source: libcfa/src/concurrency/kernel.hfa @ b7d6a36

//
// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// kernel --
//
// Author           : Thierry Delisle
// Created On       : Tue Jan 17 12:27:26 2017
// Last Modified By : Peter A. Buhr
// Last Modified On : Tue Feb  4 12:29:26 2020
// Update Count     : 22
//

#pragma once

#include <stdbool.h>

#include "invoke.h"
#include "time_t.hfa"
#include "coroutine.hfa"

extern "C" {
#include <pthread.h>
#include <semaphore.h>
}

//-----------------------------------------------------------------------------
// Locks
struct semaphore {
        __spinlock_t lock;
        int count;
        __queue_t(thread_desc) waiting;
};

void  ?{}(semaphore & this, int count = 1);
void ^?{}(semaphore & this);
void   P (semaphore & this);
void   V (semaphore & this);


//-----------------------------------------------------------------------------
// Processor
extern struct cluster * mainCluster;

enum FinishOpCode { No_Action, Release, Schedule, Release_Schedule, Release_Multi, Release_Multi_Schedule, Callback };

typedef void (*__finish_callback_fptr_t)(void);

//TODO use union, many of these fields are mutually exclusive (i.e. MULTI vs NOMULTI)
struct FinishAction {
        FinishOpCode action_code;
        /*
        // Union of possible actions
        union {
                // Option 1 : locks and threads
                struct {
                        // 1 thread or N thread
                        union {
                                thread_desc * thrd;
                                struct {
                                        thread_desc ** thrds;
                                        unsigned short thrd_count;
                                };
                        };
                        // 1 lock or N lock
                        union {
                                __spinlock_t * lock;
                                struct {
                                        __spinlock_t ** locks;
                                        unsigned short lock_count;
                                };
                        };
                };
                // Option 2 : action pointer
                __finish_callback_fptr_t callback;
        };
        /*/
        thread_desc * thrd;
        thread_desc ** thrds;
        unsigned short thrd_count;
        __spinlock_t * lock;
        __spinlock_t ** locks;
        unsigned short lock_count;
        __finish_callback_fptr_t callback;
        //*/
};
static inline void ?{}(FinishAction & this) {
        this.action_code = No_Action;
        this.thrd = 0p;
        this.lock = 0p;
}
static inline void ^?{}(FinishAction &) {}

// Processor
coroutine processorCtx_t {
        struct processor * proc;
};

// Wrapper around kernel threads
struct processor {
        // Main state
        // Coroutine ctx who does keeps the state of the processor
        struct processorCtx_t runner;

        // Cluster from which to get threads
        struct cluster * cltr;
        unsigned int id;

        // Name of the processor
        const char * name;

        // Handle to pthreads
        pthread_t kernel_thread;

        // RunThread data
        // Action to do after a thread is ran
        struct FinishAction finish;

        // Preemption data
        // Node which is added in the discrete event simulaiton
        struct alarm_node_t * preemption_alarm;

        // If true, a preemption was triggered in an unsafe region, the processor must preempt as soon as possible
        bool pending_preemption;

        // Idle lock
        __bin_sem_t idleLock;

        // Termination
        // Set to true to notify the processor should terminate
        volatile bool do_terminate;

        // Termination synchronisation
        semaphore terminated;

        // pthread Stack
        void * stack;

        // Link lists fields
        struct __dbg_node_proc {
                struct processor * next;
                struct processor * prev;
        } node;

#ifdef __CFA_DEBUG__
        // Last function to enable preemption on this processor
        const char * last_enable;
#endif
};

void  ?{}(processor & this, const char name[], struct cluster & cltr);
void ^?{}(processor & this);

static inline void  ?{}(processor & this)                    { this{ "Anonymous Processor", *mainCluster}; }
static inline void  ?{}(processor & this, struct cluster & cltr)    { this{ "Anonymous Processor", cltr}; }
static inline void  ?{}(processor & this, const char name[]) { this{name, *mainCluster }; }

static inline [processor *&, processor *& ] __get( processor & this ) {
        return this.node.[next, prev];
}


//-----------------------------------------------------------------------------
// Cluster Tools

// Cells use by the reader writer lock
// while not generic it only relies on a opaque pointer
struct __processor_id;

// Reader-Writer lock protecting the ready-queue
// while this lock is mostly generic some aspects
// have been hard-coded to for the ready-queue for
// simplicity and performance
struct __clusterRWLock_t {
        // total cachelines allocated
        unsigned int max;

        // cachelines currently in use
        volatile unsigned int alloc;

        // cachelines ready to itereate over
        // (!= to alloc when thread is in second half of doregister)
        volatile unsigned int ready;

        // writer lock
        volatile bool lock;

        // data pointer
        __processor_id * data;
};

void  ?{}(__clusterRWLock_t & this);
void ^?{}(__clusterRWLock_t & this);

// Intrusives lanes which are used by the relaxed ready queue
struct __attribute__((aligned(128))) __intrusive_lane_t {
        // spin lock protecting the queue
        volatile bool lock;

        // anchor for the head and the tail of the queue
        struct __sentinel_t {
                // Link lists fields
                // instrusive link field for threads
                // must be exactly as in thread_desc
                __thread_desc_link link;
        } before, after;

#if defined(__CFA_WITH_VERIFY__)
        // id of last processor to acquire the lock
        // needed only to check for mutual exclusion violations
        unsigned int last_id;

        // number of items on this list
        // needed only to check for deadlocks
        unsigned int count;
#endif

        // Optional statistic counters
        #if !defined(__CFA_NO_SCHED_STATS__)
                struct __attribute__((aligned(64))) {
                        // difference between number of push and pops
                        ssize_t diff;

                        // total number of pushes and pops
                        size_t  push;
                        size_t  pop ;
                } stat;
        #endif
};

void  ?{}(__intrusive_lane_t & this);
void ^?{}(__intrusive_lane_t & this);

typedef unsigned long long __cfa_readyQ_mask_t;

// enum {
//      __cfa_ready_queue_mask_size = (64 - sizeof(size_t)) / sizeof(size_t),
//      __cfa_max_ready_queues = __cfa_ready_queue_mask_size * 8 * sizeof(size_t)
// };

#define __cfa_lane_mask_size ((64 - sizeof(size_t)) / sizeof(__cfa_readyQ_mask_t))
#define __cfa_max_lanes (__cfa_lane_mask_size * 8 * sizeof(__cfa_readyQ_mask_t))

//TODO adjust cache size to ARCHITECTURE
// Structure holding the relaxed ready queue
struct __attribute__((aligned(128))) __ready_queue_t {
        // Data tracking how many/which lanes are used
        // Aligned to 128 for cache locality
        struct {
                // number of non-empty lanes
                volatile size_t count;

                // bit mask, set bits indentify which lanes are non-empty
                volatile __cfa_readyQ_mask_t mask[ __cfa_lane_mask_size ];
        } used;

        // Data tracking the actual lanes
        // On a seperate cacheline from the used struct since
        // used can change on each push/pop but this data
        // only changes on shrink/grow
        struct __attribute__((aligned(64))) {
                // Arary of lanes
                __intrusive_lane_t * volatile data;

                // Number of lanes (empty or not)
                volatile size_t count;
        } lanes;

        // Statistics
        #if !defined(__CFA_NO_STATISTICS__)
                __attribute__((aligned(64))) struct {
                        struct {
                                // Push statistic
                                struct {
                                        // number of attemps at pushing something
                                        volatile size_t attempt;

                                        // number of successes at pushing
                                        volatile size_t success;
                                } push;

                                // Pop statistic
                                struct {
                                        // number of reads of the mask
                                        // picking an empty __cfa_readyQ_mask_t counts here
                                        // but not as an attempt
                                        volatile size_t maskrds;

                                        // number of attemps at poping something
                                        volatile size_t attempt;

                                        // number of successes at poping
                                        volatile size_t success;
                                } pop;
                        } pick;

                        // stats on the "used" struct of the queue
                        // tracks average number of queues that are not empty
                        // when pushing / poping
                        struct {
                                volatile size_t value;
                                volatile size_t count;
                        } used;
                } global_stats;

        #endif
};

void  ?{}(__ready_queue_t & this);
void ^?{}(__ready_queue_t & this);

//-----------------------------------------------------------------------------
// Cluster
struct cluster {
        // Ready queue locks
        __clusterRWLock_t ready_lock;

        // Ready queue for threads
        __ready_queue_t ready_queue;

        // Name of the cluster
        const char * name;

        // Preemption rate on this cluster
        Duration preemption_rate;

        // List of processors
        __spinlock_t proc_list_lock;
        __dllist_t(struct processor) idles;

        // List of threads
        __spinlock_t thread_list_lock;
        __dllist_t(struct thread_desc) threads;
        unsigned int nthreads;

        // Link lists fields
        struct __dbg_node_cltr {
                cluster * next;
                cluster * prev;
        } node;
};
extern Duration default_preemption();

void ?{} (cluster & this, const char name[], Duration preemption_rate);
void ^?{}(cluster & this);

static inline void ?{} (cluster & this)                           { this{"Anonymous Cluster", default_preemption()}; }
static inline void ?{} (cluster & this, Duration preemption_rate) { this{"Anonymous Cluster", preemption_rate}; }
static inline void ?{} (cluster & this, const char name[])        { this{name, default_preemption()}; }

static inline [cluster *&, cluster *& ] __get( cluster & this ) {
        return this.node.[next, prev];
}

static inline struct processor * active_processor() { return TL_GET( this_processor ); } // UNSAFE
static inline struct cluster   * active_cluster  () { return TL_GET( this_processor )->cltr; }

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