Illumos 5243 - zdb -b could be much faster

5243 zdb -b could be much faster
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Richard Elling <richard.elling@gmail.com>
Approved by: Dan McDonald <danmcd@omniti.com>

References:
  https://www.illumos.org/issues/5243
  https://github.com/illumos/illumos-gate/commit/f7950bf

Ported-by: Don Brady <don.brady@intel.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3414

diff --git a/cmd/zdb/zdb.c b/cmd/zdb/zdb.c
index d0bebbe60f70574ce867a10a501e1cdc7ccce043..fc6e3fff0c1d352f0066f32045940f739e19aee1 100644 (file)
--- a/cmd/zdb/zdb.c
+++ b/cmd/zdb/zdb.c
@@ -76,9 +76,11 @@
 #ifndef lint
 extern int zfs_recover;
 extern uint64_t zfs_arc_max, zfs_arc_meta_limit;
+extern int zfs_vdev_async_read_max_active;
 #else
 int zfs_recover;
 uint64_t zfs_arc_max, zfs_arc_meta_limit;
+int zfs_vdev_async_read_max_active;
 #endif
 
 const char cmdname[] = "zdb";
@@ -2513,8 +2515,14 @@ zdb_blkptr_cb(spa_t *spa, zilog_t *zilog, const blkptr_t *bp,
 
        zcb->zcb_readfails = 0;
 
-       if (dump_opt['b'] < 5 &&
-           gethrtime() > zcb->zcb_lastprint + NANOSEC) {
+       /* only call gethrtime() every 100 blocks */
+       static int iters;
+       if (++iters > 100)
+               iters = 0;
+       else
+               return (0);
+
+       if (dump_opt['b'] < 5 && gethrtime() > zcb->zcb_lastprint + NANOSEC) {
                uint64_t now = gethrtime();
                char buf[10];
                uint64_t bytes = zcb->zcb_type[ZB_TOTAL][ZDB_OT_TOTAL].zb_asize;
@@ -2625,6 +2633,14 @@ zdb_leak_init(spa_t *spa, zdb_cb_t *zcb)
                                            (longlong_t)vd->vdev_ms_count);
 
                                        msp->ms_ops = &zdb_metaslab_ops;
+
+                                       /*
+                                        * We don't want to spend the CPU
+                                        * manipulating the size-ordered
+                                        * tree, so clear the range_tree
+                                        * ops.
+                                        */
+                                       msp->ms_tree->rt_ops = NULL;
                                        VERIFY0(space_map_load(msp->ms_sm,
                                            msp->ms_tree, SM_ALLOC));
                                        msp->ms_loaded = B_TRUE;
@@ -3675,6 +3691,13 @@ main(int argc, char **argv)
        zfs_arc_max = zfs_arc_meta_limit = 256 * 1024 * 1024;
 #endif
 
+       /*
+        * "zdb -c" uses checksum-verifying scrub i/os which are async reads.
+        * "zdb -b" uses traversal prefetch which uses async reads.
+        * For good performance, let several of them be active at once.
+        */
+       zfs_vdev_async_read_max_active = 10;
+
        kernel_init(FREAD);
        if ((g_zfs = libzfs_init()) == NULL)
                return (1);

diff --git a/module/zfs/dmu_traverse.c b/module/zfs/dmu_traverse.c
index 21e34f822a31d5f95871347a1588b2f16ff237f6..8673132a0eebf0db1f9a5adf165ad4591dacca6a 100644 (file)
--- a/module/zfs/dmu_traverse.c
+++ b/module/zfs/dmu_traverse.c
@@ -58,6 +58,7 @@ typedef struct traverse_data {
        int td_flags;
        prefetch_data_t *td_pfd;
        boolean_t td_paused;
+       uint64_t td_hole_birth_enabled_txg;
        blkptr_cb_t *td_func;
        void *td_arg;
 } traverse_data_t;
@@ -226,25 +227,20 @@ traverse_visitbp(traverse_data_t *td, const dnode_phys_t *dnp,
        }
 
        if (bp->blk_birth == 0) {
-               if (spa_feature_is_active(td->td_spa, SPA_FEATURE_HOLE_BIRTH)) {
-                       /*
-                        * Since this block has a birth time of 0 it must be a
-                        * hole created before the SPA_FEATURE_HOLE_BIRTH
-                        * feature was enabled.  If SPA_FEATURE_HOLE_BIRTH
-                        * was enabled before the min_txg for this traveral we
-                        * know the hole must have been created before the
-                        * min_txg for this traveral, so we can skip it. If
-                        * SPA_FEATURE_HOLE_BIRTH was enabled after the min_txg
-                        * for this traveral we cannot tell if the hole was
-                        * created before or after the min_txg for this
-                        * traversal, so we cannot skip it.
-                        */
-                       uint64_t hole_birth_enabled_txg;
-                       VERIFY(spa_feature_enabled_txg(td->td_spa,
-                           SPA_FEATURE_HOLE_BIRTH, &hole_birth_enabled_txg));
-                       if (hole_birth_enabled_txg < td->td_min_txg)
-                               return (0);
-               }
+               /*
+                * Since this block has a birth time of 0 it must be a
+                * hole created before the SPA_FEATURE_HOLE_BIRTH
+                * feature was enabled.  If SPA_FEATURE_HOLE_BIRTH
+                * was enabled before the min_txg for this traveral we
+                * know the hole must have been created before the
+                * min_txg for this traveral, so we can skip it. If
+                * SPA_FEATURE_HOLE_BIRTH was enabled after the min_txg
+                * for this traveral we cannot tell if the hole was
+                * created before or after the min_txg for this
+                * traversal, so we cannot skip it.
+                */
+               if (td->td_hole_birth_enabled_txg < td->td_min_txg)
+                       return (0);
        } else if (bp->blk_birth <= td->td_min_txg) {
                return (0);
        }
@@ -533,6 +529,13 @@ traverse_impl(spa_t *spa, dsl_dataset_t *ds, uint64_t objset, blkptr_t *rootbp,
        td->td_flags = flags;
        td->td_paused = B_FALSE;
 
+       if (spa_feature_is_active(spa, SPA_FEATURE_HOLE_BIRTH)) {
+               VERIFY(spa_feature_enabled_txg(spa,
+                   SPA_FEATURE_HOLE_BIRTH, &td->td_hole_birth_enabled_txg));
+       } else {
+               td->td_hole_birth_enabled_txg = 0;
+       }
+
        pd->pd_flags = flags;
        mutex_init(&pd->pd_mtx, NULL, MUTEX_DEFAULT, NULL);
        cv_init(&pd->pd_cv, NULL, CV_DEFAULT, NULL);