module/os/freebsd/zfs/arc_os.c

   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 https://opensource.org/licenses/CDDL-1.0.
  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
  22 #include <sys/spa.h>
  23 #include <sys/zio.h>
  24 #include <sys/spa_impl.h>
  25 #include <sys/counter.h>
  26 #include <sys/zio_compress.h>
  27 #include <sys/zio_checksum.h>
  28 #include <sys/zfs_context.h>
  29 #include <sys/arc.h>
  30 #include <sys/arc_os.h>
  31 #include <sys/zfs_refcount.h>
  32 #include <sys/vdev.h>
  33 #include <sys/vdev_trim.h>
  34 #include <sys/vdev_impl.h>
  35 #include <sys/dsl_pool.h>
  36 #include <sys/zio_checksum.h>
  37 #include <sys/multilist.h>
  38 #include <sys/abd.h>
  39 #include <sys/zil.h>
  40 #include <sys/fm/fs/zfs.h>
  41 #include <sys/eventhandler.h>
  42 #include <sys/callb.h>
  43 #include <sys/kstat.h>
  44 #include <sys/zthr.h>
  45 #include <zfs_fletcher.h>
  46 #include <sys/arc_impl.h>
  47 #include <sys/sdt.h>
  48 #include <sys/aggsum.h>
  49 #include <sys/vnode.h>
  50 #include <cityhash.h>
  51 #include <machine/vmparam.h>
  52 #include <sys/vm.h>
  53 #include <sys/vmmeter.h>
  54
  55 extern struct vfsops zfs_vfsops;
  56
  57 uint_t zfs_arc_free_target = 0;
  58
  59 static void
  60 arc_free_target_init(void *unused __unused)
  61 {
  62         zfs_arc_free_target = vm_cnt.v_free_target;
  63 }
  64 SYSINIT(arc_free_target_init, SI_SUB_KTHREAD_PAGE, SI_ORDER_ANY,
  65     arc_free_target_init, NULL);
  66
  67 /*
  68  * We don't have a tunable for arc_free_target due to the dependency on
  69  * pagedaemon initialisation.
  70  */
  71 ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, free_target,
  72     param_set_arc_free_target, 0, CTLFLAG_RW,
  73         "Desired number of free pages below which ARC triggers reclaim");
  74 ZFS_MODULE_PARAM_CALL(zfs_arc, zfs_arc_, no_grow_shift,
  75     param_set_arc_no_grow_shift, 0, ZMOD_RW,
  76         "log2(fraction of ARC which must be free to allow growing)");
  77
  78 int64_t
  79 arc_available_memory(void)
  80 {
  81         int64_t lowest = INT64_MAX;
  82         int64_t n __unused;
  83
  84         /*
  85          * Cooperate with pagedaemon when it's time for it to scan
  86          * and reclaim some pages.
  87          */
  88         n = PAGESIZE * ((int64_t)freemem - zfs_arc_free_target);
  89         if (n < lowest) {
  90                 lowest = n;
  91         }
  92 #if !defined(UMA_MD_SMALL_ALLOC) && !defined(UMA_USE_DMAP)
  93         /*
  94          * If we're on a platform without a direct map, it's possible that we'll
  95          * exhaust the kernel heap space before we ever run out of available
  96          * physical memory.  Most checks of the size of the heap_area compare
  97          * against tune.t_minarmem, which is the minimum available real memory
  98          * that we can have in the system.  However, this is generally fixed at
  99          * 25 pages which is so low that it's useless.  In this comparison, we
 100          * seek to calculate the total heap-size, and reclaim if more than
 101          * 3/4ths of the heap is allocated.  (Or, in the calculation, if less
 102          * than 1/4th is free)
 103          */
 104         n = uma_avail() - (long)(uma_limit() / 4);
 105         if (n < lowest) {
 106                 lowest = n;
 107         }
 108 #endif
 109
 110         DTRACE_PROBE1(arc__available_memory, int64_t, lowest);
 111         return (lowest);
 112 }
 113
 114 /*
 115  * Return a default max arc size based on the amount of physical memory.
 116  */
 117 uint64_t
 118 arc_default_max(uint64_t min, uint64_t allmem)
 119 {
 120         uint64_t size;
 121
 122         if (allmem >= 1 << 30)
 123                 size = allmem - (1 << 30);
 124         else
 125                 size = min;
 126         return (MAX(allmem * 5 / 8, size));
 127 }
 128
 129 uint64_t
 130 arc_all_memory(void)
 131 {
 132         return (ptob(physmem));
 133 }
 134
 135 int
 136 arc_memory_throttle(spa_t *spa, uint64_t reserve, uint64_t txg)
 137 {
 138         return (0);
 139 }
 140
 141 uint64_t
 142 arc_free_memory(void)
 143 {
 144         return (ptob(freemem));
 145 }
 146
 147 static eventhandler_tag arc_event_lowmem = NULL;
 148
 149 static void
 150 arc_lowmem(void *arg __unused, int howto __unused)
 151 {
 152         int64_t can_free, free_memory, to_free;
 153
 154         arc_no_grow = B_TRUE;
 155         arc_warm = B_TRUE;
 156         arc_growtime = gethrtime() + SEC2NSEC(arc_grow_retry);
 157
 158         free_memory = arc_available_memory();
 159         can_free = arc_c - arc_c_min;
 160         to_free = (MAX(can_free, 0) >> arc_shrink_shift) - MIN(free_memory, 0);
 161         DTRACE_PROBE2(arc__needfree, int64_t, free_memory, int64_t, to_free);
 162         to_free = arc_reduce_target_size(to_free);
 163
 164         /*
 165          * It is unsafe to block here in arbitrary threads, because we can come
 166          * here from ARC itself and may hold ARC locks and thus risk a deadlock
 167          * with ARC reclaim thread.
 168          */
 169         if (curproc == pageproc) {
 170                 arc_wait_for_eviction(to_free, B_FALSE, B_FALSE);
 171                 ARCSTAT_BUMP(arcstat_memory_indirect_count);
 172         } else {
 173                 ARCSTAT_BUMP(arcstat_memory_direct_count);
 174         }
 175 }
 176
 177 void
 178 arc_lowmem_init(void)
 179 {
 180         arc_event_lowmem = EVENTHANDLER_REGISTER(vm_lowmem, arc_lowmem, NULL,
 181             EVENTHANDLER_PRI_FIRST);
 182 }
 183
 184 void
 185 arc_lowmem_fini(void)
 186 {
 187         if (arc_event_lowmem != NULL)
 188                 EVENTHANDLER_DEREGISTER(vm_lowmem, arc_event_lowmem);
 189 }
 190
 191 void
 192 arc_register_hotplug(void)
 193 {
 194 }
 195
 196 void
 197 arc_unregister_hotplug(void)
 198 {
 199 }