subr_sfbuf.c

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    1 /*-
    2  * Copyright (c) 2014 Gleb Smirnoff <glebius@FreeBSD.org>
    3  * Copyright (c) 2003, 2005 Alan L. Cox <alc@cs.rice.edu>
    4  * All rights reserved.
    5  *
    6  * Redistribution and use in source and binary forms, with or without
    7  * modification, are permitted provided that the following conditions
    8  * are met:
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice, this list of conditions and the following disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  *
   15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   25  * SUCH DAMAGE.
   26  */
   27 
   28 #include <sys/cdefs.h>
   29 __FBSDID("$FreeBSD$");
   30 
   31 #include <sys/param.h>
   32 #include <sys/kernel.h>
   33 #include <sys/lock.h>
   34 #include <sys/malloc.h>
   35 #include <sys/mutex.h>
   36 #include <sys/proc.h>
   37 #include <sys/sf_buf.h>
   38 #include <sys/smp.h>
   39 #include <sys/sysctl.h>
   40 
   41 #include <vm/vm.h>
   42 #include <vm/vm_extern.h>
   43 #include <vm/vm_page.h>
   44 
   45 #ifndef NSFBUFS
   46 #define NSFBUFS         (512 + maxusers * 16)
   47 #endif
   48 
   49 static int nsfbufs;
   50 static int nsfbufspeak;
   51 static int nsfbufsused;
   52 
   53 SYSCTL_INT(_kern_ipc, OID_AUTO, nsfbufs, CTLFLAG_RDTUN, &nsfbufs, 0,
   54     "Maximum number of sendfile(2) sf_bufs available");
   55 SYSCTL_INT(_kern_ipc, OID_AUTO, nsfbufspeak, CTLFLAG_RD, &nsfbufspeak, 0,
   56     "Number of sendfile(2) sf_bufs at peak usage");
   57 SYSCTL_INT(_kern_ipc, OID_AUTO, nsfbufsused, CTLFLAG_RD, &nsfbufsused, 0,
   58     "Number of sendfile(2) sf_bufs in use");
   59 
   60 static void     sf_buf_init(void *arg);
   61 SYSINIT(sock_sf, SI_SUB_MBUF, SI_ORDER_ANY, sf_buf_init, NULL);
   62 
   63 LIST_HEAD(sf_head, sf_buf);
   64 
   65 /*
   66  * A hash table of active sendfile(2) buffers
   67  */
   68 static struct sf_head *sf_buf_active;
   69 static u_long sf_buf_hashmask;
   70 
   71 #define SF_BUF_HASH(m)  (((m) - vm_page_array) & sf_buf_hashmask)
   72 
   73 static TAILQ_HEAD(, sf_buf) sf_buf_freelist;
   74 static u_int    sf_buf_alloc_want;
   75 
   76 /*
   77  * A lock used to synchronize access to the hash table and free list
   78  */
   79 static struct mtx sf_buf_lock;
   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         struct sf_buf *sf_bufs;
   88         vm_offset_t sf_base;
   89         int i;
   90 
   91         if (PMAP_HAS_DMAP)
   92                 return;
   93 
   94         nsfbufs = NSFBUFS;
   95         TUNABLE_INT_FETCH("kern.ipc.nsfbufs", &nsfbufs);
   96 
   97         sf_buf_active = hashinit(nsfbufs, M_TEMP, &sf_buf_hashmask);
   98         TAILQ_INIT(&sf_buf_freelist);
   99         sf_base = kva_alloc(nsfbufs * PAGE_SIZE);
  100         sf_bufs = malloc(nsfbufs * sizeof(struct sf_buf), M_TEMP,
  101             M_WAITOK | M_ZERO);
  102         for (i = 0; i < nsfbufs; i++) {
  103                 sf_bufs[i].kva = sf_base + i * PAGE_SIZE;
  104                 TAILQ_INSERT_TAIL(&sf_buf_freelist, &sf_bufs[i], free_entry);
  105         }
  106         sf_buf_alloc_want = 0;
  107         mtx_init(&sf_buf_lock, "sf_buf", NULL, MTX_DEF);
  108 }
  109 
  110 /*
  111  * Get an sf_buf from the freelist.  May block if none are available.
  112  */
  113 struct sf_buf *
  114 sf_buf_alloc(struct vm_page *m, int flags)
  115 {
  116         struct sf_head *hash_list;
  117         struct sf_buf *sf;
  118         int error;
  119 
  120         if (PMAP_HAS_DMAP)
  121                 return ((struct sf_buf *)m);
  122 
  123         KASSERT(curthread->td_pinned > 0 || (flags & SFB_CPUPRIVATE) == 0,
  124             ("sf_buf_alloc(SFB_CPUPRIVATE): curthread not pinned"));
  125         hash_list = &sf_buf_active[SF_BUF_HASH(m)];
  126         mtx_lock(&sf_buf_lock);
  127         LIST_FOREACH(sf, hash_list, list_entry) {
  128                 if (sf->m == m) {
  129                         sf->ref_count++;
  130                         if (sf->ref_count == 1) {
  131                                 TAILQ_REMOVE(&sf_buf_freelist, sf, free_entry);
  132                                 nsfbufsused++;
  133                                 nsfbufspeak = imax(nsfbufspeak, nsfbufsused);
  134                         }
  135 #if defined(SMP) && defined(SFBUF_CPUSET)
  136                         sf_buf_shootdown(sf, flags);
  137 #endif
  138                         goto done;
  139                 }
  140         }
  141         while ((sf = TAILQ_FIRST(&sf_buf_freelist)) == NULL) {
  142                 if (flags & SFB_NOWAIT)
  143                         goto done;
  144                 sf_buf_alloc_want++;
  145                 SFSTAT_INC(sf_allocwait);
  146                 error = msleep(&sf_buf_freelist, &sf_buf_lock,
  147                     (flags & SFB_CATCH) ? PCATCH | PVM : PVM, "sfbufa", 0);
  148                 sf_buf_alloc_want--;
  149 
  150                 /*
  151                  * If we got a signal, don't risk going back to sleep. 
  152                  */
  153                 if (error)
  154                         goto done;
  155         }
  156         TAILQ_REMOVE(&sf_buf_freelist, sf, free_entry);
  157         if (sf->m != NULL)
  158                 LIST_REMOVE(sf, list_entry);
  159         LIST_INSERT_HEAD(hash_list, sf, list_entry);
  160         sf->ref_count = 1;
  161         sf->m = m;
  162         nsfbufsused++;
  163         nsfbufspeak = imax(nsfbufspeak, nsfbufsused);
  164         sf_buf_map(sf, flags);
  165 done:
  166         mtx_unlock(&sf_buf_lock);
  167         return (sf);
  168 }
  169 
  170 /*
  171  * Remove a reference from the given sf_buf, adding it to the free
  172  * list when its reference count reaches zero.  A freed sf_buf still,
  173  * however, retains its virtual-to-physical mapping until it is
  174  * recycled or reactivated by sf_buf_alloc(9).
  175  */
  176 void
  177 sf_buf_free(struct sf_buf *sf)
  178 {
  179 
  180         if (PMAP_HAS_DMAP)
  181                 return;
  182 
  183         mtx_lock(&sf_buf_lock);
  184         sf->ref_count--;
  185         if (sf->ref_count == 0) {
  186                 TAILQ_INSERT_TAIL(&sf_buf_freelist, sf, free_entry);
  187                 nsfbufsused--;
  188                 if (sf_buf_unmap(sf)) {
  189                         sf->m = NULL;
  190                         LIST_REMOVE(sf, list_entry);
  191                 }
  192                 if (sf_buf_alloc_want > 0)
  193                         wakeup(&sf_buf_freelist);
  194         }
  195         mtx_unlock(&sf_buf_lock);
  196 }
  197 
  198 void
  199 sf_buf_ref(struct sf_buf *sf)
  200 {
  201 
  202         if (PMAP_HAS_DMAP)
  203                 return;
  204 
  205         mtx_lock(&sf_buf_lock);
  206         KASSERT(sf->ref_count > 0, ("%s: sf %p not allocated", __func__, sf));
  207         sf->ref_count++;
  208         mtx_unlock(&sf_buf_lock);
  209 }
  210 
  211 #ifdef SFBUF_PROCESS_PAGE
  212 /*
  213  * Run callback function on sf_buf that holds a certain page.
  214  */
  215 boolean_t
  216 sf_buf_process_page(vm_page_t m, void (*cb)(struct sf_buf *))
  217 {
  218         struct sf_head *hash_list;
  219         struct sf_buf *sf;
  220 
  221         hash_list = &sf_buf_active[SF_BUF_HASH(m)];
  222         mtx_lock(&sf_buf_lock);
  223         LIST_FOREACH(sf, hash_list, list_entry) {
  224                 if (sf->m == m) {
  225                         cb(sf);
  226                         mtx_unlock(&sf_buf_lock);
  227                         return (TRUE);
  228                 }
  229         }
  230         mtx_unlock(&sf_buf_lock);
  231         return (FALSE);
  232 }
  233 #endif  /* SFBUF_PROCESS_PAGE */

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FreeBSD/Linux Kernel Cross Reference sys/kern/subr_sfbuf.c

FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_sfbuf.c