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ready_queue.cfa @ 637240f

ADTast-experimentalenumforall-pointer-decaypthread-emulationqualifiedEnum

Last change on this file since 637240f was 75c7252, checked in by Thierry Delisle <tdelisle@…>, 3 years ago
CPU workstealing now has correct remote unpark.
Property mode set to `100644`
File size: 33.3 KB

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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__
17	#define _GNU_SOURCE
18
19	// #define __CFA_DEBUG_PRINT_READY_QUEUE__
20
21
22	#define USE_RELAXED_FIFO
23	// #define USE_WORK_STEALING
24	// #define USE_CPU_WORK_STEALING
25
26	#include "bits/defs.hfa"
27	#include "device/cpu.hfa"
28	#include "kernel_private.hfa"
29
30	#include "stdlib.hfa"
31	#include "math.hfa"
32
33	#include <errno.h>
34	#include <unistd.h>
35
36	extern "C" {
37	#include <sys/syscall.h> // __NR_xxx
38	}
39
40	#include "ready_subqueue.hfa"
41
42	static const size_t cache_line_size = 64;
43
44	#if !defined(__CFA_NO_STATISTICS__)
45	#define __STATS(...) __VA_ARGS__
46	#else
47	#define __STATS(...)
48	#endif
49
50	// No overriden function, no environment variable, no define
51	// fall back to a magic number
52	#ifndef __CFA_MAX_PROCESSORS__
53	#define __CFA_MAX_PROCESSORS__ 1024
54	#endif
55
56	#if defined(USE_CPU_WORK_STEALING)
57	#define READYQ_SHARD_FACTOR 2
58	#elif defined(USE_RELAXED_FIFO)
59	#define BIAS 4
60	#define READYQ_SHARD_FACTOR 4
61	#define SEQUENTIAL_SHARD 1
62	#elif defined(USE_WORK_STEALING)
63	#define READYQ_SHARD_FACTOR 2
64	#define SEQUENTIAL_SHARD 2
65	#else
66	#error no scheduling strategy selected
67	#endif
68
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);
72	static inline [unsigned, bool] idx_from_r(unsigned r, unsigned preferred);
73
74
75	// returns the maximum number of processors the RWLock support
76	__attribute__((weak)) unsigned __max_processors() {
77	const char * max_cores_s = getenv("CFA_MAX_PROCESSORS");
78	if(!max_cores_s) {
79	__cfadbg_print_nolock(ready_queue, "No CFA_MAX_PROCESSORS in ENV\n");
80	return __CFA_MAX_PROCESSORS__;
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) {
86	__cfadbg_print_nolock(ready_queue, "CFA_MAX_PROCESSORS out of range : %ld\n", max_cores_l);
87	return __CFA_MAX_PROCESSORS__;
88	}
89	if('\0' != *endptr) {
90	__cfadbg_print_nolock(ready_queue, "CFA_MAX_PROCESSORS not a decimal number : %s\n", max_cores_s);
91	return __CFA_MAX_PROCESSORS__;
92	}
93
94	return max_cores_l;
95	}
96
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	static void __kernel_raw_rseq_register (void);
103	static 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
116	//=======================================================================
117	// Cluster wide reader-writer lock
118	//=======================================================================
119	void ?{}(__scheduler_RWLock_t & this) {
120	this.max = __max_processors();
121	this.alloc = 0;
122	this.ready = 0;
123	this.data = alloc(this.max);
124	this.write_lock = false;
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	}
130	void ^?{}(__scheduler_RWLock_t & this) {
131	free(this.data);
132	}
133
134
135	//=======================================================================
136	// Lock-Free registering/unregistering of threads
137	unsigned register_proc_id( void ) with(*__scheduler_lock) {
138	__kernel_rseq_register();
139
140	__cfadbg_print_safe(ready_queue, "Kernel : Registering proc %p for RW-Lock\n", proc);
141	bool * handle = (bool *)&kernelTLS().sched_lock;
142
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++) {
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;
157	}
158	}
159
160	if(max <= alloc) abort("Trying to create more than %ud processors", __scheduler_lock->max);
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);
164	if(max <= n) abort("Trying to create more than %ud processors", __scheduler_lock->max);
165
166	// Step - 3 : Mark space as used and then publish it.
167	data[n] = handle;
168	while() {
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;
173	Pause();
174	}
175
176	__cfadbg_print_safe(ready_queue, "Kernel : Registering proc %p done, id %lu\n", proc, n);
177
178	// Return new spot.
179	/* paranoid */ verify(n < ready);
180	/* paranoid */ verify( (kernelTLS().sched_id = n, true) );
181	return n;
182	}
183
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);
192
193	__cfadbg_print_safe(ready_queue, "Kernel : Unregister proc %p\n", proc);
194
195	__kernel_rseq_unregister();
196	}
197
198	//-----------------------------------------------------------------------
199	// Writer side : acquire when changing the ready queue, e.g. adding more
200	// queues or removing them.
201	uint_fast32_t ready_mutate_lock( void ) with(*__scheduler_lock) {
202	/* paranoid */ verify( ! __preemption_enabled() );
203	/* paranoid */ verify( ! kernelTLS().sched_lock );
204
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.
208	__atomic_acquire( &write_lock );
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++) {
216	volatile bool * llock = data[i];
217	if(llock) __atomic_acquire( llock );
218	}
219
220	/* paranoid */ verify( ! __preemption_enabled() );
221	return s;
222	}
223
224	void ready_mutate_unlock( uint_fast32_t last_s ) with(*__scheduler_lock) {
225	/* paranoid */ verify( ! __preemption_enabled() );
226
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++) {
234	volatile bool * llock = data[i];
235	if(llock) __atomic_store_n(llock, (bool)false, __ATOMIC_RELEASE);
236	}
237
238	// Step 2 : release global lock
239	/paranoid/ assert(true == write_lock);
240	__atomic_store_n(&write_lock, (bool)false, __ATOMIC_RELEASE);
241
242	/* paranoid */ verify( ! __preemption_enabled() );
243	}
244
245	//=======================================================================
246	// Cforall Ready Queue used for scheduling
247	//=======================================================================
248	unsigned long long moving_average(unsigned long long nval, unsigned long long oval) {
249	const unsigned long long tw = 16;
250	const unsigned long long nw = 4;
251	const unsigned long long ow = tw - nw;
252	return ((nw * nval) + (ow * oval)) / tw;
253	}
254
255	void ?{}(__ready_queue_t & this) with (this) {
256	#if defined(USE_CPU_WORK_STEALING)
257	lanes.count = cpu_info.hthrd_count * READYQ_SHARD_FACTOR;
258	lanes.data = alloc( lanes.count );
259	lanes.tscs = alloc( lanes.count );
260	lanes.help = alloc( cpu_info.hthrd_count );
261
262	for( idx; (size_t)lanes.count ) {
263	(lanes.data[idx]){};
264	lanes.tscs[idx].tv = rdtscl();
265	lanes.tscs[idx].ma = rdtscl();
266	}
267	for( idx; (size_t)cpu_info.hthrd_count ) {
268	lanes.help[idx].src = 0;
269	lanes.help[idx].dst = 0;
270	lanes.help[idx].tri = 0;
271	}
272	#else
273	lanes.data = 0p;
274	lanes.tscs = 0p;
275	lanes.help = 0p;
276	lanes.count = 0;
277	#endif
278	}
279
280	void ^?{}(__ready_queue_t & this) with (this) {
281	#if !defined(USE_CPU_WORK_STEALING)
282	verify( SEQUENTIAL_SHARD == lanes.count );
283	#endif
284
285	free(lanes.data);
286	free(lanes.tscs);
287	free(lanes.help);
288	}
289
290	//-----------------------------------------------------------------------
291	#if defined(USE_CPU_WORK_STEALING)
292	__attribute__((hot)) void push(struct cluster * cltr, struct thread$ * thrd, unpark_hint hint) with (cltr->ready_queue) {
293	__cfadbg_print_safe(ready_queue, "Kernel : Pushing %p on cluster %p\n", thrd, cltr);
294
295	processor * const proc = kernelTLS().this_processor;
296	const bool external = (!proc) \|\| (cltr != proc->cltr);
297
298	// Figure out the current cpu and make sure it is valid
299	const int cpu = __kernel_getcpu();
300	/* paranoid */ verify(cpu >= 0);
301	/* paranoid */ verify(cpu < cpu_info.hthrd_count);
302	/* paranoid / verify(cpu READYQ_SHARD_FACTOR < lanes.count);
303
304	// Figure out where thread was last time and make sure it's
305	/* paranoid */ verify(thrd->preferred >= 0);
306	/* paranoid */ verify(thrd->preferred < cpu_info.hthrd_count);
307	/* paranoid / verify(thrd->preferred READYQ_SHARD_FACTOR < lanes.count);
308	const int prf = thrd->preferred * READYQ_SHARD_FACTOR;
309
310	const cpu_map_entry_t & map;
311	choose(hint) {
312	case UNPARK_LOCAL : &map = &cpu_info.llc_map[cpu];
313	case UNPARK_REMOTE: &map = &cpu_info.llc_map[prf];
314	}
315	/* paranoid / verify(map.start READYQ_SHARD_FACTOR < lanes.count);
316	/* paranoid / verify(map.self READYQ_SHARD_FACTOR < lanes.count);
317	/* 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);
318
319	const int start = map.self * READYQ_SHARD_FACTOR;
320	unsigned i;
321	do {
322	unsigned r;
323	if(unlikely(external)) { r = __tls_rand(); }
324	else { r = proc->rdq.its++; }
325	choose(hint) {
326	case UNPARK_LOCAL : i = start + (r % READYQ_SHARD_FACTOR);
327	case UNPARK_REMOTE: i = prf + (r % READYQ_SHARD_FACTOR);
328	}
329	// If we can't lock it retry
330	} while( !__atomic_try_acquire( &lanes.data[i].lock ) );
331
332	// Actually push it
333	push(lanes.data[i], thrd);
334
335	// Unlock and return
336	__atomic_unlock( &lanes.data[i].lock );
337
338	#if !defined(__CFA_NO_STATISTICS__)
339	if(unlikely(external)) __atomic_fetch_add(&cltr->stats->ready.push.extrn.success, 1, __ATOMIC_RELAXED);
340	else __tls_stats()->ready.push.local.success++;
341	#endif
342
343	__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);
344
345	}
346
347	// Pop from the ready queue from a given cluster
348	__attribute__((hot)) thread$ * pop_fast(struct cluster * cltr) with (cltr->ready_queue) {
349	/* paranoid */ verify( lanes.count > 0 );
350	/* paranoid */ verify( kernelTLS().this_processor );
351
352	const int cpu = __kernel_getcpu();
353	/* paranoid */ verify(cpu >= 0);
354	/* paranoid */ verify(cpu < cpu_info.hthrd_count);
355	/* paranoid / verify(cpu READYQ_SHARD_FACTOR < lanes.count);
356
357	const cpu_map_entry_t & map = cpu_info.llc_map[cpu];
358	/* paranoid / verify(map.start READYQ_SHARD_FACTOR < lanes.count);
359	/* paranoid / verify(map.self READYQ_SHARD_FACTOR < lanes.count);
360	/* 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);
361
362	processor * const proc = kernelTLS().this_processor;
363	const int start = map.self * READYQ_SHARD_FACTOR;
364	const unsigned long long ctsc = rdtscl();
365
366	// Did we already have a help target
367	if(proc->rdq.target == -1u) {
368	unsigned long long max = 0;
369	for(i; READYQ_SHARD_FACTOR) {
370	unsigned long long tsc = moving_average(ctsc - ts(lanes.data[start + i]), lanes.tscs[start + i].ma);
371	if(tsc > max) max = tsc;
372	}
373	proc->rdq.cutoff = (max + 2 * max) / 2;
374	/* paranoid */ verify(lanes.count < 65536); // The following code assumes max 65536 cores.
375	/* paranoid */ verify(map.count < 65536); // The following code assumes max 65536 cores.
376
377	if(0 == (__tls_rand() % 100)) {
378	proc->rdq.target = __tls_rand() % lanes.count;
379	} else {
380	unsigned cpu_chaos = map.start + (__tls_rand() % map.count);
381	proc->rdq.target = (cpu_chaos * READYQ_SHARD_FACTOR) + (__tls_rand() % READYQ_SHARD_FACTOR);
382	/* paranoid / verify(proc->rdq.target >= (map.start READYQ_SHARD_FACTOR));
383	/* paranoid / verify(proc->rdq.target < ((map.start + map.count) READYQ_SHARD_FACTOR));
384	}
385
386	/* paranoid */ verify(proc->rdq.target != -1u);
387	}
388	else {
389	unsigned long long max = 0;
390	for(i; READYQ_SHARD_FACTOR) {
391	unsigned long long tsc = moving_average(ctsc - ts(lanes.data[start + i]), lanes.tscs[start + i].ma);
392	if(tsc > max) max = tsc;
393	}
394	const unsigned long long cutoff = (max + 2 * max) / 2;
395	{
396	unsigned target = proc->rdq.target;
397	proc->rdq.target = -1u;
398	lanes.help[target / READYQ_SHARD_FACTOR].tri++;
399	if(moving_average(ctsc - lanes.tscs[target].tv, lanes.tscs[target].ma) > cutoff) {
400	thread$ * t = try_pop(cltr, target __STATS(, __tls_stats()->ready.pop.help));
401	proc->rdq.last = target;
402	if(t) return t;
403	else proc->rdq.target = -1u;
404	}
405	else proc->rdq.target = -1u;
406	}
407
408	unsigned last = proc->rdq.last;
409	if(last != -1u && lanes.tscs[last].tv < cutoff && ts(lanes.data[last]) < cutoff) {
410	thread$ * t = try_pop(cltr, last __STATS(, __tls_stats()->ready.pop.help));
411	if(t) return t;
412	}
413	else {
414	proc->rdq.last = -1u;
415	}
416	}
417
418	for(READYQ_SHARD_FACTOR) {
419	unsigned i = start + (proc->rdq.itr++ % READYQ_SHARD_FACTOR);
420	if(thread$ * t = try_pop(cltr, i __STATS(, __tls_stats()->ready.pop.local))) return t;
421	}
422
423	// All lanes where empty return 0p
424	return 0p;
425	}
426
427	__attribute__((hot)) struct thread$ * pop_slow(struct cluster * cltr) with (cltr->ready_queue) {
428	processor * const proc = kernelTLS().this_processor;
429	unsigned last = proc->rdq.last;
430	if(last != -1u) {
431	struct thread$ * t = try_pop(cltr, last __STATS(, __tls_stats()->ready.pop.steal));
432	if(t) return t;
433	proc->rdq.last = -1u;
434	}
435
436	unsigned i = __tls_rand() % lanes.count;
437	return try_pop(cltr, i __STATS(, __tls_stats()->ready.pop.steal));
438	}
439	__attribute__((hot)) struct thread$ * pop_search(struct cluster * cltr) {
440	return search(cltr);
441	}
442	#endif
443	#if defined(USE_RELAXED_FIFO)
444	//-----------------------------------------------------------------------
445	// get index from random number with or without bias towards queues
446	static inline [unsigned, bool] idx_from_r(unsigned r, unsigned preferred) {
447	unsigned i;
448	bool local;
449	unsigned rlow = r % BIAS;
450	unsigned rhigh = r / BIAS;
451	if((0 != rlow) && preferred >= 0) {
452	// (BIAS - 1) out of BIAS chances
453	// Use perferred queues
454	i = preferred + (rhigh % READYQ_SHARD_FACTOR);
455	local = true;
456	}
457	else {
458	// 1 out of BIAS chances
459	// Use all queues
460	i = rhigh;
461	local = false;
462	}
463	return [i, local];
464	}
465
466	__attribute__((hot)) void push(struct cluster * cltr, struct thread$ * thrd, unpark_hint hint) with (cltr->ready_queue) {
467	__cfadbg_print_safe(ready_queue, "Kernel : Pushing %p on cluster %p\n", thrd, cltr);
468
469	const bool external = (hint != UNPARK_LOCAL) \|\| (!kernelTLS().this_processor) \|\| (cltr != kernelTLS().this_processor->cltr);
470	/* paranoid */ verify(external \|\| kernelTLS().this_processor->rdq.id < lanes.count );
471
472	bool local;
473	int preferred = external ? -1 : kernelTLS().this_processor->rdq.id;
474
475	// Try to pick a lane and lock it
476	unsigned i;
477	do {
478	// Pick the index of a lane
479	unsigned r = __tls_rand_fwd();
480	[i, local] = idx_from_r(r, preferred);
481
482	i %= __atomic_load_n( &lanes.count, __ATOMIC_RELAXED );
483
484	#if !defined(__CFA_NO_STATISTICS__)
485	if(unlikely(external)) __atomic_fetch_add(&cltr->stats->ready.push.extrn.attempt, 1, __ATOMIC_RELAXED);
486	else if(local) __tls_stats()->ready.push.local.attempt++;
487	else __tls_stats()->ready.push.share.attempt++;
488	#endif
489
490	// If we can't lock it retry
491	} while( !__atomic_try_acquire( &lanes.data[i].lock ) );
492
493	// Actually push it
494	push(lanes.data[i], thrd);
495
496	// Unlock and return
497	__atomic_unlock( &lanes.data[i].lock );
498
499	// Mark the current index in the tls rng instance as having an item
500	__tls_rand_advance_bck();
501
502	__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);
503
504	// Update statistics
505	#if !defined(__CFA_NO_STATISTICS__)
506	if(unlikely(external)) __atomic_fetch_add(&cltr->stats->ready.push.extrn.success, 1, __ATOMIC_RELAXED);
507	else if(local) __tls_stats()->ready.push.local.success++;
508	else __tls_stats()->ready.push.share.success++;
509	#endif
510	}
511
512	// Pop from the ready queue from a given cluster
513	__attribute__((hot)) thread$ * pop_fast(struct cluster * cltr) with (cltr->ready_queue) {
514	/* paranoid */ verify( lanes.count > 0 );
515	/* paranoid */ verify( kernelTLS().this_processor );
516	/* paranoid */ verify( kernelTLS().this_processor->rdq.id < lanes.count );
517
518	unsigned count = __atomic_load_n( &lanes.count, __ATOMIC_RELAXED );
519	int preferred = kernelTLS().this_processor->rdq.id;
520
521
522	// As long as the list is not empty, try finding a lane that isn't empty and pop from it
523	for(25) {
524	// Pick two lists at random
525	unsigned ri = __tls_rand_bck();
526	unsigned rj = __tls_rand_bck();
527
528	unsigned i, j;
529	__attribute__((unused)) bool locali, localj;
530	[i, locali] = idx_from_r(ri, preferred);
531	[j, localj] = idx_from_r(rj, preferred);
532
533	i %= count;
534	j %= count;
535
536	// try popping from the 2 picked lists
537	struct thread$ * thrd = try_pop(cltr, i, j __STATS(, *(locali \|\| localj ? &__tls_stats()->ready.pop.local : &__tls_stats()->ready.pop.help)));
538	if(thrd) {
539	return thrd;
540	}
541	}
542
543	// All lanes where empty return 0p
544	return 0p;
545	}
546
547	__attribute__((hot)) struct thread$ * pop_slow(struct cluster * cltr) { return pop_fast(cltr); }
548	__attribute__((hot)) struct thread$ * pop_search(struct cluster * cltr) {
549	return search(cltr);
550	}
551	#endif
552	#if defined(USE_WORK_STEALING)
553	__attribute__((hot)) void push(struct cluster * cltr, struct thread$ * thrd, unpark_hint hint) with (cltr->ready_queue) {
554	__cfadbg_print_safe(ready_queue, "Kernel : Pushing %p on cluster %p\n", thrd, cltr);
555
556	// #define USE_PREFERRED
557	#if !defined(USE_PREFERRED)
558	const bool external = (hint != UNPARK_LOCAL) \|\| (!kernelTLS().this_processor) \|\| (cltr != kernelTLS().this_processor->cltr);
559	/* paranoid */ verify(external \|\| kernelTLS().this_processor->rdq.id < lanes.count );
560	#else
561	unsigned preferred = thrd->preferred;
562	const bool external = (hint != UNPARK_LOCAL) \|\| (!kernelTLS().this_processor) \|\| preferred == -1u \|\| thrd->curr_cluster != cltr;
563	/* paranoid */ verifyf(external \|\| preferred < lanes.count, "Invalid preferred queue %u for %u lanes", preferred, lanes.count );
564
565	unsigned r = preferred % READYQ_SHARD_FACTOR;
566	const unsigned start = preferred - r;
567	#endif
568
569	// Try to pick a lane and lock it
570	unsigned i;
571	do {
572	#if !defined(__CFA_NO_STATISTICS__)
573	if(unlikely(external)) __atomic_fetch_add(&cltr->stats->ready.push.extrn.attempt, 1, __ATOMIC_RELAXED);
574	else __tls_stats()->ready.push.local.attempt++;
575	#endif
576
577	if(unlikely(external)) {
578	i = __tls_rand() % lanes.count;
579	}
580	else {
581	#if !defined(USE_PREFERRED)
582	processor * proc = kernelTLS().this_processor;
583	unsigned r = proc->rdq.its++;
584	i = proc->rdq.id + (r % READYQ_SHARD_FACTOR);
585	#else
586	i = start + (r++ % READYQ_SHARD_FACTOR);
587	#endif
588	}
589	// If we can't lock it retry
590	} while( !__atomic_try_acquire( &lanes.data[i].lock ) );
591
592	// Actually push it
593	push(lanes.data[i], thrd);
594
595	// Unlock and return
596	__atomic_unlock( &lanes.data[i].lock );
597
598	#if !defined(__CFA_NO_STATISTICS__)
599	if(unlikely(external)) __atomic_fetch_add(&cltr->stats->ready.push.extrn.success, 1, __ATOMIC_RELAXED);
600	else __tls_stats()->ready.push.local.success++;
601	#endif
602
603	__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);
604	}
605
606	// Pop from the ready queue from a given cluster
607	__attribute__((hot)) thread$ * pop_fast(struct cluster * cltr) with (cltr->ready_queue) {
608	/* paranoid */ verify( lanes.count > 0 );
609	/* paranoid */ verify( kernelTLS().this_processor );
610	/* paranoid */ verify( kernelTLS().this_processor->rdq.id < lanes.count );
611
612	processor * proc = kernelTLS().this_processor;
613
614	if(proc->rdq.target == -1u) {
615	unsigned long long min = ts(lanes.data[proc->rdq.id]);
616	for(int i = 0; i < READYQ_SHARD_FACTOR; i++) {
617	unsigned long long tsc = ts(lanes.data[proc->rdq.id + i]);
618	if(tsc < min) min = tsc;
619	}
620	proc->rdq.cutoff = min;
621	proc->rdq.target = __tls_rand() % lanes.count;
622	}
623	else {
624	unsigned target = proc->rdq.target;
625	proc->rdq.target = -1u;
626	const unsigned long long bias = 0; //2_500_000_000;
627	const unsigned long long cutoff = proc->rdq.cutoff > bias ? proc->rdq.cutoff - bias : proc->rdq.cutoff;
628	if(lanes.tscs[target].tv < cutoff && ts(lanes.data[target]) < cutoff) {
629	thread$ * t = try_pop(cltr, target __STATS(, __tls_stats()->ready.pop.help));
630	if(t) return t;
631	}
632	}
633
634	for(READYQ_SHARD_FACTOR) {
635	unsigned i = proc->rdq.id + (proc->rdq.itr++ % READYQ_SHARD_FACTOR);
636	if(thread$ * t = try_pop(cltr, i __STATS(, __tls_stats()->ready.pop.local))) return t;
637	}
638	return 0p;
639	}
640
641	__attribute__((hot)) struct thread$ * pop_slow(struct cluster * cltr) with (cltr->ready_queue) {
642	unsigned i = __tls_rand() % lanes.count;
643	return try_pop(cltr, i __STATS(, __tls_stats()->ready.pop.steal));
644	}
645
646	__attribute__((hot)) struct thread$ * pop_search(struct cluster * cltr) with (cltr->ready_queue) {
647	return search(cltr);
648	}
649	#endif
650
651	//=======================================================================
652	// Various Ready Queue utilities
653	//=======================================================================
654	// these function work the same or almost the same
655	// whether they are using work-stealing or relaxed fifo scheduling
656
657	//-----------------------------------------------------------------------
658	// try to pop from a lane given by index w
659	static inline struct thread$ * try_pop(struct cluster * cltr, unsigned w __STATS(, __stats_readyQ_pop_t & stats)) with (cltr->ready_queue) {
660	__STATS( stats.attempt++; )
661
662	// Get relevant elements locally
663	__intrusive_lane_t & lane = lanes.data[w];
664
665	// If list looks empty retry
666	if( is_empty(lane) ) {
667	return 0p;
668	}
669
670	// If we can't get the lock retry
671	if( !__atomic_try_acquire(&lane.lock) ) {
672	return 0p;
673	}
674
675	// If list is empty, unlock and retry
676	if( is_empty(lane) ) {
677	__atomic_unlock(&lane.lock);
678	return 0p;
679	}
680
681	// Actually pop the list
682	struct thread$ * thrd;
683	unsigned long long tsc_before = ts(lane);
684	unsigned long long tsv;
685	[thrd, tsv] = pop(lane);
686
687	/* paranoid */ verify(thrd);
688	/* paranoid */ verify(tsv);
689	/* paranoid */ verify(lane.lock);
690
691	// Unlock and return
692	__atomic_unlock(&lane.lock);
693
694	// Update statistics
695	__STATS( stats.success++; )
696
697	#if defined(USE_WORK_STEALING) \|\| defined(USE_CPU_WORK_STEALING)
698	unsigned long long now = rdtscl();
699	lanes.tscs[w].tv = tsv;
700	lanes.tscs[w].ma = moving_average(now > tsc_before ? now - tsc_before : 0, lanes.tscs[w].ma);
701	#endif
702
703	#if defined(USE_CPU_WORK_STEALING)
704	thrd->preferred = w / READYQ_SHARD_FACTOR;
705	#else
706	thrd->preferred = w;
707	#endif
708
709	// return the popped thread
710	return thrd;
711	}
712
713	//-----------------------------------------------------------------------
714	// try to pop from any lanes making sure you don't miss any threads push
715	// before the start of the function
716	static inline struct thread$ * search(struct cluster * cltr) with (cltr->ready_queue) {
717	/* paranoid */ verify( lanes.count > 0 );
718	unsigned count = __atomic_load_n( &lanes.count, __ATOMIC_RELAXED );
719	unsigned offset = __tls_rand();
720	for(i; count) {
721	unsigned idx = (offset + i) % count;
722	struct thread$ * thrd = try_pop(cltr, idx __STATS(, __tls_stats()->ready.pop.search));
723	if(thrd) {
724	return thrd;
725	}
726	}
727
728	// All lanes where empty return 0p
729	return 0p;
730	}
731
732	//-----------------------------------------------------------------------
733	// get preferred ready for new thread
734	unsigned ready_queue_new_preferred() {
735	unsigned pref = 0;
736	if(struct thread$ * thrd = publicTLS_get( this_thread )) {
737	pref = thrd->preferred;
738	}
739	else {
740	#if defined(USE_CPU_WORK_STEALING)
741	pref = __kernel_getcpu();
742	#endif
743	}
744
745	#if defined(USE_CPU_WORK_STEALING)
746	/* paranoid */ verify(pref >= 0);
747	/* paranoid */ verify(pref < cpu_info.hthrd_count);
748	#endif
749
750	return pref;
751	}
752
753	//-----------------------------------------------------------------------
754	// Check that all the intrusive queues in the data structure are still consistent
755	static void check( __ready_queue_t & q ) with (q) {
756	#if defined(__CFA_WITH_VERIFY__)
757	{
758	for( idx ; lanes.count ) {
759	__intrusive_lane_t & sl = lanes.data[idx];
760	assert(!lanes.data[idx].lock);
761
762	if(is_empty(sl)) {
763	assert( sl.anchor.next == 0p );
764	assert( sl.anchor.ts == -1llu );
765	assert( mock_head(sl) == sl.prev );
766	} else {
767	assert( sl.anchor.next != 0p );
768	assert( sl.anchor.ts != -1llu );
769	assert( mock_head(sl) != sl.prev );
770	}
771	}
772	}
773	#endif
774	}
775
776	//-----------------------------------------------------------------------
777	// Given 2 indexes, pick the list with the oldest push an try to pop from it
778	static inline struct thread$ * try_pop(struct cluster * cltr, unsigned i, unsigned j __STATS(, __stats_readyQ_pop_t & stats)) with (cltr->ready_queue) {
779	// Pick the bet list
780	int w = i;
781	if( __builtin_expect(!is_empty(lanes.data[j]), true) ) {
782	w = (ts(lanes.data[i]) < ts(lanes.data[j])) ? i : j;
783	}
784
785	return try_pop(cltr, w __STATS(, stats));
786	}
787
788	// Call this function of the intrusive list was moved using memcpy
789	// fixes the list so that the pointers back to anchors aren't left dangling
790	static inline void fix(__intrusive_lane_t & ll) {
791	if(is_empty(ll)) {
792	verify(ll.anchor.next == 0p);
793	ll.prev = mock_head(ll);
794	}
795	}
796
797	static void assign_list(unsigned & value, dlist(processor) & list, unsigned count) {
798	processor * it = &list`first;
799	for(unsigned i = 0; i < count; i++) {
800	/* paranoid */ verifyf( it, "Unexpected null iterator, at index %u of %u\n", i, count);
801	it->rdq.id = value;
802	it->rdq.target = -1u;
803	value += READYQ_SHARD_FACTOR;
804	it = &(*it)`next;
805	}
806	}
807
808	static void reassign_cltr_id(struct cluster * cltr) {
809	unsigned preferred = 0;
810	assign_list(preferred, cltr->procs.actives, cltr->procs.total - cltr->procs.idle);
811	assign_list(preferred, cltr->procs.idles , cltr->procs.idle );
812	}
813
814	static void fix_times( struct cluster * cltr ) with( cltr->ready_queue ) {
815	#if defined(USE_WORK_STEALING)
816	lanes.tscs = alloc(lanes.count, lanes.tscs`realloc);
817	for(i; lanes.count) {
818	unsigned long long tsc1 = ts(lanes.data[i]);
819	unsigned long long tsc2 = rdtscl();
820	lanes.tscs[i].tv = min(tsc1, tsc2);
821	}
822	#endif
823	}
824
825	#if defined(USE_CPU_WORK_STEALING)
826	// ready_queue size is fixed in this case
827	void ready_queue_grow(struct cluster * cltr) {}
828	void ready_queue_shrink(struct cluster * cltr) {}
829	#else
830	// Grow the ready queue
831	void ready_queue_grow(struct cluster * cltr) {
832	size_t ncount;
833	int target = cltr->procs.total;
834
835	/* paranoid */ verify( ready_mutate_islocked() );
836	__cfadbg_print_safe(ready_queue, "Kernel : Growing ready queue\n");
837
838	// Make sure that everything is consistent
839	/* paranoid */ check( cltr->ready_queue );
840
841	// grow the ready queue
842	with( cltr->ready_queue ) {
843	// Find new count
844	// Make sure we always have atleast 1 list
845	if(target >= 2) {
846	ncount = target * READYQ_SHARD_FACTOR;
847	} else {
848	ncount = SEQUENTIAL_SHARD;
849	}
850
851	// Allocate new array (uses realloc and memcpies the data)
852	lanes.data = alloc( ncount, lanes.data`realloc );
853
854	// Fix the moved data
855	for( idx; (size_t)lanes.count ) {
856	fix(lanes.data[idx]);
857	}
858
859	// Construct new data
860	for( idx; (size_t)lanes.count ~ ncount) {
861	(lanes.data[idx]){};
862	}
863
864	// Update original
865	lanes.count = ncount;
866	}
867
868	fix_times(cltr);
869
870	reassign_cltr_id(cltr);
871
872	// Make sure that everything is consistent
873	/* paranoid */ check( cltr->ready_queue );
874
875	__cfadbg_print_safe(ready_queue, "Kernel : Growing ready queue done\n");
876
877	/* paranoid */ verify( ready_mutate_islocked() );
878	}
879
880	// Shrink the ready queue
881	void ready_queue_shrink(struct cluster * cltr) {
882	/* paranoid */ verify( ready_mutate_islocked() );
883	__cfadbg_print_safe(ready_queue, "Kernel : Shrinking ready queue\n");
884
885	// Make sure that everything is consistent
886	/* paranoid */ check( cltr->ready_queue );
887
888	int target = cltr->procs.total;
889
890	with( cltr->ready_queue ) {
891	// Remember old count
892	size_t ocount = lanes.count;
893
894	// Find new count
895	// Make sure we always have atleast 1 list
896	lanes.count = target >= 2 ? target * READYQ_SHARD_FACTOR: SEQUENTIAL_SHARD;
897	/* paranoid */ verify( ocount >= lanes.count );
898	/* paranoid / verify( lanes.count == target READYQ_SHARD_FACTOR \|\| target < 2 );
899
900	// for printing count the number of displaced threads
901	#if defined(__CFA_DEBUG_PRINT__) \|\| defined(__CFA_DEBUG_PRINT_READY_QUEUE__)
902	__attribute__((unused)) size_t displaced = 0;
903	#endif
904
905	// redistribute old data
906	for( idx; (size_t)lanes.count ~ ocount) {
907	// Lock is not strictly needed but makes checking invariants much easier
908	__attribute__((unused)) bool locked = __atomic_try_acquire(&lanes.data[idx].lock);
909	verify(locked);
910
911	// As long as we can pop from this lane to push the threads somewhere else in the queue
912	while(!is_empty(lanes.data[idx])) {
913	struct thread$ * thrd;
914	unsigned long long _;
915	[thrd, _] = pop(lanes.data[idx]);
916
917	push(cltr, thrd, true);
918
919	// for printing count the number of displaced threads
920	#if defined(__CFA_DEBUG_PRINT__) \|\| defined(__CFA_DEBUG_PRINT_READY_QUEUE__)
921	displaced++;
922	#endif
923	}
924
925	// Unlock the lane
926	__atomic_unlock(&lanes.data[idx].lock);
927
928	// TODO print the queue statistics here
929
930	^(lanes.data[idx]){};
931	}
932
933	__cfadbg_print_safe(ready_queue, "Kernel : Shrinking ready queue displaced %zu threads\n", displaced);
934
935	// Allocate new array (uses realloc and memcpies the data)
936	lanes.data = alloc( lanes.count, lanes.data`realloc );
937
938	// Fix the moved data
939	for( idx; (size_t)lanes.count ) {
940	fix(lanes.data[idx]);
941	}
942	}
943
944	fix_times(cltr);
945
946	reassign_cltr_id(cltr);
947
948	// Make sure that everything is consistent
949	/* paranoid */ check( cltr->ready_queue );
950
951	__cfadbg_print_safe(ready_queue, "Kernel : Shrinking ready queue done\n");
952	/* paranoid */ verify( ready_mutate_islocked() );
953	}
954	#endif
955
956	#if !defined(__CFA_NO_STATISTICS__)
957	unsigned cnt(const __ready_queue_t & this, unsigned idx) {
958	/* paranoid */ verify(this.lanes.count > idx);
959	return this.lanes.data[idx].cnt;
960	}
961	#endif
962
963
964	#if defined(CFA_HAVE_LINUX_LIBRSEQ)
965	// No definition needed
966	#elif defined(CFA_HAVE_LINUX_RSEQ_H)
967
968	#if defined( __x86_64 ) \|\| defined( __i386 )
969	#define RSEQ_SIG 0x53053053
970	#elif defined( __ARM_ARCH )
971	#ifdef __ARMEB__
972	#define RSEQ_SIG 0xf3def5e7 /* udf #24035 ; 0x5de3 (ARMv6+) */
973	#else
974	#define RSEQ_SIG 0xe7f5def3 /* udf #24035 ; 0x5de3 */
975	#endif
976	#endif
977
978	extern void __disable_interrupts_hard();
979	extern void __enable_interrupts_hard();
980
981	static void __kernel_raw_rseq_register (void) {
982	/* paranoid */ verify( __cfaabi_rseq.cpu_id == RSEQ_CPU_ID_UNINITIALIZED );
983
984	// int ret = syscall(__NR_rseq, &__cfaabi_rseq, sizeof(struct rseq), 0, (sigset_t *)0p, _NSIG / 8);
985	int ret = syscall(__NR_rseq, &__cfaabi_rseq, sizeof(struct rseq), 0, RSEQ_SIG);
986	if(ret != 0) {
987	int e = errno;
988	switch(e) {
989	case EINVAL: abort("KERNEL ERROR: rseq register invalid argument");
990	case ENOSYS: abort("KERNEL ERROR: rseq register no supported");
991	case EFAULT: abort("KERNEL ERROR: rseq register with invalid argument");
992	case EBUSY : abort("KERNEL ERROR: rseq register already registered");
993	case EPERM : abort("KERNEL ERROR: rseq register sig argument on unregistration does not match the signature received on registration");
994	default: abort("KERNEL ERROR: rseq register unexpected return %d", e);
995	}
996	}
997	}
998
999	static void __kernel_raw_rseq_unregister(void) {
1000	/* paranoid */ verify( __cfaabi_rseq.cpu_id >= 0 );
1001
1002	// int ret = syscall(__NR_rseq, &__cfaabi_rseq, sizeof(struct rseq), RSEQ_FLAG_UNREGISTER, (sigset_t *)0p, _NSIG / 8);
1003	int ret = syscall(__NR_rseq, &__cfaabi_rseq, sizeof(struct rseq), RSEQ_FLAG_UNREGISTER, RSEQ_SIG);
1004	if(ret != 0) {
1005	int e = errno;
1006	switch(e) {
1007	case EINVAL: abort("KERNEL ERROR: rseq unregister invalid argument");
1008	case ENOSYS: abort("KERNEL ERROR: rseq unregister no supported");
1009	case EFAULT: abort("KERNEL ERROR: rseq unregister with invalid argument");
1010	case EBUSY : abort("KERNEL ERROR: rseq unregister already registered");
1011	case EPERM : abort("KERNEL ERROR: rseq unregister sig argument on unregistration does not match the signature received on registration");
1012	default: abort("KERNEL ERROR: rseq unregisteunexpected return %d", e);
1013	}
1014	}
1015	}
1016	#else
1017	// No definition needed
1018	#endif

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