BRT: Skip duplicate BRT prefetches

If there is a pending entry for this block, then we've already issued BRT prefetch for it within this TXG, so don't do it again. BRT vdev lookup and following zap_prefetch_uint64() call can be pretty expensive and should be avoided when not necessary. Signed-off-by: Alexander Motin <[email protected]> Sponsored by: iXsystems, Inc.
openzfs · Feb 28, 2024 · 74fc769 · 74fc769
1 parent 8f2f6cd
commit 74fc769
Showing 1 changed file with 3 additions and 3 deletions.
diff --git a/module/zfs/brt.c b/module/zfs/brt.c
@@ -1471,10 +1471,10 @@ brt_pending_add(spa_t *spa, const blkptr_t *bp, dmu_tx_t *tx)
 		kmem_cache_free(brt_pending_entry_cache, newbpe);
 	} else {
 		ASSERT(bpe == NULL);
-	}
 
-	/* Prefetch BRT entry, as we will need it in the syncing context. */
-	brt_prefetch(brt, bp);
+		/* Prefetch BRT entry for the syncing context. */
+		brt_prefetch(brt, bp);
+	}
 }
 
 void