* 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>
* 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_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 },
- { "io_issued", KSTAT_DATA_UINT64 },
+ { "io_issued", KSTAT_DATA_UINT64 },
+ { "io_active", KSTAT_DATA_UINT64 },
};
struct {
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, val)
-kstat_t *zfetch_ksp;
+static kstat_t *zfetch_ksp;
static int
zfetch_kstats_update(kstat_t *ksp, int rw)
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);
}
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),
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);
}
/*
}
/*
- * 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 if still active. 1 -- zf_stream reference.
*/
if (zfs_refcount_count(&zs->zs_refs) != 1)
continue;
- if (((now - zs->zs_atime) / NANOSEC) >
- zfetch_min_sec_reap)
+ if (zs->zs_atime > t)
+ continue;
+ 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_blkid1 = blkid;
- zs->zs_pf_blkid = blkid;
- zs->zs_ipf_blkid1 = blkid;
- zs->zs_ipf_blkid = blkid;
- zs->zs_atime = now;
+ zs = kmem_zalloc(sizeof (*zs), KM_SLEEP);
zs->zs_fetch = zf;
- zs->zs_missed = B_FALSE;
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 (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);
}
/*
boolean_t fetch_data, boolean_t have_lock)
{
zstream_t *zs;
- int64_t pf_start, ipf_start;
- int64_t pf_ahead_blks, max_blks;
- int max_dist_blks, pf_nblks, ipf_nblks;
- uint64_t end_of_access_blkid, maxblkid;
- 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)
+ if (zfs_prefetch_disable || os_prefetch == ZFS_PREFETCH_NONE)
return (NULL);
+
+ if (os_prefetch == ZFS_PREFETCH_METADATA)
+ fetch_data = B_FALSE;
+
/*
* If we haven't yet loaded the indirect vdevs' mappings, we
* can only read from blocks that we carefully ensure are on
* A fast path for small files for which no prefetch will
* happen.
*/
- maxblkid = zf->zf_dnode->dn_maxblkid;
+ uint64_t maxblkid = zf->zf_dnode->dn_maxblkid;
if (maxblkid < 2) {
if (!have_lock)
rw_exit(&zf->zf_dnode->dn_struct_rwlock);
* 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);
/*
* 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);
- if (zs->zs_pf_blkid1 < end_of_access_blkid)
- zs->zs_pf_blkid1 = end_of_access_blkid;
- if (zs->zs_ipf_blkid1 < end_of_access_blkid)
- zs->zs_ipf_blkid1 = 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;
}
+ 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;
- zs->zs_pf_blkid = pf_start + 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).
- */
- 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).
+ * Do the same for indirects, starting where we will stop reading
+ * data blocks (and the indirects that point to them).
*/
- pf_ahead_blks = zs->zs_ipf_blkid - blkid + nblks + pf_nblks;
- max_blks = max_dist_blks - (ipf_start - zs->zs_pf_blkid);
- ipf_nblks = MIN(pf_ahead_blks, max_blks);
- zs->zs_ipf_blkid = ipf_start + ipf_nblks;
+ 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_blkid = end_of_access_blkid;
/* Protect the stream from reclamation. */
mutex_enter(&zf->zf_lock);
if (zs->zs_missed) {
- pf_start = zs->zs_pf_blkid1;
- pf_end = zs->zs_pf_blkid1 = zs->zs_pf_blkid;
+ pf_start = zs->zs_pf_start;
+ pf_end = zs->zs_pf_start = zs->zs_pf_end;
} else {
pf_start = pf_end = 0;
}
- ipf_start = MAX(zs->zs_pf_blkid1, zs->zs_ipf_blkid1);
- ipf_end = zs->zs_ipf_blkid1 = zs->zs_ipf_blkid;
+ 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);
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_many(&zs->zs_refs, issued - 1, NULL);
+ 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;
}
+ 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, ARC_FLAG_PREDICTIVE_PREFETCH,
- dmu_zfetch_stream_done, zs);
+ 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)
dmu_zfetch_run(zs, missed, have_lock);
}
-/* BEGIN CSTYLED */
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