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9486 reduce memory used by device removal on fragmented pools

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In the most fragmented real-world cases, this reduces memory used by the
mapping from ~1GB to ~50MB of RAM per 1TB of storage removed. Less
fragmented cases will typically also see around 50-100MB of RAM per 1TB
of storage.

illumos/illumos-gate@cfd63e1b1b

Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed by: Tim Chase <tim@chase2k.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Author:     Matthew Ahrens <mahrens@delphix.com>
This commit is contained in:
Alexander Motin 2018-08-02 21:57:59 +00:00
parent 7444ba2086
commit 9f2ee4de7e
5 changed files with 244 additions and 46 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
uts/common/fs/zfs/range_tree.c
View File

@ -298,7 +298,6 @@ range_tree_remove(void *arg, uint64_t start, uint64_t size)
static range_seg_t *
range_tree_find_impl(range_tree_t *rt, uint64_t start, uint64_t size)
{
avl_index_t where;
range_seg_t rsearch;
uint64_t end = start + size;
@ -306,7 +305,7 @@ range_tree_find_impl(range_tree_t *rt, uint64_t start, uint64_t size)
rsearch.rs_start = start;
rsearch.rs_end = end;
return (avl_find(&rt->rt_root, &rsearch, &where));
return (avl_find(&rt->rt_root, &rsearch, NULL));
}
static range_seg_t *
@ -407,3 +406,23 @@ range_tree_is_empty(range_tree_t *rt)
ASSERT(rt != NULL);
return (range_tree_space(rt) == 0);
}
uint64_t
range_tree_min(range_tree_t *rt)
{
range_seg_t *rs = avl_first(&rt->rt_root);
return (rs != NULL ? rs->rs_start : 0);
}
uint64_t
range_tree_max(range_tree_t *rt)
{
range_seg_t *rs = avl_last(&rt->rt_root);
return (rs != NULL ? rs->rs_end : 0);
}
uint64_t
range_tree_span(range_tree_t *rt)
{
return (range_tree_max(rt) - range_tree_min(rt));
}

3
uts/common/fs/zfs/sys/range_tree.h
View File

@ -86,6 +86,9 @@ boolean_t range_tree_is_empty(range_tree_t *rt);
void range_tree_verify(range_tree_t *rt, uint64_t start, uint64_t size);
void range_tree_swap(range_tree_t **rtsrc, range_tree_t **rtdst);
void range_tree_stat_verify(range_tree_t *rt);
uint64_t range_tree_min(range_tree_t *rt);
uint64_t range_tree_max(range_tree_t *rt);
uint64_t range_tree_span(range_tree_t *rt);
void range_tree_add(void *arg, uint64_t start, uint64_t size);
void range_tree_remove(void *arg, uint64_t start, uint64_t size);

3
uts/common/fs/zfs/sys/vdev_removal.h
View File

@ -86,6 +86,9 @@ extern void spa_vdev_remove_suspend(spa_t *);
extern int spa_vdev_remove_cancel(spa_t *);
extern void spa_vdev_removal_destroy(spa_vdev_removal_t *svr);
extern int vdev_removal_max_span;
extern int zfs_remove_max_segment;
#ifdef __cplusplus
}
#endif

53
uts/common/fs/zfs/vdev_label.c
View File

@ -33,15 +33,15 @@
* 1. Uniquely identify this device as part of a ZFS pool and confirm its
* identity within the pool.
*
* 2. Verify that all the devices given in a configuration are present
* 2. Verify that all the devices given in a configuration are present
* within the pool.
*
* 3. Determine the uberblock for the pool.
* 3. Determine the uberblock for the pool.
*
* 4. In case of an import operation, determine the configuration of the
* 4. In case of an import operation, determine the configuration of the
* toplevel vdev of which it is a part.
*
* 5. If an import operation cannot find all the devices in the pool,
* 5. If an import operation cannot find all the devices in the pool,
* provide enough information to the administrator to determine which
* devices are missing.
*
@ -77,9 +77,9 @@
* In order to identify which labels are valid, the labels are written in the
* following manner:
*
* 1. For each vdev, update 'L1' to the new label
* 2. Update the uberblock
* 3. For each vdev, update 'L2' to the new label
* 1. For each vdev, update 'L1' to the new label
* 2. Update the uberblock
* 3. For each vdev, update 'L2' to the new label
*
* Given arbitrary failure, we can determine the correct label to use based on
* the transaction group. If we fail after updating L1 but before updating the
@ -117,19 +117,19 @@
*
* The nvlist describing the pool and vdev contains the following elements:
*
* version ZFS on-disk version
* name Pool name
* state Pool state
* txg Transaction group in which this label was written
* pool_guid Unique identifier for this pool
* vdev_tree An nvlist describing vdev tree.
* version ZFS on-disk version
* name Pool name
* state Pool state
* txg Transaction group in which this label was written
* pool_guid Unique identifier for this pool
* vdev_tree An nvlist describing vdev tree.
* features_for_read
* An nvlist of the features necessary for reading the MOS.
*
* Each leaf device label also contains the following:
*
* top_guid Unique ID for top-level vdev in which this is contained
* guid Unique ID for the leaf vdev
* top_guid Unique ID for top-level vdev in which this is contained
* guid Unique ID for the leaf vdev
*
* The 'vs' configuration follows the format described in 'spa_config.c'.
*/
@ -390,22 +390,33 @@ vdev_config_generate(spa_t *spa, vdev_t *vd, boolean_t getstats,
* histograms.
*/
uint64_t seg_count = 0;
uint64_t to_alloc = vd->vdev_stat.vs_alloc;
/*
* There are the same number of allocated segments
* as free segments, so we will have at least one
* entry per free segment.
* entry per free segment. However, small free
* segments (smaller than vdev_removal_max_span)
* will be combined with adjacent allocated segments
* as a single mapping.
*/
for (int i = 0; i < RANGE_TREE_HISTOGRAM_SIZE; i++) {
seg_count += vd->vdev_mg->mg_histogram[i];
if (1ULL << (i + 1) < vdev_removal_max_span) {
to_alloc +=
vd->vdev_mg->mg_histogram[i] <<
i + 1;
} else {
seg_count +=
vd->vdev_mg->mg_histogram[i];
}
}
/*
* The maximum length of a mapping is SPA_MAXBLOCKSIZE,
* so we need at least one entry per SPA_MAXBLOCKSIZE
* of allocated data.
* The maximum length of a mapping is
* zfs_remove_max_segment, so we need at least one entry
* per zfs_remove_max_segment of allocated data.
*/
seg_count += vd->vdev_stat.vs_alloc / SPA_MAXBLOCKSIZE;
seg_count += to_alloc / zfs_remove_max_segment;
fnvlist_add_uint64(nv, ZPOOL_CONFIG_INDIRECT_SIZE,
seg_count *

208
uts/common/fs/zfs/vdev_removal.c
View File

@ -105,6 +105,24 @@ int zfs_remove_max_copy_bytes = 64 * 1024 * 1024;
*/
int zfs_remove_max_segment = 1024 * 1024;
/*
* Allow a remap segment to span free chunks of at most this size. The main
* impact of a larger span is that we will read and write larger, more
* contiguous chunks, with more "unnecessary" data -- trading off bandwidth
* for iops. The value here was chosen to align with
* zfs_vdev_read_gap_limit, which is a similar concept when doing regular
* reads (but there's no reason it has to be the same).
*
* Additionally, a higher span will have the following relatively minor
* effects:
* - the mapping will be smaller, since one entry can cover more allocated
* segments
* - more of the fragmentation in the removing device will be preserved
* - we'll do larger allocations, which may fail and fall back on smaller
* allocations
*/
int vdev_removal_max_span = 32 * 1024;
/*
* This is used by the test suite so that it can ensure that certain
* actions happen while in the middle of a removal.
@ -726,13 +744,52 @@ vdev_mapping_sync(void *arg, dmu_tx_t *tx)
spa_sync_removing_state(spa, tx);
}
typedef struct vdev_copy_segment_arg {
spa_t *vcsa_spa;
dva_t *vcsa_dest_dva;
uint64_t vcsa_txg;
range_tree_t *vcsa_obsolete_segs;
} vdev_copy_segment_arg_t;
static void
unalloc_seg(void *arg, uint64_t start, uint64_t size)
{
vdev_copy_segment_arg_t *vcsa = arg;
spa_t *spa = vcsa->vcsa_spa;
blkptr_t bp = { 0 };
BP_SET_BIRTH(&bp, TXG_INITIAL, TXG_INITIAL);
BP_SET_LSIZE(&bp, size);
BP_SET_PSIZE(&bp, size);
BP_SET_COMPRESS(&bp, ZIO_COMPRESS_OFF);
BP_SET_CHECKSUM(&bp, ZIO_CHECKSUM_OFF);
BP_SET_TYPE(&bp, DMU_OT_NONE);
BP_SET_LEVEL(&bp, 0);
BP_SET_DEDUP(&bp, 0);
BP_SET_BYTEORDER(&bp, ZFS_HOST_BYTEORDER);
DVA_SET_VDEV(&bp.blk_dva[0], DVA_GET_VDEV(vcsa->vcsa_dest_dva));
DVA_SET_OFFSET(&bp.blk_dva[0],
DVA_GET_OFFSET(vcsa->vcsa_dest_dva) + start);
DVA_SET_ASIZE(&bp.blk_dva[0], size);
zio_free(spa, vcsa->vcsa_txg, &bp);
}
/*
* All reads and writes associated with a call to spa_vdev_copy_segment()
* are done.
*/
static void
spa_vdev_copy_nullzio_done(zio_t *zio)
spa_vdev_copy_segment_done(zio_t *zio)
{
vdev_copy_segment_arg_t *vcsa = zio->io_private;
range_tree_vacate(vcsa->vcsa_obsolete_segs,
unalloc_seg, vcsa);
range_tree_destroy(vcsa->vcsa_obsolete_segs);
kmem_free(vcsa, sizeof (*vcsa));
spa_config_exit(zio->io_spa, SCL_STATE, zio->io_spa);
}
@ -849,7 +906,8 @@ spa_vdev_copy_one_child(vdev_copy_arg_t *vca, zio_t *nzio,
* read from the old location and write to the new location.
*/
static int
spa_vdev_copy_segment(vdev_t *vd, uint64_t start, uint64_t size, uint64_t txg,
spa_vdev_copy_segment(vdev_t *vd, range_tree_t *segs,
uint64_t maxalloc, uint64_t txg,
vdev_copy_arg_t *vca, zio_alloc_list_t *zal)
{
metaslab_group_t *mg = vd->vdev_mg;
@ -857,8 +915,39 @@ spa_vdev_copy_segment(vdev_t *vd, uint64_t start, uint64_t size, uint64_t txg,
spa_vdev_removal_t *svr = spa->spa_vdev_removal;
vdev_indirect_mapping_entry_t *entry;
dva_t dst = { 0 };
uint64_t start = range_tree_min(segs);
ASSERT3U(size, <=, SPA_MAXBLOCKSIZE);
ASSERT3U(maxalloc, <=, SPA_MAXBLOCKSIZE);
uint64_t size = range_tree_span(segs);
if (range_tree_span(segs) > maxalloc) {
/*
* We can't allocate all the segments. Prefer to end
* the allocation at the end of a segment, thus avoiding
* additional split blocks.
*/
range_seg_t search;
avl_index_t where;
search.rs_start = start + maxalloc;
search.rs_end = search.rs_start;
range_seg_t *rs = avl_find(&segs->rt_root, &search, &where);
if (rs == NULL) {
rs = avl_nearest(&segs->rt_root, where, AVL_BEFORE);
} else {
rs = AVL_PREV(&segs->rt_root, rs);
}
if (rs != NULL) {
size = rs->rs_end - start;
} else {
/*
* There are no segments that end before maxalloc.
* I.e. the first segment is larger than maxalloc,
* so we must split it.
*/
size = maxalloc;
}
}
ASSERT3U(size, <=, maxalloc);
/*
* We use allocator 0 for this I/O because we don't expect device remap
@ -872,6 +961,31 @@ spa_vdev_copy_segment(vdev_t *vd, uint64_t start, uint64_t size, uint64_t txg,
if (error != 0)
return (error);
/*
* Determine the ranges that are not actually needed. Offsets are
* relative to the start of the range to be copied (i.e. relative to the
* local variable "start").
*/
range_tree_t *obsolete_segs = range_tree_create(NULL, NULL);
range_seg_t *rs = avl_first(&segs->rt_root);
ASSERT3U(rs->rs_start, ==, start);
uint64_t prev_seg_end = rs->rs_end;
while ((rs = AVL_NEXT(&segs->rt_root, rs)) != NULL) {
if (rs->rs_start >= start + size) {
break;
} else {
range_tree_add(obsolete_segs,
prev_seg_end - start,
rs->rs_start - prev_seg_end);
}
prev_seg_end = rs->rs_end;
}
/* We don't end in the middle of an obsolete range */
ASSERT3U(start + size, <=, prev_seg_end);
range_tree_clear(segs, start, size);
/*
* We can't have any padding of the allocated size, otherwise we will
* misunderstand what's allocated, and the size of the mapping.
@ -883,13 +997,22 @@ spa_vdev_copy_segment(vdev_t *vd, uint64_t start, uint64_t size, uint64_t txg,
entry = kmem_zalloc(sizeof (vdev_indirect_mapping_entry_t), KM_SLEEP);
DVA_MAPPING_SET_SRC_OFFSET(&entry->vime_mapping, start);
entry->vime_mapping.vimep_dst = dst;
if (spa_feature_is_enabled(spa, SPA_FEATURE_OBSOLETE_COUNTS)) {
entry->vime_obsolete_count = range_tree_space(obsolete_segs);
}
vdev_copy_segment_arg_t *vcsa = kmem_zalloc(sizeof (*vcsa), KM_SLEEP);
vcsa->vcsa_dest_dva = &entry->vime_mapping.vimep_dst;
vcsa->vcsa_obsolete_segs = obsolete_segs;
vcsa->vcsa_spa = spa;
vcsa->vcsa_txg = txg;
/*
* See comment before spa_vdev_copy_one_child().
*/
spa_config_enter(spa, SCL_STATE, spa, RW_READER);
zio_t *nzio = zio_null(spa->spa_txg_zio[txg & TXG_MASK], spa, NULL,
spa_vdev_copy_nullzio_done, NULL, 0);
spa_vdev_copy_segment_done, vcsa, 0);
vdev_t *dest_vd = vdev_lookup_top(spa, DVA_GET_VDEV(&dst));
if (dest_vd->vdev_ops == &vdev_mirror_ops) {
for (int i = 0; i < dest_vd->vdev_children; i++) {
@ -1092,39 +1215,78 @@ spa_vdev_copy_impl(vdev_t *vd, spa_vdev_removal_t *svr, vdev_copy_arg_t *vca,
mutex_enter(&svr->svr_lock);
range_seg_t *rs = avl_first(&svr->svr_allocd_segs->rt_root);
if (rs == NULL) {
/*
* Determine how big of a chunk to copy. We can allocate up
* to max_alloc bytes, and we can span up to vdev_removal_max_span
* bytes of unallocated space at a time. "segs" will track the
* allocated segments that we are copying. We may also be copying
* free segments (of up to vdev_removal_max_span bytes).
*/
range_tree_t *segs = range_tree_create(NULL, NULL);
for (;;) {
range_seg_t *rs = avl_first(&svr->svr_allocd_segs->rt_root);
if (rs == NULL)
break;
uint64_t seg_length;
if (range_tree_is_empty(segs)) {
/* need to truncate the first seg based on max_alloc */
seg_length =
MIN(rs->rs_end - rs->rs_start, *max_alloc);
} else {
if (rs->rs_start - range_tree_max(segs) >
vdev_removal_max_span) {
/*
* Including this segment would cause us to
* copy a larger unneeded chunk than is allowed.
*/
break;
} else if (rs->rs_end - range_tree_min(segs) >
*max_alloc) {
/*
* This additional segment would extend past
* max_alloc. Rather than splitting this
* segment, leave it for the next mapping.
*/
break;
} else {
seg_length = rs->rs_end - rs->rs_start;
}
}
range_tree_add(segs, rs->rs_start, seg_length);
range_tree_remove(svr->svr_allocd_segs,
rs->rs_start, seg_length);
}
if (range_tree_is_empty(segs)) {
mutex_exit(&svr->svr_lock);
range_tree_destroy(segs);
return;
}
uint64_t offset = rs->rs_start;
uint64_t length = MIN(rs->rs_end - rs->rs_start, *max_alloc);
range_tree_remove(svr->svr_allocd_segs, offset, length);
if (svr->svr_max_offset_to_sync[txg & TXG_MASK] == 0) {
dsl_sync_task_nowait(dmu_tx_pool(tx), vdev_mapping_sync,
svr, 0, ZFS_SPACE_CHECK_NONE, tx);
}
svr->svr_max_offset_to_sync[txg & TXG_MASK] = offset + length;
svr->svr_max_offset_to_sync[txg & TXG_MASK] = range_tree_max(segs);
/*
* Note: this is the amount of *allocated* space
* that we are taking care of each txg.
*/
svr->svr_bytes_done[txg & TXG_MASK] += length;
svr->svr_bytes_done[txg & TXG_MASK] += range_tree_space(segs);
mutex_exit(&svr->svr_lock);
zio_alloc_list_t zal;
metaslab_trace_init(&zal);
uint64_t thismax = *max_alloc;
while (length > 0) {
uint64_t mylen = MIN(length, thismax);
uint64_t thismax = SPA_MAXBLOCKSIZE;
while (!range_tree_is_empty(segs)) {
int error = spa_vdev_copy_segment(vd,
offset, mylen, txg, vca, &zal);
segs, thismax, txg, vca, &zal);
if (error == ENOSPC) {
/*
@ -1138,18 +1300,17 @@ spa_vdev_copy_impl(vdev_t *vd, spa_vdev_removal_t *svr, vdev_copy_arg_t *vca,
*/
ASSERT3U(spa->spa_max_ashift, >=, SPA_MINBLOCKSHIFT);
ASSERT3U(spa->spa_max_ashift, ==, spa->spa_min_ashift);
thismax = P2ROUNDUP(mylen / 2,
uint64_t attempted =
MIN(range_tree_span(segs), thismax);
thismax = P2ROUNDUP(attempted / 2,
1 << spa->spa_max_ashift);
ASSERT3U(thismax, <, mylen);
/*
* The minimum-size allocation can not fail.
*/
ASSERT3U(mylen, >, 1 << spa->spa_max_ashift);
*max_alloc = mylen - (1 << spa->spa_max_ashift);
ASSERT3U(attempted, >, 1 << spa->spa_max_ashift);
*max_alloc = attempted - (1 << spa->spa_max_ashift);
} else {
ASSERT0(error);
length -= mylen;
offset += mylen;
/*
* We've performed an allocation, so reset the
@ -1160,6 +1321,7 @@ spa_vdev_copy_impl(vdev_t *vd, spa_vdev_removal_t *svr, vdev_copy_arg_t *vca,
}
}
metaslab_trace_fini(&zal);
range_tree_destroy(segs);
}
/*