diff --git a/man/man5/zfs-module-parameters.5 b/man/man5/zfs-module-parameters.5
index e0000a23a1..321b6285ca 100644
--- a/man/man5/zfs-module-parameters.5
+++ b/man/man5/zfs-module-parameters.5
@@ -1379,17 +1379,6 @@ Max commit bytes to separate log device
 Default value: \fB1,048,576\fR.
 .RE
 
-.sp
-.ne 2
-.na
-\fBzio_bulk_flags\fR (int)
-.ad
-.RS 12n
-Additional flags to pass to bulk buffers
-.sp
-Default value: \fB0\fR.
-.RE
-
 .sp
 .ne 2
 .na
diff --git a/module/zfs/zio.c b/module/zfs/zio.c
index 7dcb420066..d904b30b21 100644
--- a/module/zfs/zio.c
+++ b/module/zfs/zio.c
@@ -57,7 +57,6 @@ kmem_cache_t *zio_cache;
 kmem_cache_t *zio_link_cache;
 kmem_cache_t *zio_buf_cache[SPA_MAXBLOCKSIZE >> SPA_MINBLOCKSHIFT];
 kmem_cache_t *zio_data_buf_cache[SPA_MAXBLOCKSIZE >> SPA_MINBLOCKSHIFT];
-int zio_bulk_flags = 0;
 int zio_delay_max = ZIO_DELAY_MAX;
 
 /*
@@ -142,6 +141,7 @@ zio_init(void)
 		size_t size = (c + 1) << SPA_MINBLOCKSHIFT;
 		size_t p2 = size;
 		size_t align = 0;
+		size_t cflags = (size > zio_buf_debug_limit) ? KMC_NODEBUG : 0;
 
 		while (p2 & (p2 - 1))
 			p2 &= p2 - 1;
@@ -166,16 +166,14 @@ zio_init(void)
 
 		if (align != 0) {
 			char name[36];
-			int flags = zio_bulk_flags;
-
 			(void) sprintf(name, "zio_buf_%lu", (ulong_t)size);
 			zio_buf_cache[c] = kmem_cache_create(name, size,
-			    align, NULL, NULL, NULL, NULL, NULL, flags);
+			    align, NULL, NULL, NULL, NULL, NULL, cflags);
 
 			(void) sprintf(name, "zio_data_buf_%lu", (ulong_t)size);
 			zio_data_buf_cache[c] = kmem_cache_create(name, size,
 			    align, NULL, NULL, NULL, NULL,
-			    data_alloc_arena, flags);
+			    data_alloc_arena, cflags);
 		}
 	}
 
@@ -3398,9 +3396,6 @@ EXPORT_SYMBOL(zio_data_buf_alloc);
 EXPORT_SYMBOL(zio_buf_free);
 EXPORT_SYMBOL(zio_data_buf_free);
 
-module_param(zio_bulk_flags, int, 0644);
-MODULE_PARM_DESC(zio_bulk_flags, "Additional flags to pass to bulk buffers");
-
 module_param(zio_delay_max, int, 0644);
 MODULE_PARM_DESC(zio_delay_max, "Max zio millisec delay before posting event");
 
diff --git a/scripts/zpios-survey.sh b/scripts/zpios-survey.sh
index cb751b467e..78601695ff 100755
--- a/scripts/zpios-survey.sh
+++ b/scripts/zpios-survey.sh
@@ -120,40 +120,13 @@ zpios_survey_pending() {
 		tee -a ${ZPIOS_SURVEY_LOG}
 }
 
-# To avoid memory fragmentation issues our slab implementation can be
-# based on a virtual address space.  Interestingly, we take a pretty
-# substantial performance penalty for this somewhere in the low level
-# IO drivers.  If we back the slab with kmem pages we see far better
-# read performance numbers at the cost of memory fragmention and general
-# system instability due to large allocations.  This may be because of
-# an optimization in the low level drivers due to the contigeous kmem
-# based memory.  This needs to be explained.  The good news here is that
-# with zerocopy interfaces added at the DMU layer we could gaurentee
-# kmem based memory for a pool of pages.
-#
-# 0x100 = KMC_KMEM - Force kmem_* based slab
-# 0x200 = KMC_VMEM - Force vmem_* based slab
-zpios_survey_kmem() {
-	TEST_NAME="${ZPOOL_CONFIG}+${ZPIOS_TEST}+kmem"
-	print_header ${TEST_NAME}
-
-	${ZFS_SH} ${VERBOSE_FLAG}             \  
-		zfs="zio_bulk_flags=0x100" | \
-		tee -a ${ZPIOS_SURVEY_LOG}
-	${ZPIOS_SH} ${VERBOSE_FLAG} -c ${ZPOOL_CONFIG} -t ${ZPIOS_TEST} | \
-		tee -a ${ZPIOS_SURVEY_LOG}
-	${ZFS_SH} -u ${VERBOSE_FLAG} | \
-		tee -a ${ZPIOS_SURVEY_LOG}
-}
-
 # Apply all possible turning concurrently to get a best case number
 zpios_survey_all() {
 	TEST_NAME="${ZPOOL_CONFIG}+${ZPIOS_TEST}+all"
 	print_header ${TEST_NAME}
 
 	${ZFS_SH} ${VERBOSE_FLAG}                \  
-		zfs="zfs_vdev_max_pending=1024" \
-		zfs="zio_bulk_flags=0x100" |    \
+		zfs="zfs_vdev_max_pending=1024" | \
 		tee -a ${ZPIOS_SURVEY_LOG}
 	${ZPIOS_SH} ${VERBOSE_FLAG} -c ${ZPOOL_CONFIG} -t ${ZPIOS_TEST} \
 		-o "--noprefetch --zerocopy"                           \
@@ -209,7 +182,6 @@ zpios_survey_prefetch
 zpios_survey_zerocopy
 zpios_survey_checksum
 zpios_survey_pending
-zpios_survey_kmem
 zpios_survey_all
 
 exit 0