sys/kern/kern_sfbuf.c

   1 /*
   2  * Copyright (c) 1998 David Greenman.  All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  14  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  16  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  17  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  18  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  19  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  20  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  21  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  22  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  23  * SUCH DAMAGE.
  24  *
  25  * $DragonFly: src/sys/kern/kern_sfbuf.c,v 1.15 2007/04/30 07:18:53 dillon Exp $
  26  */
  27
  28 #include <sys/param.h>
  29 #include <sys/types.h>
  30 #include <sys/systm.h>
  31 #include <sys/kernel.h>
  32 #include <sys/malloc.h>
  33 #include <sys/queue.h>
  34 #include <sys/sfbuf.h>
  35 #include <sys/globaldata.h>
  36 #include <sys/thread.h>
  37 #include <sys/sysctl.h>
  38 #include <vm/vm.h>
  39 #include <vm/vm_extern.h>
  40 #include <vm/vm_kern.h>
  41 #include <vm/vm_page.h>
  42 #include <vm/pmap.h>
  43 #include <sys/thread2.h>
  44
  45 static void sf_buf_init(void *arg);
  46 SYSINIT(sock_sf, SI_BOOT2_MACHDEP, SI_ORDER_ANY, sf_buf_init, NULL)
  47
  48 LIST_HEAD(sf_buf_list, sf_buf);
  49
  50 SYSCTL_INT(_kern_ipc, OID_AUTO, nsfbufs, CTLFLAG_RD, &nsfbufs, 0,
  51         "Maximum number of sf_bufs available to the system");
  52
  53 /*
  54  * A hash table of active sendfile(2) buffers
  55  */
  56 static struct sf_buf_list *sf_buf_hashtable;
  57 static u_long sf_buf_hashmask;
  58
  59 static TAILQ_HEAD(, sf_buf) sf_buf_freelist;
  60 static u_int sf_buf_alloc_want;
  61
  62 static vm_offset_t sf_base;
  63 static struct sf_buf *sf_bufs;
  64
  65 static int sfbuf_quick = 1;
  66 SYSCTL_INT(_debug, OID_AUTO, sfbuf_quick, CTLFLAG_RW, &sfbuf_quick, 0, "");
  67 static int nsffree;
  68 SYSCTL_INT(_kern_ipc, OID_AUTO, nsffree, CTLFLAG_RD, &nsffree, 0,
  69         "Number of free sf_bufs available to the system");
  70
  71 static __inline
  72 int
  73 sf_buf_hash(vm_page_t m)
  74 {
  75     int hv;
  76
  77     hv = ((int)m / sizeof(vm_page_t)) + ((int)m >> 12);
  78     return(hv & sf_buf_hashmask);
  79 }
  80
  81 /*
  82  * Allocate a pool of sf_bufs (sendfile(2) or "super-fast" if you prefer. :-))
  83  */
  84 static void
  85 sf_buf_init(void *arg)
  86 {
  87         int i;
  88
  89         sf_buf_hashtable = hashinit(nsfbufs, M_TEMP, &sf_buf_hashmask);
  90         TAILQ_INIT(&sf_buf_freelist);
  91         sf_base = kmem_alloc_nofault(&kernel_map, nsfbufs * PAGE_SIZE);
  92         sf_bufs = kmalloc(nsfbufs * sizeof(struct sf_buf), M_TEMP,
  93                             M_WAITOK | M_ZERO);
  94         for (i = 0; i < nsfbufs; i++) {
  95                 sf_bufs[i].kva = sf_base + i * PAGE_SIZE;
  96                 sf_bufs[i].flags |= SFBA_ONFREEQ;
  97                 TAILQ_INSERT_TAIL(&sf_buf_freelist, &sf_bufs[i], free_entry);
  98                 ++nsffree;
  99         }
 100 }
 101
 102 /*
 103  * Get an sf_buf from the freelist. Will block if none are available.
 104  */
 105 struct sf_buf *
 106 sf_buf_alloc(struct vm_page *m, int flags)
 107 {
 108         struct sf_buf_list *hash_chain;
 109         struct sf_buf *sf;
 110         globaldata_t gd;
 111         int error;
 112         int pflags;
 113
 114         gd = mycpu;
 115         crit_enter();
 116         hash_chain = &sf_buf_hashtable[sf_buf_hash(m)];
 117         LIST_FOREACH(sf, hash_chain, list_entry) {
 118                 if (sf->m == m) {
 119                         /*
 120                          * cache hit
 121                          *
 122                          * We must invalidate the TLB entry based on whether
 123                          * it need only be valid on the local cpu (SFB_CPUPRIVATE),
 124                          * or on all cpus.  This is conditionalized and in
 125                          * most cases no system-wide invalidation should be
 126                          * needed.
 127                          *
 128                          * Note: we do not remove the entry from the freelist
 129                          * on the 0->1 transition.
 130                          */
 131                         ++sf->refcnt;
 132                         if ((flags & SFB_CPUPRIVATE) && sfbuf_quick) {
 133                                 if ((sf->cpumask & gd->gd_cpumask) == 0) {
 134                                         pmap_kenter_sync_quick(sf->kva);
 135                                         sf->cpumask |= gd->gd_cpumask;
 136                                 }
 137                         } else {
 138                                 if (sf->cpumask != (cpumask_t)-1) {
 139                                         pmap_kenter_sync(sf->kva);
 140                                         sf->cpumask = (cpumask_t)-1;
 141                                 }
 142                         }
 143                         goto done;      /* found existing mapping */
 144                 }
 145         }
 146
 147         /*
 148          * Didn't find old mapping.  Get a buffer off the freelist.  We
 149          * may have to remove and skip buffers with non-zero ref counts
 150          * that were lazily allocated.
 151          */
 152         for (;;) {
 153                 if ((sf = TAILQ_FIRST(&sf_buf_freelist)) == NULL) {
 154                         pflags = (flags & SFB_CATCH) ? PCATCH : 0;
 155                         ++sf_buf_alloc_want;
 156                         error = tsleep(&sf_buf_freelist, pflags, "sfbufa", 0);
 157                         --sf_buf_alloc_want;
 158                         if (error)
 159                                 goto done;
 160                 } else {
 161                         /*
 162                          * We may have to do delayed removals for referenced
 163                          * sf_buf's here in addition to locating a sf_buf
 164                          * to reuse.  The sf_bufs must be removed.
 165                          *
 166                          * We are finished when we find an sf_buf with a
 167                          * refcnt of 0.  We theoretically do not have to
 168                          * remove it from the freelist but it's a good idea
 169                          * to do so to preserve LRU operation for the
 170                          * (1) never before seen before case and (2)
 171                          * accidently recycled due to prior cached uses not
 172                          * removing the buffer case.
 173                          */
 174                         KKASSERT(sf->flags & SFBA_ONFREEQ);
 175                         TAILQ_REMOVE(&sf_buf_freelist, sf, free_entry);
 176                         --nsffree;
 177                         sf->flags &= ~SFBA_ONFREEQ;
 178                         if (sf->refcnt == 0)
 179                                 break;
 180                 }
 181         }
 182         if (sf->m != NULL)      /* remove previous mapping from hash table */
 183                 LIST_REMOVE(sf, list_entry);
 184         LIST_INSERT_HEAD(hash_chain, sf, list_entry);
 185         sf->refcnt = 1;
 186         sf->m = m;
 187         if ((flags & SFB_CPUPRIVATE) && sfbuf_quick) {
 188                 pmap_kenter_quick(sf->kva, sf->m->phys_addr);
 189                 sf->cpumask = gd->gd_cpumask;
 190         } else {
 191                 pmap_kenter(sf->kva, sf->m->phys_addr);
 192                 sf->cpumask = (cpumask_t)-1;
 193         }
 194 done:
 195         crit_exit();
 196         return (sf);
 197 }
 198
 199 #if 0
 200
 201 /*
 202  * Add a reference to a buffer (currently unused)
 203  */
 204 void
 205 sf_buf_ref(struct sf_buf *sf)
 206 {
 207         if (sf->refcnt == 0)
 208                 panic("sf_buf_ref: referencing a free sf_buf");
 209         crit_enter();
 210         sf->refcnt++;
 211         crit_exit();
 212 }
 213
 214 #endif
 215
 216 /*
 217  * Lose a reference to an sf_buf. When none left, detach mapped page
 218  * and release resources back to the system.  Note that the sfbuf's
 219  * removal from the freelist is delayed, so it may in fact already be
 220  * on the free list.  This is the optimal (and most likely) scenario.
 221  *
 222  * Must be called at splimp.
 223  */
 224 void
 225 sf_buf_free(struct sf_buf *sf)
 226 {
 227         if (sf->refcnt == 0)
 228                 panic("sf_buf_free: freeing free sf_buf");
 229         crit_enter();
 230         sf->refcnt--;
 231         if (sf->refcnt == 0 && (sf->flags & SFBA_ONFREEQ) == 0) {
 232                 TAILQ_INSERT_TAIL(&sf_buf_freelist, sf, free_entry);
 233                 ++nsffree;
 234                 sf->flags |= SFBA_ONFREEQ;
 235                 if (sf_buf_alloc_want > 0)
 236                         wakeup_one(&sf_buf_freelist);
 237         }
 238         crit_exit();
 239 }
 240