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ready_queue.cfa@ 42a02ce

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Last change on this file since 42a02ce was e84ab3d, checked in by Thierry Delisle <tdelisle@…>, 4 years ago
Step 1 of changing $thread to thread$
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Rev	Line
[7768b8d]	1	//
	2	// Cforall Version 1.0.0 Copyright (C) 2019 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	// ready_queue.cfa --
	8	//
	9	// Author : Thierry Delisle
	10	// Created On : Mon Nov dd 16:29:18 2019
	11	// Last Modified By :
	12	// Last Modified On :
	13	// Update Count :
	14	//
	15
	16	#define __cforall_thread__
[43784ac]	17	#define _GNU_SOURCE
	18
[1b143de]	19	// #define __CFA_DEBUG_PRINT_READY_QUEUE__
[7768b8d]	20
[1eb239e4]	21
[6ba6846]	22	#define USE_RELAXED_FIFO
[9cc3a18]	23	// #define USE_WORK_STEALING
[6ba6846]	24	// #define USE_CPU_WORK_STEALING
[9cc3a18]	25
[7768b8d]	26	#include "bits/defs.hfa"
[12daa43]	27	#include "device/cpu.hfa"
[7768b8d]	28	#include "kernel_private.hfa"
	29
	30	#include "stdlib.hfa"
[61d7bec]	31	#include "math.hfa"
[7768b8d]	32
[0ee224b]	33	#include <errno.h>
[04b5cef]	34	#include <unistd.h>
	35
[0ee224b]	36	extern "C" {
	37	#include <sys/syscall.h> // __NR_xxx
	38	}
	39
[13c5e19]	40	#include "ready_subqueue.hfa"
	41
[7768b8d]	42	static const size_t cache_line_size = 64;
	43
[d2fadeb]	44	#if !defined(__CFA_NO_STATISTICS__)
	45	#define __STATS(...) __VA_ARGS__
	46	#else
	47	#define __STATS(...)
	48	#endif
	49
[dca5802]	50	// No overriden function, no environment variable, no define
	51	// fall back to a magic number
	52	#ifndef __CFA_MAX_PROCESSORS__
[b388ee81]	53	#define __CFA_MAX_PROCESSORS__ 1024
[dca5802]	54	#endif
[7768b8d]	55
[12daa43]	56	#if defined(USE_CPU_WORK_STEALING)
	57	#define READYQ_SHARD_FACTOR 2
	58	#elif defined(USE_RELAXED_FIFO)
[9cc3a18]	59	#define BIAS 4
	60	#define READYQ_SHARD_FACTOR 4
[5f6a172]	61	#define SEQUENTIAL_SHARD 1
[9cc3a18]	62	#elif defined(USE_WORK_STEALING)
	63	#define READYQ_SHARD_FACTOR 2
[5f6a172]	64	#define SEQUENTIAL_SHARD 2
[9cc3a18]	65	#else
	66	#error no scheduling strategy selected
	67	#endif
	68
[e84ab3d]	69	static inline struct thread$ * try_pop(struct cluster * cltr, unsigned w __STATS(, __stats_readyQ_pop_t & stats));
	70	static inline struct thread$ * try_pop(struct cluster * cltr, unsigned i, unsigned j __STATS(, __stats_readyQ_pop_t & stats));
	71	static inline struct thread$ * search(struct cluster * cltr);
[d2fadeb]	72	static inline [unsigned, bool] idx_from_r(unsigned r, unsigned preferred);
[9cc3a18]	73
[04b5cef]	74
[dca5802]	75	// returns the maximum number of processors the RWLock support
[7768b8d]	76	__attribute__((weak)) unsigned __max_processors() {
	77	const char * max_cores_s = getenv("CFA_MAX_PROCESSORS");
	78	if(!max_cores_s) {
[504a7dc]	79	__cfadbg_print_nolock(ready_queue, "No CFA_MAX_PROCESSORS in ENV\n");
[dca5802]	80	return __CFA_MAX_PROCESSORS__;
[7768b8d]	81	}
	82
	83	char * endptr = 0p;
	84	long int max_cores_l = strtol(max_cores_s, &endptr, 10);
	85	if(max_cores_l < 1 \|\| max_cores_l > 65535) {
[504a7dc]	86	__cfadbg_print_nolock(ready_queue, "CFA_MAX_PROCESSORS out of range : %ld\n", max_cores_l);
[dca5802]	87	return __CFA_MAX_PROCESSORS__;
[7768b8d]	88	}
	89	if('\0' != *endptr) {
[504a7dc]	90	__cfadbg_print_nolock(ready_queue, "CFA_MAX_PROCESSORS not a decimal number : %s\n", max_cores_s);
[dca5802]	91	return __CFA_MAX_PROCESSORS__;
[7768b8d]	92	}
	93
	94	return max_cores_l;
	95	}
	96
[0ee224b]	97	#if defined(CFA_HAVE_LINUX_LIBRSEQ)
	98	// No forward declaration needed
	99	#define __kernel_rseq_register rseq_register_current_thread
	100	#define __kernel_rseq_unregister rseq_unregister_current_thread
	101	#elif defined(CFA_HAVE_LINUX_RSEQ_H)
	102	void __kernel_raw_rseq_register (void);
	103	void __kernel_raw_rseq_unregister(void);
	104
	105	#define __kernel_rseq_register __kernel_raw_rseq_register
	106	#define __kernel_rseq_unregister __kernel_raw_rseq_unregister
	107	#else
	108	// No forward declaration needed
	109	// No initialization needed
	110	static inline void noop(void) {}
	111
	112	#define __kernel_rseq_register noop
	113	#define __kernel_rseq_unregister noop
	114	#endif
	115
[7768b8d]	116	//=======================================================================
	117	// Cluster wide reader-writer lock
	118	//=======================================================================
[b388ee81]	119	void ?{}(__scheduler_RWLock_t & this) {
[7768b8d]	120	this.max = __max_processors();
	121	this.alloc = 0;
	122	this.ready = 0;
	123	this.data = alloc(this.max);
[c993b15]	124	this.write_lock = false;
[7768b8d]	125
	126	/paranoid/ verify(__atomic_is_lock_free(sizeof(this.alloc), &this.alloc));
	127	/paranoid/ verify(__atomic_is_lock_free(sizeof(this.ready), &this.ready));
	128
	129	}
[b388ee81]	130	void ^?{}(__scheduler_RWLock_t & this) {
[7768b8d]	131	free(this.data);
	132	}
	133
	134
	135	//=======================================================================
	136	// Lock-Free registering/unregistering of threads
[c993b15]	137	unsigned register_proc_id( void ) with(*__scheduler_lock) {
[0ee224b]	138	__kernel_rseq_register();
	139
[b388ee81]	140	__cfadbg_print_safe(ready_queue, "Kernel : Registering proc %p for RW-Lock\n", proc);
[c993b15]	141	bool * handle = (bool *)&kernelTLS().sched_lock;
[504a7dc]	142
[7768b8d]	143	// Step - 1 : check if there is already space in the data
	144	uint_fast32_t s = ready;
	145
	146	// Check among all the ready
	147	for(uint_fast32_t i = 0; i < s; i++) {
[c993b15]	148	bool * volatile * cell = (bool * volatile *)&data[i]; // Cforall is bugged and the double volatiles causes problems
	149	/* paranoid / verify( handle != cell );
	150
	151	bool * null = 0p; // Re-write every loop since compare thrashes it
	152	if( __atomic_load_n(cell, (int)__ATOMIC_RELAXED) == null
	153	&& __atomic_compare_exchange_n( cell, &null, handle, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)) {
	154	/* paranoid */ verify(i < ready);
	155	/* paranoid */ verify( (kernelTLS().sched_id = i, true) );
	156	return i;
[7768b8d]	157	}
	158	}
	159
[b388ee81]	160	if(max <= alloc) abort("Trying to create more than %ud processors", __scheduler_lock->max);
[7768b8d]	161
	162	// Step - 2 : F&A to get a new spot in the array.
	163	uint_fast32_t n = __atomic_fetch_add(&alloc, 1, __ATOMIC_SEQ_CST);
[b388ee81]	164	if(max <= n) abort("Trying to create more than %ud processors", __scheduler_lock->max);
[7768b8d]	165
	166	// Step - 3 : Mark space as used and then publish it.
[c993b15]	167	data[n] = handle;
[fd9b524]	168	while() {
[7768b8d]	169	unsigned copy = n;
	170	if( __atomic_load_n(&ready, __ATOMIC_RELAXED) == n
	171	&& __atomic_compare_exchange_n(&ready, &copy, n + 1, true, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST))
	172	break;
[fd9b524]	173	Pause();
[7768b8d]	174	}
	175
[1b143de]	176	__cfadbg_print_safe(ready_queue, "Kernel : Registering proc %p done, id %lu\n", proc, n);
[504a7dc]	177
[7768b8d]	178	// Return new spot.
[c993b15]	179	/* paranoid */ verify(n < ready);
	180	/* paranoid */ verify( (kernelTLS().sched_id = n, true) );
	181	return n;
[7768b8d]	182	}
	183
[c993b15]	184	void unregister_proc_id( unsigned id ) with(*__scheduler_lock) {
	185	/* paranoid */ verify(id < ready);
	186	/* paranoid */ verify(id == kernelTLS().sched_id);
	187	/* paranoid */ verify(data[id] == &kernelTLS().sched_lock);
	188
	189	bool * volatile * cell = (bool * volatile *)&data[id]; // Cforall is bugged and the double volatiles causes problems
	190
	191	__atomic_store_n(cell, 0p, __ATOMIC_RELEASE);
[504a7dc]	192
	193	__cfadbg_print_safe(ready_queue, "Kernel : Unregister proc %p\n", proc);
[0ee224b]	194
	195	__kernel_rseq_unregister();
[7768b8d]	196	}
	197
	198	//-----------------------------------------------------------------------
	199	// Writer side : acquire when changing the ready queue, e.g. adding more
	200	// queues or removing them.
[b388ee81]	201	uint_fast32_t ready_mutate_lock( void ) with(*__scheduler_lock) {
[8fc652e0]	202	/* paranoid */ verify( ! __preemption_enabled() );
[c993b15]	203	/* paranoid */ verify( ! kernelTLS().sched_lock );
[62502cc4]	204
[7768b8d]	205	// Step 1 : lock global lock
	206	// It is needed to avoid processors that register mid Critical-Section
	207	// to simply lock their own lock and enter.
[c993b15]	208	__atomic_acquire( &write_lock );
[7768b8d]	209
	210	// Step 2 : lock per-proc lock
	211	// Processors that are currently being registered aren't counted
	212	// but can't be in read_lock or in the critical section.
	213	// All other processors are counted
	214	uint_fast32_t s = ready;
	215	for(uint_fast32_t i = 0; i < s; i++) {
[c993b15]	216	volatile bool * llock = data[i];
	217	if(llock) __atomic_acquire( llock );
[7768b8d]	218	}
	219
[8fc652e0]	220	/* paranoid */ verify( ! __preemption_enabled() );
[7768b8d]	221	return s;
	222	}
	223
[b388ee81]	224	void ready_mutate_unlock( uint_fast32_t last_s ) with(*__scheduler_lock) {
[8fc652e0]	225	/* paranoid */ verify( ! __preemption_enabled() );
[62502cc4]	226
[7768b8d]	227	// Step 1 : release local locks
	228	// This must be done while the global lock is held to avoid
	229	// threads that where created mid critical section
	230	// to race to lock their local locks and have the writer
	231	// immidiately unlock them
	232	// Alternative solution : return s in write_lock and pass it to write_unlock
	233	for(uint_fast32_t i = 0; i < last_s; i++) {
[c993b15]	234	volatile bool * llock = data[i];
	235	if(llock) __atomic_store_n(llock, (bool)false, __ATOMIC_RELEASE);
[7768b8d]	236	}
	237
	238	// Step 2 : release global lock
[c993b15]	239	/paranoid/ assert(true == write_lock);
	240	__atomic_store_n(&write_lock, (bool)false, __ATOMIC_RELEASE);
[62502cc4]	241
[8fc652e0]	242	/* paranoid */ verify( ! __preemption_enabled() );
[7768b8d]	243	}
	244
	245	//=======================================================================
[9cc3a18]	246	// Cforall Ready Queue used for scheduling
[b798713]	247	//=======================================================================
	248	void ?{}(__ready_queue_t & this) with (this) {
[12daa43]	249	#if defined(USE_CPU_WORK_STEALING)
	250	lanes.count = cpu_info.hthrd_count * READYQ_SHARD_FACTOR;
	251	lanes.data = alloc( lanes.count );
	252	lanes.tscs = alloc( lanes.count );
	253
	254	for( idx; (size_t)lanes.count ) {
	255	(lanes.data[idx]){};
	256	lanes.tscs[idx].tv = rdtscl();
	257	}
	258	#else
	259	lanes.data = 0p;
	260	lanes.tscs = 0p;
	261	lanes.count = 0;
	262	#endif
[b798713]	263	}
	264
	265	void ^?{}(__ready_queue_t & this) with (this) {
[12daa43]	266	#if !defined(USE_CPU_WORK_STEALING)
	267	verify( SEQUENTIAL_SHARD == lanes.count );
	268	#endif
	269
[dca5802]	270	free(lanes.data);
[9cc3a18]	271	free(lanes.tscs);
[dca5802]	272	}
	273
[64a7146]	274	//-----------------------------------------------------------------------
[12daa43]	275	#if defined(USE_CPU_WORK_STEALING)
[e84ab3d]	276	__attribute__((hot)) void push(struct cluster * cltr, struct thread$ * thrd, bool push_local) with (cltr->ready_queue) {
[12daa43]	277	__cfadbg_print_safe(ready_queue, "Kernel : Pushing %p on cluster %p\n", thrd, cltr);
	278
	279	processor * const proc = kernelTLS().this_processor;
	280	const bool external = !push_local \|\| (!proc) \|\| (cltr != proc->cltr);
	281
	282	const int cpu = __kernel_getcpu();
	283	/* paranoid */ verify(cpu >= 0);
	284	/* paranoid */ verify(cpu < cpu_info.hthrd_count);
	285	/* paranoid / verify(cpu READYQ_SHARD_FACTOR < lanes.count);
	286
[df7597e0]	287	const cpu_map_entry_t & map = cpu_info.llc_map[cpu];
	288	/* paranoid / verify(map.start READYQ_SHARD_FACTOR < lanes.count);
	289	/* paranoid / verify(map.self READYQ_SHARD_FACTOR < lanes.count);
[5614552a]	290	/* paranoid / verifyf((map.start + map.count) READYQ_SHARD_FACTOR <= lanes.count, "have %zu lanes but map can go up to %u", lanes.count, (map.start + map.count) * READYQ_SHARD_FACTOR);
[df7597e0]	291
	292	const int start = map.self * READYQ_SHARD_FACTOR;
[12daa43]	293	unsigned i;
	294	do {
	295	unsigned r;
	296	if(unlikely(external)) { r = __tls_rand(); }
	297	else { r = proc->rdq.its++; }
	298	i = start + (r % READYQ_SHARD_FACTOR);
	299	// If we can't lock it retry
	300	} while( !__atomic_try_acquire( &lanes.data[i].lock ) );
	301
	302	// Actually push it
	303	push(lanes.data[i], thrd);
	304
	305	// Unlock and return
	306	__atomic_unlock( &lanes.data[i].lock );
	307
	308	#if !defined(__CFA_NO_STATISTICS__)
	309	if(unlikely(external)) __atomic_fetch_add(&cltr->stats->ready.push.extrn.success, 1, __ATOMIC_RELAXED);
	310	else __tls_stats()->ready.push.local.success++;
	311	#endif
	312
	313	__cfadbg_print_safe(ready_queue, "Kernel : Pushed %p on cluster %p (idx: %u, mask %llu, first %d)\n", thrd, cltr, i, used.mask[0], lane_first);
	314
	315	}
	316
	317	// Pop from the ready queue from a given cluster
[e84ab3d]	318	__attribute__((hot)) thread$ * pop_fast(struct cluster * cltr) with (cltr->ready_queue) {
[12daa43]	319	/* paranoid */ verify( lanes.count > 0 );
	320	/* paranoid */ verify( kernelTLS().this_processor );
	321
	322	const int cpu = __kernel_getcpu();
	323	/* paranoid */ verify(cpu >= 0);
	324	/* paranoid */ verify(cpu < cpu_info.hthrd_count);
[df7597e0]	325	/* paranoid / verify(cpu READYQ_SHARD_FACTOR < lanes.count);
	326
	327	const cpu_map_entry_t & map = cpu_info.llc_map[cpu];
	328	/* paranoid / verify(map.start READYQ_SHARD_FACTOR < lanes.count);
	329	/* paranoid / verify(map.self READYQ_SHARD_FACTOR < lanes.count);
[5614552a]	330	/* paranoid / verifyf((map.start + map.count) READYQ_SHARD_FACTOR <= lanes.count, "have %zu lanes but map can go up to %u", lanes.count, (map.start + map.count) * READYQ_SHARD_FACTOR);
[12daa43]	331
	332	processor * const proc = kernelTLS().this_processor;
[df7597e0]	333	const int start = map.self * READYQ_SHARD_FACTOR;
[12daa43]	334
	335	// Did we already have a help target
	336	if(proc->rdq.target == -1u) {
	337	// if We don't have a
	338	unsigned long long min = ts(lanes.data[start]);
	339	for(i; READYQ_SHARD_FACTOR) {
	340	unsigned long long tsc = ts(lanes.data[start + i]);
	341	if(tsc < min) min = tsc;
	342	}
	343	proc->rdq.cutoff = min;
[953827a]	344
	345	/* paranoid */ verify(lanes.count < 65536); // The following code assumes max 65536 cores.
	346	/* paranoid */ verify(map.count < 65536); // The following code assumes max 65536 cores.
	347	uint64_t chaos = __tls_rand();
	348	uint64_t high_chaos = (chaos >> 32);
	349	uint64_t mid_chaos = (chaos >> 16) & 0xffff;
	350	uint64_t low_chaos = chaos & 0xffff;
	351
	352	unsigned me = map.self;
	353	unsigned cpu_chaos = map.start + (mid_chaos % map.count);
	354	bool global = cpu_chaos == me;
	355
	356	if(global) {
	357	proc->rdq.target = high_chaos % lanes.count;
	358	} else {
	359	proc->rdq.target = (cpu_chaos * READYQ_SHARD_FACTOR) + (low_chaos % READYQ_SHARD_FACTOR);
	360	/* paranoid / verify(proc->rdq.target >= (map.start READYQ_SHARD_FACTOR));
	361	/* paranoid / verify(proc->rdq.target < ((map.start + map.count) READYQ_SHARD_FACTOR));
	362	}
	363
	364	/* paranoid */ verify(proc->rdq.target != -1u);
[12daa43]	365	}
	366	else {
	367	const unsigned long long bias = 0; //2_500_000_000;
	368	const unsigned long long cutoff = proc->rdq.cutoff > bias ? proc->rdq.cutoff - bias : proc->rdq.cutoff;
	369	{
	370	unsigned target = proc->rdq.target;
	371	proc->rdq.target = -1u;
	372	if(lanes.tscs[target].tv < cutoff && ts(lanes.data[target]) < cutoff) {
[e84ab3d]	373	thread$ * t = try_pop(cltr, target __STATS(, __tls_stats()->ready.pop.help));
[12daa43]	374	proc->rdq.last = target;
	375	if(t) return t;
	376	}
	377	}
	378
	379	unsigned last = proc->rdq.last;
	380	if(last != -1u && lanes.tscs[last].tv < cutoff && ts(lanes.data[last]) < cutoff) {
[e84ab3d]	381	thread$ * t = try_pop(cltr, last __STATS(, __tls_stats()->ready.pop.help));
[12daa43]	382	if(t) return t;
	383	}
	384	else {
	385	proc->rdq.last = -1u;
	386	}
	387	}
	388
	389	for(READYQ_SHARD_FACTOR) {
	390	unsigned i = start + (proc->rdq.itr++ % READYQ_SHARD_FACTOR);
[e84ab3d]	391	if(thread$ * t = try_pop(cltr, i __STATS(, __tls_stats()->ready.pop.local))) return t;
[12daa43]	392	}
	393
	394	// All lanes where empty return 0p
	395	return 0p;
	396	}
	397
[e84ab3d]	398	__attribute__((hot)) struct thread$ * pop_slow(struct cluster * cltr) with (cltr->ready_queue) {
[12daa43]	399	processor * const proc = kernelTLS().this_processor;
	400	unsigned last = proc->rdq.last;
[953827a]	401	if(last != -1u) {
[e84ab3d]	402	struct thread$ * t = try_pop(cltr, last __STATS(, __tls_stats()->ready.pop.steal));
[953827a]	403	if(t) return t;
	404	proc->rdq.last = -1u;
	405	}
[12daa43]	406
	407	unsigned i = __tls_rand() % lanes.count;
	408	return try_pop(cltr, i __STATS(, __tls_stats()->ready.pop.steal));
	409	}
[e84ab3d]	410	__attribute__((hot)) struct thread$ * pop_search(struct cluster * cltr) {
[12daa43]	411	return search(cltr);
	412	}
	413	#endif
[431cd4f]	414	#if defined(USE_RELAXED_FIFO)
	415	//-----------------------------------------------------------------------
	416	// get index from random number with or without bias towards queues
	417	static inline [unsigned, bool] idx_from_r(unsigned r, unsigned preferred) {
	418	unsigned i;
	419	bool local;
	420	unsigned rlow = r % BIAS;
	421	unsigned rhigh = r / BIAS;
	422	if((0 != rlow) && preferred >= 0) {
	423	// (BIAS - 1) out of BIAS chances
	424	// Use perferred queues
	425	i = preferred + (rhigh % READYQ_SHARD_FACTOR);
	426	local = true;
	427	}
	428	else {
	429	// 1 out of BIAS chances
	430	// Use all queues
	431	i = rhigh;
	432	local = false;
	433	}
	434	return [i, local];
	435	}
	436
[e84ab3d]	437	__attribute__((hot)) void push(struct cluster * cltr, struct thread$ * thrd, bool push_local) with (cltr->ready_queue) {
[431cd4f]	438	__cfadbg_print_safe(ready_queue, "Kernel : Pushing %p on cluster %p\n", thrd, cltr);
[1b143de]	439
[b808625]	440	const bool external = !push_local \|\| (!kernelTLS().this_processor) \|\| (cltr != kernelTLS().this_processor->cltr);
[431cd4f]	441	/* paranoid */ verify(external \|\| kernelTLS().this_processor->rdq.id < lanes.count );
[fd1f65e]	442
[431cd4f]	443	bool local;
	444	int preferred = external ? -1 : kernelTLS().this_processor->rdq.id;
[52769ba]	445
[431cd4f]	446	// Try to pick a lane and lock it
	447	unsigned i;
	448	do {
	449	// Pick the index of a lane
	450	unsigned r = __tls_rand_fwd();
	451	[i, local] = idx_from_r(r, preferred);
[772411a]	452
[431cd4f]	453	i %= __atomic_load_n( &lanes.count, __ATOMIC_RELAXED );
	454
	455	#if !defined(__CFA_NO_STATISTICS__)
[d2fadeb]	456	if(unlikely(external)) __atomic_fetch_add(&cltr->stats->ready.push.extrn.attempt, 1, __ATOMIC_RELAXED);
	457	else if(local) __tls_stats()->ready.push.local.attempt++;
	458	else __tls_stats()->ready.push.share.attempt++;
[431cd4f]	459	#endif
[b798713]	460
[431cd4f]	461	// If we can't lock it retry
	462	} while( !__atomic_try_acquire( &lanes.data[i].lock ) );
	463
	464	// Actually push it
	465	push(lanes.data[i], thrd);
	466
[b808625]	467	// Unlock and return
	468	__atomic_unlock( &lanes.data[i].lock );
[431cd4f]	469
	470	// Mark the current index in the tls rng instance as having an item
	471	__tls_rand_advance_bck();
	472
	473	__cfadbg_print_safe(ready_queue, "Kernel : Pushed %p on cluster %p (idx: %u, mask %llu, first %d)\n", thrd, cltr, i, used.mask[0], lane_first);
	474
	475	// Update statistics
[b798713]	476	#if !defined(__CFA_NO_STATISTICS__)
[d2fadeb]	477	if(unlikely(external)) __atomic_fetch_add(&cltr->stats->ready.push.extrn.success, 1, __ATOMIC_RELAXED);
	478	else if(local) __tls_stats()->ready.push.local.success++;
	479	else __tls_stats()->ready.push.share.success++;
[b798713]	480	#endif
[431cd4f]	481	}
[b798713]	482
[431cd4f]	483	// Pop from the ready queue from a given cluster
[e84ab3d]	484	__attribute__((hot)) thread$ * pop_fast(struct cluster * cltr) with (cltr->ready_queue) {
[431cd4f]	485	/* paranoid */ verify( lanes.count > 0 );
	486	/* paranoid */ verify( kernelTLS().this_processor );
	487	/* paranoid */ verify( kernelTLS().this_processor->rdq.id < lanes.count );
[b798713]	488
[431cd4f]	489	unsigned count = __atomic_load_n( &lanes.count, __ATOMIC_RELAXED );
	490	int preferred = kernelTLS().this_processor->rdq.id;
[dca5802]	491
	492
[431cd4f]	493	// As long as the list is not empty, try finding a lane that isn't empty and pop from it
	494	for(25) {
	495	// Pick two lists at random
	496	unsigned ri = __tls_rand_bck();
	497	unsigned rj = __tls_rand_bck();
[c426b03]	498
[431cd4f]	499	unsigned i, j;
	500	__attribute__((unused)) bool locali, localj;
	501	[i, locali] = idx_from_r(ri, preferred);
	502	[j, localj] = idx_from_r(rj, preferred);
[1b143de]	503
[431cd4f]	504	i %= count;
	505	j %= count;
[9cc3a18]	506
[431cd4f]	507	// try popping from the 2 picked lists
[e84ab3d]	508	struct thread$ * thrd = try_pop(cltr, i, j __STATS(, *(locali \|\| localj ? &__tls_stats()->ready.pop.local : &__tls_stats()->ready.pop.help)));
[431cd4f]	509	if(thrd) {
	510	return thrd;
	511	}
	512	}
[13c5e19]	513
[431cd4f]	514	// All lanes where empty return 0p
	515	return 0p;
	516	}
[772411a]	517
[e84ab3d]	518	__attribute__((hot)) struct thread$ * pop_slow(struct cluster * cltr) { return pop_fast(cltr); }
	519	__attribute__((hot)) struct thread$ * pop_search(struct cluster * cltr) {
[431cd4f]	520	return search(cltr);
	521	}
	522	#endif
	523	#if defined(USE_WORK_STEALING)
[e84ab3d]	524	__attribute__((hot)) void push(struct cluster * cltr, struct thread$ * thrd, bool push_local) with (cltr->ready_queue) {
[431cd4f]	525	__cfadbg_print_safe(ready_queue, "Kernel : Pushing %p on cluster %p\n", thrd, cltr);
[772411a]	526
[d3ba775]	527	// #define USE_PREFERRED
	528	#if !defined(USE_PREFERRED)
[b808625]	529	const bool external = !push_local \|\| (!kernelTLS().this_processor) \|\| (cltr != kernelTLS().this_processor->cltr);
[431cd4f]	530	/* paranoid */ verify(external \|\| kernelTLS().this_processor->rdq.id < lanes.count );
[d3ba775]	531	#else
	532	unsigned preferred = thrd->preferred;
[b808625]	533	const bool external = push_local \|\| (!kernelTLS().this_processor) \|\| preferred == -1u \|\| thrd->curr_cluster != cltr;
[d3ba775]	534	/* paranoid */ verifyf(external \|\| preferred < lanes.count, "Invalid preferred queue %u for %u lanes", preferred, lanes.count );
[772411a]	535
[d3ba775]	536	unsigned r = preferred % READYQ_SHARD_FACTOR;
	537	const unsigned start = preferred - r;
[2b96031]	538	#endif
[431cd4f]	539
	540	// Try to pick a lane and lock it
	541	unsigned i;
	542	do {
[d2fadeb]	543	#if !defined(__CFA_NO_STATISTICS__)
	544	if(unlikely(external)) __atomic_fetch_add(&cltr->stats->ready.push.extrn.attempt, 1, __ATOMIC_RELAXED);
	545	else __tls_stats()->ready.push.local.attempt++;
	546	#endif
	547
[431cd4f]	548	if(unlikely(external)) {
	549	i = __tls_rand() % lanes.count;
	550	}
	551	else {
[d3ba775]	552	#if !defined(USE_PREFERRED)
[b808625]	553	processor * proc = kernelTLS().this_processor;
	554	unsigned r = proc->rdq.its++;
	555	i = proc->rdq.id + (r % READYQ_SHARD_FACTOR);
	556	#else
[d3ba775]	557	i = start + (r++ % READYQ_SHARD_FACTOR);
	558	#endif
	559	}
[431cd4f]	560	// If we can't lock it retry
	561	} while( !__atomic_try_acquire( &lanes.data[i].lock ) );
[13c5e19]	562
[431cd4f]	563	// Actually push it
	564	push(lanes.data[i], thrd);
[13c5e19]	565
[b808625]	566	// Unlock and return
	567	__atomic_unlock( &lanes.data[i].lock );
[431cd4f]	568
[d2fadeb]	569	#if !defined(__CFA_NO_STATISTICS__)
	570	if(unlikely(external)) __atomic_fetch_add(&cltr->stats->ready.push.extrn.success, 1, __ATOMIC_RELAXED);
	571	else __tls_stats()->ready.push.local.success++;
	572	#endif
	573
[431cd4f]	574	__cfadbg_print_safe(ready_queue, "Kernel : Pushed %p on cluster %p (idx: %u, mask %llu, first %d)\n", thrd, cltr, i, used.mask[0], lane_first);
[13c5e19]	575	}
	576
[431cd4f]	577	// Pop from the ready queue from a given cluster
[e84ab3d]	578	__attribute__((hot)) thread$ * pop_fast(struct cluster * cltr) with (cltr->ready_queue) {
[431cd4f]	579	/* paranoid */ verify( lanes.count > 0 );
	580	/* paranoid */ verify( kernelTLS().this_processor );
	581	/* paranoid */ verify( kernelTLS().this_processor->rdq.id < lanes.count );
	582
	583	processor * proc = kernelTLS().this_processor;
	584
	585	if(proc->rdq.target == -1u) {
[1680072]	586	unsigned long long min = ts(lanes.data[proc->rdq.id]);
	587	for(int i = 0; i < READYQ_SHARD_FACTOR; i++) {
	588	unsigned long long tsc = ts(lanes.data[proc->rdq.id + i]);
	589	if(tsc < min) min = tsc;
	590	}
	591	proc->rdq.cutoff = min;
[f55d54d]	592	proc->rdq.target = __tls_rand() % lanes.count;
[431cd4f]	593	}
[341aa39]	594	else {
	595	unsigned target = proc->rdq.target;
[431cd4f]	596	proc->rdq.target = -1u;
[9cac0da]	597	const unsigned long long bias = 0; //2_500_000_000;
	598	const unsigned long long cutoff = proc->rdq.cutoff > bias ? proc->rdq.cutoff - bias : proc->rdq.cutoff;
	599	if(lanes.tscs[target].tv < cutoff && ts(lanes.data[target]) < cutoff) {
[e84ab3d]	600	thread$ * t = try_pop(cltr, target __STATS(, __tls_stats()->ready.pop.help));
[341aa39]	601	if(t) return t;
	602	}
[431cd4f]	603	}
[13c5e19]	604
[431cd4f]	605	for(READYQ_SHARD_FACTOR) {
[f55d54d]	606	unsigned i = proc->rdq.id + (proc->rdq.itr++ % READYQ_SHARD_FACTOR);
[e84ab3d]	607	if(thread$ * t = try_pop(cltr, i __STATS(, __tls_stats()->ready.pop.local))) return t;
[431cd4f]	608	}
	609	return 0p;
[1eb239e4]	610	}
	611
[e84ab3d]	612	__attribute__((hot)) struct thread$ * pop_slow(struct cluster * cltr) with (cltr->ready_queue) {
[fc59df78]	613	unsigned i = __tls_rand() % lanes.count;
	614	return try_pop(cltr, i __STATS(, __tls_stats()->ready.pop.steal));
	615	}
[431cd4f]	616
[e84ab3d]	617	__attribute__((hot)) struct thread$ * pop_search(struct cluster * cltr) with (cltr->ready_queue) {
[431cd4f]	618	return search(cltr);
	619	}
	620	#endif
[1eb239e4]	621
[9cc3a18]	622	//=======================================================================
	623	// Various Ready Queue utilities
	624	//=======================================================================
	625	// these function work the same or almost the same
	626	// whether they are using work-stealing or relaxed fifo scheduling
[1eb239e4]	627
[9cc3a18]	628	//-----------------------------------------------------------------------
	629	// try to pop from a lane given by index w
[e84ab3d]	630	static inline struct thread$ * try_pop(struct cluster * cltr, unsigned w __STATS(, __stats_readyQ_pop_t & stats)) with (cltr->ready_queue) {
[d2fadeb]	631	__STATS( stats.attempt++; )
	632
[dca5802]	633	// Get relevant elements locally
	634	__intrusive_lane_t & lane = lanes.data[w];
	635
[b798713]	636	// If list looks empty retry
[d2fadeb]	637	if( is_empty(lane) ) {
	638	return 0p;
	639	}
[b798713]	640
	641	// If we can't get the lock retry
[d2fadeb]	642	if( !__atomic_try_acquire(&lane.lock) ) {
	643	return 0p;
	644	}
[b798713]	645
	646	// If list is empty, unlock and retry
[dca5802]	647	if( is_empty(lane) ) {
	648	__atomic_unlock(&lane.lock);
[b798713]	649	return 0p;
	650	}
	651
	652	// Actually pop the list
[e84ab3d]	653	struct thread$ * thrd;
[f302d80]	654	unsigned long long tsv;
	655	[thrd, tsv] = pop(lane);
[b798713]	656
[dca5802]	657	/* paranoid */ verify(thrd);
[78ea291]	658	/* paranoid */ verify(tsv);
[dca5802]	659	/* paranoid */ verify(lane.lock);
[b798713]	660
	661	// Unlock and return
[dca5802]	662	__atomic_unlock(&lane.lock);
[b798713]	663
[dca5802]	664	// Update statistics
[d2fadeb]	665	__STATS( stats.success++; )
[b798713]	666
[431cd4f]	667	#if defined(USE_WORK_STEALING)
[f302d80]	668	lanes.tscs[w].tv = tsv;
[9cc3a18]	669	#endif
[d72c074]	670
[d3ba775]	671	thrd->preferred = w;
	672
[dca5802]	673	// return the popped thread
[b798713]	674	return thrd;
	675	}
[04b5cef]	676
[9cc3a18]	677	//-----------------------------------------------------------------------
	678	// try to pop from any lanes making sure you don't miss any threads push
	679	// before the start of the function
[e84ab3d]	680	static inline struct thread$ * search(struct cluster * cltr) with (cltr->ready_queue) {
[9cc3a18]	681	/* paranoid */ verify( lanes.count > 0 );
	682	unsigned count = __atomic_load_n( &lanes.count, __ATOMIC_RELAXED );
	683	unsigned offset = __tls_rand();
	684	for(i; count) {
	685	unsigned idx = (offset + i) % count;
[e84ab3d]	686	struct thread$ * thrd = try_pop(cltr, idx __STATS(, __tls_stats()->ready.pop.search));
[9cc3a18]	687	if(thrd) {
	688	return thrd;
	689	}
[13c5e19]	690	}
[9cc3a18]	691
	692	// All lanes where empty return 0p
	693	return 0p;
[b798713]	694	}
	695
	696	//-----------------------------------------------------------------------
[9cc3a18]	697	// Check that all the intrusive queues in the data structure are still consistent
[b798713]	698	static void check( __ready_queue_t & q ) with (q) {
[d3ba775]	699	#if defined(__CFA_WITH_VERIFY__)
[b798713]	700	{
[dca5802]	701	for( idx ; lanes.count ) {
	702	__intrusive_lane_t & sl = lanes.data[idx];
	703	assert(!lanes.data[idx].lock);
[b798713]	704
[2b96031]	705	if(is_empty(sl)) {
	706	assert( sl.anchor.next == 0p );
[ef94ae7]	707	assert( sl.anchor.ts == -1llu );
[2b96031]	708	assert( mock_head(sl) == sl.prev );
	709	} else {
	710	assert( sl.anchor.next != 0p );
[ef94ae7]	711	assert( sl.anchor.ts != -1llu );
[2b96031]	712	assert( mock_head(sl) != sl.prev );
	713	}
[b798713]	714	}
	715	}
	716	#endif
	717	}
	718
[9cc3a18]	719	//-----------------------------------------------------------------------
	720	// Given 2 indexes, pick the list with the oldest push an try to pop from it
[e84ab3d]	721	static inline struct thread$ * try_pop(struct cluster * cltr, unsigned i, unsigned j __STATS(, __stats_readyQ_pop_t & stats)) with (cltr->ready_queue) {
[9cc3a18]	722	// Pick the bet list
	723	int w = i;
	724	if( __builtin_expect(!is_empty(lanes.data[j]), true) ) {
	725	w = (ts(lanes.data[i]) < ts(lanes.data[j])) ? i : j;
	726	}
	727
[d2fadeb]	728	return try_pop(cltr, w __STATS(, stats));
[9cc3a18]	729	}
	730
[b798713]	731	// Call this function of the intrusive list was moved using memcpy
[dca5802]	732	// fixes the list so that the pointers back to anchors aren't left dangling
	733	static inline void fix(__intrusive_lane_t & ll) {
[2b96031]	734	if(is_empty(ll)) {
	735	verify(ll.anchor.next == 0p);
	736	ll.prev = mock_head(ll);
	737	}
[b798713]	738	}
	739
[69914cbc]	740	static void assign_list(unsigned & value, dlist(processor) & list, unsigned count) {
[a017ee7]	741	processor * it = &list`first;
	742	for(unsigned i = 0; i < count; i++) {
	743	/* paranoid */ verifyf( it, "Unexpected null iterator, at index %u of %u\n", i, count);
[431cd4f]	744	it->rdq.id = value;
	745	it->rdq.target = -1u;
[9cc3a18]	746	value += READYQ_SHARD_FACTOR;
[a017ee7]	747	it = &(*it)`next;
	748	}
	749	}
	750
[9cc3a18]	751	static void reassign_cltr_id(struct cluster * cltr) {
[a017ee7]	752	unsigned preferred = 0;
[9cc3a18]	753	assign_list(preferred, cltr->procs.actives, cltr->procs.total - cltr->procs.idle);
	754	assign_list(preferred, cltr->procs.idles , cltr->procs.idle );
[a017ee7]	755	}
	756
[431cd4f]	757	static void fix_times( struct cluster * cltr ) with( cltr->ready_queue ) {
	758	#if defined(USE_WORK_STEALING)
	759	lanes.tscs = alloc(lanes.count, lanes.tscs`realloc);
	760	for(i; lanes.count) {
[ef94ae7]	761	unsigned long long tsc1 = ts(lanes.data[i]);
[6ba6846]	762	unsigned long long tsc2 = rdtscl();
[ef94ae7]	763	lanes.tscs[i].tv = min(tsc1, tsc2);
[431cd4f]	764	}
	765	#endif
	766	}
	767
[12daa43]	768	#if defined(USE_CPU_WORK_STEALING)
	769	// ready_queue size is fixed in this case
	770	void ready_queue_grow(struct cluster * cltr) {}
	771	void ready_queue_shrink(struct cluster * cltr) {}
	772	#else
	773	// Grow the ready queue
	774	void ready_queue_grow(struct cluster * cltr) {
	775	size_t ncount;
	776	int target = cltr->procs.total;
	777
	778	/* paranoid */ verify( ready_mutate_islocked() );
	779	__cfadbg_print_safe(ready_queue, "Kernel : Growing ready queue\n");
	780
	781	// Make sure that everything is consistent
	782	/* paranoid */ check( cltr->ready_queue );
	783
	784	// grow the ready queue
	785	with( cltr->ready_queue ) {
	786	// Find new count
	787	// Make sure we always have atleast 1 list
	788	if(target >= 2) {
	789	ncount = target * READYQ_SHARD_FACTOR;
	790	} else {
	791	ncount = SEQUENTIAL_SHARD;
	792	}
[b798713]	793
[12daa43]	794	// Allocate new array (uses realloc and memcpies the data)
	795	lanes.data = alloc( ncount, lanes.data`realloc );
[b798713]	796
[12daa43]	797	// Fix the moved data
	798	for( idx; (size_t)lanes.count ) {
	799	fix(lanes.data[idx]);
	800	}
[b798713]	801
[12daa43]	802	// Construct new data
	803	for( idx; (size_t)lanes.count ~ ncount) {
	804	(lanes.data[idx]){};
	805	}
[b798713]	806
[12daa43]	807	// Update original
	808	lanes.count = ncount;
	809	}
[b798713]	810
[12daa43]	811	fix_times(cltr);
[9cc3a18]	812
[12daa43]	813	reassign_cltr_id(cltr);
[a017ee7]	814
[12daa43]	815	// Make sure that everything is consistent
	816	/* paranoid */ check( cltr->ready_queue );
[dca5802]	817
[12daa43]	818	__cfadbg_print_safe(ready_queue, "Kernel : Growing ready queue done\n");
[dca5802]	819
[12daa43]	820	/* paranoid */ verify( ready_mutate_islocked() );
	821	}
[b798713]	822
[12daa43]	823	// Shrink the ready queue
	824	void ready_queue_shrink(struct cluster * cltr) {
	825	/* paranoid */ verify( ready_mutate_islocked() );
	826	__cfadbg_print_safe(ready_queue, "Kernel : Shrinking ready queue\n");
[dca5802]	827
[12daa43]	828	// Make sure that everything is consistent
	829	/* paranoid */ check( cltr->ready_queue );
[dca5802]	830
[12daa43]	831	int target = cltr->procs.total;
[a017ee7]	832
[12daa43]	833	with( cltr->ready_queue ) {
	834	// Remember old count
	835	size_t ocount = lanes.count;
[b798713]	836
[12daa43]	837	// Find new count
	838	// Make sure we always have atleast 1 list
	839	lanes.count = target >= 2 ? target * READYQ_SHARD_FACTOR: SEQUENTIAL_SHARD;
	840	/* paranoid */ verify( ocount >= lanes.count );
	841	/* paranoid / verify( lanes.count == target READYQ_SHARD_FACTOR \|\| target < 2 );
[dca5802]	842
[12daa43]	843	// for printing count the number of displaced threads
	844	#if defined(__CFA_DEBUG_PRINT__) \|\| defined(__CFA_DEBUG_PRINT_READY_QUEUE__)
	845	__attribute__((unused)) size_t displaced = 0;
	846	#endif
[b798713]	847
[12daa43]	848	// redistribute old data
	849	for( idx; (size_t)lanes.count ~ ocount) {
	850	// Lock is not strictly needed but makes checking invariants much easier
	851	__attribute__((unused)) bool locked = __atomic_try_acquire(&lanes.data[idx].lock);
	852	verify(locked);
[dca5802]	853
[12daa43]	854	// As long as we can pop from this lane to push the threads somewhere else in the queue
	855	while(!is_empty(lanes.data[idx])) {
[e84ab3d]	856	struct thread$ * thrd;
[12daa43]	857	unsigned long long _;
	858	[thrd, _] = pop(lanes.data[idx]);
[dca5802]	859
[12daa43]	860	push(cltr, thrd, true);
[dca5802]	861
[12daa43]	862	// for printing count the number of displaced threads
	863	#if defined(__CFA_DEBUG_PRINT__) \|\| defined(__CFA_DEBUG_PRINT_READY_QUEUE__)
	864	displaced++;
	865	#endif
	866	}
[b798713]	867
[12daa43]	868	// Unlock the lane
	869	__atomic_unlock(&lanes.data[idx].lock);
[b798713]	870
[12daa43]	871	// TODO print the queue statistics here
[b798713]	872
[12daa43]	873	^(lanes.data[idx]){};
	874	}
[b798713]	875
[12daa43]	876	__cfadbg_print_safe(ready_queue, "Kernel : Shrinking ready queue displaced %zu threads\n", displaced);
[c84b4be]	877
[12daa43]	878	// Allocate new array (uses realloc and memcpies the data)
	879	lanes.data = alloc( lanes.count, lanes.data`realloc );
[b798713]	880
[12daa43]	881	// Fix the moved data
	882	for( idx; (size_t)lanes.count ) {
	883	fix(lanes.data[idx]);
	884	}
[b798713]	885	}
	886
[12daa43]	887	fix_times(cltr);
[9cc3a18]	888
[12daa43]	889	reassign_cltr_id(cltr);
[a017ee7]	890
[12daa43]	891	// Make sure that everything is consistent
	892	/* paranoid */ check( cltr->ready_queue );
[dca5802]	893
[12daa43]	894	__cfadbg_print_safe(ready_queue, "Kernel : Shrinking ready queue done\n");
	895	/* paranoid */ verify( ready_mutate_islocked() );
	896	}
	897	#endif
[8cd5434]	898
	899	#if !defined(__CFA_NO_STATISTICS__)
	900	unsigned cnt(const __ready_queue_t & this, unsigned idx) {
	901	/* paranoid */ verify(this.lanes.count > idx);
	902	return this.lanes.data[idx].cnt;
	903	}
	904	#endif
[0ee224b]	905
	906
	907	#if defined(CFA_HAVE_LINUX_LIBRSEQ)
	908	// No definition needed
	909	#elif defined(CFA_HAVE_LINUX_RSEQ_H)
	910
	911	#if defined( __x86_64 ) \|\| defined( __i386 )
	912	#define RSEQ_SIG 0x53053053
	913	#elif defined( __ARM_ARCH )
	914	#ifdef __ARMEB__
	915	#define RSEQ_SIG 0xf3def5e7 /* udf #24035 ; 0x5de3 (ARMv6+) */
	916	#else
	917	#define RSEQ_SIG 0xe7f5def3 /* udf #24035 ; 0x5de3 */
	918	#endif
	919	#endif
	920
	921	extern void __disable_interrupts_hard();
	922	extern void __enable_interrupts_hard();
	923
	924	void __kernel_raw_rseq_register (void) {
	925	/* paranoid */ verify( __cfaabi_rseq.cpu_id == RSEQ_CPU_ID_UNINITIALIZED );
	926
	927	// int ret = syscall(__NR_rseq, &__cfaabi_rseq, sizeof(struct rseq), 0, (sigset_t *)0p, _NSIG / 8);
	928	int ret = syscall(__NR_rseq, &__cfaabi_rseq, sizeof(struct rseq), 0, RSEQ_SIG);
	929	if(ret != 0) {
	930	int e = errno;
	931	switch(e) {
	932	case EINVAL: abort("KERNEL ERROR: rseq register invalid argument");
	933	case ENOSYS: abort("KERNEL ERROR: rseq register no supported");
	934	case EFAULT: abort("KERNEL ERROR: rseq register with invalid argument");
	935	case EBUSY : abort("KERNEL ERROR: rseq register already registered");
	936	case EPERM : abort("KERNEL ERROR: rseq register sig argument on unregistration does not match the signature received on registration");
	937	default: abort("KERNEL ERROR: rseq register unexpected return %d", e);
	938	}
	939	}
	940	}
	941
	942	void __kernel_raw_rseq_unregister(void) {
	943	/* paranoid */ verify( __cfaabi_rseq.cpu_id >= 0 );
	944
	945	// int ret = syscall(__NR_rseq, &__cfaabi_rseq, sizeof(struct rseq), RSEQ_FLAG_UNREGISTER, (sigset_t *)0p, _NSIG / 8);
	946	int ret = syscall(__NR_rseq, &__cfaabi_rseq, sizeof(struct rseq), RSEQ_FLAG_UNREGISTER, RSEQ_SIG);
	947	if(ret != 0) {
	948	int e = errno;
	949	switch(e) {
	950	case EINVAL: abort("KERNEL ERROR: rseq unregister invalid argument");
	951	case ENOSYS: abort("KERNEL ERROR: rseq unregister no supported");
	952	case EFAULT: abort("KERNEL ERROR: rseq unregister with invalid argument");
	953	case EBUSY : abort("KERNEL ERROR: rseq unregister already registered");
	954	case EPERM : abort("KERNEL ERROR: rseq unregister sig argument on unregistration does not match the signature received on registration");
	955	default: abort("KERNEL ERROR: rseq unregisteunexpected return %d", e);
	956	}
	957	}
	958	}
	959	#else
	960	// No definition needed
	961	#endif

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