source: libcfa/src/concurrency/kernel.cfa @ 708ae38

ADTast-experimentalenumpthread-emulationqualifiedEnum
Last change on this file since 708ae38 was 708ae38, checked in by Thierry Delisle <tdelisle@…>, 3 years ago

Some more cleanup and grow/shrink now readjusts io timestamps.
(They are still unused).

  • Property mode set to 100644
File size: 28.9 KB
Line 
1//
2// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
3//
4// The contents of this file are covered under the licence agreement in the
5// file "LICENCE" distributed with Cforall.
6//
7// kernel.c --
8//
9// Author           : Thierry Delisle
10// Created On       : Tue Jan 17 12:27:26 2017
11// Last Modified By : Peter A. Buhr
12// Last Modified On : Mon Aug 31 07:08:20 2020
13// Update Count     : 71
14//
15
16#define __cforall_thread__
17#define _GNU_SOURCE
18
19// #define __CFA_DEBUG_PRINT_RUNTIME_CORE__
20
21#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, io_future_t & future, iovec & iov);
135static bool mark_idle (__cluster_proc_list & idles, processor & proc);
136static void mark_awake(__cluster_proc_list & idles, processor & proc);
137
138extern void __cfa_io_start( processor * );
139extern bool __cfa_io_drain( processor * );
140extern bool __cfa_io_flush( processor *, int min_comp );
141extern void __cfa_io_stop ( processor * );
142static inline bool __maybe_io_drain( processor * );
143
144#if defined(CFA_WITH_IO_URING_IDLE)
145        extern bool __kernel_read(processor * proc, io_future_t & future, iovec &, int fd);
146#endif
147
148extern void __disable_interrupts_hard();
149extern void __enable_interrupts_hard();
150
151
152//=============================================================================================
153// Kernel Scheduling logic
154//=============================================================================================
155//Main of the processor contexts
156void main(processorCtx_t & runner) {
157        // Because of a bug, we couldn't initialized the seed on construction
158        // Do it here
159        __cfaabi_tls.rand_seed ^= rdtscl();
160        __cfaabi_tls.ready_rng.fwd_seed = 25214903917_l64u * (rdtscl() ^ (uintptr_t)&runner);
161        __tls_rand_advance_bck();
162
163        processor * this = runner.proc;
164        verify(this);
165
166        io_future_t future; // used for idle sleep when io_uring is present
167        future.self.ptr = 1p;  // mark it as already fulfilled so we know if there is a pending request or not
168        eventfd_t idle_val;
169        iovec idle_iovec = { &idle_val, sizeof(idle_val) };
170
171        __cfa_io_start( this );
172
173        __cfadbg_print_safe(runtime_core, "Kernel : core %p starting\n", this);
174        #if !defined(__CFA_NO_STATISTICS__)
175                if( this->print_halts ) {
176                        __cfaabi_bits_print_safe( STDOUT_FILENO, "Processor : %d - %s (%p)\n", this->unique_id, this->name, (void*)this);
177                }
178        #endif
179
180        {
181                // Setup preemption data
182                preemption_scope scope = { this };
183
184                // if we need to run some special setup, now is the time to do it.
185                if(this->init.thrd) {
186                        this->init.thrd->curr_cluster = this->cltr;
187                        __run_thread(this, this->init.thrd);
188                }
189
190                __cfadbg_print_safe(runtime_core, "Kernel : core %p started\n", this);
191
192                thread$ * readyThread = 0p;
193                MAIN_LOOP:
194                for() {
195                        // Check if there is pending io
196                        __maybe_io_drain( this );
197
198                        // Try to get the next thread
199                        readyThread = __next_thread( this->cltr );
200
201                        if( !readyThread ) {
202                                __IO_STATS__(true, io.flush.idle++; )
203                                __cfa_io_flush( this, 0 );
204
205                                readyThread = __next_thread( this->cltr );
206                        }
207
208                        if( !readyThread ) for(5) {
209                                __IO_STATS__(true, io.flush.idle++; )
210
211                                readyThread = __next_thread_slow( this->cltr );
212
213                                if( readyThread ) break;
214
215                                __cfa_io_flush( this, 0 );
216                        }
217
218                        HALT:
219                        if( !readyThread ) {
220                                // Don't block if we are done
221                                if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
222
223                                // Push self to idle stack
224                                if(!mark_idle(this->cltr->procs, * this)) continue MAIN_LOOP;
225
226                                // Confirm the ready-queue is empty
227                                readyThread = __next_thread_search( this->cltr );
228                                if( readyThread ) {
229                                        // A thread was found, cancel the halt
230                                        mark_awake(this->cltr->procs, * this);
231
232                                        __STATS__(true, ready.sleep.cancels++; )
233
234                                        // continue the mai loop
235                                        break HALT;
236                                }
237
238                                idle_sleep( this, future, idle_iovec );
239
240                                // We were woken up, remove self from idle
241                                mark_awake(this->cltr->procs, * this);
242
243                                // DON'T just proceed, start looking again
244                                continue MAIN_LOOP;
245                        }
246
247                        /* paranoid */ verify( readyThread );
248
249                        // Reset io dirty bit
250                        this->io.dirty = false;
251
252                        // We found a thread run it
253                        __run_thread(this, readyThread);
254
255                        // Are we done?
256                        if( __atomic_load_n(&this->do_terminate, __ATOMIC_SEQ_CST) ) break MAIN_LOOP;
257
258                        if(__atomic_load_n(&this->io.pending, __ATOMIC_RELAXED) && !__atomic_load_n(&this->io.dirty, __ATOMIC_RELAXED)) {
259                                __IO_STATS__(true, io.flush.dirty++; )
260                                __cfa_io_flush( this, 0 );
261                        }
262                }
263
264                __cfadbg_print_safe(runtime_core, "Kernel : core %p stopping\n", this);
265        }
266
267        for(int i = 0; !available(future); i++) {
268                if(i > 1000) __cfaabi_dbg_write( "ERROR: kernel has bin spinning on a flush after exit loop.\n", 60);
269                __cfa_io_flush( this, 1 );
270        }
271
272        __cfa_io_stop( this );
273
274        post( this->terminated );
275
276        if(this == mainProcessor) {
277                // HACK : the coroutine context switch expects this_thread to be set
278                // and it make sense for it to be set in all other cases except here
279                // fake it
280                __cfaabi_tls.this_thread = mainThread;
281        }
282
283        __cfadbg_print_safe(runtime_core, "Kernel : core %p terminated\n", this);
284}
285
286static int * __volatile_errno() __attribute__((noinline));
287static int * __volatile_errno() { asm(""); return &errno; }
288
289// KERNEL ONLY
290// runThread runs a thread by context switching
291// from the processor coroutine to the target thread
292static void __run_thread(processor * this, thread$ * thrd_dst) {
293        /* paranoid */ verify( ! __preemption_enabled() );
294        /* paranoid */ verifyf( thrd_dst->state == Ready || thrd_dst->preempted != __NO_PREEMPTION, "state : %d, preempted %d\n", thrd_dst->state, thrd_dst->preempted);
295        /* paranoid */ verifyf( thrd_dst->link.next == 0p, "Expected null got %p", thrd_dst->link.next );
296        __builtin_prefetch( thrd_dst->context.SP );
297
298        __cfadbg_print_safe(runtime_core, "Kernel : core %p running thread %p (%s)\n", this, thrd_dst, thrd_dst->self_cor.name);
299
300        coroutine$ * proc_cor = get_coroutine(this->runner);
301
302        // set state of processor coroutine to inactive
303        verify(proc_cor->state == Active);
304        proc_cor->state = Blocked;
305
306        // Actually run the thread
307        RUNNING:  while(true) {
308                thrd_dst->preempted = __NO_PREEMPTION;
309                thrd_dst->state = Active;
310
311                // Update global state
312                kernelTLS().this_thread = thrd_dst;
313
314                /* paranoid */ verify( ! __preemption_enabled() );
315                /* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
316                /* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
317                /* paranoid */ verify( thrd_dst->context.SP );
318                /* paranoid */ verify( thrd_dst->state != Halted );
319                /* 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
320                /* 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
321                /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
322
323
324
325                // set context switch to the thread that the processor is executing
326                __cfactx_switch( &proc_cor->context, &thrd_dst->context );
327                // when __cfactx_switch returns we are back in the processor coroutine
328
329
330
331                /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_dst->canary );
332                /* 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 );
333                /* 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 );
334                /* paranoid */ verify( thrd_dst->context.SP );
335                /* paranoid */ verify( thrd_dst->curr_cluster == this->cltr );
336                /* paranoid */ verify( kernelTLS().this_thread == thrd_dst );
337                /* paranoid */ verify( ! __preemption_enabled() );
338
339                // Reset global state
340                kernelTLS().this_thread = 0p;
341
342                // We just finished running a thread, there are a few things that could have happened.
343                // 1 - Regular case : the thread has blocked and now one has scheduled it yet.
344                // 2 - Racy case    : the thread has blocked but someone has already tried to schedule it.
345                // 4 - Preempted
346                // In case 1, we may have won a race so we can't write to the state again.
347                // In case 2, we lost the race so we now own the thread.
348
349                if(unlikely(thrd_dst->preempted != __NO_PREEMPTION)) {
350                        // The thread was preempted, reschedule it and reset the flag
351                        schedule_thread$( thrd_dst, UNPARK_LOCAL );
352                        break RUNNING;
353                }
354
355                if(unlikely(thrd_dst->state == Halting)) {
356                        // The thread has halted, it should never be scheduled/run again
357                        // finish the thread
358                        __thread_finish( thrd_dst );
359                        break RUNNING;
360                }
361
362                /* paranoid */ verify( thrd_dst->state == Active );
363                thrd_dst->state = Blocked;
364
365                // set state of processor coroutine to active and the thread to inactive
366                int old_ticket = __atomic_fetch_sub(&thrd_dst->ticket, 1, __ATOMIC_SEQ_CST);
367                switch(old_ticket) {
368                        case TICKET_RUNNING:
369                                // This is case 1, the regular case, nothing more is needed
370                                break RUNNING;
371                        case TICKET_UNBLOCK:
372                                __STATS__(true, ready.threads.threads++; )
373                                // This is case 2, the racy case, someone tried to run this thread before it finished blocking
374                                // In this case, just run it again.
375                                continue RUNNING;
376                        default:
377                                // This makes no sense, something is wrong abort
378                                abort();
379                }
380        }
381
382        // Just before returning to the processor, set the processor coroutine to active
383        proc_cor->state = Active;
384
385        __cfadbg_print_safe(runtime_core, "Kernel : core %p finished running thread %p\n", this, thrd_dst);
386
387        __STATS__(true, ready.threads.threads--; )
388
389        /* paranoid */ verify( ! __preemption_enabled() );
390}
391
392// KERNEL_ONLY
393void returnToKernel() {
394        /* paranoid */ verify( ! __preemption_enabled() );
395        coroutine$ * proc_cor = get_coroutine(kernelTLS().this_processor->runner);
396        thread$ * thrd_src = kernelTLS().this_thread;
397
398        __STATS_DEF( thrd_src->last_proc = kernelTLS().this_processor; )
399
400        // Run the thread on this processor
401        {
402                int local_errno = *__volatile_errno();
403                #if defined( __i386 ) || defined( __x86_64 )
404                        __x87_store;
405                #endif
406                /* paranoid */ verify( proc_cor->context.SP );
407                /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
408                __cfactx_switch( &thrd_src->context, &proc_cor->context );
409                /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd_src->canary );
410                #if defined( __i386 ) || defined( __x86_64 )
411                        __x87_load;
412                #endif
413                *__volatile_errno() = local_errno;
414        }
415
416        #if !defined(__CFA_NO_STATISTICS__)
417                /* paranoid */ verify( thrd_src->last_proc != 0p );
418                if(thrd_src->last_proc != kernelTLS().this_processor) {
419                        __tls_stats()->ready.threads.migration++;
420                }
421        #endif
422
423        /* paranoid */ verify( ! __preemption_enabled() );
424        /* 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 );
425        /* 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 );
426}
427
428//-----------------------------------------------------------------------------
429// Scheduler routines
430// KERNEL ONLY
431static void __schedule_thread( thread$ * thrd, unpark_hint hint ) {
432        /* paranoid */ verify( ! __preemption_enabled() );
433        /* paranoid */ verify( ready_schedule_islocked());
434        /* paranoid */ verify( thrd );
435        /* paranoid */ verify( thrd->state != Halted );
436        /* paranoid */ verify( thrd->curr_cluster );
437        /* paranoid */ #if defined( __CFA_WITH_VERIFY__ )
438        /* paranoid */  if( thrd->state == Blocked || thrd->state == Start ) assertf( thrd->preempted == __NO_PREEMPTION,
439                                        "Error inactive thread marked as preempted, state %d, preemption %d\n", thrd->state, thrd->preempted );
440        /* paranoid */  if( thrd->preempted != __NO_PREEMPTION ) assertf(thrd->state == Active,
441                                        "Error preempted thread marked as not currently running, state %d, preemption %d\n", thrd->state, thrd->preempted );
442        /* paranoid */ #endif
443        /* paranoid */ verifyf( thrd->link.next == 0p, "Expected null got %p", thrd->link.next );
444        /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
445
446        if (thrd->preempted == __NO_PREEMPTION) thrd->state = Ready;
447
448        // Dereference the thread now because once we push it, there is not guaranteed it's still valid.
449        struct cluster * cl = thrd->curr_cluster;
450        __STATS_DEF(bool outside = hint == UNPARK_LOCAL && thrd->last_proc && thrd->last_proc != kernelTLS().this_processor; )
451
452        // push the thread to the cluster ready-queue
453        push( cl, thrd, hint );
454
455        // variable thrd is no longer safe to use
456        thrd = 0xdeaddeaddeaddeadp;
457
458        // wake the cluster using the save variable.
459        __wake_one( cl );
460
461        #if !defined(__CFA_NO_STATISTICS__)
462                if( kernelTLS().this_stats ) {
463                        __tls_stats()->ready.threads.threads++;
464                        if(outside) {
465                                __tls_stats()->ready.threads.extunpark++;
466                        }
467                }
468                else {
469                        __atomic_fetch_add(&cl->stats->ready.threads.threads, 1, __ATOMIC_RELAXED);
470                        __atomic_fetch_add(&cl->stats->ready.threads.extunpark, 1, __ATOMIC_RELAXED);
471                }
472        #endif
473
474        /* paranoid */ verify( ready_schedule_islocked());
475        /* paranoid */ verify( ! __preemption_enabled() );
476}
477
478void schedule_thread$( thread$ * thrd, unpark_hint hint ) {
479        ready_schedule_lock();
480                __schedule_thread( thrd, hint );
481        ready_schedule_unlock();
482}
483
484// KERNEL ONLY
485static inline thread$ * __next_thread(cluster * this) with( *this ) {
486        /* paranoid */ verify( ! __preemption_enabled() );
487
488        ready_schedule_lock();
489                thread$ * thrd = pop_fast( this );
490        ready_schedule_unlock();
491
492        /* paranoid */ verify( ! __preemption_enabled() );
493        return thrd;
494}
495
496// KERNEL ONLY
497static inline thread$ * __next_thread_slow(cluster * this) with( *this ) {
498        /* paranoid */ verify( ! __preemption_enabled() );
499
500        ready_schedule_lock();
501                thread$ * thrd = pop_slow( this );
502        ready_schedule_unlock();
503
504        /* paranoid */ verify( ! __preemption_enabled() );
505        return thrd;
506}
507
508// KERNEL ONLY
509static inline thread$ * __next_thread_search(cluster * this) with( *this ) {
510        /* paranoid */ verify( ! __preemption_enabled() );
511
512        ready_schedule_lock();
513                thread$ * thrd = pop_search( this );
514        ready_schedule_unlock();
515
516        /* paranoid */ verify( ! __preemption_enabled() );
517        return thrd;
518}
519
520static inline bool __must_unpark( thread$ * thrd ) {
521        int old_ticket = __atomic_fetch_add(&thrd->ticket, 1, __ATOMIC_SEQ_CST);
522        switch(old_ticket) {
523                case TICKET_RUNNING:
524                        // Wake won the race, the thread will reschedule/rerun itself
525                        return false;
526                case TICKET_BLOCKED:
527                        /* paranoid */ verify( ! thrd->preempted != __NO_PREEMPTION );
528                        /* paranoid */ verify( thrd->state == Blocked );
529                        return true;
530                default:
531                        // This makes no sense, something is wrong abort
532                        abort("Thread %p (%s) has mismatch park/unpark\n", thrd, thrd->self_cor.name);
533        }
534}
535
536void __kernel_unpark( thread$ * thrd, unpark_hint hint ) {
537        /* paranoid */ verify( ! __preemption_enabled() );
538        /* paranoid */ verify( ready_schedule_islocked());
539
540        if( !thrd ) return;
541
542        if(__must_unpark(thrd)) {
543                // Wake lost the race,
544                __schedule_thread( thrd, hint );
545        }
546
547        /* paranoid */ verify( ready_schedule_islocked());
548        /* paranoid */ verify( ! __preemption_enabled() );
549}
550
551void unpark( thread$ * thrd, unpark_hint hint ) {
552        if( !thrd ) return;
553
554        if(__must_unpark(thrd)) {
555                disable_interrupts();
556                        // Wake lost the race,
557                        schedule_thread$( thrd, hint );
558                enable_interrupts(false);
559        }
560}
561
562void park( void ) {
563        __disable_interrupts_checked();
564                /* paranoid */ verify( kernelTLS().this_thread->preempted == __NO_PREEMPTION );
565                returnToKernel();
566        __enable_interrupts_checked();
567
568}
569
570extern "C" {
571        // Leave the thread monitor
572        // last routine called by a thread.
573        // Should never return
574        void __cfactx_thrd_leave() {
575                thread$ * thrd = active_thread();
576                monitor$ * this = &thrd->self_mon;
577
578                // Lock the monitor now
579                lock( this->lock __cfaabi_dbg_ctx2 );
580
581                disable_interrupts();
582
583                /* paranoid */ verify( ! __preemption_enabled() );
584                /* paranoid */ verify( thrd->state == Active );
585                /* paranoid */ verify( 0x0D15EA5E0D15EA5Ep == thrd->canary );
586                /* paranoid */ verify( kernelTLS().this_thread == thrd );
587                /* paranoid */ verify( thrd->context.SP );
588                /* 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 );
589                /* 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 );
590
591                thrd->state = Halting;
592                if( TICKET_RUNNING != thrd->ticket ) { abort( "Thread terminated with pending unpark" ); }
593                if( thrd != this->owner ) { abort( "Thread internal monitor has incorrect owner" ); }
594                if( this->recursion != 1) { abort( "Thread internal monitor has unbalanced recursion" ); }
595
596                // Leave the thread
597                returnToKernel();
598
599                // Control flow should never reach here!
600                abort();
601        }
602}
603
604// KERNEL ONLY
605bool force_yield( __Preemption_Reason reason ) {
606        __disable_interrupts_checked();
607                thread$ * thrd = kernelTLS().this_thread;
608                /* paranoid */ verify(thrd->state == Active);
609
610                // SKULLDUGGERY: It is possible that we are preempting this thread just before
611                // it was going to park itself. If that is the case and it is already using the
612                // intrusive fields then we can't use them to preempt the thread
613                // If that is the case, abandon the preemption.
614                bool preempted = false;
615                if(thrd->link.next == 0p) {
616                        preempted = true;
617                        thrd->preempted = reason;
618                        returnToKernel();
619                }
620        __enable_interrupts_checked( false );
621        return preempted;
622}
623
624//=============================================================================================
625// Kernel Idle Sleep
626//=============================================================================================
627// Wake a thread from the front if there are any
628static void __wake_one(cluster * this) {
629        eventfd_t val;
630
631        /* paranoid */ verify( ! __preemption_enabled() );
632        /* paranoid */ verify( ready_schedule_islocked() );
633
634        // Check if there is a sleeping processor
635        struct __fd_waitctx * fdp = __atomic_load_n(&this->procs.fdw, __ATOMIC_SEQ_CST);
636
637        // If no one is sleeping: we are done
638        if( fdp == 0p ) return;
639
640        int fd = 1;
641        if( __atomic_load_n(&fdp->fd, __ATOMIC_SEQ_CST) != 1 ) {
642                fd = __atomic_exchange_n(&fdp->fd, 1, __ATOMIC_RELAXED);
643        }
644
645        switch(fd) {
646        case 0:
647                // If the processor isn't ready to sleep then the exchange will already wake it up
648                #if !defined(__CFA_NO_STATISTICS__)
649                        if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.early++;
650                        } else { __atomic_fetch_add(&this->stats->ready.sleep.early, 1, __ATOMIC_RELAXED); }
651                #endif
652                break;
653        case 1:
654                // If someone else already said they will wake them: we are done
655                #if !defined(__CFA_NO_STATISTICS__)
656                        if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.seen++;
657                        } else { __atomic_fetch_add(&this->stats->ready.sleep.seen, 1, __ATOMIC_RELAXED); }
658                #endif
659                break;
660        default:
661                // If the processor was ready to sleep, we need to wake it up with an actual write
662                val = 1;
663                eventfd_write( fd, val );
664
665                #if !defined(__CFA_NO_STATISTICS__)
666                        if( kernelTLS().this_stats ) { __tls_stats()->ready.sleep.wakes++;
667                        } else { __atomic_fetch_add(&this->stats->ready.sleep.wakes, 1, __ATOMIC_RELAXED); }
668                #endif
669                break;
670        }
671
672        /* paranoid */ verify( ready_schedule_islocked() );
673        /* paranoid */ verify( ! __preemption_enabled() );
674
675        return;
676}
677
678// Unconditionnaly wake a thread
679void __wake_proc(processor * this) {
680        /* paranoid */ verify( ! __preemption_enabled() );
681
682        __cfadbg_print_safe(runtime_core, "Kernel : waking Processor %p\n", this);
683
684        this->idle_wctx.fd = 1;
685
686        eventfd_t val;
687        val = 1;
688        eventfd_write( this->idle_fd, val );
689
690        /* paranoid */ verify( ! __preemption_enabled() );
691}
692
693static void idle_sleep(processor * this, io_future_t & future, iovec & iov) {
694        // Tell everyone we are ready to go do sleep
695        for() {
696                int expected = this->idle_wctx.fd;
697
698                // Someone already told us to wake-up! No time for a nap.
699                if(expected == 1) { return; }
700
701                // Try to mark that we are going to sleep
702                if(__atomic_compare_exchange_n(&this->idle_wctx.fd, &expected, this->idle_fd, false,  __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) ) {
703                        // Every one agreed, taking a nap
704                        break;
705                }
706        }
707
708
709        #if !defined(CFA_WITH_IO_URING_IDLE)
710                #if !defined(__CFA_NO_STATISTICS__)
711                        if(this->print_halts) {
712                                __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 0\n", this->unique_id, rdtscl());
713                        }
714                #endif
715
716                __cfadbg_print_safe(runtime_core, "Kernel : core %p waiting on eventfd %d\n", this, this->idle_fd);
717
718                {
719                        eventfd_t val;
720                        ssize_t ret = read( this->idle_fd, &val, sizeof(val) );
721                        if(ret < 0) {
722                                switch((int)errno) {
723                                case EAGAIN:
724                                #if EAGAIN != EWOULDBLOCK
725                                        case EWOULDBLOCK:
726                                #endif
727                                case EINTR:
728                                        // No need to do anything special here, just assume it's a legitimate wake-up
729                                        break;
730                                default:
731                                        abort( "KERNEL : internal error, read failure on idle eventfd, error(%d) %s.", (int)errno, strerror( (int)errno ) );
732                                }
733                        }
734                }
735
736                #if !defined(__CFA_NO_STATISTICS__)
737                        if(this->print_halts) {
738                                __cfaabi_bits_print_safe( STDOUT_FILENO, "PH:%d - %lld 1\n", this->unique_id, rdtscl());
739                        }
740                #endif
741        #else
742                // Do we already have a pending read
743                if(available(future)) {
744                        // There is no pending read, we need to add one
745                        reset(future);
746
747                        __kernel_read(this, future, iov, this->idle_fd );
748                }
749
750                __cfa_io_flush( this, 1 );
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.fd = 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                __atomic_store_n(&this.fdw, &proc.idle_wctx, __ATOMIC_SEQ_CST);
767        unlock( this );
768        /* paranoid */ verify( ! __preemption_enabled() );
769
770        return true;
771}
772
773static void mark_awake(__cluster_proc_list & this, processor & proc) {
774        /* paranoid */ verify( ! __preemption_enabled() );
775        lock( this );
776                this.idle--;
777                /* paranoid */ verify( this.idle >= 0 );
778                remove(proc);
779                insert_last(this.actives, proc);
780
781                {
782                        struct __fd_waitctx * wctx = 0;
783                        if(!this.idles`isEmpty) wctx = &this.idles`first.idle_wctx;
784                        __atomic_store_n(&this.fdw, wctx, __ATOMIC_SEQ_CST);
785                }
786
787        unlock( this );
788        /* paranoid */ verify( ! __preemption_enabled() );
789}
790
791//=============================================================================================
792// Unexpected Terminating logic
793//=============================================================================================
794void __kernel_abort_msg( char * abort_text, int abort_text_size ) {
795        thread$ * thrd = __cfaabi_tls.this_thread;
796
797        if(thrd) {
798                int len = snprintf( abort_text, abort_text_size, "Error occurred while executing thread %.256s (%p)", thrd->self_cor.name, thrd );
799                __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
800
801                if ( &thrd->self_cor != thrd->curr_cor ) {
802                        len = snprintf( abort_text, abort_text_size, " in coroutine %.256s (%p).\n", thrd->curr_cor->name, thrd->curr_cor );
803                        __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
804                }
805                else {
806                        __cfaabi_bits_write( STDERR_FILENO, ".\n", 2 );
807                }
808        }
809        else {
810                int len = snprintf( abort_text, abort_text_size, "Error occurred outside of any thread.\n" );
811                __cfaabi_bits_write( STDERR_FILENO, abort_text, len );
812        }
813}
814
815int __kernel_abort_lastframe( void ) __attribute__ ((__nothrow__)) {
816        return get_coroutine(__cfaabi_tls.this_thread) == get_coroutine(mainThread) ? 4 : 2;
817}
818
819static __spinlock_t kernel_debug_lock;
820
821extern "C" {
822        void __cfaabi_bits_acquire() {
823                lock( kernel_debug_lock __cfaabi_dbg_ctx2 );
824        }
825
826        void __cfaabi_bits_release() {
827                unlock( kernel_debug_lock );
828        }
829}
830
831//=============================================================================================
832// Kernel Utilities
833//=============================================================================================
834#if defined(CFA_HAVE_LINUX_IO_URING_H)
835#include "io/types.hfa"
836#endif
837
838static inline bool __maybe_io_drain( processor * proc ) {
839        bool ret = false;
840        #if defined(CFA_HAVE_LINUX_IO_URING_H)
841                __cfadbg_print_safe(runtime_core, "Kernel : core %p checking io for ring %d\n", proc, proc->io.ctx->fd);
842
843                // Check if we should drain the queue
844                $io_context * ctx = proc->io.ctx;
845                unsigned head = *ctx->cq.head;
846                unsigned tail = *ctx->cq.tail;
847                if(head == tail) return false;
848                ready_schedule_lock();
849                ret = __cfa_io_drain( proc );
850                ready_schedule_unlock();
851        #endif
852        return ret;
853}
854
855//-----------------------------------------------------------------------------
856// Debug
857__cfaabi_dbg_debug_do(
858        extern "C" {
859                void __cfaabi_dbg_record_lock(__spinlock_t & this, const char prev_name[]) {
860                        this.prev_name = prev_name;
861                        this.prev_thrd = kernelTLS().this_thread;
862                }
863        }
864)
865
866//-----------------------------------------------------------------------------
867// Debug
868bool threading_enabled(void) __attribute__((const)) {
869        return true;
870}
871
872//-----------------------------------------------------------------------------
873// Statistics
874#if !defined(__CFA_NO_STATISTICS__)
875        void print_halts( processor & this ) {
876                this.print_halts = true;
877        }
878
879        static void crawl_list( cluster * cltr, dlist(processor) & list, unsigned count ) {
880                /* paranoid */ verify( cltr->stats );
881
882                processor * it = &list`first;
883                for(unsigned i = 0; i < count; i++) {
884                        /* paranoid */ verifyf( it, "Unexpected null iterator, at index %u of %u\n", i, count);
885                        /* paranoid */ verify( it->local_data->this_stats );
886                        // __print_stats( it->local_data->this_stats, cltr->print_stats, "Processor", it->name, (void*)it );
887                        __tally_stats( cltr->stats, it->local_data->this_stats );
888                        it = &(*it)`next;
889                }
890        }
891
892        void crawl_cluster_stats( cluster & this ) {
893                // Stop the world, otherwise stats could get really messed-up
894                // this doesn't solve all problems but does solve many
895                // so it's probably good enough
896                disable_interrupts();
897                uint_fast32_t last_size = ready_mutate_lock();
898
899                        crawl_list(&this, this.procs.actives, this.procs.total - this.procs.idle);
900                        crawl_list(&this, this.procs.idles  , this.procs.idle );
901
902                // Unlock the RWlock
903                ready_mutate_unlock( last_size );
904                enable_interrupts();
905        }
906
907
908        void print_stats_now( cluster & this, int flags ) {
909                crawl_cluster_stats( this );
910                __print_stats( this.stats, this.print_stats, "Cluster", this.name, (void*)&this );
911        }
912#endif
913// Local Variables: //
914// mode: c //
915// tab-width: 4 //
916// End: //
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