sys/vm/vm_pager.c

   1 /*
   2  * (MPSAFE)
   3  *
   4  * Copyright (c) 1991, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * The Mach Operating System project at Carnegie-Mellon University.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  *      from: @(#)vm_pager.c    8.6 (Berkeley) 1/12/94
  35  *
  36  *
  37  * Copyright (c) 1987, 1990 Carnegie-Mellon University.
  38  * All rights reserved.
  39  *
  40  * Authors: Avadis Tevanian, Jr., Michael Wayne Young
  41  *
  42  * Permission to use, copy, modify and distribute this software and
  43  * its documentation is hereby granted, provided that both the copyright
  44  * notice and this permission notice appear in all copies of the
  45  * software, derivative works or modified versions, and any portions
  46  * thereof, and that both notices appear in supporting documentation.
  47  *
  48  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  49  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
  50  * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  51  *
  52  * Carnegie Mellon requests users of this software to return to
  53  *
  54  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  55  *  School of Computer Science
  56  *  Carnegie Mellon University
  57  *  Pittsburgh PA 15213-3890
  58  *
  59  * any improvements or extensions that they make and grant Carnegie the
  60  * rights to redistribute these changes.
  61  *
  62  * $FreeBSD: src/sys/vm/vm_pager.c,v 1.54.2.2 2001/11/18 07:11:00 dillon Exp $
  63  */
  64
  65 /*
  66  *      Paging space routine stubs.  Emulates a matchmaker-like interface
  67  *      for builtin pagers.
  68  */
  69
  70 #include <sys/param.h>
  71 #include <sys/systm.h>
  72 #include <sys/kernel.h>
  73 #include <sys/vnode.h>
  74 #include <sys/buf.h>
  75 #include <sys/ucred.h>
  76 #include <sys/dsched.h>
  77 #include <sys/proc.h>
  78 #include <sys/sysctl.h>
  79 #include <sys/thread2.h>
  80
  81 #include <vm/vm.h>
  82 #include <vm/vm_param.h>
  83 #include <vm/vm_kern.h>
  84 #include <vm/vm_object.h>
  85 #include <vm/vm_page.h>
  86 #include <vm/vm_pager.h>
  87 #include <vm/vm_extern.h>
  88
  89 #include <sys/buf2.h>
  90 #include <vm/vm_page2.h>
  91
  92 extern struct pagerops defaultpagerops;
  93 extern struct pagerops swappagerops;
  94 extern struct pagerops vnodepagerops;
  95 extern struct pagerops devicepagerops;
  96 extern struct pagerops physpagerops;
  97
  98 int cluster_pbuf_freecnt = -1;  /* unlimited to begin with */
  99
 100 static int dead_pager_getpage (vm_object_t, vm_page_t *, int);
 101 static void dead_pager_putpages (vm_object_t, vm_page_t *, int, int, int *);
 102 static boolean_t dead_pager_haspage (vm_object_t, vm_pindex_t);
 103 static void dead_pager_dealloc (vm_object_t);
 104
 105 /*
 106  * No requirements.
 107  */
 108 static int
 109 dead_pager_getpage(vm_object_t obj, vm_page_t *mpp, int seqaccess)
 110 {
 111         return VM_PAGER_FAIL;
 112 }
 113
 114 /*
 115  * No requirements.
 116  */
 117 static void
 118 dead_pager_putpages(vm_object_t object, vm_page_t *m, int count, int flags,
 119                     int *rtvals)
 120 {
 121         int i;
 122
 123         for (i = 0; i < count; i++) {
 124                 rtvals[i] = VM_PAGER_AGAIN;
 125         }
 126 }
 127
 128 /*
 129  * No requirements.
 130  */
 131 static boolean_t
 132 dead_pager_haspage(vm_object_t object, vm_pindex_t pindex)
 133 {
 134         return FALSE;
 135 }
 136
 137 /*
 138  * No requirements.
 139  */
 140 static void
 141 dead_pager_dealloc(vm_object_t object)
 142 {
 143         KKASSERT(object->swblock_count == 0);
 144         return;
 145 }
 146
 147 static struct pagerops deadpagerops = {
 148         dead_pager_dealloc,
 149         dead_pager_getpage,
 150         dead_pager_putpages,
 151         dead_pager_haspage
 152 };
 153
 154 struct pagerops *pagertab[] = {
 155         &defaultpagerops,       /* OBJT_DEFAULT */
 156         &swappagerops,          /* OBJT_SWAP */
 157         &vnodepagerops,         /* OBJT_VNODE */
 158         &devicepagerops,        /* OBJT_DEVICE */
 159         &devicepagerops,        /* OBJT_MGTDEVICE */
 160         &physpagerops,          /* OBJT_PHYS */
 161         &deadpagerops           /* OBJT_DEAD */
 162 };
 163
 164 int npagers = NELEM(pagertab);
 165
 166 /*
 167  * Kernel address space for mapping pages.
 168  * Used by pagers where KVAs are needed for IO.
 169  *
 170  * XXX needs to be large enough to support the number of pending async
 171  * cleaning requests (NPENDINGIO == 64) * the maximum swap cluster size
 172  * (MAXPHYS == 64k) if you want to get the most efficiency.
 173  */
 174 #define PAGER_MAP_SIZE  (8 * 1024 * 1024)
 175
 176 #define BSWHSIZE        16
 177 #define BSWHMASK        (BSWHSIZE - 1)
 178
 179 TAILQ_HEAD(swqueue, buf);
 180
 181 int pager_map_size = PAGER_MAP_SIZE;
 182 struct vm_map pager_map;
 183
 184 static vm_offset_t swapbkva_mem;        /* swap buffers kva */
 185 static vm_offset_t swapbkva_kva;        /* swap buffers kva */
 186 static struct swqueue bswlist_mem[BSWHSIZE];    /* with preallocated memory */
 187 static struct swqueue bswlist_kva[BSWHSIZE];    /* with kva */
 188 static struct swqueue bswlist_raw[BSWHSIZE];    /* without kva */
 189 static struct spinlock bswspin_mem[BSWHSIZE];
 190 static struct spinlock bswspin_kva[BSWHSIZE];
 191 static struct spinlock bswspin_raw[BSWHSIZE];
 192 static int pbuf_raw_count;
 193 static int pbuf_kva_count;
 194 static int pbuf_mem_count;
 195
 196 SYSCTL_INT(_vfs, OID_AUTO, pbuf_raw_count, CTLFLAG_RD, &pbuf_raw_count, 0,
 197     "Kernel pbuf raw reservations");
 198 SYSCTL_INT(_vfs, OID_AUTO, pbuf_kva_count, CTLFLAG_RD, &pbuf_kva_count, 0,
 199     "Kernel pbuf kva reservations");
 200 SYSCTL_INT(_vfs, OID_AUTO, pbuf_mem_count, CTLFLAG_RD, &pbuf_mem_count, 0,
 201     "Kernel pbuf mem reservations");
 202
 203 /*
 204  * Initialize the swap buffer list.
 205  *
 206  * Called from the low level boot code only.
 207  */
 208 static void
 209 vm_pager_init(void *arg __unused)
 210 {
 211         int i;
 212
 213         for (i = 0; i < BSWHSIZE; ++i) {
 214                 TAILQ_INIT(&bswlist_mem[i]);
 215                 TAILQ_INIT(&bswlist_kva[i]);
 216                 TAILQ_INIT(&bswlist_raw[i]);
 217                 spin_init(&bswspin_mem[i], "bswmem");
 218                 spin_init(&bswspin_kva[i], "bswkva");
 219                 spin_init(&bswspin_raw[i], "bswraw");
 220         }
 221 }
 222 SYSINIT(vm_mem, SI_BOOT1_VM, SI_ORDER_SECOND, vm_pager_init, NULL);
 223
 224 /*
 225  * Called from the low level boot code only.
 226  */
 227 static
 228 void
 229 vm_pager_bufferinit(void *dummy __unused)
 230 {
 231         struct buf *bp;
 232         long i;
 233
 234         /*
 235          * Reserve KVM space for pbuf data.
 236          */
 237         swapbkva_mem = kmem_alloc_pageable(&pager_map, nswbuf_mem * MAXPHYS);
 238         if (!swapbkva_mem)
 239                 panic("Not enough pager_map VM space for physical buffers");
 240         swapbkva_kva = kmem_alloc_pageable(&pager_map, nswbuf_kva * MAXPHYS);
 241         if (!swapbkva_kva)
 242                 panic("Not enough pager_map VM space for physical buffers");
 243
 244         /*
 245          * Initial pbuf setup.
 246          *
 247          * mem - These pbufs have permanently allocated memory
 248          * kva - These pbufs have unallocated kva reservations
 249          * raw - These pbufs have no kva reservations
 250          */
 251
 252         /*
 253          * Buffers with pre-allocated kernel memory can be convenient for
 254          * copyin/copyout because no SMP page invalidation or other pmap
 255          * operations are needed.
 256          */
 257 #if 1
 258         bp = swbuf_mem;
 259         for (i = 0; i < nswbuf_mem; ++i, ++bp) {
 260                 vm_page_t m;
 261                 vm_pindex_t pg;
 262                 int j;
 263
 264                 bp->b_kvabase = (caddr_t)((intptr_t)i * MAXPHYS) + swapbkva_mem;
 265                 bp->b_kvasize = MAXPHYS;
 266                 bp->b_swindex = i & BSWHMASK;
 267                 BUF_LOCKINIT(bp);
 268                 buf_dep_init(bp);
 269                 TAILQ_INSERT_HEAD(&bswlist_mem[i & BSWHMASK], bp, b_freelist);
 270                 atomic_add_int(&pbuf_mem_count, 1);
 271                 bp->b_data = bp->b_kvabase;
 272                 bp->b_bcount = MAXPHYS;
 273                 bp->b_xio.xio_pages = bp->b_xio.xio_internal_pages;
 274
 275                 pg = (vm_offset_t)bp->b_kvabase >> PAGE_SHIFT;
 276                 vm_object_hold(&kernel_object);
 277                 for (j = 0; j < MAXPHYS / PAGE_SIZE; ++j) {
 278                         m = vm_page_alloc(&kernel_object, pg, VM_ALLOC_NORMAL |
 279                                                               VM_ALLOC_SYSTEM);
 280                         KKASSERT(m != NULL);
 281                         bp->b_xio.xio_internal_pages[j] = m;
 282                         vm_page_wire(m);
 283                         /* early boot, no other cpus running yet */
 284                         pmap_kenter_noinval(pg * PAGE_SIZE, VM_PAGE_TO_PHYS(m));
 285                         cpu_invlpg((void *)(pg * PAGE_SIZE));
 286                         vm_page_wakeup(m);
 287                         ++pg;
 288                 }
 289                 vm_object_drop(&kernel_object);
 290                 bp->b_xio.xio_npages = j;
 291         }
 292 #endif
 293
 294         /*
 295          * Buffers with pre-assigned KVA bases.  The KVA has no memory pages
 296          * assigned to it.  Saves the caller from having to reserve KVA for
 297          * the page map.
 298          */
 299         bp = swbuf_kva;
 300         for (i = 0; i < nswbuf_kva; ++i, ++bp) {
 301                 bp->b_kvabase = (caddr_t)((intptr_t)i * MAXPHYS) + swapbkva_kva;
 302                 bp->b_kvasize = MAXPHYS;
 303                 bp->b_swindex = i & BSWHMASK;
 304                 BUF_LOCKINIT(bp);
 305                 buf_dep_init(bp);
 306                 TAILQ_INSERT_HEAD(&bswlist_kva[i & BSWHMASK], bp, b_freelist);
 307                 atomic_add_int(&pbuf_kva_count, 1);
 308         }
 309
 310         /*
 311          * RAW buffers with no KVA mappings.
 312          *
 313          * NOTE: We use KM_NOTLBSYNC here to reduce unnecessary IPIs
 314          *       during startup, which can really slow down emulated
 315          *       systems.
 316          */
 317         nswbuf_raw = nbuf * 2;
 318         swbuf_raw = (void *)kmem_alloc3(&kernel_map,
 319                                 round_page(nswbuf_raw * sizeof(struct buf)),
 320                                 KM_NOTLBSYNC);
 321         smp_invltlb();
 322         bp = swbuf_raw;
 323         for (i = 0; i < nswbuf_raw; ++i, ++bp) {
 324                 bp->b_swindex = i & BSWHMASK;
 325                 BUF_LOCKINIT(bp);
 326                 buf_dep_init(bp);
 327                 TAILQ_INSERT_HEAD(&bswlist_raw[i & BSWHMASK], bp, b_freelist);
 328                 atomic_add_int(&pbuf_raw_count, 1);
 329         }
 330
 331         /*
 332          * Allow the clustering code to use half of our pbufs.
 333          */
 334         cluster_pbuf_freecnt = nswbuf_kva / 2;
 335 }
 336
 337 SYSINIT(do_vmpg, SI_BOOT2_MACHDEP, SI_ORDER_FIRST, vm_pager_bufferinit, NULL);
 338
 339 /*
 340  * No requirements.
 341  */
 342 void
 343 vm_pager_deallocate(vm_object_t object)
 344 {
 345         (*pagertab[object->type]->pgo_dealloc) (object);
 346 }
 347
 348 /*
 349  * vm_pager_get_pages() - inline, see vm/vm_pager.h
 350  * vm_pager_put_pages() - inline, see vm/vm_pager.h
 351  * vm_pager_has_page() - inline, see vm/vm_pager.h
 352  * vm_pager_page_inserted() - inline, see vm/vm_pager.h
 353  * vm_pager_page_removed() - inline, see vm/vm_pager.h
 354  */
 355
 356 /*
 357  * Search the specified pager object list for an object with the
 358  * specified handle.  If an object with the specified handle is found,
 359  * increase its reference count and return it.  Otherwise, return NULL.
 360  *
 361  * The pager object list must be locked.
 362  */
 363 vm_object_t
 364 vm_pager_object_lookup(struct pagerlst *pg_list, void *handle)
 365 {
 366         vm_object_t object;
 367
 368         TAILQ_FOREACH(object, pg_list, pager_object_list) {
 369                 if (object->handle == handle) {
 370                         VM_OBJECT_LOCK(object);
 371                         if ((object->flags & OBJ_DEAD) == 0) {
 372                                 vm_object_reference_locked(object);
 373                                 VM_OBJECT_UNLOCK(object);
 374                                 break;
 375                         }
 376                         VM_OBJECT_UNLOCK(object);
 377                 }
 378         }
 379         return (object);
 380 }
 381
 382 /*
 383  * Initialize a physical buffer.
 384  *
 385  * No requirements.
 386  */
 387 static void
 388 initpbuf(struct buf *bp)
 389 {
 390         bp->b_qindex = 0;               /* BQUEUE_NONE */
 391         bp->b_data = bp->b_kvabase;     /* NULL if pbuf sans kva */
 392         bp->b_flags = B_PAGING;
 393         bp->b_cmd = BUF_CMD_DONE;
 394         bp->b_error = 0;
 395         bp->b_bcount = 0;
 396         bp->b_bufsize = MAXPHYS;
 397         initbufbio(bp);
 398         xio_init(&bp->b_xio);
 399         BUF_LOCK(bp, LK_EXCLUSIVE);
 400 }
 401
 402 /*
 403  * Allocate a physical buffer
 404  *
 405  *      There are a limited number of physical buffers.  We need to make
 406  *      sure that no single subsystem is able to hog all of them,
 407  *      so each subsystem implements a counter which is typically initialized
 408  *      to 1/2 nswbuf.  getpbuf() decrements this counter in allocation and
 409  *      increments it on release, and blocks if the counter hits zero.  A
 410  *      subsystem may initialize the counter to -1 to disable the feature,
 411  *      but it must still be sure to match up all uses of getpbuf() with
 412  *      relpbuf() using the same variable.
 413  *
 414  *      NOTE: pfreecnt can be NULL, but this 'feature' will be removed
 415  *      relatively soon when the rest of the subsystems get smart about it. XXX
 416  *
 417  *      Physical buffers can be with or without KVA space reserved.  There
 418  *      are severe limitations on the ones with KVA reserved, and fewer
 419  *      limitations on the ones without.  getpbuf() gets one without,
 420  *      getpbuf_kva() gets one with.
 421  *
 422  * No requirements.
 423  */
 424 struct buf *
 425 getpbuf(int *pfreecnt)  /* raw */
 426 {
 427         struct buf *bp;
 428         int iter;
 429         int loops;
 430
 431         for (;;) {
 432                 while (pfreecnt && *pfreecnt <= 0) {
 433                         tsleep_interlock(pfreecnt, 0);
 434                         if ((int)atomic_fetchadd_int(pfreecnt, 0) <= 0)
 435                                 tsleep(pfreecnt, PINTERLOCKED, "wswbuf0", 0);
 436                 }
 437                 if (pbuf_raw_count <= 0) {
 438                         tsleep_interlock(&pbuf_raw_count, 0);
 439                         if ((int)atomic_fetchadd_int(&pbuf_raw_count, 0) <= 0)
 440                                 tsleep(&pbuf_raw_count, PINTERLOCKED,
 441                                        "wswbuf0", 0);
 442                         continue;
 443                 }
 444                 iter = mycpuid & BSWHMASK;
 445                 for (loops = BSWHSIZE; loops; --loops) {
 446                         if (TAILQ_FIRST(&bswlist_raw[iter]) == NULL) {
 447                                 iter = (iter + 1) & BSWHMASK;
 448                                 continue;
 449                         }
 450                         spin_lock(&bswspin_raw[iter]);
 451                         if ((bp = TAILQ_FIRST(&bswlist_raw[iter])) == NULL) {
 452                                 spin_unlock(&bswspin_raw[iter]);
 453                                 iter = (iter + 1) & BSWHMASK;
 454                                 continue;
 455                         }
 456                         TAILQ_REMOVE(&bswlist_raw[iter], bp, b_freelist);
 457                         atomic_add_int(&pbuf_raw_count, -1);
 458                         if (pfreecnt)
 459                                 atomic_add_int(pfreecnt, -1);
 460                         spin_unlock(&bswspin_raw[iter]);
 461                         initpbuf(bp);
 462
 463                         return bp;
 464                 }
 465         }
 466         /* not reached */
 467 }
 468
 469 struct buf *
 470 getpbuf_kva(int *pfreecnt)
 471 {
 472         struct buf *bp;
 473         int iter;
 474         int loops;
 475
 476         for (;;) {
 477                 while (pfreecnt && *pfreecnt <= 0) {
 478                         tsleep_interlock(pfreecnt, 0);
 479                         if ((int)atomic_fetchadd_int(pfreecnt, 0) <= 0)
 480                                 tsleep(pfreecnt, PINTERLOCKED, "wswbuf0", 0);
 481                 }
 482                 if (pbuf_kva_count <= 0) {
 483                         tsleep_interlock(&pbuf_kva_count, 0);
 484                         if ((int)atomic_fetchadd_int(&pbuf_kva_count, 0) <= 0)
 485                                 tsleep(&pbuf_kva_count, PINTERLOCKED,
 486                                        "wswbuf0", 0);
 487                         continue;
 488                 }
 489                 iter = mycpuid & BSWHMASK;
 490                 for (loops = BSWHSIZE; loops; --loops) {
 491                         if (TAILQ_FIRST(&bswlist_kva[iter]) == NULL) {
 492                                 iter = (iter + 1) & BSWHMASK;
 493                                 continue;
 494                         }
 495                         spin_lock(&bswspin_kva[iter]);
 496                         if ((bp = TAILQ_FIRST(&bswlist_kva[iter])) == NULL) {
 497                                 spin_unlock(&bswspin_kva[iter]);
 498                                 iter = (iter + 1) & BSWHMASK;
 499                                 continue;
 500                         }
 501                         TAILQ_REMOVE(&bswlist_kva[iter], bp, b_freelist);
 502                         atomic_add_int(&pbuf_kva_count, -1);
 503                         if (pfreecnt)
 504                                 atomic_add_int(pfreecnt, -1);
 505                         spin_unlock(&bswspin_kva[iter]);
 506                         initpbuf(bp);
 507
 508                         return bp;
 509                 }
 510         }
 511         /* not reached */
 512 }
 513
 514 /*
 515  * Allocate a pbuf with kernel memory already preallocated.  Caller must
 516  * not change the mapping.
 517  */
 518 struct buf *
 519 getpbuf_mem(int *pfreecnt)
 520 {
 521         struct buf *bp;
 522         int iter;
 523         int loops;
 524
 525         for (;;) {
 526                 while (pfreecnt && *pfreecnt <= 0) {
 527                         tsleep_interlock(pfreecnt, 0);
 528                         if ((int)atomic_fetchadd_int(pfreecnt, 0) <= 0)
 529                                 tsleep(pfreecnt, PINTERLOCKED, "wswbuf0", 0);
 530                 }
 531                 if (pbuf_mem_count <= 0) {
 532                         tsleep_interlock(&pbuf_mem_count, 0);
 533                         if ((int)atomic_fetchadd_int(&pbuf_mem_count, 0) <= 0)
 534                                 tsleep(&pbuf_mem_count, PINTERLOCKED,
 535                                        "wswbuf0", 0);
 536                         continue;
 537                 }
 538                 iter = mycpuid & BSWHMASK;
 539                 for (loops = BSWHSIZE; loops; --loops) {
 540                         if (TAILQ_FIRST(&bswlist_mem[iter]) == NULL) {
 541                                 iter = (iter + 1) & BSWHMASK;
 542                                 continue;
 543                         }
 544                         spin_lock(&bswspin_mem[iter]);
 545                         if ((bp = TAILQ_FIRST(&bswlist_mem[iter])) == NULL) {
 546                                 spin_unlock(&bswspin_mem[iter]);
 547                                 iter = (iter + 1) & BSWHMASK;
 548                                 continue;
 549                         }
 550                         TAILQ_REMOVE(&bswlist_mem[iter], bp, b_freelist);
 551                         atomic_add_int(&pbuf_mem_count, -1);
 552                         if (pfreecnt)
 553                                 atomic_add_int(pfreecnt, -1);
 554                         spin_unlock(&bswspin_mem[iter]);
 555                         initpbuf(bp);
 556
 557                         return bp;
 558                 }
 559         }
 560         /* not reached */
 561 }
 562
 563 /*
 564  * Allocate a physical buffer, if one is available.
 565  *
 566  * Note that there is no NULL hack here - all subsystems using this
 567  * call understand how to use pfreecnt.
 568  *
 569  * No requirements.
 570  */
 571 struct buf *
 572 trypbuf(int *pfreecnt)          /* raw */
 573 {
 574         struct buf *bp;
 575         int iter = mycpuid & BSWHMASK;
 576         int loops;
 577
 578         for (loops = BSWHSIZE; loops; --loops) {
 579                 if (*pfreecnt <= 0 || TAILQ_FIRST(&bswlist_raw[iter]) == NULL) {
 580                         iter = (iter + 1) & BSWHMASK;
 581                         continue;
 582                 }
 583                 spin_lock(&bswspin_raw[iter]);
 584                 if (*pfreecnt <= 0 ||
 585                     (bp = TAILQ_FIRST(&bswlist_raw[iter])) == NULL) {
 586                         spin_unlock(&bswspin_raw[iter]);
 587                         iter = (iter + 1) & BSWHMASK;
 588                         continue;
 589                 }
 590                 TAILQ_REMOVE(&bswlist_raw[iter], bp, b_freelist);
 591                 atomic_add_int(&pbuf_raw_count, -1);
 592                 atomic_add_int(pfreecnt, -1);
 593
 594                 spin_unlock(&bswspin_raw[iter]);
 595
 596                 initpbuf(bp);
 597
 598                 return bp;
 599         }
 600         return NULL;
 601 }
 602
 603 struct buf *
 604 trypbuf_kva(int *pfreecnt)
 605 {
 606         struct buf *bp;
 607         int iter = mycpuid & BSWHMASK;
 608         int loops;
 609
 610         for (loops = BSWHSIZE; loops; --loops) {
 611                 if (*pfreecnt <= 0 || TAILQ_FIRST(&bswlist_kva[iter]) == NULL) {
 612                         iter = (iter + 1) & BSWHMASK;
 613                         continue;
 614                 }
 615                 spin_lock(&bswspin_kva[iter]);
 616                 if (*pfreecnt <= 0 ||
 617                     (bp = TAILQ_FIRST(&bswlist_kva[iter])) == NULL) {
 618                         spin_unlock(&bswspin_kva[iter]);
 619                         iter = (iter + 1) & BSWHMASK;
 620                         continue;
 621                 }
 622                 TAILQ_REMOVE(&bswlist_kva[iter], bp, b_freelist);
 623                 atomic_add_int(&pbuf_kva_count, -1);
 624                 atomic_add_int(pfreecnt, -1);
 625
 626                 spin_unlock(&bswspin_kva[iter]);
 627
 628                 initpbuf(bp);
 629
 630                 return bp;
 631         }
 632         return NULL;
 633 }
 634
 635 /*
 636  * Release a physical buffer
 637  *
 638  *      NOTE: pfreecnt can be NULL, but this 'feature' will be removed
 639  *      relatively soon when the rest of the subsystems get smart about it. XXX
 640  *
 641  * No requirements.
 642  */
 643 void
 644 relpbuf(struct buf *bp, int *pfreecnt)
 645 {
 646         int wake = 0;
 647         int wake_free = 0;
 648         int iter = bp->b_swindex;
 649
 650         KKASSERT(bp->b_flags & B_PAGING);
 651         dsched_buf_exit(bp);
 652
 653         BUF_UNLOCK(bp);
 654
 655         if (bp >= swbuf_mem && bp < &swbuf_mem[nswbuf_mem]) {
 656                 KKASSERT(bp->b_kvabase);
 657                 spin_lock(&bswspin_mem[iter]);
 658                 TAILQ_INSERT_HEAD(&bswlist_mem[iter], bp, b_freelist);
 659                 if (atomic_fetchadd_int(&pbuf_mem_count, 1) == nswbuf_mem / 4)
 660                         wake = 1;
 661                 if (pfreecnt) {
 662                         if (atomic_fetchadd_int(pfreecnt, 1) == 1)
 663                                 wake_free = 1;
 664                 }
 665                 spin_unlock(&bswspin_mem[iter]);
 666                 if (wake)
 667                         wakeup(&pbuf_mem_count);
 668         } else if (bp >= swbuf_kva && bp < &swbuf_kva[nswbuf_kva]) {
 669                 KKASSERT(bp->b_kvabase);
 670                 spin_lock(&bswspin_kva[iter]);
 671                 TAILQ_INSERT_HEAD(&bswlist_kva[iter], bp, b_freelist);
 672                 if (atomic_fetchadd_int(&pbuf_kva_count, 1) == nswbuf_kva / 4)
 673                         wake = 1;
 674                 if (pfreecnt) {
 675                         if (atomic_fetchadd_int(pfreecnt, 1) == 1)
 676                                 wake_free = 1;
 677                 }
 678                 spin_unlock(&bswspin_kva[iter]);
 679                 if (wake)
 680                         wakeup(&pbuf_kva_count);
 681         } else {
 682                 KKASSERT(bp->b_kvabase == NULL);
 683                 KKASSERT(bp >= swbuf_raw && bp < &swbuf_raw[nswbuf_raw]);
 684                 spin_lock(&bswspin_raw[iter]);
 685                 TAILQ_INSERT_HEAD(&bswlist_raw[iter], bp, b_freelist);
 686                 if (atomic_fetchadd_int(&pbuf_raw_count, 1) == nswbuf_raw / 4)
 687                         wake = 1;
 688                 if (pfreecnt) {
 689                         if (atomic_fetchadd_int(pfreecnt, 1) == 1)
 690                                 wake_free = 1;
 691                 }
 692                 spin_unlock(&bswspin_raw[iter]);
 693                 if (wake)
 694                         wakeup(&pbuf_raw_count);
 695         }
 696         if (wake_free)
 697                 wakeup(pfreecnt);
 698 }
 699
 700 void
 701 pbuf_adjcount(int *pfreecnt, int n)
 702 {
 703         if (n) {
 704                 atomic_add_int(pfreecnt, n);
 705                 wakeup(pfreecnt);
 706         }
 707 }