source: libcfa/src/concurrency/kernel_private.hfa @ dca5802

//
// 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_private.hfa --
//
// Author           : Thierry Delisle
// Created On       : Mon Feb 13 12:27:26 2017
// Last Modified By : Peter A. Buhr
// Last Modified On : Sat Nov 30 19:25:02 2019
// Update Count     : 8
//

#pragma once

#include "kernel.hfa"
#include "thread.hfa"

#include "alarm.hfa"


//-----------------------------------------------------------------------------
// Scheduler

extern "C" {
        void disable_interrupts() OPTIONAL_THREAD;
        void enable_interrupts_noPoll();
        void enable_interrupts( __cfaabi_dbg_ctx_param );
}

void ScheduleThread( thread_desc * );
static inline void WakeThread( thread_desc * thrd ) {
        if( !thrd ) return;

        verify(thrd->state == Inactive);

        disable_interrupts();
        ScheduleThread( thrd );
        enable_interrupts( __cfaabi_dbg_ctx );
}
thread_desc * nextThread(cluster * this);

//Block current thread and release/wake-up the following resources
void BlockInternal(void);
void BlockInternal(__spinlock_t * lock);
void BlockInternal(thread_desc * thrd);
void BlockInternal(__spinlock_t * lock, thread_desc * thrd);
void BlockInternal(__spinlock_t * locks [], unsigned short count);
void BlockInternal(__spinlock_t * locks [], unsigned short count, thread_desc * thrds [], unsigned short thrd_count);
void BlockInternal(__finish_callback_fptr_t callback);
void LeaveThread(__spinlock_t * lock, thread_desc * thrd);

//-----------------------------------------------------------------------------
// Processor
void main(processorCtx_t *);

void * create_pthread( pthread_t *, void * (*)(void *), void * );

static inline void wake_fast(processor * this) {
        __cfaabi_dbg_print_safe("Kernel : Waking up processor %p\n", this);
        post( this->idleLock );
}

static inline void wake(processor * this) {
        disable_interrupts();
        wake_fast(this);
        enable_interrupts( __cfaabi_dbg_ctx );
}

struct event_kernel_t {
        alarm_list_t alarms;
        __spinlock_t lock;
};

extern event_kernel_t * event_kernel;

struct __cfa_kernel_preemption_state_t {
        bool enabled;
        bool in_progress;
        unsigned short disable_count;
};

extern volatile thread_local __cfa_kernel_preemption_state_t preemption_state __attribute__ ((tls_model ( "initial-exec" )));

//-----------------------------------------------------------------------------
// Threads
extern "C" {
      forall(dtype T | is_thread(T))
      void CtxInvokeThread(T * this);
}

extern void ThreadCtxSwitch(coroutine_desc * src, coroutine_desc * dst);

__cfaabi_dbg_debug_do(
        extern void __cfaabi_dbg_thread_register  ( thread_desc * thrd );
        extern void __cfaabi_dbg_thread_unregister( thread_desc * thrd );
)

//-----------------------------------------------------------------------------
// Utils
#define KERNEL_STORAGE(T,X) __attribute((aligned(__alignof__(T)))) static char storage_##X[sizeof(T)]

static inline uint32_t tls_rand() {
        kernelTLS.rand_seed ^= kernelTLS.rand_seed << 6;
        kernelTLS.rand_seed ^= kernelTLS.rand_seed >> 21;
        kernelTLS.rand_seed ^= kernelTLS.rand_seed << 7;
        return kernelTLS.rand_seed;
}


void doregister( struct cluster & cltr );
void unregister( struct cluster & cltr );

void doregister( struct cluster * cltr, struct thread_desc & thrd );
void unregister( struct cluster * cltr, struct thread_desc & thrd );

//=======================================================================
// Cluster lock API
//=======================================================================
struct __attribute__((aligned(64))) __processor_id {
        processor * volatile handle;
        volatile bool lock;
};

// Lock-Free registering/unregistering of threads
// Register a processor to a given cluster and get its unique id in return
unsigned doregister( struct cluster * cltr, struct processor * proc );

// Unregister a processor from a given cluster using its id, getting back the original pointer
void     unregister( struct cluster * cltr, struct processor * proc );

//=======================================================================
// Reader-writer lock implementation
// Concurrent with doregister/unregister,
//    i.e., threads can be added at any point during or between the entry/exit

//-----------------------------------------------------------------------
// simple spinlock underlying the RWLock
// Blocking acquire
static inline void __atomic_acquire(volatile bool * ll) {
        while( __builtin_expect(__atomic_exchange_n(ll, (bool)true, __ATOMIC_SEQ_CST), false) ) {
                while(__atomic_load_n(ll, (int)__ATOMIC_RELAXED))
                        asm volatile("pause");
        }
        /* paranoid */ verify(*ll);
}

// Non-Blocking acquire
static inline bool __atomic_try_acquire(volatile bool * ll) {
        return !__atomic_exchange_n(ll, (bool)true, __ATOMIC_SEQ_CST);
}

// Release
static inline void __atomic_unlock(volatile bool * ll) {
        /* paranoid */ verify(*ll);
        __atomic_store_n(ll, (bool)false, __ATOMIC_RELEASE);
}

//-----------------------------------------------------------------------
// Reader side : acquire when using the ready queue to schedule but not
//  creating/destroying queues
static inline void ready_schedule_lock( struct cluster * cltr, struct processor * proc) with(cltr->ready_lock) {
        unsigned iproc = proc->id;
        /*paranoid*/ verify(data[iproc].handle == proc);
        /*paranoid*/ verify(iproc < ready);

        // Step 1 : make sure no writer are in the middle of the critical section
        while(__atomic_load_n(&lock, (int)__ATOMIC_RELAXED))
                asm volatile("pause");

        // Fence needed because we don't want to start trying to acquire the lock
        // before we read a false.
        // Not needed on x86
        // std::atomic_thread_fence(std::memory_order_seq_cst);

        // Step 2 : acquire our local lock
        __atomic_acquire( &data[iproc].lock );
        /*paranoid*/ verify(data[iproc].lock);
}

static inline void ready_schedule_unlock( struct cluster * cltr, struct processor * proc) with(cltr->ready_lock) {
        unsigned iproc = proc->id;
        /*paranoid*/ verify(data[iproc].handle == proc);
        /*paranoid*/ verify(iproc < ready);
        /*paranoid*/ verify(data[iproc].lock);
        __atomic_unlock(&data[iproc].lock);
}

//-----------------------------------------------------------------------
// Writer side : acquire when changing the ready queue, e.g. adding more
//  queues or removing them.
uint_fast32_t ready_mutate_lock( struct cluster & cltr );

void ready_mutate_unlock( struct cluster & cltr, uint_fast32_t /* value returned by lock */ );

//=======================================================================
// Ready-Queue API
//-----------------------------------------------------------------------
// push thread onto a ready queue for a cluster
// returns true if the list was previously empty, false otherwise
__attribute__((hot)) bool push(struct cluster * cltr, struct thread_desc * thrd);

//-----------------------------------------------------------------------
// pop thread from the ready queue of a cluster
// returns 0p if empty
__attribute__((hot)) thread_desc * pop(struct cluster * cltr);

//-----------------------------------------------------------------------
// Increase the width of the ready queue (number of lanes) by 4
void ready_queue_grow  (struct cluster * cltr);

//-----------------------------------------------------------------------
// Decrease the width of the ready queue (number of lanes) by 4
void ready_queue_shrink(struct cluster * cltr);

//-----------------------------------------------------------------------
// Statics call at the end of each thread to register statistics
#if !defined(__CFA_NO_STATISTICS__)
void stats_tls_tally(struct cluster * cltr);
#else
static inline void stats_tls_tally(struct cluster * cltr) {}
#endif

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