1 /*- 2 * Copyright (c) 1982, 1986, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)vmmeter.h 8.2 (Berkeley) 7/10/94 30 * $FreeBSD: src/sys/sys/vmmeter.h,v 1.21.2.2 2002/10/10 19:28:21 dillon Exp $ 31 */ 32 33 #ifndef _VM_VM_PAGE2_H_ 34 #define _VM_VM_PAGE2_H_ 35 36 #ifdef _KERNEL 37 38 #ifndef _SYS_VMMETER_H_ 39 #include <sys/vmmeter.h> 40 #endif 41 #ifndef _SYS_QUEUE_H_ 42 #include <sys/queue.h> 43 #endif 44 #ifndef _VM_VM_PAGE_H_ 45 #include <vm/vm_page.h> 46 #endif 47 #ifndef _SYS_SPINLOCK_H_ 48 #include <sys/spinlock.h> 49 #endif 50 #ifndef _SYS_SPINLOCK2_H_ 51 #include <sys/spinlock2.h> 52 #endif 53 54 /* 55 * SMP NOTE 56 * 57 * VM fault rates are highly dependent on SMP locking conflicts and, on 58 * multi-socket systems, cache mastership changes for globals due to atomic 59 * ops (even simple atomic_add_*() calls). Cache mastership changes can 60 * limit the aggregate fault rate. 61 * 62 * For this reason we go through some hoops to access VM statistics for 63 * low-memory handling, pageout, and other triggers. Each cpu collects 64 * adjustments in gd->gd_vmstats_adj. These get rolled up into the global 65 * vmstats structure. The global vmstats structure is then pulled into 66 * gd->gd_vmstats by each cpu when it needs it. Critical path checks always 67 * use the pcpu gd->gd_vmstats structure. 68 */ 69 /* 70 * Return TRUE if we are under our severe low-free-pages threshold 71 * 72 * This causes user processes to stall to avoid exhausting memory that 73 * the kernel might need. 74 * 75 * reserved < severe < minimum < target < paging_target 76 */ 77 static __inline 78 int 79 vm_page_count_severe(void) 80 { 81 globaldata_t gd = mycpu; 82 83 return (gd->gd_vmstats.v_free_severe > 84 gd->gd_vmstats.v_free_count + gd->gd_vmstats.v_cache_count || 85 gd->gd_vmstats.v_free_reserved > gd->gd_vmstats.v_free_count); 86 } 87 88 /* 89 * Return TRUE if we are under our minimum low-free-pages threshold. 90 * This activates the pageout demon. The pageout demon tries to 91 * reach the target but may stop once it satisfies the minimum. 92 * 93 * reserved < severe < minimum < target < paging_target 94 */ 95 static __inline 96 int 97 vm_page_count_min(int donotcount) 98 { 99 globaldata_t gd = mycpu; 100 101 return (gd->gd_vmstats.v_free_min + donotcount > 102 (gd->gd_vmstats.v_free_count + gd->gd_vmstats.v_cache_count) || 103 gd->gd_vmstats.v_free_reserved > gd->gd_vmstats.v_free_count); 104 } 105 106 /* 107 * Return TRUE if we are under our free page target. The pageout demon 108 * tries to reach the target but may stop once it gets past the min. 109 * 110 * User threads doing normal allocations might wait based on this 111 * function but MUST NOT wait in a loop based on this function as the 112 * VM load may prevent the target from being reached. 113 */ 114 static __inline 115 int 116 vm_page_count_target(void) 117 { 118 globaldata_t gd = mycpu; 119 120 return (gd->gd_vmstats.v_free_target > 121 (gd->gd_vmstats.v_free_count + gd->gd_vmstats.v_cache_count) || 122 gd->gd_vmstats.v_free_reserved > gd->gd_vmstats.v_free_count); 123 } 124 125 /* 126 * Return the number of pages the pageout daemon needs to move into the 127 * cache or free lists. A negative number means we have sufficient free 128 * pages. 129 * 130 * The target free+cache is greater than vm_page_count_target(). The 131 * frontend uses vm_page_count_target() while the backend continue freeing 132 * based on vm_paging_target(). 133 * 134 * This function DOES NOT return TRUE or FALSE. 135 */ 136 static __inline 137 int 138 vm_paging_target(void) 139 { 140 globaldata_t gd = mycpu; 141 142 return ((gd->gd_vmstats.v_free_target + gd->gd_vmstats.v_cache_min) - 143 (gd->gd_vmstats.v_free_count + gd->gd_vmstats.v_cache_count)); 144 } 145 146 /* 147 * Return TRUE if hysteresis dictates we should nominally wakeup the 148 * pageout daemon to start working on freeing up some memory. This 149 * routine should NOT be used to determine when to block on the VM system. 150 * We want to wakeup the pageout daemon before we might otherwise block. 151 * 152 * Paging begins when cache+free drops below cache_min + free_min. 153 */ 154 static __inline 155 int 156 vm_paging_needed(void) 157 { 158 globaldata_t gd = mycpu; 159 160 if (gd->gd_vmstats.v_free_min + gd->gd_vmstats.v_cache_min > 161 gd->gd_vmstats.v_free_count + gd->gd_vmstats.v_cache_count) { 162 return 1; 163 } 164 if (gd->gd_vmstats.v_free_min > gd->gd_vmstats.v_free_count) 165 return 1; 166 return 0; 167 } 168 169 /* 170 * Clear dirty bits in the VM page but truncate the 171 * end to a DEV_BSIZE'd boundary. 172 * 173 * Used when reading data in, typically via getpages. 174 * The partial device block at the end of the truncation 175 * range should not lose its dirty bit. 176 * 177 * NOTE: This function does not clear the pmap modified bit. 178 */ 179 static __inline 180 void 181 vm_page_clear_dirty_end_nonincl(vm_page_t m, int base, int size) 182 { 183 size = (base + size) & ~DEV_BMASK; 184 if (base < size) 185 vm_page_clear_dirty(m, base, size - base); 186 } 187 188 /* 189 * Clear dirty bits in the VM page but truncate the 190 * beginning to a DEV_BSIZE'd boundary. 191 * 192 * Used when truncating a buffer. The partial device 193 * block at the beginning of the truncation range 194 * should not lose its dirty bit. 195 * 196 * NOTE: This function does not clear the pmap modified bit. 197 */ 198 static __inline 199 void 200 vm_page_clear_dirty_beg_nonincl(vm_page_t m, int base, int size) 201 { 202 size += base; 203 base = (base + DEV_BMASK) & ~DEV_BMASK; 204 if (base < size) 205 vm_page_clear_dirty(m, base, size - base); 206 } 207 208 static __inline 209 void 210 vm_page_spin_lock(vm_page_t m) 211 { 212 spin_lock(&m->spin); 213 } 214 215 static __inline 216 void 217 vm_page_spin_unlock(vm_page_t m) 218 { 219 spin_unlock(&m->spin); 220 } 221 222 /* 223 * Wire a vm_page that is already wired. Does not require a busied 224 * page. 225 */ 226 static __inline 227 void 228 vm_page_wire_quick(vm_page_t m) 229 { 230 if (atomic_fetchadd_int(&m->wire_count, 1) == 0) 231 panic("vm_page_wire_quick: wire_count was 0"); 232 } 233 234 /* 235 * Unwire a vm_page quickly, does not require a busied page. 236 * 237 * This routine refuses to drop the wire_count to 0 and will return 238 * TRUE if it would have had to (instead of decrementing it to 0). 239 * The caller can then busy the page and deal with it. 240 */ 241 static __inline 242 int 243 vm_page_unwire_quick(vm_page_t m) 244 { 245 KKASSERT(m->wire_count > 0); 246 for (;;) { 247 u_int wire_count = m->wire_count; 248 249 cpu_ccfence(); 250 if (wire_count == 1) 251 return TRUE; 252 if (atomic_cmpset_int(&m->wire_count, wire_count, wire_count - 1)) 253 return FALSE; 254 } 255 } 256 257 /* 258 * Functions implemented as macros 259 */ 260 261 static __inline void 262 vm_page_flag_set(vm_page_t m, unsigned int bits) 263 { 264 atomic_set_int(&(m)->flags, bits); 265 } 266 267 static __inline void 268 vm_page_flag_clear(vm_page_t m, unsigned int bits) 269 { 270 atomic_clear_int(&(m)->flags, bits); 271 } 272 273 /* 274 * Wakeup anyone waiting for the page after potentially unbusying 275 * (hard or soft) or doing other work on a page that might make a 276 * waiter ready. The setting of PBUSY_WANTED is integrated into the 277 * related flags and it can't be set once the flags are already 278 * clear, so there should be no races here. 279 */ 280 static __inline void 281 vm_page_flash(vm_page_t m) 282 { 283 if (m->busy_count & PBUSY_WANTED) { 284 atomic_clear_int(&m->busy_count, PBUSY_WANTED); 285 wakeup(m); 286 } 287 } 288 289 /* 290 * Adjust the soft-busy count on a page. The drop code will issue an 291 * integrated wakeup if busy_count becomes 0. 292 */ 293 static __inline void 294 vm_page_sbusy_hold(vm_page_t m) 295 { 296 atomic_add_int(&m->busy_count, 1); 297 } 298 299 static __inline void 300 vm_page_sbusy_drop(vm_page_t m) 301 { 302 uint32_t ocount; 303 304 ocount = atomic_fetchadd_int(&m->busy_count, -1); 305 if (ocount - 1 == PBUSY_WANTED) { 306 /* WANTED and no longer BUSY or SBUSY */ 307 atomic_clear_int(&m->busy_count, PBUSY_WANTED); 308 wakeup(m); 309 } 310 } 311 312 /* 313 * Reduce the protection of a page. This routine never raises the 314 * protection and therefore can be safely called if the page is already 315 * at VM_PROT_NONE (it will be a NOP effectively ). 316 * 317 * VM_PROT_NONE will remove all user mappings of a page. This is often 318 * necessary when a page changes state (for example, turns into a copy-on-write 319 * page or needs to be frozen for write I/O) in order to force a fault, or 320 * to force a page's dirty bits to be synchronized and avoid hardware 321 * (modified/accessed) bit update races with pmap changes. 322 * 323 * Since 'prot' is usually a constant, this inline usually winds up optimizing 324 * out the primary conditional. 325 * 326 * WARNING: VM_PROT_NONE can block, but will loop until all mappings have 327 * been cleared. Callers should be aware that other page related elements 328 * might have changed, however. 329 */ 330 static __inline void 331 vm_page_protect(vm_page_t m, int prot) 332 { 333 KKASSERT(m->busy_count & PBUSY_LOCKED); 334 if (prot == VM_PROT_NONE) { 335 if (m->flags & (PG_WRITEABLE|PG_MAPPED)) { 336 pmap_page_protect(m, VM_PROT_NONE); 337 /* PG_WRITEABLE & PG_MAPPED cleared by call */ 338 } 339 } else if ((prot == VM_PROT_READ) && (m->flags & PG_WRITEABLE)) { 340 pmap_page_protect(m, VM_PROT_READ); 341 /* PG_WRITEABLE cleared by call */ 342 } 343 } 344 345 /* 346 * Zero-fill the specified page. The entire contents of the page will be 347 * zero'd out. 348 */ 349 static __inline boolean_t 350 vm_page_zero_fill(vm_page_t m) 351 { 352 pmap_zero_page(VM_PAGE_TO_PHYS(m)); 353 return (TRUE); 354 } 355 356 /* 357 * Copy the contents of src_m to dest_m. The pages must be stable but spl 358 * and other protections depend on context. 359 */ 360 static __inline void 361 vm_page_copy(vm_page_t src_m, vm_page_t dest_m) 362 { 363 pmap_copy_page(VM_PAGE_TO_PHYS(src_m), VM_PAGE_TO_PHYS(dest_m)); 364 dest_m->valid = VM_PAGE_BITS_ALL; 365 dest_m->dirty = VM_PAGE_BITS_ALL; 366 } 367 368 /* 369 * Free a page. The page must be marked BUSY. 370 */ 371 static __inline void 372 vm_page_free(vm_page_t m) 373 { 374 vm_page_free_toq(m); 375 } 376 377 /* 378 * Free a page to the zerod-pages queue. The caller must ensure that the 379 * page has been zerod. 380 */ 381 static __inline void 382 vm_page_free_zero(vm_page_t m) 383 { 384 #ifdef PMAP_DEBUG 385 #ifdef PHYS_TO_DMAP 386 char *p = (char *)PHYS_TO_DMAP(VM_PAGE_TO_PHYS(m)); 387 int i; 388 389 for (i = 0; i < PAGE_SIZE; i++) { 390 if (p[i] != 0) { 391 panic("non-zero page in vm_page_free_zero()"); 392 } 393 } 394 #endif 395 #endif 396 vm_page_free_toq(m); 397 } 398 399 /* 400 * Set page to not be dirty. Note: does not clear pmap modify bits . 401 */ 402 static __inline void 403 vm_page_undirty(vm_page_t m) 404 { 405 m->dirty = 0; 406 } 407 408 #endif /* _KERNEL */ 409 #endif /* _VM_VM_PAGE2_H_ */ 410 411