source: src/libcfa/concurrency/kernel.c @ eafb094

ADTaaron-thesisarm-ehast-experimentalcleanup-dtorsdeferred_resndemanglerenumforall-pointer-decayjacob/cs343-translationjenkins-sandboxnew-astnew-ast-unique-exprnew-envno_listpersistent-indexerpthread-emulationqualifiedEnumresolv-newwith_gc
Last change on this file since eafb094 was eafb094, checked in by Thierry Delisle <tdelisle@…>, 7 years ago

Removed global spinlock

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File size: 12.9 KB
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[8118303]1//                              -*- Mode: CFA -*-
2//
3// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
4//
5// The contents of this file are covered under the licence agreement in the
6// file "LICENCE" distributed with Cforall.
7//
8// kernel.c --
9//
10// Author           : Thierry Delisle
[75f3522]11// Created On       : Tue Jan 17 12:27:26 2017
[8118303]12// Last Modified By : Thierry Delisle
13// Last Modified On : --
14// Update Count     : 0
15//
16
[0c92c9f]17//Start and stop routine for the kernel, declared first to make sure they run first
18void kernel_startup(void)  __attribute__((constructor(101)));
19void kernel_shutdown(void) __attribute__((destructor(101)));
20
[8118303]21//Header
[75f3522]22#include "kernel_private.h"
[8118303]23
24//C Includes
[c84e80a]25#include <stddef.h>
[eb2e723]26extern "C" {
[8fcbb4c]27#include <fenv.h>
[eb2e723]28#include <sys/resource.h>
29}
[8118303]30
31//CFA Includes
32#include "libhdr.h"
33
34//Private includes
35#define __CFA_INVOKE_PRIVATE__
36#include "invoke.h"
37
[8def349]38//-----------------------------------------------------------------------------
39// Kernel storage
40#define KERNEL_STORAGE(T,X) static char X##_storage[sizeof(T)]
41
42KERNEL_STORAGE(processorCtx_t, systemProcessorCtx);
43KERNEL_STORAGE(cluster, systemCluster);
44KERNEL_STORAGE(processor, systemProcessor);
[e15df4c]45KERNEL_STORAGE(thread, mainThread);
[8def349]46KERNEL_STORAGE(machine_context_t, mainThread_context);
47
[bd98b58]48cluster * systemCluster;
[eb2e723]49processor * systemProcessor;
[e15df4c]50thread * mainThread;
[eb2e723]51
[bd98b58]52//-----------------------------------------------------------------------------
53// Global state
54
[8def349]55thread_local processor * this_processor;
56
57processor * get_this_processor() {
58        return this_processor;
59}
[c84e80a]60
[bd98b58]61coroutine * this_coroutine(void) {
62        return this_processor->current_coroutine;
63}
64
[e15df4c]65thread * this_thread(void) {
[bd98b58]66        return this_processor->current_thread;
[c84e80a]67}
68
69//-----------------------------------------------------------------------------
[8def349]70// Main thread construction
71struct current_stack_info_t {
72        machine_context_t ctx; 
73        unsigned int size;              // size of stack
74        void *base;                             // base of stack
75        void *storage;                  // pointer to stack
76        void *limit;                    // stack grows towards stack limit
77        void *context;                  // address of cfa_context_t
78        void *top;                              // address of top of storage
[c84e80a]79};
80
[8def349]81void ?{}( current_stack_info_t * this ) {
82        CtxGet( &this->ctx );
83        this->base = this->ctx.FP;
84        this->storage = this->ctx.SP;
85
86        rlimit r;
[132fad4]87        getrlimit( RLIMIT_STACK, &r);
[8def349]88        this->size = r.rlim_cur;
89
90        this->limit = (void *)(((intptr_t)this->base) - this->size);
91        this->context = &mainThread_context_storage;
92        this->top = this->base;
93}
94
95void ?{}( coStack_t * this, current_stack_info_t * info) {
96        this->size = info->size;
97        this->storage = info->storage;
98        this->limit = info->limit;
99        this->base = info->base;
100        this->context = info->context;
101        this->top = info->top;
102        this->userStack = true;
103}
104
105void ?{}( coroutine * this, current_stack_info_t * info) {
106        (&this->stack){ info }; 
107        this->name = "Main Thread";
108        this->errno_ = 0;
[ee897e4b]109        this->state = Start;
[8def349]110}
111
[e15df4c]112void ?{}( thread * this, current_stack_info_t * info) {
[8def349]113        (&this->c){ info };
114}
[c84e80a]115
[8def349]116//-----------------------------------------------------------------------------
117// Processor coroutine
[eb2e723]118void ?{}(processorCtx_t * this, processor * proc) {
119        (&this->c){};
[c84e80a]120        this->proc = proc;
[8fcbb4c]121        proc->runner = this;
[8def349]122}
123
124void ?{}(processorCtx_t * this, processor * proc, current_stack_info_t * info) {
125        (&this->c){ info };
126        this->proc = proc;
[8fcbb4c]127        proc->runner = this;
[8def349]128}
129
130void ?{}(processor * this) {
131        this{ systemCluster };
132}
133
134void ?{}(processor * this, cluster * cltr) {
135        this->cltr = cltr;
136        this->current_coroutine = NULL;
137        this->current_thread = NULL;
[db6f06a]138        (&this->terminated){};
139        this->is_terminated = false;
[8def349]140
141        start( this );
[c84e80a]142}
143
[8fcbb4c]144void ?{}(processor * this, cluster * cltr, processorCtx_t * runner) {
[8def349]145        this->cltr = cltr;
146        this->current_coroutine = NULL;
147        this->current_thread = NULL;
[db6f06a]148        (&this->terminated){};
149        this->is_terminated = false;
[8def349]150
[8fcbb4c]151        this->runner = runner;
152        LIB_DEBUG_PRINTF("Kernel : constructing processor context %p\n", runner);
153        runner{ this };
[8def349]154}
155
156void ^?{}(processor * this) {
[db6f06a]157        if( ! this->is_terminated ) {
[8def349]158                LIB_DEBUG_PRINTF("Kernel : core %p signaling termination\n", this);
[db6f06a]159                this->is_terminated = true;
160                wait( &this->terminated );
[8def349]161        }
162}
163
164void ?{}(cluster * this) {
165        ( &this->ready_queue ){};
[eafb094]166        ( &this->lock ){};
[8def349]167}
168
169void ^?{}(cluster * this) {
[8fcbb4c]170       
[c84e80a]171}
172
[75f3522]173//=============================================================================================
174// Kernel Scheduling logic
175//=============================================================================================
[8fcbb4c]176//Main of the processor contexts
177void main(processorCtx_t * runner) {
178        processor * this = runner->proc;
[eb2e723]179        LIB_DEBUG_PRINTF("Kernel : core %p starting\n", this);
[8118303]180
[e15df4c]181        thread * readyThread = NULL;
[db6f06a]182        for( unsigned int spin_count = 0; ! this->is_terminated; spin_count++ ) 
[75f3522]183        {
[bd98b58]184                readyThread = nextThread( this->cltr );
[8118303]185
[75f3522]186                if(readyThread) 
187                {
188                        runThread(this, readyThread);
189
190                        //Some actions need to be taken from the kernel
[db6f06a]191                        finishRunning(this);
[75f3522]192
[c84e80a]193                        spin_count = 0;
[75f3522]194                } 
195                else 
196                {
[c84e80a]197                        spin(this, &spin_count);
198                }               
199        }
[8118303]200
[8def349]201        LIB_DEBUG_PRINTF("Kernel : core %p unlocking thread\n", this);
[db6f06a]202        signal( &this->terminated );
[c84e80a]203        LIB_DEBUG_PRINTF("Kernel : core %p terminated\n", this);
204}
205
[75f3522]206// runThread runs a thread by context switching
[0c92c9f]207// from the processor coroutine to the target thread
[75f3522]208void runThread(processor * this, thread * dst) {
209        coroutine * proc_cor = get_coroutine(this->runner);
210        coroutine * thrd_cor = get_coroutine(dst);
211       
212        //Reset the terminating actions here
[db6f06a]213        this->finish.action_code = No_Action;
[8fcbb4c]214
[75f3522]215        //Update global state
216        this->current_thread = dst;
217
218        // Context Switch to the thread
219        ThreadCtxSwitch(proc_cor, thrd_cor);
220        // when ThreadCtxSwitch returns we are back in the processor coroutine
221}
222
223// Once a thread has finished running, some of
224// its final actions must be executed from the kernel
[db6f06a]225void finishRunning(processor * this) {
226        if( this->finish.action_code == Release ) {
227                unlock( this->finish.lock );
228        }
229        else if( this->finish.action_code == Schedule ) {
230                ScheduleThread( this->finish.thrd );
231        }
232        else if( this->finish.action_code == Release_Schedule ) {
233                unlock( this->finish.lock );           
234                ScheduleThread( this->finish.thrd );
235        }
236        else {
237                assert(this->finish.action_code == No_Action);
[8fcbb4c]238        }
[c84e80a]239}
240
[0c92c9f]241// Handles spinning logic
242// TODO : find some strategy to put cores to sleep after some time
[c84e80a]243void spin(processor * this, unsigned int * spin_count) {
244        (*spin_count)++;
245}
246
[0c92c9f]247// Context invoker for processors
248// This is the entry point for processors (kernel threads)
249// It effectively constructs a coroutine by stealing the pthread stack
[8def349]250void * CtxInvokeProcessor(void * arg) {
251        processor * proc = (processor *) arg;
252        this_processor = proc;
253        // SKULLDUGGERY: We want to create a context for the processor coroutine
254        // which is needed for the 2-step context switch. However, there is no reason
255        // to waste the perfectly valid stack create by pthread.
256        current_stack_info_t info;
257        machine_context_t ctx;
258        info.context = &ctx;
259        processorCtx_t proc_cor_storage = { proc, &info };
260
[8fcbb4c]261        LIB_DEBUG_PRINTF("Coroutine : created stack %p\n", proc_cor_storage.c.stack.base);
262
[0c92c9f]263        //Set global state
[8fcbb4c]264        proc->current_coroutine = &proc->runner->c;
[8def349]265        proc->current_thread = NULL;
266
267        //We now have a proper context from which to schedule threads
[8fcbb4c]268        LIB_DEBUG_PRINTF("Kernel : core %p created (%p, %p)\n", proc, proc->runner, &ctx);
[8def349]269
270        // SKULLDUGGERY: Since the coroutine doesn't have its own stack, we can't
271        // resume it to start it like it normally would, it will just context switch
272        // back to here. Instead directly call the main since we already are on the
273        // appropriate stack.
274        proc_cor_storage.c.state = Active;
275      main( &proc_cor_storage );
[ee897e4b]276      proc_cor_storage.c.state = Halted;
[8def349]277
[0c92c9f]278        // Main routine of the core returned, the core is now fully terminated
[8fcbb4c]279        LIB_DEBUG_PRINTF("Kernel : core %p main ended (%p)\n", proc, proc->runner);     
[8def349]280
281        return NULL;
[c84e80a]282}
283
[8def349]284void start(processor * this) {
285        LIB_DEBUG_PRINTF("Kernel : Starting core %p\n", this);
286       
[8fcbb4c]287        // pthread_attr_t attributes;
288        // pthread_attr_init( &attributes );
[eb2e723]289
[8fcbb4c]290        pthread_create( &this->kernel_thread, NULL, CtxInvokeProcessor, (void*)this );
[eb2e723]291
[8fcbb4c]292        // pthread_attr_destroy( &attributes );
[eb2e723]293
[8def349]294        LIB_DEBUG_PRINTF("Kernel : core %p started\n", this);   
[eb2e723]295}
296
[8def349]297//-----------------------------------------------------------------------------
298// Scheduler routines
[75f3522]299void ScheduleThread( thread * thrd ) {
[8def349]300        assertf( thrd->next == NULL, "Expected null got %p", thrd->next );
301       
[db6f06a]302        lock( &systemProcessor->cltr->lock );
[8def349]303        append( &systemProcessor->cltr->ready_queue, thrd );
[db6f06a]304        unlock( &systemProcessor->cltr->lock );
305}
306
307thread * nextThread(cluster * this) {
308        lock( &this->lock );
309        thread * head = pop_head( &this->ready_queue );
310        unlock( &this->lock );
311        return head;
[eb2e723]312}
313
[75f3522]314void ScheduleInternal() {
315        suspend();
316}
317
[db6f06a]318void ScheduleInternal( spinlock * lock ) {
319        get_this_processor()->finish.action_code = Release;
320        get_this_processor()->finish.lock = lock;
321        suspend();
322}
323
324void ScheduleInternal( thread * thrd ) {
325        get_this_processor()->finish.action_code = Schedule;
326        get_this_processor()->finish.thrd = thrd;
327        suspend();
328}
329
330void ScheduleInternal( spinlock * lock, thread * thrd ) {
331        get_this_processor()->finish.action_code = Release_Schedule;
332        get_this_processor()->finish.lock = lock;
333        get_this_processor()->finish.thrd = thrd;
334        suspend();
[eb2e723]335}
336
337//-----------------------------------------------------------------------------
338// Kernel boot procedures
339void kernel_startup(void) {
340        LIB_DEBUG_PRINTF("Kernel : Starting\n");       
341
342        // Start by initializing the main thread
[8fcbb4c]343        // SKULLDUGGERY: the mainThread steals the process main thread
344        // which will then be scheduled by the systemProcessor normally
[e15df4c]345        mainThread = (thread *)&mainThread_storage;
[8fcbb4c]346        current_stack_info_t info;
[8def349]347        mainThread{ &info };
[eb2e723]348
[bd98b58]349        // Initialize the system cluster
350        systemCluster = (cluster *)&systemCluster_storage;
351        systemCluster{};
352
[8def349]353        // Initialize the system processor and the system processor ctx
[eb2e723]354        // (the coroutine that contains the processing control flow)
[8def349]355        systemProcessor = (processor *)&systemProcessor_storage;
356        systemProcessor{ systemCluster, (processorCtx_t *)&systemProcessorCtx_storage };
[eb2e723]357
[dcb42b8]358        // Add the main thread to the ready queue
359        // once resume is called on systemProcessor->ctx the mainThread needs to be scheduled like any normal thread
[75f3522]360        ScheduleThread(mainThread);
[eb2e723]361
[dcb42b8]362        //initialize the global state variables
[bd98b58]363        this_processor = systemProcessor;
364        this_processor->current_thread = mainThread;
365        this_processor->current_coroutine = &mainThread->c;
[eb2e723]366
[dcb42b8]367        // SKULLDUGGERY: Force a context switch to the system processor to set the main thread's context to the current UNIX
368        // context. Hence, the main thread does not begin through CtxInvokeThread, like all other threads. The trick here is that
369        // mainThread is on the ready queue when this call is made.
[8fcbb4c]370        resume(systemProcessor->runner);
[eb2e723]371
[dcb42b8]372
373
374        // THE SYSTEM IS NOW COMPLETELY RUNNING
[eb2e723]375        LIB_DEBUG_PRINTF("Kernel : Started\n--------------------------------------------------\n\n");
376}
377
[dcb42b8]378void kernel_shutdown(void) {
379        LIB_DEBUG_PRINTF("\n--------------------------------------------------\nKernel : Shutting down\n");
[eb2e723]380
[dcb42b8]381        // SKULLDUGGERY: Notify the systemProcessor it needs to terminates.
382        // When its coroutine terminates, it return control to the mainThread
383        // which is currently here
[db6f06a]384        systemProcessor->is_terminated = true;
[eb2e723]385        suspend();
386
[dcb42b8]387        // THE SYSTEM IS NOW COMPLETELY STOPPED
[eb2e723]388
[dcb42b8]389        // Destroy the system processor and its context in reverse order of construction
390        // These were manually constructed so we need manually destroy them
[8fcbb4c]391        ^(systemProcessor->runner){};
[eb2e723]392        ^(systemProcessor){};
393
[dcb42b8]394        // Final step, destroy the main thread since it is no longer needed
395        // Since we provided a stack to this taxk it will not destroy anything
[eb2e723]396        ^(mainThread){};
397
398        LIB_DEBUG_PRINTF("Kernel : Shutdown complete\n");       
[8118303]399}
400
[bd98b58]401//-----------------------------------------------------------------------------
402// Locks
[db6f06a]403void ?{}( spinlock * this ) {
404        this->lock = 0;
[bd98b58]405}
[db6f06a]406void ^?{}( spinlock * this ) {
[bd98b58]407
[db6f06a]408}
409
410void lock( spinlock * this ) {
411        for ( unsigned int i = 1;; i += 1 ) {
412                if ( this->lock == 0 && __sync_lock_test_and_set_4( &this->lock, 1 ) == 0 ) break;
413        }
414}
[bd98b58]415
[db6f06a]416void unlock( spinlock * this ) {
417        __sync_lock_release_4( &this->lock );
[bd98b58]418}
419
[db6f06a]420void ?{}( signal_once * this ) {
421        this->condition = false;
422}
423void ^?{}( signal_once * this ) {
424
425}
426
427void wait( signal_once * this ) {
428        lock( &this->lock );
429        if( !this->condition ) {
[8def349]430                append( &this->blocked, this_thread() );
[db6f06a]431                ScheduleInternal( &this->lock );
432                lock( &this->lock );
[8def349]433        }
[db6f06a]434        unlock( &this->lock );
[bd98b58]435}
436
[db6f06a]437void signal( signal_once * this ) {
438        lock( &this->lock );
439        {
440                this->condition = true;
441
442                thread * it;
443                while( it = pop_head( &this->blocked) ) {
444                        ScheduleThread( it );
445                }
[bd98b58]446        }
[db6f06a]447        unlock( &this->lock );
[bd98b58]448}
449
450//-----------------------------------------------------------------------------
451// Queues
452void ?{}( simple_thread_list * this ) {
453        this->head = NULL;
454        this->tail = &this->head;
455}
456
[e15df4c]457void append( simple_thread_list * this, thread * t ) {
[bd98b58]458        assert( t->next == NULL );
459        *this->tail = t;
460        this->tail = &t->next;
461}
462
[e15df4c]463thread * pop_head( simple_thread_list * this ) {
464        thread * head = this->head;
[bd98b58]465        if( head ) {
466                this->head = head->next;
467                if( !head->next ) {
468                        this->tail = &this->head;
469                }
470                head->next = NULL;
471        }       
472       
473        return head;
474}
[8118303]475// Local Variables: //
476// mode: c //
477// tab-width: 4 //
478// End: //
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