This patch adds plug/unplug callouts for iblock. For initiator drivers
like iscsi which wants to pass multiple cmds to its xmit thread instead
of one cmd at a time, this increases IOPs by around 10% with vhost-scsi
(combined with the last patches we can see a total 40-50% increase). For
driver combos like tcm_loop and faster drivers like the iser initiator, we
can still see IOPs increase by 20-30% when tcm_loop's nr_hw_queues setting
is also increased.
Signed-off-by: Mike Christie <michael.christie@xxxxxxxxxx>
---
drivers/target/target_core_iblock.c | 44 ++++++++++++++++++++++++++++-
drivers/target/target_core_iblock.h | 10 +++++++
2 files changed, 53 insertions(+), 1 deletion(-)
diff --git a/drivers/target/target_core_iblock.c b/drivers/target/target_core_iblock.c
index 8ed93fd205c7..33c88eca090f 100644
--- a/drivers/target/target_core_iblock.c
+++ b/drivers/target/target_core_iblock.c
@@ -61,9 +61,18 @@ static struct se_device *iblock_alloc_device(struct se_hba *hba, const char *nam
return NULL;
}
+ ib_dev->ibd_plug = kcalloc(nr_cpu_ids, sizeof(*ib_dev->ibd_plug),
+ GFP_KERNEL);
+ if (!ib_dev->ibd_plug)
+ goto free_dev;
+
pr_debug( "IBLOCK: Allocated ib_dev for %s\n", name);
return &ib_dev->dev;
+
+free_dev:
+ kfree(ib_dev);
+ return NULL;
}
static int iblock_configure_device(struct se_device *dev)
@@ -171,6 +180,7 @@ static void iblock_dev_call_rcu(struct rcu_head *p)
struct se_device *dev = container_of(p, struct se_device, rcu_head);
struct iblock_dev *ib_dev = IBLOCK_DEV(dev);
+ kfree(ib_dev->ibd_plug);
kfree(ib_dev);
}
@@ -188,6 +198,33 @@ static void iblock_destroy_device(struct se_device *dev)
bioset_exit(&ib_dev->ibd_bio_set);
}
+static struct se_dev_plug *iblock_plug_device(struct se_device *se_dev)
+{
+ struct iblock_dev *ib_dev = IBLOCK_DEV(se_dev);
+ struct iblock_dev_plug *ib_dev_plug;
+
+ /*
+ * Each se_device has a per cpu work this can be run from. Wwe
+ * shouldn't have multiple threads on the same cpu calling this
+ * at the same time.
+ */
+ ib_dev_plug = &ib_dev->ibd_plug[smp_processor_id()];
+ if (test_and_set_bit(IBD_PLUGF_PLUGGED, &ib_dev_plug->flags))
+ return NULL;
+
+ blk_start_plug(&ib_dev_plug->blk_plug);
+ return &ib_dev_plug->se_plug;
+}
+
+static void iblock_unplug_device(struct se_dev_plug *se_plug)
+{
+ struct iblock_dev_plug *ib_dev_plug = container_of(se_plug,
+ struct iblock_dev_plug, se_plug);
+
+ blk_finish_plug(&ib_dev_plug->blk_plug);
+ clear_bit(IBD_PLUGF_PLUGGED, &ib_dev_plug->flags);
+}
+
static unsigned long long iblock_emulate_read_cap_with_block_size(
struct se_device *dev,
struct block_device *bd,
@@ -337,7 +374,10 @@ static void iblock_submit_bios(struct bio_list *list)
{
struct blk_plug plug;
struct bio *bio;
-
+ /*
+ * The block layer handles nested plugs, so just plug/unplug to handle
+ * fabric drivers that didn't support batching and multi bio cmds.
+ */
blk_start_plug(&plug);
while ((bio = bio_list_pop(list)))
submit_bio(bio);
@@ -870,6 +910,8 @@ static const struct target_backend_ops iblock_ops = {
.configure_device = iblock_configure_device,
.destroy_device = iblock_destroy_device,
.free_device = iblock_free_device,
+ .plug_device = iblock_plug_device,
+ .unplug_device = iblock_unplug_device,
.parse_cdb = iblock_parse_cdb,
.set_configfs_dev_params = iblock_set_configfs_dev_params,
.show_configfs_dev_params = iblock_show_configfs_dev_params,
diff --git a/drivers/target/target_core_iblock.h b/drivers/target/target_core_iblock.h
index cefc641145b3..8c55375d2f75 100644
--- a/drivers/target/target_core_iblock.h
+++ b/drivers/target/target_core_iblock.h
@@ -4,6 +4,7 @@
#include <linux/atomic.h>
#include <linux/refcount.h>
+#include <linux/blkdev.h>
#include <target/target_core_base.h>
#define IBLOCK_VERSION "4.0"
@@ -17,6 +18,14 @@ struct iblock_req {
#define IBDF_HAS_UDEV_PATH 0x01
+#define IBD_PLUGF_PLUGGED 0x01
+
+struct iblock_dev_plug {
+ struct se_dev_plug se_plug;
+ struct blk_plug blk_plug;
+ unsigned long flags;
+};
+
struct iblock_dev {
struct se_device dev;
unsigned char ibd_udev_path[SE_UDEV_PATH_LEN];
@@ -24,6 +33,7 @@ struct iblock_dev {
struct bio_set ibd_bio_set;
struct block_device *ibd_bd;
bool ibd_readonly;
+ struct iblock_dev_plug *ibd_plug;
} ____cacheline_aligned;
#endif /* TARGET_CORE_IBLOCK_H */
--
2.25.1
