* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
- * or http://www.opensolaris.org/os/licensing.
+ * or https://opensource.org/licenses/CDDL-1.0.
* See the License for the specific language governing permissions
* and limitations under the License.
*
*/
#include <sys/zfs_context.h>
+#include <sys/arc_impl.h>
#include <sys/dnode.h>
#include <sys/dmu_objset.h>
#include <sys/dmu_zfetch.h>
#include <sys/dmu.h>
#include <sys/dbuf.h>
#include <sys/kstat.h>
+#include <sys/wmsum.h>
/*
* This tunable disables predictive prefetch. Note that it leaves "prescient"
* so it can't hurt performance.
*/
-int zfs_prefetch_disable = B_FALSE;
+static int zfs_prefetch_disable = B_FALSE;
/* max # of streams per zfetch */
-unsigned int zfetch_max_streams = 8;
+static unsigned int zfetch_max_streams = 8;
/* min time before stream reclaim */
-unsigned int zfetch_min_sec_reap = 2;
+static unsigned int zfetch_min_sec_reap = 1;
+/* max time before stream delete */
+static unsigned int zfetch_max_sec_reap = 2;
+#ifdef _ILP32
+/* min bytes to prefetch per stream (default 2MB) */
+static unsigned int zfetch_min_distance = 2 * 1024 * 1024;
/* max bytes to prefetch per stream (default 8MB) */
unsigned int zfetch_max_distance = 8 * 1024 * 1024;
+#else
+/* min bytes to prefetch per stream (default 4MB) */
+static unsigned int zfetch_min_distance = 4 * 1024 * 1024;
+/* max bytes to prefetch per stream (default 64MB) */
+unsigned int zfetch_max_distance = 64 * 1024 * 1024;
+#endif
/* max bytes to prefetch indirects for per stream (default 64MB) */
unsigned int zfetch_max_idistance = 64 * 1024 * 1024;
-/* max number of bytes in an array_read in which we allow prefetching (1MB) */
-unsigned long zfetch_array_rd_sz = 1024 * 1024;
typedef struct zfetch_stats {
kstat_named_t zfetchstat_hits;
kstat_named_t zfetchstat_misses;
kstat_named_t zfetchstat_max_streams;
- kstat_named_t zfetchstat_max_completion_us;
- kstat_named_t zfetchstat_last_completion_us;
kstat_named_t zfetchstat_io_issued;
+ kstat_named_t zfetchstat_io_active;
} zfetch_stats_t;
static zfetch_stats_t zfetch_stats = {
{ "hits", KSTAT_DATA_UINT64 },
{ "misses", KSTAT_DATA_UINT64 },
{ "max_streams", KSTAT_DATA_UINT64 },
- { "max_completion_us", KSTAT_DATA_UINT64 },
- { "last_completion_us", KSTAT_DATA_UINT64 },
- { "io_issued", KSTAT_DATA_UINT64 },
+ { "io_issued", KSTAT_DATA_UINT64 },
+ { "io_active", KSTAT_DATA_UINT64 },
};
-#define ZFETCHSTAT_BUMP(stat) \
- atomic_inc_64(&zfetch_stats.stat.value.ui64)
+struct {
+ wmsum_t zfetchstat_hits;
+ wmsum_t zfetchstat_misses;
+ wmsum_t zfetchstat_max_streams;
+ wmsum_t zfetchstat_io_issued;
+ aggsum_t zfetchstat_io_active;
+} zfetch_sums;
+
+#define ZFETCHSTAT_BUMP(stat) \
+ wmsum_add(&zfetch_sums.stat, 1)
#define ZFETCHSTAT_ADD(stat, val) \
- atomic_add_64(&zfetch_stats.stat.value.ui64, val)
-#define ZFETCHSTAT_SET(stat, val) \
- zfetch_stats.stat.value.ui64 = val
-#define ZFETCHSTAT_GET(stat) \
- zfetch_stats.stat.value.ui64
+ wmsum_add(&zfetch_sums.stat, val)
+
+static kstat_t *zfetch_ksp;
-kstat_t *zfetch_ksp;
+static int
+zfetch_kstats_update(kstat_t *ksp, int rw)
+{
+ zfetch_stats_t *zs = ksp->ks_data;
+
+ if (rw == KSTAT_WRITE)
+ return (EACCES);
+ zs->zfetchstat_hits.value.ui64 =
+ wmsum_value(&zfetch_sums.zfetchstat_hits);
+ zs->zfetchstat_misses.value.ui64 =
+ wmsum_value(&zfetch_sums.zfetchstat_misses);
+ zs->zfetchstat_max_streams.value.ui64 =
+ wmsum_value(&zfetch_sums.zfetchstat_max_streams);
+ zs->zfetchstat_io_issued.value.ui64 =
+ wmsum_value(&zfetch_sums.zfetchstat_io_issued);
+ zs->zfetchstat_io_active.value.ui64 =
+ aggsum_value(&zfetch_sums.zfetchstat_io_active);
+ return (0);
+}
void
zfetch_init(void)
{
+ wmsum_init(&zfetch_sums.zfetchstat_hits, 0);
+ wmsum_init(&zfetch_sums.zfetchstat_misses, 0);
+ wmsum_init(&zfetch_sums.zfetchstat_max_streams, 0);
+ wmsum_init(&zfetch_sums.zfetchstat_io_issued, 0);
+ aggsum_init(&zfetch_sums.zfetchstat_io_active, 0);
+
zfetch_ksp = kstat_create("zfs", 0, "zfetchstats", "misc",
KSTAT_TYPE_NAMED, sizeof (zfetch_stats) / sizeof (kstat_named_t),
KSTAT_FLAG_VIRTUAL);
if (zfetch_ksp != NULL) {
zfetch_ksp->ks_data = &zfetch_stats;
+ zfetch_ksp->ks_update = zfetch_kstats_update;
kstat_install(zfetch_ksp);
}
}
kstat_delete(zfetch_ksp);
zfetch_ksp = NULL;
}
+
+ wmsum_fini(&zfetch_sums.zfetchstat_hits);
+ wmsum_fini(&zfetch_sums.zfetchstat_misses);
+ wmsum_fini(&zfetch_sums.zfetchstat_max_streams);
+ wmsum_fini(&zfetch_sums.zfetchstat_io_issued);
+ ASSERT0(aggsum_value(&zfetch_sums.zfetchstat_io_active));
+ aggsum_fini(&zfetch_sums.zfetchstat_io_active);
}
/*
static void
dmu_zfetch_stream_fini(zstream_t *zs)
{
- mutex_destroy(&zs->zs_lock);
+ ASSERT(!list_link_active(&zs->zs_node));
+ zfs_refcount_destroy(&zs->zs_callers);
+ zfs_refcount_destroy(&zs->zs_refs);
kmem_free(zs, sizeof (*zs));
}
{
ASSERT(MUTEX_HELD(&zf->zf_lock));
list_remove(&zf->zf_stream, zs);
- dmu_zfetch_stream_fini(zs);
- zf->zf_numstreams--;
-}
-
-static void
-dmu_zfetch_stream_orphan(zfetch_t *zf, zstream_t *zs)
-{
- ASSERT(MUTEX_HELD(&zf->zf_lock));
- list_remove(&zf->zf_stream, zs);
- zs->zs_fetch = NULL;
zf->zf_numstreams--;
+ membar_producer();
+ if (zfs_refcount_remove(&zs->zs_refs, NULL) == 0)
+ dmu_zfetch_stream_fini(zs);
}
/*
zstream_t *zs;
mutex_enter(&zf->zf_lock);
- while ((zs = list_head(&zf->zf_stream)) != NULL) {
- if (zfs_refcount_count(&zs->zs_blocks) != 0)
- dmu_zfetch_stream_orphan(zf, zs);
- else
- dmu_zfetch_stream_remove(zf, zs);
- }
+ while ((zs = list_head(&zf->zf_stream)) != NULL)
+ dmu_zfetch_stream_remove(zf, zs);
mutex_exit(&zf->zf_lock);
list_destroy(&zf->zf_stream);
mutex_destroy(&zf->zf_lock);
}
/*
- * If there aren't too many streams already, create a new stream.
+ * If there aren't too many active streams already, create one more.
+ * In process delete/reuse all streams without hits for zfetch_max_sec_reap.
+ * If needed, reuse oldest stream without hits for zfetch_min_sec_reap or ever.
* The "blkid" argument is the next block that we expect this stream to access.
- * While we're here, clean up old streams (which haven't been
- * accessed for at least zfetch_min_sec_reap seconds).
*/
static void
dmu_zfetch_stream_create(zfetch_t *zf, uint64_t blkid)
{
- zstream_t *zs_next;
- hrtime_t now = gethrtime();
+ zstream_t *zs, *zs_next, *zs_old = NULL;
+ hrtime_t now = gethrtime(), t;
ASSERT(MUTEX_HELD(&zf->zf_lock));
/*
- * Clean up old streams.
+ * Delete too old streams, reusing the first found one.
*/
- for (zstream_t *zs = list_head(&zf->zf_stream);
- zs != NULL; zs = zs_next) {
+ t = now - SEC2NSEC(zfetch_max_sec_reap);
+ for (zs = list_head(&zf->zf_stream); zs != NULL; zs = zs_next) {
zs_next = list_next(&zf->zf_stream, zs);
/*
- * Skip gethrtime() call if there are still references
+ * Skip if still active. 1 -- zf_stream reference.
*/
- if (zfs_refcount_count(&zs->zs_blocks) != 0)
+ if (zfs_refcount_count(&zs->zs_refs) != 1)
+ continue;
+ if (zs->zs_atime > t)
continue;
- if (((now - zs->zs_atime) / NANOSEC) >
- zfetch_min_sec_reap)
+ if (zs_old)
dmu_zfetch_stream_remove(zf, zs);
+ else
+ zs_old = zs;
+ }
+ if (zs_old) {
+ zs = zs_old;
+ goto reuse;
}
/*
* The maximum number of streams is normally zfetch_max_streams,
* but for small files we lower it such that it's at least possible
* for all the streams to be non-overlapping.
- *
- * If we are already at the maximum number of streams for this file,
- * even after removing old streams, then don't create this stream.
*/
uint32_t max_streams = MAX(1, MIN(zfetch_max_streams,
zf->zf_dnode->dn_maxblkid * zf->zf_dnode->dn_datablksz /
zfetch_max_distance));
if (zf->zf_numstreams >= max_streams) {
+ t = now - SEC2NSEC(zfetch_min_sec_reap);
+ for (zs = list_head(&zf->zf_stream); zs != NULL;
+ zs = list_next(&zf->zf_stream, zs)) {
+ if (zfs_refcount_count(&zs->zs_refs) != 1)
+ continue;
+ if (zs->zs_atime > t)
+ continue;
+ if (zs_old == NULL || zs->zs_atime < zs_old->zs_atime)
+ zs_old = zs;
+ }
+ if (zs_old) {
+ zs = zs_old;
+ goto reuse;
+ }
ZFETCHSTAT_BUMP(zfetchstat_max_streams);
return;
}
- zstream_t *zs = kmem_zalloc(sizeof (*zs), KM_SLEEP);
- zs->zs_blkid = blkid;
- zs->zs_pf_blkid = blkid;
- zs->zs_ipf_blkid = blkid;
- zs->zs_atime = now;
+ zs = kmem_zalloc(sizeof (*zs), KM_SLEEP);
zs->zs_fetch = zf;
- zfs_refcount_create(&zs->zs_blocks);
- mutex_init(&zs->zs_lock, NULL, MUTEX_DEFAULT, NULL);
+ zfs_refcount_create(&zs->zs_callers);
+ zfs_refcount_create(&zs->zs_refs);
+ /* One reference for zf_stream. */
+ zfs_refcount_add(&zs->zs_refs, NULL);
zf->zf_numstreams++;
list_insert_head(&zf->zf_stream, zs);
+
+reuse:
+ zs->zs_blkid = blkid;
+ zs->zs_pf_dist = 0;
+ zs->zs_pf_start = blkid;
+ zs->zs_pf_end = blkid;
+ zs->zs_ipf_dist = 0;
+ zs->zs_ipf_start = blkid;
+ zs->zs_ipf_end = blkid;
+ /* Allow immediate stream reuse until first hit. */
+ zs->zs_atime = now - SEC2NSEC(zfetch_min_sec_reap);
+ zs->zs_missed = B_FALSE;
+ zs->zs_more = B_FALSE;
}
static void
-dmu_zfetch_stream_done(void *arg, boolean_t io_issued)
+dmu_zfetch_done(void *arg, uint64_t level, uint64_t blkid, boolean_t io_issued)
{
zstream_t *zs = arg;
- if (zs->zs_start_time && io_issued) {
- hrtime_t now = gethrtime();
- hrtime_t delta = NSEC2USEC(now - zs->zs_start_time);
-
- zs->zs_start_time = 0;
- ZFETCHSTAT_SET(zfetchstat_last_completion_us, delta);
- if (delta > ZFETCHSTAT_GET(zfetchstat_max_completion_us))
- ZFETCHSTAT_SET(zfetchstat_max_completion_us, delta);
- }
-
- if (zfs_refcount_remove(&zs->zs_blocks, NULL) != 0)
- return;
-
- /*
- * The parent fetch structure has gone away
- */
- if (zs->zs_fetch == NULL)
+ if (io_issued && level == 0 && blkid < zs->zs_blkid)
+ zs->zs_more = B_TRUE;
+ if (zfs_refcount_remove(&zs->zs_refs, NULL) == 0)
dmu_zfetch_stream_fini(zs);
+ aggsum_add(&zfetch_sums.zfetchstat_io_active, -1);
}
/*
- * This is the predictive prefetch entry point. It associates dnode access
- * specified with blkid and nblks arguments with prefetch stream, predicts
- * further accesses based on that stats and initiates speculative prefetch.
+ * This is the predictive prefetch entry point. dmu_zfetch_prepare()
+ * associates dnode access specified with blkid and nblks arguments with
+ * prefetch stream, predicts further accesses based on that stats and returns
+ * the stream pointer on success. That pointer must later be passed to
+ * dmu_zfetch_run() to initiate the speculative prefetch for the stream and
+ * release it. dmu_zfetch() is a wrapper for simple cases when window between
+ * prediction and prefetch initiation is not needed.
* fetch_data argument specifies whether actual data blocks should be fetched:
* FALSE -- prefetch only indirect blocks for predicted data blocks;
* TRUE -- prefetch predicted data blocks plus following indirect blocks.
*/
-void
-dmu_zfetch(zfetch_t *zf, uint64_t blkid, uint64_t nblks, boolean_t fetch_data,
- boolean_t have_lock)
+zstream_t *
+dmu_zfetch_prepare(zfetch_t *zf, uint64_t blkid, uint64_t nblks,
+ boolean_t fetch_data, boolean_t have_lock)
{
zstream_t *zs;
- int64_t pf_start, ipf_start, ipf_istart, ipf_iend;
- int64_t pf_ahead_blks, max_blks;
- int epbs, max_dist_blks, pf_nblks, ipf_nblks, issued;
- uint64_t end_of_access_blkid;
- end_of_access_blkid = blkid + nblks;
spa_t *spa = zf->zf_dnode->dn_objset->os_spa;
+ zfs_prefetch_type_t os_prefetch = zf->zf_dnode->dn_objset->os_prefetch;
+
+ if (zfs_prefetch_disable || os_prefetch == ZFS_PREFETCH_NONE)
+ return (NULL);
+
+ if (os_prefetch == ZFS_PREFETCH_METADATA)
+ fetch_data = B_FALSE;
- if (zfs_prefetch_disable)
- return;
/*
* If we haven't yet loaded the indirect vdevs' mappings, we
* can only read from blocks that we carefully ensure are on
* blocks (e.g. of the MOS's dnode object).
*/
if (!spa_indirect_vdevs_loaded(spa))
- return;
+ return (NULL);
/*
* As a fast path for small (single-block) files, ignore access
* to the first block.
*/
if (!have_lock && blkid == 0)
- return;
+ return (NULL);
if (!have_lock)
rw_enter(&zf->zf_dnode->dn_struct_rwlock, RW_READER);
* A fast path for small files for which no prefetch will
* happen.
*/
- if (zf->zf_dnode->dn_maxblkid < 2) {
+ uint64_t maxblkid = zf->zf_dnode->dn_maxblkid;
+ if (maxblkid < 2) {
if (!have_lock)
rw_exit(&zf->zf_dnode->dn_struct_rwlock);
- return;
+ return (NULL);
}
mutex_enter(&zf->zf_lock);
*/
for (zs = list_head(&zf->zf_stream); zs != NULL;
zs = list_next(&zf->zf_stream, zs)) {
- if (blkid == zs->zs_blkid || blkid + 1 == zs->zs_blkid) {
- mutex_enter(&zs->zs_lock);
- /*
- * zs_blkid could have changed before we
- * acquired zs_lock; re-check them here.
- */
- if (blkid == zs->zs_blkid) {
- break;
- } else if (blkid + 1 == zs->zs_blkid) {
- blkid++;
- nblks--;
- if (nblks == 0) {
- /* Already prefetched this before. */
- mutex_exit(&zs->zs_lock);
- mutex_exit(&zf->zf_lock);
- if (!have_lock) {
- rw_exit(&zf->zf_dnode->
- dn_struct_rwlock);
- }
- return;
- }
- break;
- }
- mutex_exit(&zs->zs_lock);
+ if (blkid == zs->zs_blkid) {
+ break;
+ } else if (blkid + 1 == zs->zs_blkid) {
+ blkid++;
+ nblks--;
+ break;
}
}
+ /*
+ * If the file is ending, remove the matching stream if found.
+ * If not found then it is too late to create a new one now.
+ */
+ uint64_t end_of_access_blkid = blkid + nblks;
+ if (end_of_access_blkid >= maxblkid) {
+ if (zs != NULL)
+ dmu_zfetch_stream_remove(zf, zs);
+ mutex_exit(&zf->zf_lock);
+ if (!have_lock)
+ rw_exit(&zf->zf_dnode->dn_struct_rwlock);
+ return (NULL);
+ }
+
+ /* Exit if we already prefetched this block before. */
+ if (nblks == 0) {
+ mutex_exit(&zf->zf_lock);
+ if (!have_lock)
+ rw_exit(&zf->zf_dnode->dn_struct_rwlock);
+ return (NULL);
+ }
+
if (zs == NULL) {
/*
* This access is not part of any existing stream. Create
* a new stream for it.
*/
- ZFETCHSTAT_BUMP(zfetchstat_misses);
-
dmu_zfetch_stream_create(zf, end_of_access_blkid);
mutex_exit(&zf->zf_lock);
if (!have_lock)
rw_exit(&zf->zf_dnode->dn_struct_rwlock);
- return;
+ ZFETCHSTAT_BUMP(zfetchstat_misses);
+ return (NULL);
}
/*
* This access was to a block that we issued a prefetch for on
- * behalf of this stream. Issue further prefetches for this stream.
+ * behalf of this stream. Calculate further prefetch distances.
*
- * Normally, we start prefetching where we stopped
- * prefetching last (zs_pf_blkid). But when we get our first
- * hit on this stream, zs_pf_blkid == zs_blkid, we don't
- * want to prefetch the block we just accessed. In this case,
- * start just after the block we just accessed.
- */
- pf_start = MAX(zs->zs_pf_blkid, end_of_access_blkid);
-
- /*
- * Double our amount of prefetched data, but don't let the
- * prefetch get further ahead than zfetch_max_distance.
+ * Start prefetch from the demand access size (nblks). Double the
+ * distance every access up to zfetch_min_distance. After that only
+ * if needed increase the distance by 1/8 up to zfetch_max_distance.
+ *
+ * Don't double the distance beyond single block if we have more
+ * than ~6% of ARC held by active prefetches. It should help with
+ * getting out of RAM on some badly mispredicted read patterns.
*/
+ unsigned int dbs = zf->zf_dnode->dn_datablkshift;
+ unsigned int nbytes = nblks << dbs;
+ unsigned int pf_nblks;
if (fetch_data) {
- max_dist_blks =
- zfetch_max_distance >> zf->zf_dnode->dn_datablkshift;
- /*
- * Previously, we were (zs_pf_blkid - blkid) ahead. We
- * want to now be double that, so read that amount again,
- * plus the amount we are catching up by (i.e. the amount
- * read just now).
- */
- pf_ahead_blks = zs->zs_pf_blkid - blkid + nblks;
- max_blks = max_dist_blks - (pf_start - end_of_access_blkid);
- pf_nblks = MIN(pf_ahead_blks, max_blks);
+ if (unlikely(zs->zs_pf_dist < nbytes))
+ zs->zs_pf_dist = nbytes;
+ else if (zs->zs_pf_dist < zfetch_min_distance &&
+ (zs->zs_pf_dist < (1 << dbs) ||
+ aggsum_compare(&zfetch_sums.zfetchstat_io_active,
+ arc_c_max >> (4 + dbs)) < 0))
+ zs->zs_pf_dist *= 2;
+ else if (zs->zs_more)
+ zs->zs_pf_dist += zs->zs_pf_dist / 8;
+ zs->zs_more = B_FALSE;
+ if (zs->zs_pf_dist > zfetch_max_distance)
+ zs->zs_pf_dist = zfetch_max_distance;
+ pf_nblks = zs->zs_pf_dist >> dbs;
} else {
pf_nblks = 0;
}
-
- zs->zs_pf_blkid = pf_start + pf_nblks;
+ if (zs->zs_pf_start < end_of_access_blkid)
+ zs->zs_pf_start = end_of_access_blkid;
+ if (zs->zs_pf_end < end_of_access_blkid + pf_nblks)
+ zs->zs_pf_end = end_of_access_blkid + pf_nblks;
/*
- * Do the same for indirects, starting from where we stopped last,
- * or where we will stop reading data blocks (and the indirects
- * that point to them).
+ * Do the same for indirects, starting where we will stop reading
+ * data blocks (and the indirects that point to them).
*/
- ipf_start = MAX(zs->zs_ipf_blkid, zs->zs_pf_blkid);
- max_dist_blks = zfetch_max_idistance >> zf->zf_dnode->dn_datablkshift;
- /*
- * We want to double our distance ahead of the data prefetch
- * (or reader, if we are not prefetching data). Previously, we
- * were (zs_ipf_blkid - blkid) ahead. To double that, we read
- * that amount again, plus the amount we are catching up by
- * (i.e. the amount read now + the amount of data prefetched now).
- */
- pf_ahead_blks = zs->zs_ipf_blkid - blkid + nblks + pf_nblks;
- max_blks = max_dist_blks - (ipf_start - end_of_access_blkid);
- ipf_nblks = MIN(pf_ahead_blks, max_blks);
- zs->zs_ipf_blkid = ipf_start + ipf_nblks;
-
- epbs = zf->zf_dnode->dn_indblkshift - SPA_BLKPTRSHIFT;
- ipf_istart = P2ROUNDUP(ipf_start, 1 << epbs) >> epbs;
- ipf_iend = P2ROUNDUP(zs->zs_ipf_blkid, 1 << epbs) >> epbs;
+ if (unlikely(zs->zs_ipf_dist < nbytes))
+ zs->zs_ipf_dist = nbytes;
+ else
+ zs->zs_ipf_dist *= 2;
+ if (zs->zs_ipf_dist > zfetch_max_idistance)
+ zs->zs_ipf_dist = zfetch_max_idistance;
+ pf_nblks = zs->zs_ipf_dist >> dbs;
+ if (zs->zs_ipf_start < zs->zs_pf_end)
+ zs->zs_ipf_start = zs->zs_pf_end;
+ if (zs->zs_ipf_end < zs->zs_pf_end + pf_nblks)
+ zs->zs_ipf_end = zs->zs_pf_end + pf_nblks;
- zs->zs_atime = gethrtime();
- /* no prior reads in progress */
- if (zfs_refcount_count(&zs->zs_blocks) == 0)
- zs->zs_start_time = zs->zs_atime;
zs->zs_blkid = end_of_access_blkid;
- zfs_refcount_add_many(&zs->zs_blocks, pf_nblks + ipf_iend - ipf_istart,
- NULL);
- mutex_exit(&zs->zs_lock);
+ /* Protect the stream from reclamation. */
+ zs->zs_atime = gethrtime();
+ zfs_refcount_add(&zs->zs_refs, NULL);
+ /* Count concurrent callers. */
+ zfs_refcount_add(&zs->zs_callers, NULL);
mutex_exit(&zf->zf_lock);
- issued = 0;
+
+ if (!have_lock)
+ rw_exit(&zf->zf_dnode->dn_struct_rwlock);
+
+ ZFETCHSTAT_BUMP(zfetchstat_hits);
+ return (zs);
+}
+
+void
+dmu_zfetch_run(zstream_t *zs, boolean_t missed, boolean_t have_lock)
+{
+ zfetch_t *zf = zs->zs_fetch;
+ int64_t pf_start, pf_end, ipf_start, ipf_end;
+ int epbs, issued;
+
+ if (missed)
+ zs->zs_missed = missed;
/*
- * dbuf_prefetch() is asynchronous (even when it needs to read
- * indirect blocks), but we still prefer to drop our locks before
- * calling it to reduce the time we hold them.
+ * Postpone the prefetch if there are more concurrent callers.
+ * It happens when multiple requests are waiting for the same
+ * indirect block. The last one will run the prefetch for all.
*/
+ if (zfs_refcount_remove(&zs->zs_callers, NULL) != 0) {
+ /* Drop reference taken in dmu_zfetch_prepare(). */
+ if (zfs_refcount_remove(&zs->zs_refs, NULL) == 0)
+ dmu_zfetch_stream_fini(zs);
+ return;
+ }
+
+ mutex_enter(&zf->zf_lock);
+ if (zs->zs_missed) {
+ pf_start = zs->zs_pf_start;
+ pf_end = zs->zs_pf_start = zs->zs_pf_end;
+ } else {
+ pf_start = pf_end = 0;
+ }
+ ipf_start = zs->zs_ipf_start;
+ ipf_end = zs->zs_ipf_start = zs->zs_ipf_end;
+ mutex_exit(&zf->zf_lock);
+ ASSERT3S(pf_start, <=, pf_end);
+ ASSERT3S(ipf_start, <=, ipf_end);
- for (int i = 0; i < pf_nblks; i++) {
- issued += dbuf_prefetch_impl(zf->zf_dnode, 0, pf_start + i,
- ZIO_PRIORITY_ASYNC_READ, ARC_FLAG_PREDICTIVE_PREFETCH,
- dmu_zfetch_stream_done, zs);
+ epbs = zf->zf_dnode->dn_indblkshift - SPA_BLKPTRSHIFT;
+ ipf_start = P2ROUNDUP(ipf_start, 1 << epbs) >> epbs;
+ ipf_end = P2ROUNDUP(ipf_end, 1 << epbs) >> epbs;
+ ASSERT3S(ipf_start, <=, ipf_end);
+ issued = pf_end - pf_start + ipf_end - ipf_start;
+ if (issued > 1) {
+ /* More references on top of taken in dmu_zfetch_prepare(). */
+ zfs_refcount_add_few(&zs->zs_refs, issued - 1, NULL);
+ } else if (issued == 0) {
+ /* Some other thread has done our work, so drop the ref. */
+ if (zfs_refcount_remove(&zs->zs_refs, NULL) == 0)
+ dmu_zfetch_stream_fini(zs);
+ return;
}
- for (int64_t iblk = ipf_istart; iblk < ipf_iend; iblk++) {
+ aggsum_add(&zfetch_sums.zfetchstat_io_active, issued);
+
+ if (!have_lock)
+ rw_enter(&zf->zf_dnode->dn_struct_rwlock, RW_READER);
+
+ issued = 0;
+ for (int64_t blk = pf_start; blk < pf_end; blk++) {
+ issued += dbuf_prefetch_impl(zf->zf_dnode, 0, blk,
+ ZIO_PRIORITY_ASYNC_READ, 0, dmu_zfetch_done, zs);
+ }
+ for (int64_t iblk = ipf_start; iblk < ipf_end; iblk++) {
issued += dbuf_prefetch_impl(zf->zf_dnode, 1, iblk,
- ZIO_PRIORITY_ASYNC_READ, ARC_FLAG_PREDICTIVE_PREFETCH,
- dmu_zfetch_stream_done, zs);
+ ZIO_PRIORITY_ASYNC_READ, 0, dmu_zfetch_done, zs);
}
+
if (!have_lock)
rw_exit(&zf->zf_dnode->dn_struct_rwlock);
- ZFETCHSTAT_BUMP(zfetchstat_hits);
if (issued)
ZFETCHSTAT_ADD(zfetchstat_io_issued, issued);
}
-/* BEGIN CSTYLED */
+void
+dmu_zfetch(zfetch_t *zf, uint64_t blkid, uint64_t nblks, boolean_t fetch_data,
+ boolean_t missed, boolean_t have_lock)
+{
+ zstream_t *zs;
+
+ zs = dmu_zfetch_prepare(zf, blkid, nblks, fetch_data, have_lock);
+ if (zs)
+ dmu_zfetch_run(zs, missed, have_lock);
+}
+
ZFS_MODULE_PARAM(zfs_prefetch, zfs_prefetch_, disable, INT, ZMOD_RW,
"Disable all ZFS prefetching");
ZFS_MODULE_PARAM(zfs_prefetch, zfetch_, min_sec_reap, UINT, ZMOD_RW,
"Min time before stream reclaim");
+ZFS_MODULE_PARAM(zfs_prefetch, zfetch_, max_sec_reap, UINT, ZMOD_RW,
+ "Max time before stream delete");
+
+ZFS_MODULE_PARAM(zfs_prefetch, zfetch_, min_distance, UINT, ZMOD_RW,
+ "Min bytes to prefetch per stream");
+
ZFS_MODULE_PARAM(zfs_prefetch, zfetch_, max_distance, UINT, ZMOD_RW,
"Max bytes to prefetch per stream");
ZFS_MODULE_PARAM(zfs_prefetch, zfetch_, max_idistance, UINT, ZMOD_RW,
"Max bytes to prefetch indirects for per stream");
-
-ZFS_MODULE_PARAM(zfs_prefetch, zfetch_, array_rd_sz, ULONG, ZMOD_RW,
- "Number of bytes in a array_read");
-/* END CSTYLED */
projects / mirror_zfs.git / blobdiff