Add ddt, ddt_entry, and l2arc_hdr caches

Back the allocations for ddt tables+entries and l2arc headers with
kmem caches.  This will reduce the cost of allocating these commonly
used structures and allow for greater visibility of them through the
/proc/spl/kmem/slab interface.

Signed-off-by: John Layman <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes #1893

3 files changed, 40 insertions, 16 deletions

diff --git a/module/zfs/arc.c b/module/zfs/arc.c
index 222614c3d..2459c9326 100644
--- a/module/zfs/arc.c
+++ b/module/zfs/arc.c
@@ -899,6 +899,7 @@ buf_hash_remove(arc_buf_hdr_t *buf)
  */
 static kmem_cache_t *hdr_cache;
 static kmem_cache_t *buf_cache;
+static kmem_cache_t *l2arc_hdr_cache;
 
 static void
 buf_fini(void)
@@ -920,6 +921,7 @@ buf_fini(void)
 		mutex_destroy(&buf_hash_table.ht_locks[i].ht_lock);
 	kmem_cache_destroy(hdr_cache);
 	kmem_cache_destroy(buf_cache);
+	kmem_cache_destroy(l2arc_hdr_cache);
 }
 
 /*
@@ -1020,6 +1022,8 @@ retry:
 	    0, hdr_cons, hdr_dest, NULL, NULL, NULL, 0);
 	buf_cache = kmem_cache_create("arc_buf_t", sizeof (arc_buf_t),
 	    0, buf_cons, buf_dest, NULL, NULL, NULL, 0);
+	l2arc_hdr_cache = kmem_cache_create("l2arc_buf_hdr_t", L2HDR_SIZE,
+	    0, NULL, NULL, NULL, NULL, NULL, 0);
 
 	for (i = 0; i < 256; i++)
 		for (ct = zfs_crc64_table + i, *ct = i, j = 8; j > 0; j--)
@@ -1678,7 +1682,7 @@ arc_hdr_destroy(arc_buf_hdr_t *hdr)
 			list_remove(l2hdr->b_dev->l2ad_buflist, hdr);
 			ARCSTAT_INCR(arcstat_l2_size, -hdr->b_size);
 			ARCSTAT_INCR(arcstat_l2_asize, -l2hdr->b_asize);
-			kmem_free(l2hdr, sizeof (l2arc_buf_hdr_t));
+			kmem_cache_free(l2arc_hdr_cache, l2hdr);
 			arc_space_return(L2HDR_SIZE, ARC_SPACE_L2HDRS);
 			if (hdr->b_state == arc_l2c_only)
 				l2arc_hdr_stat_remove();
@@ -3684,7 +3688,7 @@ arc_release(arc_buf_t *buf, void *tag)
 	if (l2hdr) {
 		ARCSTAT_INCR(arcstat_l2_asize, -l2hdr->b_asize);
 		list_remove(l2hdr->b_dev->l2ad_buflist, hdr);
-		kmem_free(l2hdr, sizeof (l2arc_buf_hdr_t));
+		kmem_cache_free(l2arc_hdr_cache, l2hdr);
 		arc_space_return(L2HDR_SIZE, ARC_SPACE_L2HDRS);
 		ARCSTAT_INCR(arcstat_l2_size, -buf_size);
 		mutex_exit(&l2arc_buflist_mtx);
@@ -4572,7 +4576,7 @@ l2arc_write_done(zio_t *zio)
 			list_remove(buflist, ab);
 			ARCSTAT_INCR(arcstat_l2_asize, -abl2->b_asize);
 			ab->b_l2hdr = NULL;
-			kmem_free(abl2, sizeof (l2arc_buf_hdr_t));
+			kmem_cache_free(l2arc_hdr_cache, abl2);
 			arc_space_return(L2HDR_SIZE, ARC_SPACE_L2HDRS);
 			ARCSTAT_INCR(arcstat_l2_size, -ab->b_size);
 		}
@@ -4827,7 +4831,7 @@ top:
 				abl2 = ab->b_l2hdr;
 				ARCSTAT_INCR(arcstat_l2_asize, -abl2->b_asize);
 				ab->b_l2hdr = NULL;
-				kmem_free(abl2, sizeof (l2arc_buf_hdr_t));
+				kmem_cache_free(l2arc_hdr_cache, abl2);
 				arc_space_return(L2HDR_SIZE, ARC_SPACE_L2HDRS);
 				ARCSTAT_INCR(arcstat_l2_size, -ab->b_size);
 			}
@@ -4973,9 +4977,9 @@ l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz,
 			/*
 			 * Create and add a new L2ARC header.
 			 */
-			l2hdr = kmem_zalloc(sizeof (l2arc_buf_hdr_t),
-			    KM_PUSHPAGE);
+			l2hdr = kmem_cache_alloc(l2arc_hdr_cache, KM_PUSHPAGE);
 			l2hdr->b_dev = dev;
+			l2hdr->b_daddr = 0;
 			arc_space_consume(L2HDR_SIZE, ARC_SPACE_L2HDRS);
 
 			ab->b_flags |= ARC_L2_WRITING;
diff --git a/module/zfs/ddt.c b/module/zfs/ddt.c
index b923df13a..070c83155 100644
--- a/module/zfs/ddt.c
+++ b/module/zfs/ddt.c
@@ -37,6 +37,9 @@
 #include <sys/zio_compress.h>
 #include <sys/dsl_scan.h>
 
+static kmem_cache_t *ddt_cache;
+static kmem_cache_t *ddt_entry_cache;
+
 /*
  * Enable/disable prefetching of dedup-ed blocks which are going to be freed.
  */
@@ -515,7 +518,6 @@ ddt_get_dedup_stats(spa_t *spa, ddt_stat_t *dds_total)
 {
 	ddt_histogram_t *ddh_total;
 
-	/* XXX: Move to a slab */
 	ddh_total = kmem_zalloc(sizeof (ddt_histogram_t), KM_PUSHPAGE);
 	ddt_get_dedup_histogram(spa, ddh_total);
 	ddt_histogram_stat(dds_total, ddh_total);
@@ -659,13 +661,29 @@ ddt_exit(ddt_t *ddt)
 	mutex_exit(&ddt->ddt_lock);
 }
 
+void
+ddt_init(void)
+{
+	ddt_cache = kmem_cache_create("ddt_cache",
+	    sizeof (ddt_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
+	ddt_entry_cache = kmem_cache_create("ddt_entry_cache",
+	    sizeof (ddt_entry_t), 0, NULL, NULL, NULL, NULL, NULL, 0);
+}
+
+void
+ddt_fini(void)
+{
+	kmem_cache_destroy(ddt_entry_cache);
+	kmem_cache_destroy(ddt_cache);
+}
+
 static ddt_entry_t *
 ddt_alloc(const ddt_key_t *ddk)
 {
 	ddt_entry_t *dde;
 
-	/* XXX: Move to a slab */
-	dde = kmem_zalloc(sizeof (ddt_entry_t), KM_PUSHPAGE);
+	dde = kmem_cache_alloc(ddt_entry_cache, KM_PUSHPAGE);
+	bzero(dde, sizeof (ddt_entry_t));
 	cv_init(&dde->dde_cv, NULL, CV_DEFAULT, NULL);
 
 	dde->dde_key = *ddk;
@@ -688,7 +706,7 @@ ddt_free(ddt_entry_t *dde)
 		    DDK_GET_PSIZE(&dde->dde_key));
 
 	cv_destroy(&dde->dde_cv);
-	kmem_free(dde, sizeof (*dde));
+	kmem_cache_free(ddt_entry_cache, dde);
 }
 
 void
@@ -813,8 +831,8 @@ ddt_table_alloc(spa_t *spa, enum zio_checksum c)
 {
 	ddt_t *ddt;
 
-	/* XXX: Move to a slab */
-	ddt = kmem_zalloc(sizeof (*ddt), KM_PUSHPAGE | KM_NODEBUG);
+	ddt = kmem_cache_alloc(ddt_cache, KM_PUSHPAGE | KM_NODEBUG);
+	bzero(ddt, sizeof (ddt_t));
 
 	mutex_init(&ddt->ddt_lock, NULL, MUTEX_DEFAULT, NULL);
 	avl_create(&ddt->ddt_tree, ddt_entry_compare,
@@ -836,7 +854,7 @@ ddt_table_free(ddt_t *ddt)
 	avl_destroy(&ddt->ddt_tree);
 	avl_destroy(&ddt->ddt_repair_tree);
 	mutex_destroy(&ddt->ddt_lock);
-	kmem_free(ddt, sizeof (*ddt));
+	kmem_cache_free(ddt_cache, ddt);
 }
 
 void
@@ -916,20 +934,20 @@ ddt_class_contains(spa_t *spa, enum ddt_class max_class, const blkptr_t *bp)
 		return (B_TRUE);
 
 	ddt = spa->spa_ddt[BP_GET_CHECKSUM(bp)];
-	dde = kmem_alloc(sizeof (ddt_entry_t), KM_PUSHPAGE);
+	dde = kmem_cache_alloc(ddt_entry_cache, KM_PUSHPAGE);
 
 	ddt_key_fill(&(dde->dde_key), bp);
 
 	for (type = 0; type < DDT_TYPES; type++) {
 		for (class = 0; class <= max_class; class++) {
 			if (ddt_object_lookup(ddt, type, class, dde) == 0) {
-				kmem_free(dde, sizeof (ddt_entry_t));
+				kmem_cache_free(ddt_entry_cache, dde);
 				return (B_TRUE);
 			}
 		}
 	}
 
-	kmem_free(dde, sizeof (ddt_entry_t));
+	kmem_cache_free(ddt_entry_cache, dde);
 	return (B_FALSE);
 }
 
diff --git a/module/zfs/spa_misc.c b/module/zfs/spa_misc.c
index 07bfb3112..58c4e67bd 100644
--- a/module/zfs/spa_misc.c
+++ b/module/zfs/spa_misc.c
@@ -1653,6 +1653,7 @@ spa_init(int mode)
 	refcount_init();
 	unique_init();
 	space_map_init();
+	ddt_init();
 	zio_init();
 	dmu_init();
 	zil_init();
@@ -1675,6 +1676,7 @@ spa_fini(void)
 	zil_fini();
 	dmu_fini();
 	zio_fini();
+	ddt_fini();
 	space_map_fini();
 	unique_fini();
 	refcount_fini();