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fwd.hfa @ 2210cfc

ADTast-experimentalenumforall-pointer-decaypthread-emulationqualifiedEnum

Last change on this file since 2210cfc was 24e321c, checked in by Thierry Delisle <tdelisle@…>, 3 years ago
Unpark now takes a hint on locality.
Property mode set to `100644`
File size: 12.5 KB

Rev	Line
[e660761]	1	//
	2	// Cforall Version 1.0.0 Copyright (C) 2020 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	//
[454f478]	7	// kernel/fwd.hfa -- PUBLIC
	8	// Fundamental code needed to implement threading M.E.S. algorithms.
[e660761]	9	//
	10	// Author : Thierry Delisle
	11	// Created On : Thu Jul 30 16:46:41 2020
	12	// Last Modified By :
	13	// Last Modified On :
	14	// Update Count :
	15	//
	16
[3e2b9c9]	17	#pragma once
	18
[e660761]	19	#include "bits/defs.hfa"
	20	#include "bits/debug.hfa"
	21
[3e2b9c9]	22	#ifdef __cforall
	23	#include "bits/random.hfa"
[e660761]	24	#endif
	25
[e84ab3d]	26	struct thread$;
[e660761]	27	struct processor;
	28	struct cluster;
	29
[3e2b9c9]	30	enum __Preemption_Reason { __NO_PREEMPTION, __ALARM_PREEMPTION, __POLL_PREEMPTION, __MANUAL_PREEMPTION };
	31
	32	#define KERNEL_STORAGE(T,X) __attribute((aligned(__alignof__(T)))) static char storage_##X[sizeof(T)]
	33
[e660761]	34	#ifdef __cforall
	35	extern "C" {
[3e2b9c9]	36	extern "Cforall" {
[e660761]	37	extern __attribute__((aligned(128))) thread_local struct KernelThreadData {
[e84ab3d]	38	struct thread$ * volatile this_thread;
[e873838]	39	struct processor * volatile this_processor;
[c993b15]	40	volatile bool sched_lock;
[e660761]	41
	42	struct {
	43	volatile unsigned short disable_count;
	44	volatile bool enabled;
	45	volatile bool in_progress;
	46	} preemption_state;
	47
	48	#if defined(__SIZEOF_INT128__)
	49	__uint128_t rand_seed;
	50	#else
	51	uint64_t rand_seed;
	52	#endif
[f2384c9a]	53	struct {
	54	uint64_t fwd_seed;
	55	uint64_t bck_seed;
	56	} ready_rng;
[c993b15]	57
	58	struct __stats_t * volatile this_stats;
	59
	60
	61	#ifdef __CFA_WITH_VERIFY__
	62	// Debug, check if the rwlock is owned for reading
	63	bool in_sched_lock;
	64	unsigned sched_id;
	65	#endif
[8fc652e0]	66	} __cfaabi_tls __attribute__ ((tls_model ( "initial-exec" )));
[3e2b9c9]	67
[8fc652e0]	68	extern bool __preemption_enabled();
[f2384c9a]	69
[8fc652e0]	70	static inline KernelThreadData & kernelTLS( void ) {
	71	/* paranoid */ verify( ! __preemption_enabled() );
	72	return __cfaabi_tls;
	73	}
	74
	75	extern uintptr_t __cfatls_get( unsigned long int member );
[82a2fed]	76	#define publicTLS_get( member ) ((typeof(__cfaabi_tls.member))__cfatls_get( __builtin_offsetof(KernelThreadData, member) ))
[f2384c9a]	77
[3e2b9c9]	78	static inline uint64_t __tls_rand() {
	79	#if defined(__SIZEOF_INT128__)
[8fc652e0]	80	return __lehmer64( kernelTLS().rand_seed );
[3e2b9c9]	81	#else
[8fc652e0]	82	return __xorshift64( kernelTLS().rand_seed );
[3e2b9c9]	83	#endif
	84	}
[f2384c9a]	85
	86	#define M (1_l64u << 48_l64u)
	87	#define A (25214903917_l64u)
	88	#define AI (18446708753438544741_l64u)
	89	#define C (11_l64u)
	90	#define D (16_l64u)
	91
	92	static inline unsigned __tls_rand_fwd() {
	93
[8fc652e0]	94	kernelTLS().ready_rng.fwd_seed = (A * kernelTLS().ready_rng.fwd_seed + C) & (M - 1);
	95	return kernelTLS().ready_rng.fwd_seed >> D;
[f2384c9a]	96	}
	97
	98	static inline unsigned __tls_rand_bck() {
[8fc652e0]	99	unsigned int r = kernelTLS().ready_rng.bck_seed >> D;
	100	kernelTLS().ready_rng.bck_seed = AI * (kernelTLS().ready_rng.bck_seed - C) & (M - 1);
[f2384c9a]	101	return r;
	102	}
	103
	104	#undef M
	105	#undef A
	106	#undef AI
	107	#undef C
	108	#undef D
	109
	110	static inline void __tls_rand_advance_bck(void) {
[8fc652e0]	111	kernelTLS().ready_rng.bck_seed = kernelTLS().ready_rng.fwd_seed;
[f2384c9a]	112	}
[e660761]	113	}
	114
[8fc652e0]	115
[3e2b9c9]	116
	117	extern void disable_interrupts();
[a3821fa]	118	extern void enable_interrupts( bool poll = false );
[e660761]	119
[3e2b9c9]	120	extern "Cforall" {
[24e321c]	121	enum unpark_hint { UNPARK_LOCAL, UNPARK_REMOTE };
	122
[e235429]	123	extern void park( void );
[24e321c]	124	extern void unpark( struct thread$ *, unpark_hint );
	125	static inline void unpark( struct thread$ * thrd ) { unpark(thrd, UNPARK_LOCAL); }
[e84ab3d]	126	static inline struct thread$ * active_thread () {
	127	struct thread$ * t = publicTLS_get( this_thread );
[8fc652e0]	128	/* paranoid */ verify( t );
	129	return t;
	130	}
[3e2b9c9]	131
	132	extern bool force_yield( enum __Preemption_Reason );
[e660761]	133
[3e2b9c9]	134	static inline void yield() {
	135	force_yield(__MANUAL_PREEMPTION);
	136	}
[e660761]	137
[3e2b9c9]	138	// Yield: yield N times
	139	static inline void yield( unsigned times ) {
	140	for( times ) {
	141	yield();
	142	}
	143	}
	144
[fe9468e2]	145	extern uint64_t thread_rand();
	146
[454f478]	147	// Semaphore which only supports a single thread
	148	struct single_sem {
[e84ab3d]	149	struct thread$ * volatile ptr;
[454f478]	150	};
	151
	152	static inline {
	153	void ?{}(single_sem & this) {
	154	this.ptr = 0p;
	155	}
	156
	157	void ^?{}(single_sem &) {}
	158
	159	bool wait(single_sem & this) {
	160	for() {
[e84ab3d]	161	struct thread$ * expected = this.ptr;
[454f478]	162	if(expected == 1p) {
	163	if(__atomic_compare_exchange_n(&this.ptr, &expected, 0p, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)) {
	164	return false;
	165	}
	166	}
	167	else {
	168	/* paranoid */ verify( expected == 0p );
	169	if(__atomic_compare_exchange_n(&this.ptr, &expected, active_thread(), false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)) {
	170	park();
	171	return true;
	172	}
	173	}
	174
	175	}
	176	}
	177
	178	bool post(single_sem & this) {
	179	for() {
[e84ab3d]	180	struct thread$ * expected = this.ptr;
[454f478]	181	if(expected == 1p) return false;
	182	if(expected == 0p) {
	183	if(__atomic_compare_exchange_n(&this.ptr, &expected, 1p, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)) {
	184	return false;
	185	}
	186	}
	187	else {
	188	if(__atomic_compare_exchange_n(&this.ptr, &expected, 0p, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)) {
	189	unpark( expected );
	190	return true;
	191	}
	192	}
	193	}
	194	}
	195	}
	196
	197	// Synchronozation primitive which only supports a single thread and one post
	198	// Similar to a binary semaphore with a 'one shot' semantic
	199	// is expected to be discarded after each party call their side
	200	struct oneshot {
	201	// Internal state :
	202	// 0p : is initial state (wait will block)
	203	// 1p : fulfilled (wait won't block)
	204	// any thread : a thread is currently waiting
[e84ab3d]	205	struct thread$ * volatile ptr;
[454f478]	206	};
	207
	208	static inline {
	209	void ?{}(oneshot & this) {
	210	this.ptr = 0p;
	211	}
	212
	213	void ^?{}(oneshot &) {}
	214
	215	// Wait for the post, return immidiately if it already happened.
	216	// return true if the thread was parked
	217	bool wait(oneshot & this) {
	218	for() {
[e84ab3d]	219	struct thread$ * expected = this.ptr;
[454f478]	220	if(expected == 1p) return false;
	221	/* paranoid */ verify( expected == 0p );
	222	if(__atomic_compare_exchange_n(&this.ptr, &expected, active_thread(), false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)) {
	223	park();
	224	/* paranoid */ verify( this.ptr == 1p );
	225	return true;
	226	}
	227	}
	228	}
	229
	230	// Mark as fulfilled, wake thread if needed
	231	// return true if a thread was unparked
[e84ab3d]	232	thread$ * post(oneshot & this, bool do_unpark = true) {
	233	struct thread$ * got = __atomic_exchange_n( &this.ptr, 1p, __ATOMIC_SEQ_CST);
[a76efc8]	234	if( got == 0p ) return 0p;
	235	if(do_unpark) unpark( got );
	236	return got;
[454f478]	237	}
	238	}
	239
	240	// base types for future to build upon
	241	// It is based on the 'oneshot' type to allow multiple futures
	242	// to block on the same instance, permitting users to block a single
	243	// thread on "any of" [a given set of] futures.
	244	// does not support multiple threads waiting on the same future
	245	struct future_t {
	246	// Internal state :
	247	// 0p : is initial state (wait will block)
	248	// 1p : fulfilled (wait won't block)
	249	// 2p : in progress ()
	250	// 3p : abandoned, server should delete
	251	// any oneshot : a context has been setup to wait, a thread could wait on it
	252	struct oneshot * volatile ptr;
	253	};
	254
	255	static inline {
	256	void ?{}(future_t & this) {
	257	this.ptr = 0p;
	258	}
	259
	260	void ^?{}(future_t &) {}
	261
	262	void reset(future_t & this) {
	263	// needs to be in 0p or 1p
	264	__atomic_exchange_n( &this.ptr, 0p, __ATOMIC_SEQ_CST);
	265	}
	266
	267	// check if the future is available
	268	bool available( future_t & this ) {
	269	return this.ptr == 1p;
	270	}
	271
	272	// Prepare the future to be waited on
	273	// intented to be use by wait, wait_any, waitfor, etc. rather than used directly
	274	bool setup( future_t & this, oneshot & wait_ctx ) {
	275	/* paranoid */ verify( wait_ctx.ptr == 0p );
	276	// The future needs to set the wait context
	277	for() {
	278	struct oneshot * expected = this.ptr;
	279	// Is the future already fulfilled?
	280	if(expected == 1p) return false; // Yes, just return false (didn't block)
	281
	282	// The future is not fulfilled, try to setup the wait context
	283	/* paranoid */ verify( expected == 0p );
	284	if(__atomic_compare_exchange_n(&this.ptr, &expected, &wait_ctx, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)) {
	285	return true;
	286	}
	287	}
	288	}
	289
	290	// Stop waiting on a future
	291	// When multiple futures are waited for together in "any of" pattern
	292	// futures that weren't fulfilled before the thread woke up
	293	// should retract the wait ctx
	294	// intented to be use by wait, wait_any, waitfor, etc. rather than used directly
	295	void retract( future_t & this, oneshot & wait_ctx ) {
	296	// Remove the wait context
	297	struct oneshot * got = __atomic_exchange_n( &this.ptr, 0p, __ATOMIC_SEQ_CST);
	298
	299	// got == 0p: future was never actually setup, just return
	300	if( got == 0p ) return;
	301
	302	// got == wait_ctx: since fulfil does an atomic_swap,
	303	// if we got back the original then no one else saw context
	304	// It is safe to delete (which could happen after the return)
	305	if( got == &wait_ctx ) return;
	306
	307	// got == 1p: the future is ready and the context was fully consumed
	308	// the server won't use the pointer again
	309	// It is safe to delete (which could happen after the return)
	310	if( got == 1p ) return;
	311
	312	// got == 2p: the future is ready but the context hasn't fully been consumed
	313	// spin until it is safe to move on
	314	if( got == 2p ) {
	315	while( this.ptr != 1p ) Pause();
	316	return;
	317	}
	318
	319	// got == any thing else, something wen't wrong here, abort
	320	abort("Future in unexpected state");
	321	}
	322
	323	// Mark the future as abandoned, meaning it will be deleted by the server
	324	bool abandon( future_t & this ) {
	325	/* paranoid */ verify( this.ptr != 3p );
	326
	327	// Mark the future as abandonned
	328	struct oneshot * got = __atomic_exchange_n( &this.ptr, 3p, __ATOMIC_SEQ_CST);
	329
	330	// If the future isn't already fulfilled, let the server delete it
	331	if( got == 0p ) return false;
	332
	333	// got == 2p: the future is ready but the context hasn't fully been consumed
	334	// spin until it is safe to move on
	335	if( got == 2p ) {
	336	while( this.ptr != 1p ) Pause();
	337	got = 1p;
	338	}
	339
	340	// The future is completed delete it now
	341	/* paranoid */ verify( this.ptr != 1p );
	342	free( &this );
	343	return true;
	344	}
	345
	346	// from the server side, mark the future as fulfilled
	347	// delete it if needed
[e84ab3d]	348	thread$ * fulfil( future_t & this, bool do_unpark = true ) {
[454f478]	349	for() {
	350	struct oneshot * expected = this.ptr;
	351	// was this abandoned?
	352	#if defined(__GNUC__) && __GNUC__ >= 7
	353	#pragma GCC diagnostic push
	354	#pragma GCC diagnostic ignored "-Wfree-nonheap-object"
	355	#endif
[a76efc8]	356	if( expected == 3p ) { free( &this ); return 0p; }
[454f478]	357	#if defined(__GNUC__) && __GNUC__ >= 7
	358	#pragma GCC diagnostic pop
	359	#endif
	360
	361	/* paranoid */ verify( expected != 1p ); // Future is already fulfilled, should not happen
	362	/* paranoid */ verify( expected != 2p ); // Future is bein fulfilled by someone else, this is even less supported then the previous case.
	363
	364	// If there is a wait context, we need to consume it and mark it as consumed after
	365	// If there is no context then we can skip the in progress phase
	366	struct oneshot * want = expected == 0p ? 1p : 2p;
	367	if(__atomic_compare_exchange_n(&this.ptr, &expected, want, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)) {
[a76efc8]	368	if( expected == 0p ) { /* paranoid */ verify( this.ptr == 1p); return 0p; }
[e84ab3d]	369	thread$ * ret = post( *expected, do_unpark );
[454f478]	370	__atomic_store_n( &this.ptr, 1p, __ATOMIC_SEQ_CST);
	371	return ret;
	372	}
	373	}
	374
	375	}
	376
	377	// Wait for the future to be fulfilled
	378	bool wait( future_t & this ) {
	379	oneshot temp;
	380	if( !setup(this, temp) ) return false;
	381
	382	// Wait context is setup, just wait on it
	383	bool ret = wait( temp );
	384
	385	// Wait for the future to tru
	386	while( this.ptr == 2p ) Pause();
	387	// Make sure the state makes sense
	388	// Should be fulfilled, could be in progress but it's out of date if so
	389	// since if that is the case, the oneshot was fulfilled (unparking this thread)
	390	// and the oneshot should not be needed any more
	391	__attribute__((unused)) struct oneshot * was = this.ptr;
	392	/* paranoid */ verifyf( was == 1p, "Expected this.ptr to be 1p, was %p\n", was );
	393
	394	// Mark the future as fulfilled, to be consistent
	395	// with potential calls to avail
	396	// this.ptr = 1p;
	397	return ret;
	398	}
	399	}
	400
[3e2b9c9]	401	//-----------------------------------------------------------------------
	402	// Statics call at the end of each thread to register statistics
	403	#if !defined(__CFA_NO_STATISTICS__)
	404	static inline struct __stats_t * __tls_stats() {
[8fc652e0]	405	/* paranoid */ verify( ! __preemption_enabled() );
	406	/* paranoid */ verify( kernelTLS().this_stats );
	407	return kernelTLS().this_stats;
[3e2b9c9]	408	}
	409
	410	#define __STATS__(in_kernel, ...) { \
	411	if( !(in_kernel) ) disable_interrupts(); \
	412	with( *__tls_stats() ) { \
	413	__VA_ARGS__ \
	414	} \
[a3821fa]	415	if( !(in_kernel) ) enable_interrupts(); \
[3e2b9c9]	416	}
	417	#else
	418	#define __STATS__(in_kernel, ...)
	419	#endif
	420	}
[e660761]	421	}
[442b624]	422	#endif

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