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 http://www.opensolaris.org/os/licensing.
  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/zfs_refcount.h>
  31 #include <sys/vdev.h>
  32 #include <sys/vdev_trim.h>
  33 #include <sys/vdev_impl.h>
  34 #include <sys/dsl_pool.h>
  35 #include <sys/zio_checksum.h>
  36 #include <sys/multilist.h>
  37 #include <sys/abd.h>
  38 #include <sys/zil.h>
  39 #include <sys/fm/fs/zfs.h>
  40 #include <sys/eventhandler.h>
  41 #include <sys/callb.h>
  42 #include <sys/kstat.h>
  43 #include <sys/zthr.h>
  44 #include <zfs_fletcher.h>
  45 #include <sys/arc_impl.h>
  46 #include <sys/sdt.h>
  47 #include <sys/aggsum.h>
  48 #include <sys/vnode.h>
  49 #include <cityhash.h>
  50 #include <machine/vmparam.h>
  51 #include <sys/vm.h>
  52 #include <sys/vmmeter.h>
  53
  54 #if __FreeBSD_version >= 1300139
  55 static struct sx arc_vnlru_lock;
  56 static struct vnode *arc_vnlru_marker;
  57 #endif
  58
  59 extern struct vfsops zfs_vfsops;
  60
  61 uint_t zfs_arc_free_target = 0;
  62
  63 static void
  64 arc_free_target_init(void *unused __unused)
  65 {
  66         zfs_arc_free_target = vm_cnt.v_free_target;
  67 }
  68 SYSINIT(arc_free_target_init, SI_SUB_KTHREAD_PAGE, SI_ORDER_ANY,
  69     arc_free_target_init, NULL);
  70
  71 /*
  72  * We don't have a tunable for arc_free_target due to the dependency on
  73  * pagedaemon initialisation.
  74  */
  75 static int
  76 sysctl_vfs_zfs_arc_free_target(SYSCTL_HANDLER_ARGS)
  77 {
  78         uint_t val;
  79         int err;
  80
  81         val = zfs_arc_free_target;
  82         err = sysctl_handle_int(oidp, &val, 0, req);
  83         if (err != 0 || req->newptr == NULL)
  84                 return (err);
  85
  86         if (val < minfree)
  87                 return (EINVAL);
  88         if (val > vm_cnt.v_page_count)
  89                 return (EINVAL);
  90
  91         zfs_arc_free_target = val;
  92
  93         return (0);
  94 }
  95 SYSCTL_DECL(_vfs_zfs);
  96 SYSCTL_PROC(_vfs_zfs, OID_AUTO, arc_free_target,
  97     CTLTYPE_UINT | CTLFLAG_MPSAFE | CTLFLAG_RW, 0, sizeof (uint_t),
  98     sysctl_vfs_zfs_arc_free_target, "IU",
  99         "Desired number of free pages below which ARC triggers reclaim");
 100
 101 int64_t
 102 arc_available_memory(void)
 103 {
 104         int64_t lowest = INT64_MAX;
 105         int64_t n __unused;
 106
 107         /*
 108          * Cooperate with pagedaemon when it's time for it to scan
 109          * and reclaim some pages.
 110          */
 111         n = PAGESIZE * ((int64_t)freemem - zfs_arc_free_target);
 112         if (n < lowest) {
 113                 lowest = n;
 114         }
 115 #if defined(__i386) || !defined(UMA_MD_SMALL_ALLOC)
 116         /*
 117          * If we're on an i386 platform, it's possible that we'll exhaust the
 118          * kernel heap space before we ever run out of available physical
 119          * memory.  Most checks of the size of the heap_area compare against
 120          * tune.t_minarmem, which is the minimum available real memory that we
 121          * can have in the system.  However, this is generally fixed at 25 pages
 122          * which is so low that it's useless.  In this comparison, we seek to
 123          * calculate the total heap-size, and reclaim if more than 3/4ths of the
 124          * heap is allocated.  (Or, in the calculation, if less than 1/4th is
 125          * free)
 126          */
 127         n = uma_avail() - (long)(uma_limit() / 4);
 128         if (n < lowest) {
 129                 lowest = n;
 130         }
 131 #endif
 132
 133         DTRACE_PROBE1(arc__available_memory, int64_t, lowest);
 134         return (lowest);
 135 }
 136
 137 /*
 138  * Return a default max arc size based on the amount of physical memory.
 139  */
 140 uint64_t
 141 arc_default_max(uint64_t min, uint64_t allmem)
 142 {
 143         uint64_t size;
 144
 145         if (allmem >= 1 << 30)
 146                 size = allmem - (1 << 30);
 147         else
 148                 size = min;
 149         return (MAX(allmem * 5 / 8, size));
 150 }
 151
 152 /*
 153  * Helper function for arc_prune_async() it is responsible for safely
 154  * handling the execution of a registered arc_prune_func_t.
 155  */
 156 static void
 157 arc_prune_task(void *arg)
 158 {
 159         int64_t nr_scan = (intptr_t)arg;
 160
 161         arc_reduce_target_size(ptob(nr_scan));
 162 #if __FreeBSD_version >= 1300139
 163         sx_xlock(&arc_vnlru_lock);
 164         vnlru_free_vfsops(nr_scan, &zfs_vfsops, arc_vnlru_marker);
 165         sx_xunlock(&arc_vnlru_lock);
 166 #else
 167         vnlru_free(nr_scan, &zfs_vfsops);
 168 #endif
 169 }
 170
 171 /*
 172  * Notify registered consumers they must drop holds on a portion of the ARC
 173  * buffered they reference.  This provides a mechanism to ensure the ARC can
 174  * honor the arc_meta_limit and reclaim otherwise pinned ARC buffers.  This
 175  * is analogous to dnlc_reduce_cache() but more generic.
 176  *
 177  * This operation is performed asynchronously so it may be safely called
 178  * in the context of the arc_reclaim_thread().  A reference is taken here
 179  * for each registered arc_prune_t and the arc_prune_task() is responsible
 180  * for releasing it once the registered arc_prune_func_t has completed.
 181  */
 182 void
 183 arc_prune_async(int64_t adjust)
 184 {
 185
 186 #ifndef __LP64__
 187         if (adjust > INTPTR_MAX)
 188                 adjust = INTPTR_MAX;
 189 #endif
 190         taskq_dispatch(arc_prune_taskq, arc_prune_task,
 191             (void *)(intptr_t)adjust, TQ_SLEEP);
 192         ARCSTAT_BUMP(arcstat_prune);
 193 }
 194
 195 uint64_t
 196 arc_all_memory(void)
 197 {
 198         return (ptob(physmem));
 199 }
 200
 201 int
 202 arc_memory_throttle(spa_t *spa, uint64_t reserve, uint64_t txg)
 203 {
 204         return (0);
 205 }
 206
 207 uint64_t
 208 arc_free_memory(void)
 209 {
 210         return (ptob(freemem));
 211 }
 212
 213 static eventhandler_tag arc_event_lowmem = NULL;
 214
 215 static void
 216 arc_lowmem(void *arg __unused, int howto __unused)
 217 {
 218         int64_t free_memory, to_free;
 219
 220         arc_no_grow = B_TRUE;
 221         arc_warm = B_TRUE;
 222         arc_growtime = gethrtime() + SEC2NSEC(arc_grow_retry);
 223         free_memory = arc_available_memory();
 224         to_free = (arc_c >> arc_shrink_shift) - MIN(free_memory, 0);
 225         DTRACE_PROBE2(arc__needfree, int64_t, free_memory, int64_t, to_free);
 226         arc_reduce_target_size(to_free);
 227
 228         /*
 229          * It is unsafe to block here in arbitrary threads, because we can come
 230          * here from ARC itself and may hold ARC locks and thus risk a deadlock
 231          * with ARC reclaim thread.
 232          */
 233         if (curproc == pageproc)
 234                 arc_wait_for_eviction(to_free, B_FALSE);
 235 }
 236
 237 void
 238 arc_lowmem_init(void)
 239 {
 240         arc_event_lowmem = EVENTHANDLER_REGISTER(vm_lowmem, arc_lowmem, NULL,
 241             EVENTHANDLER_PRI_FIRST);
 242 #if __FreeBSD_version >= 1300139
 243         arc_vnlru_marker = vnlru_alloc_marker();
 244         sx_init(&arc_vnlru_lock, "arc vnlru lock");
 245 #endif
 246 }
 247
 248 void
 249 arc_lowmem_fini(void)
 250 {
 251         if (arc_event_lowmem != NULL)
 252                 EVENTHANDLER_DEREGISTER(vm_lowmem, arc_event_lowmem);
 253 #if __FreeBSD_version >= 1300139
 254         if (arc_vnlru_marker != NULL) {
 255                 vnlru_free_marker(arc_vnlru_marker);
 256                 sx_destroy(&arc_vnlru_lock);
 257         }
 258 #endif
 259 }
 260
 261 void
 262 arc_register_hotplug(void)
 263 {
 264 }
 265
 266 void
 267 arc_unregister_hotplug(void)
 268 {
 269 }