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author | avg <avg@FreeBSD.org> | 2014-01-16 16:05:21 +0000 |
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committer | avg <avg@FreeBSD.org> | 2014-01-16 16:05:21 +0000 |
commit | 926bf5d72726506433072f19f7a994c972a0e7b0 (patch) | |
tree | 9b7a64b59ef7ec917368d2aa07796188253e7fcc /sys/cddl/contrib/opensolaris/uts/common/fs/zfs/metaslab.c | |
parent | 26096ba436a54f225f8e56bb965a0e2214256c71 (diff) | |
download | FreeBSD-src-926bf5d72726506433072f19f7a994c972a0e7b0.zip FreeBSD-src-926bf5d72726506433072f19f7a994c972a0e7b0.tar.gz |
MFC r258633: MFV r255256: 3954 metaslabs continue to load even after
hitting zfs_mg_alloc_failure limit
Diffstat (limited to 'sys/cddl/contrib/opensolaris/uts/common/fs/zfs/metaslab.c')
-rw-r--r-- | sys/cddl/contrib/opensolaris/uts/common/fs/zfs/metaslab.c | 111 |
1 files changed, 108 insertions, 3 deletions
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/metaslab.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/metaslab.c index 50a1e82..707686a 100644 --- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/metaslab.c +++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/metaslab.c @@ -65,7 +65,8 @@ int zfs_condense_pct = 200; /* * This value defines the number of allowed allocation failures per vdev. * If a device reaches this threshold in a given txg then we consider skipping - * allocations on that device. + * allocations on that device. The value of zfs_mg_alloc_failures is computed + * in zio_init() unless it has been overridden in /etc/system. */ int zfs_mg_alloc_failures = 0; TUNABLE_INT("vfs.zfs.mg_alloc_failures", &zfs_mg_alloc_failures); @@ -74,6 +75,21 @@ SYSCTL_INT(_vfs_zfs, OID_AUTO, mg_alloc_failures, CTLFLAG_RWTUN, "Number of allowed allocation failures per vdev"); /* + * The zfs_mg_noalloc_threshold defines which metaslab groups should + * be eligible for allocation. The value is defined as a percentage of + * a free space. Metaslab groups that have more free space than + * zfs_mg_noalloc_threshold are always eligible for allocations. Once + * a metaslab group's free space is less than or equal to the + * zfs_mg_noalloc_threshold the allocator will avoid allocating to that + * group unless all groups in the pool have reached zfs_mg_noalloc_threshold. + * Once all groups in the pool reach zfs_mg_noalloc_threshold then all + * groups are allowed to accept allocations. Gang blocks are always + * eligible to allocate on any metaslab group. The default value of 0 means + * no metaslab group will be excluded based on this criterion. + */ +int zfs_mg_noalloc_threshold = 0; + +/* * Metaslab debugging: when set, keeps all space maps in core to verify frees. */ static int metaslab_debug = 0; @@ -289,6 +305,53 @@ metaslab_compare(const void *x1, const void *x2) return (0); } +/* + * Update the allocatable flag and the metaslab group's capacity. + * The allocatable flag is set to true if the capacity is below + * the zfs_mg_noalloc_threshold. If a metaslab group transitions + * from allocatable to non-allocatable or vice versa then the metaslab + * group's class is updated to reflect the transition. + */ +static void +metaslab_group_alloc_update(metaslab_group_t *mg) +{ + vdev_t *vd = mg->mg_vd; + metaslab_class_t *mc = mg->mg_class; + vdev_stat_t *vs = &vd->vdev_stat; + boolean_t was_allocatable; + + ASSERT(vd == vd->vdev_top); + + mutex_enter(&mg->mg_lock); + was_allocatable = mg->mg_allocatable; + + mg->mg_free_capacity = ((vs->vs_space - vs->vs_alloc) * 100) / + (vs->vs_space + 1); + + mg->mg_allocatable = (mg->mg_free_capacity > zfs_mg_noalloc_threshold); + + /* + * The mc_alloc_groups maintains a count of the number of + * groups in this metaslab class that are still above the + * zfs_mg_noalloc_threshold. This is used by the allocating + * threads to determine if they should avoid allocations to + * a given group. The allocator will avoid allocations to a group + * if that group has reached or is below the zfs_mg_noalloc_threshold + * and there are still other groups that are above the threshold. + * When a group transitions from allocatable to non-allocatable or + * vice versa we update the metaslab class to reflect that change. + * When the mc_alloc_groups value drops to 0 that means that all + * groups have reached the zfs_mg_noalloc_threshold making all groups + * eligible for allocations. This effectively means that all devices + * are balanced again. + */ + if (was_allocatable && !mg->mg_allocatable) + mc->mc_alloc_groups--; + else if (!was_allocatable && mg->mg_allocatable) + mc->mc_alloc_groups++; + mutex_exit(&mg->mg_lock); +} + metaslab_group_t * metaslab_group_create(metaslab_class_t *mc, vdev_t *vd) { @@ -339,6 +402,7 @@ metaslab_group_activate(metaslab_group_t *mg) return; mg->mg_aliquot = metaslab_aliquot * MAX(1, mg->mg_vd->vdev_children); + metaslab_group_alloc_update(mg); if ((mgprev = mc->mc_rotor) == NULL) { mg->mg_prev = mg; @@ -426,6 +490,29 @@ metaslab_group_sort(metaslab_group_t *mg, metaslab_t *msp, uint64_t weight) } /* + * Determine if a given metaslab group should skip allocations. A metaslab + * group should avoid allocations if its used capacity has crossed the + * zfs_mg_noalloc_threshold and there is at least one metaslab group + * that can still handle allocations. + */ +static boolean_t +metaslab_group_allocatable(metaslab_group_t *mg) +{ + vdev_t *vd = mg->mg_vd; + spa_t *spa = vd->vdev_spa; + metaslab_class_t *mc = mg->mg_class; + + /* + * A metaslab group is considered allocatable if its free capacity + * is greater than the set value of zfs_mg_noalloc_threshold, it's + * associated with a slog, or there are no other metaslab groups + * with free capacity greater than zfs_mg_noalloc_threshold. + */ + return (mg->mg_free_capacity > zfs_mg_noalloc_threshold || + mc != spa_normal_class(spa) || mc->mc_alloc_groups == 0); +} + +/* * ========================================================================== * Common allocator routines * ========================================================================== @@ -1374,6 +1461,8 @@ metaslab_sync_reassess(metaslab_group_t *mg) vdev_t *vd = mg->mg_vd; int64_t failures = mg->mg_alloc_failures; + metaslab_group_alloc_update(mg); + /* * Re-evaluate all metaslabs which have lower offsets than the * bonus area. @@ -1475,6 +1564,8 @@ metaslab_group_alloc(metaslab_group_t *mg, uint64_t psize, uint64_t asize, if (msp == NULL) return (-1ULL); + mutex_enter(&msp->ms_lock); + /* * If we've already reached the allowable number of failed * allocation attempts on this metaslab group then we @@ -1491,11 +1582,10 @@ metaslab_group_alloc(metaslab_group_t *mg, uint64_t psize, uint64_t asize, "asize %llu, failures %llu", spa_name(spa), mg->mg_vd->vdev_id, txg, mg, psize, asize, mg->mg_alloc_failures); + mutex_exit(&msp->ms_lock); return (-1ULL); } - mutex_enter(&msp->ms_lock); - /* * Ensure that the metaslab we have selected is still * capable of handling our request. It's possible that @@ -1648,6 +1738,21 @@ top: } else { allocatable = vdev_allocatable(vd); } + + /* + * Determine if the selected metaslab group is eligible + * for allocations. If we're ganging or have requested + * an allocation for the smallest gang block size + * then we don't want to avoid allocating to the this + * metaslab group. If we're in this condition we should + * try to allocate from any device possible so that we + * don't inadvertently return ENOSPC and suspend the pool + * even though space is still available. + */ + if (allocatable && CAN_FASTGANG(flags) && + psize > SPA_GANGBLOCKSIZE) + allocatable = metaslab_group_allocatable(mg); + if (!allocatable) goto next; |