
784 struct __fd_waitctx * wctx = 0;
785 if(!this.idles`isEmpty) wctx = &this.idles`first.idle_wctx;
786 __atomic_store_n(&this.fdw, wctx, __ATOMIC_SEQ_CST);
787 }
788
789 unlock( this );
790 /* paranoid */ verify( ! __preemption_enabled() );
791}
792
793//=============================================================================================
794// Unexpected Terminating logic
795//=============================================================================================
796void __kernel_abort_msg( char * abort_text, int abort_text_size ) {
797 thread$ * thrd = __cfaabi_tls.this_thread;
798
799 if(thrd) {
800 int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
801 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
802
803 if ( &thrd->self_cor != thrd->curr_cor ) {
804 len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
805 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
806 }
807 else {
808 __cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
809 }
810 }
811 else {
812 int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
813 __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
814 }
815}
816
817int __kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
818 return get_coroutine(__cfaabi_tls.this_thread) == get_coroutine(mainThread) ? 4 : 2;
819}
820
821static __spinlock_t kernel_debug_lock;
822
823extern "C" {
824 void __cfaabi_bits_acquire() {
825 lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
826 }
827
828 void __cfaabi_bits_release() {
829 unlock( kernel_debug_lock );
830 }
831}
832
833//=============================================================================================
834// Kernel Utilities
835//=============================================================================================
836#if defined(CFA_HAVE_LINUX_IO_URING_H)
837#include "io/types.hfa"
838#endif
839
840//-----------------------------------------------------------------------------
841// Debug
842bool threading_enabled(void) __attribute__((const)) libcfa_public {
843 return true;
844}
845
846//-----------------------------------------------------------------------------
847// Statistics
848#if !defined(__CFA_NO_STATISTICS__)
849 void print_halts( processor & this ) libcfa_public {
850 this.print_halts = true;
851 }
852
853 static void crawl_list( cluster * cltr, dlist(processor) & list, unsigned count ) {
854 /* paranoid */ verify( cltr->stats );
855
856 processor * it = &list`first;
857 for(unsigned i = 0; i < count; i++) {
858 /* paranoid */ verifyf( it, "Unexpected null iterator, at index %u of %u\n", i, count);
859 /* paranoid */ verify( it->local_data->this_stats );
860 // __print_stats( it->local_data->this_stats, cltr->print_stats, "Processor", it->name, (void*)it );
861 __tally_stats( cltr->stats, it->local_data->this_stats );
862 it = &(*it)`next;
863 }
864 }
865
866 static void crawl_cluster_stats( cluster & this ) {
867 // Stop the world, otherwise stats could get really messed-up
868 // this doesn't solve all problems but does solve many
869 // so it's probably good enough
870 disable_interrupts();
871 uint_fast32_t last_size = ready_mutate_lock();
872
873 crawl_list(&this, this.procs.actives, this.procs.total - this.procs.idle);
874 crawl_list(&this, this.procs.idles , this.procs.idle );
875
876 // Unlock the RWlock
877 ready_mutate_unlock( last_size );
878 enable_interrupts();
879 }
880
881
882 void print_stats_now( cluster & this, int flags ) libcfa_public {
883 crawl_cluster_stats( this );
884 __print_stats( this.stats, flags, "Cluster", this.name, (void*)&this );
885 }
886#endif
887// Local Variables: //
888// mode: c //
889// tab-width: 4 //
890// End: //
Note: See TracBrowser for help on using the repository browser.