1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 /* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */ 22 /* All Rights Reserved */ 23 24 25 /* 26 * Copyright 2008 Sun Microsystems, Inc. All rights reserved. 27 * Use is subject to license terms. 28 */ 29 30 #ifndef _SYS_CALLO_H 31 #define _SYS_CALLO_H 32 33 #include <sys/t_lock.h> 34 #include <sys/taskq.h> 35 #include <sys/lgrp.h> 36 #include <sys/processor.h> 37 #include <sys/cyclic.h> 38 #include <sys/kstat.h> 39 #include <sys/systm.h> 40 41 #ifdef __cplusplus 42 extern "C" { 43 #endif 44 45 #ifdef _KERNEL 46 47 typedef struct callout_list callout_list_t; 48 49 /* 50 * The callout mechanism provides general-purpose event scheduling: 51 * an arbitrary function is called in a specified amount of time. 52 * The expiration time for a callout is kept in its callout list 53 * structure. 54 */ 55 typedef struct callout { 56 struct callout *c_idnext; /* next in ID hash, or on freelist */ 57 struct callout *c_idprev; /* prev in ID hash */ 58 struct callout *c_clnext; /* next in callout list */ 59 struct callout *c_clprev; /* prev in callout list */ 60 callout_id_t c_xid; /* extended callout ID; see below */ 61 callout_list_t *c_list; /* callout list */ 62 void (*c_func)(void *); /* function to call */ 63 void *c_arg; /* argument to function */ 64 } callout_t; 65 66 /* 67 * The callout ID (callout_id_t) uniquely identifies a callout. The callout 68 * ID is always 64 bits internally. The lower 32 bits contain an ID value. 69 * The upper 32 bits contain a generation number and flags. When the ID value 70 * wraps the generation number is incremented during ID generation. This 71 * protects callers from ID collisions that can happen as a result of the wrap. 72 * 73 * The kernel internal interface, timeout_generic(), always returns a 74 * callout_id_t. But the legacy interfaces, timeout() and realtime_timeout() 75 * return a timeout_id_t. On a 64-bit system, timeout_id_t is also 64 bits. 76 * So, the full 64-bit ID (sans the flags) can be returned. However, on 32-bit 77 * systems, timeout_id_t is 32 bits. So, only the lower 32 bits can be 78 * returned. In such cases, a default generation number of 0 is assigned to 79 * the legacy IDs. 80 * 81 * The lower 32-bit ID space is partitioned into two spaces - one for 32-bit 82 * IDs and the other for 64-bit IDs. The 32-bit ID space is further divided 83 * into two spaces - one for short-term callouts and one for long-term. 84 * 85 * Here is the bit layout for the callout ID: 86 * 87 * 63 62 61 ... 32 31 30 29 .. X+1 X ... 1 0 88 * ----------------------------------------------------------------------- 89 * | Exec | Hres | Generation | Long | Counter | ID bits | Table | Type | 90 * | | time | number | term | High | | number | | 91 * ----------------------------------------------------------------------- 92 * 93 * Exec(uting): 94 * This is the executing bit which is only set in the extended callout 95 * ID. This bit indicates that the callout handler is currently being 96 * executed. 97 * 98 * Hrestime: 99 * Kernel features like condition variables use hrestime (system date) in 100 * conjunction with callouts. Under normal circumstances, these callouts 101 * are handled in the usual manner. They go off at specified times. But 102 * when the system time is changed abruptly (e.g., via stime()), these 103 * callouts are required to be processed immediately so that they can 104 * wakeup their threads immediately. The Hrestime bit is used to mark 105 * such callouts. When the system time is changed, the callout subsystem 106 * is called to process all callouts with this bit set. 107 * 108 * Generation number: 109 * This is the generation part of the ID. 110 * 111 * Long term: 112 * This bit indicates whether this is a short-term or a long-term callout. 113 * The long-term bit exists to address the problem of callout ID collision 114 * on 32-bit systems. This is an issue because the system typically 115 * generates a large number of timeout() requests, which means that callout 116 * IDs eventually get recycled. Most timeouts are very short-lived, so that 117 * ID recycling isn't a problem; but there are a handful of timeouts which 118 * are sufficiently long-lived to see their own IDs reused. We use the 119 * long-term bit to partition the ID namespace into pieces; the short-term 120 * space gets all the heavy traffic and can wrap frequently (i.e., on the 121 * order of a day) with no ill effects; the long-term space gets very little 122 * traffic and thus never wraps. That said, we need to future proof callouts 123 * in case 32-bit systems grow in size and are able to consume callout IDs 124 * at faster rates. So, we should make all the kernel clients that use 125 * callouts to use the internal interface so that they can use IDs outside 126 * of the legacy space with a proper generation number. 127 * 128 * Counter High + ID counter bits: 129 * These bits represent the actual ID bits in the callout ID. 130 * The highest bit of the running counter is always set; this ensures that 131 * the callout ID is always non-zero, thus eliminating the need for an 132 * explicit wrap-around test during ID generation. 133 * 134 * Table number: 135 * These bits carry the table number for the callout table where the callout 136 * is queued. Each CPU has its own callout table. So, the callout tables are 137 * numbered from 0 - (max_ncpus - 1). Because max_ncpus is different on 138 * different systems, the actual number of table number bits will vary 139 * accordingly. And so will the ID counter bits. 140 * 141 * Type: 142 * This bit represents the callout (table) type. Each CPU has one realtime 143 * and one normal callout table. 144 */ 145 #define CALLOUT_EXECUTING 0x8000000000000000ULL 146 #define CALLOUT_HRESTIME 0x4000000000000000ULL 147 #define CALLOUT_ID_MASK ~(CALLOUT_EXECUTING | CALLOUT_HRESTIME) 148 #define CALLOUT_GENERATION_LOW 0x100000000ULL 149 #define CALLOUT_LONGTERM 0x80000000 150 #define CALLOUT_COUNTER_HIGH 0x40000000 151 #define CALLOUT_TYPE_BITS 1 152 #define CALLOUT_NTYPES (1 << CALLOUT_TYPE_BITS) 153 #define CALLOUT_TYPE_MASK (CALLOUT_NTYPES - 1) 154 #define CALLOUT_COUNTER_SHIFT callout_table_bits 155 #define CALLOUT_TABLE(t, f) (((f) << CALLOUT_TYPE_BITS) | (t)) 156 #define CALLOUT_TABLE_NUM(ct) ((ct) - callout_table) 157 #define CALLOUT_TABLE_TYPE(ct) (CALLOUT_TABLE_NUM(ct) & CALLOUT_TYPE_MASK) 158 #define CALLOUT_TABLE_SEQID(ct) (CALLOUT_TABLE_NUM(ct) >> CALLOUT_TYPE_BITS) 159 160 /* 161 * We assume that during any period of CALLOUT_LONGTERM_TICKS ticks, at most 162 * (CALLOUT_COUNTER_HIGH / callout_counter_low) callouts will be generated. 163 */ 164 #define CALLOUT_LONGTERM_TICKS 0x4000UL 165 #define CALLOUT_BUCKET_SHIFT 9 166 #define CALLOUT_BUCKETS (1 << CALLOUT_BUCKET_SHIFT) 167 #define CALLOUT_BUCKET_MASK (CALLOUT_BUCKETS - 1) 168 #define CALLOUT_HASH(x) ((x) & CALLOUT_BUCKET_MASK) 169 #define CALLOUT_IDHASH(x) CALLOUT_HASH((x) >> CALLOUT_COUNTER_SHIFT) 170 /* 171 * The multiply by 0 and 1 below are cosmetic. Just to align things better 172 * and make it more readable. The multiplications will be done at compile 173 * time. 174 */ 175 #define CALLOUT_CLHASH(x) \ 176 CALLOUT_HASH( \ 177 ((x)>>(CALLOUT_BUCKET_SHIFT*0)) ^ \ 178 ((x)>>(CALLOUT_BUCKET_SHIFT*1)) ^ \ 179 ((x)>>(CALLOUT_BUCKET_SHIFT*2)) ^ \ 180 ((x)>>(CALLOUT_BUCKET_SHIFT*3))) 181 182 #define CALLOUT_ID_TO_TABLE(id) ((id) & callout_table_mask) 183 184 #define CALLOUT_SHORT_ID(table) \ 185 ((callout_id_t)(table) | CALLOUT_COUNTER_HIGH) 186 #define CALLOUT_LONG_ID(table) \ 187 (CALLOUT_SHORT_ID(table) | CALLOUT_LONGTERM) 188 189 #define CALLOUT_THREADS 2 /* keep it simple for now */ 190 191 #define CALLOUT_REALTIME 0 /* realtime callout type */ 192 #define CALLOUT_NORMAL 1 /* normal callout type */ 193 194 /* 195 * callout_t's are cache-aligned structures allocated from kmem caches. One kmem 196 * cache is created per lgrp and is shared by all CPUs in that lgrp. Benefits: 197 * - cache pages are mapped only in the TLBs of the CPUs of the lgrp 198 * - data in cache pages is present only in those CPU caches 199 * - memory access performance improves with locality-awareness in kmem 200 * 201 * The following structure is used to manage per-lgroup kmem caches. 202 * 203 * NOTE: Free callout_t's go to a callout table's freelist. CPUs map to callout 204 * tables via their sequence IDs, not CPU IDs. DR operations can cause a 205 * free list to have callouts from multiple lgrp caches. This takes away some 206 * performance, but is no worse than if we did not use lgrp caches at all. 207 */ 208 typedef struct callout_cache { 209 struct callout_cache *cc_next; /* link in the global list */ 210 lgrp_handle_t cc_hand; /* lgroup handle */ 211 kmem_cache_t *cc_cache; /* kmem cache pointer */ 212 kmem_cache_t *cc_lcache; /* kmem cache pointer */ 213 } callout_cache_t; 214 215 /* 216 * The callout hash structure is used for queueing both callouts and 217 * callout lists. That is why the fields are declared as void *. 218 */ 219 typedef struct callout_hash { 220 void *ch_head; 221 void *ch_tail; 222 } callout_hash_t; 223 224 struct callout_list { 225 callout_list_t *cl_next; /* next in clhash */ 226 callout_list_t *cl_prev; /* prev in clhash */ 227 hrtime_t cl_expiration; /* expiration for callouts in list */ 228 callout_hash_t cl_callouts; /* list of callouts */ 229 kcondvar_t cl_done; /* signal callout completion */ 230 ushort_t cl_waiting; /* count of waiting untimeouts */ 231 kthread_id_t cl_executor; /* thread executing callout */ 232 ulong_t cl_pad; /* cache alignment */ 233 }; 234 235 /* 236 * Per-callout table kstats. 237 * 238 * CALLOUT_TIMEOUTS 239 * Callouts created since boot. 240 * CALLOUT_TIMEOUTS_PENDING 241 * Number of outstanding callouts. 242 * CALLOUT_UNTIMEOUTS_UNEXPIRED 243 * Number of cancelled callouts that have not expired. 244 * CALLOUT_UNTIMEOUTS_EXECUTING 245 * Number of cancelled callouts that were executing at the time of 246 * cancellation. 247 * CALLOUT_UNTIMEOUTS_EXPIRED 248 * Number of cancelled callouts that had already expired at the time 249 * of cancellations. 250 * CALLOUT_EXPIRATIONS 251 * Number of callouts that expired. 252 * CALLOUT_ALLOCATIONS 253 * Number of callout structures allocated. 254 */ 255 typedef enum callout_stat_type { 256 CALLOUT_TIMEOUTS, 257 CALLOUT_TIMEOUTS_PENDING, 258 CALLOUT_UNTIMEOUTS_UNEXPIRED, 259 CALLOUT_UNTIMEOUTS_EXECUTING, 260 CALLOUT_UNTIMEOUTS_EXPIRED, 261 CALLOUT_EXPIRATIONS, 262 CALLOUT_ALLOCATIONS, 263 CALLOUT_NUM_STATS 264 } callout_stat_type_t; 265 266 /* 267 * Callout flags: 268 * 269 * CALLOUT_FLAG_ROUNDUP 270 * Roundup the expiration time to the nearest resolution boundary. 271 * If this flag is not specified, the expiration time is rounded down. 272 * CALLOUT_FLAG_ABSOLUTE 273 * Normally, the expiration passed to the timeout API functions is an 274 * expiration interval. If this flag is specified, then it is 275 * interpreted as the expiration time itself. 276 * CALLOUT_FLAG_HRESTIME 277 * Normally, callouts are not affected by changes to system time 278 * (hrestime). This flag is used to create a callout that is affected 279 * by system time. If system time changes, these timers must expire 280 * at once. These are used by condition variables and LWP timers that 281 * need this behavior. 282 * CALLOUT_FLAG_32BIT 283 * Legacy interfaces timeout() and realtime_timeout() pass this flag 284 * to timeout_generic() to indicate that a 32-bit ID should be allocated. 285 */ 286 #define CALLOUT_FLAG_ROUNDUP 0x1 287 #define CALLOUT_FLAG_ABSOLUTE 0x2 288 #define CALLOUT_FLAG_HRESTIME 0x4 289 #define CALLOUT_FLAG_32BIT 0x8 290 291 /* 292 * On 32-bit systems, the legacy interfaces, timeout() and realtime_timeout(), 293 * must pass CALLOUT_FLAG_32BIT to timeout_generic() so that a 32-bit ID 294 * can be generated. 295 */ 296 #ifdef _LP64 297 #define CALLOUT_LEGACY 0 298 #else 299 #define CALLOUT_LEGACY CALLOUT_FLAG_32BIT 300 #endif 301 302 /* 303 * Callout table flags: 304 * 305 * CALLOUT_TABLE_SUSPENDED 306 * Callout processing on this table has been suspended. 307 */ 308 #define CALLOUT_TABLE_SUSPENDED 0x1UL 309 310 /* 311 * All of the state information associated with a callout table. 312 * The fields are ordered with cache performance in mind. 313 */ 314 typedef struct callout_table { 315 kmutex_t ct_mutex; /* protects all callout state */ 316 callout_t *ct_free; /* free callout structures */ 317 callout_list_t *ct_lfree; /* free callout list structures */ 318 callout_id_t ct_short_id; /* most recently issued short-term ID */ 319 callout_id_t ct_long_id; /* most recently issued long-term ID */ 320 callout_hash_t *ct_idhash; /* ID hash chains */ 321 callout_hash_t *ct_clhash; /* callout list hash */ 322 kstat_named_t *ct_kstat_data; /* callout kstat data */ 323 324 ulong_t ct_flags; /* flags */ 325 cyclic_id_t ct_cyclic; /* cyclic for this table */ 326 hrtime_t *ct_heap; /* callout expiration heap */ 327 ulong_t ct_heap_num; /* occupied slots in the heap */ 328 ulong_t ct_heap_max; /* end of the heap */ 329 kmem_cache_t *ct_cache; /* callout kmem cache */ 330 kmem_cache_t *ct_lcache; /* callout list kmem cache */ 331 callout_id_t ct_gen_id; /* generation based ID */ 332 333 callout_hash_t ct_expired; /* list of expired callout lists */ 334 taskq_t *ct_taskq; /* taskq to execute normal callouts */ 335 kstat_t *ct_kstats; /* callout kstats */ 336 #ifdef _LP64 337 ulong_t ct_pad[4]; /* cache alignment */ 338 #else 339 ulong_t ct_pad[8]; /* cache alignment */ 340 #endif 341 } callout_table_t; 342 343 /* 344 * Short hand definitions for the callout kstats. 345 */ 346 #define ct_timeouts \ 347 ct_kstat_data[CALLOUT_TIMEOUTS].value.ui64 348 #define ct_timeouts_pending \ 349 ct_kstat_data[CALLOUT_TIMEOUTS_PENDING].value.ui64 350 #define ct_untimeouts_unexpired \ 351 ct_kstat_data[CALLOUT_UNTIMEOUTS_UNEXPIRED].value.ui64 352 #define ct_untimeouts_executing \ 353 ct_kstat_data[CALLOUT_UNTIMEOUTS_EXECUTING].value.ui64 354 #define ct_untimeouts_expired \ 355 ct_kstat_data[CALLOUT_UNTIMEOUTS_EXPIRED].value.ui64 356 #define ct_expirations \ 357 ct_kstat_data[CALLOUT_EXPIRATIONS].value.ui64 358 #define ct_allocations \ 359 ct_kstat_data[CALLOUT_ALLOCATIONS].value.ui64 360 361 #define CALLOUT_CHUNK 128 362 363 #define CALLOUT_HEAP_PARENT(index) (((index) - 1) >> 1) 364 #define CALLOUT_HEAP_RIGHT(index) (((index) + 1) << 1) 365 #define CALLOUT_HEAP_LEFT(index) ((((index) + 1) << 1) - 1) 366 367 #define CALLOUT_CYCLIC_HANDLER(t) \ 368 ((t == CALLOUT_REALTIME) ? callout_realtime : callout_normal) 369 370 /* 371 * We define a blanket minimum resolution for callouts of 1 millisecond. 372 * 1 millisecond is a safe value as it is already supported when the clock 373 * resolution is set to high. 374 */ 375 #define CALLOUT_MIN_RESOLUTION 1000000ULL 376 #define CALLOUT_TCP_RESOLUTION 10000000ULL 377 378 #define CALLOUT_ALIGN 64 /* cache line size */ 379 380 extern void callout_init(void); 381 extern void membar_sync(void); 382 extern void callout_cpu_configure(cpu_t *); 383 extern void callout_cpu_online(cpu_t *); 384 extern void callout_cpu_init(cpu_t *); 385 extern void callout_hrestime(void); 386 #endif 387 388 #ifdef __cplusplus 389 } 390 #endif 391 392 #endif /* _SYS_CALLO_H */ 393