This allows userspace to request the fabric drivers do direct submissions
if they support it. With the new device file, submit_type, users can
write 0 - 2 to control how commands are submitted to the backend:
0 - TARGET_FABRIC_DEFAULT_SUBMIT - LIO will use the fabric's default
submission type. This is the default for compat.
1 - TARGET_DIRECT_SUBMIT - LIO will submit the cmd to the backend from
the calling context if the fabric the cmd was received on supports it,
else it will use the fabric's default type.
2 - TARGET_QUEUE_SUBMIT - LIO will queue the cmd to the LIO submission
workqueue which will pass it to the backend.
When using a nvme drive and vhost-scsi with direct submission we see
around a 20% improvement in 4K IOs:
fio jobs 1 2 4 8 10
--------------------------------------------------
defer 94K 190K 394K 770K 890K
direct 128K 252K 488K 950K -
And when using the queueing mode, we now no longer see issues like where
the iSCSI tx thread is blocked in the block layer waiting on a tag so it
can't respond to a nop or perform IOs for other LUs.
Signed-off-by: Mike Christie <michael.christie@xxxxxxxxxx>
---
drivers/target/loopback/tcm_loop.c | 2 +-
drivers/target/target_core_configfs.c | 22 ++++++++++++++
drivers/target/target_core_device.c | 1 +
drivers/target/target_core_transport.c | 41 +++++++++++++++++++-------
drivers/vhost/scsi.c | 2 +-
include/target/target_core_base.h | 1 +
6 files changed, 57 insertions(+), 12 deletions(-)
diff --git a/drivers/target/loopback/tcm_loop.c b/drivers/target/loopback/tcm_loop.c
index fbacccdd2ff6..8e4035ff3674 100644
--- a/drivers/target/loopback/tcm_loop.c
+++ b/drivers/target/loopback/tcm_loop.c
@@ -154,7 +154,7 @@ static void tcm_loop_target_queue_cmd(struct tcm_loop_cmd *tl_cmd)
GFP_ATOMIC))
return;
- target_queue_submission(se_cmd);
+ target_submit(se_cmd);
return;
out_done:
diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c
index d5860c1c1f46..a5f58988130a 100644
--- a/drivers/target/target_core_configfs.c
+++ b/drivers/target/target_core_configfs.c
@@ -577,6 +577,7 @@ DEF_CONFIGFS_ATTRIB_SHOW(unmap_granularity_alignment);
DEF_CONFIGFS_ATTRIB_SHOW(unmap_zeroes_data);
DEF_CONFIGFS_ATTRIB_SHOW(max_write_same_len);
DEF_CONFIGFS_ATTRIB_SHOW(emulate_rsoc);
+DEF_CONFIGFS_ATTRIB_SHOW(submit_type);
#define DEF_CONFIGFS_ATTRIB_STORE_U32(_name) \
static ssize_t _name##_store(struct config_item *item, const char *page,\
@@ -1231,6 +1232,24 @@ static ssize_t emulate_rsoc_store(struct config_item *item,
return count;
}
+static ssize_t submit_type_store(struct config_item *item, const char *page,
+ size_t count)
+{
+ struct se_dev_attrib *da = to_attrib(item);
+ int ret;
+ u8 val;
+
+ ret = kstrtou8(page, 0, &val);
+ if (ret < 0)
+ return ret;
+
+ if (val > TARGET_QUEUE_SUBMIT)
+ return -EINVAL;
+
+ da->submit_type = val;
+ return count;
+}
+
CONFIGFS_ATTR(, emulate_model_alias);
CONFIGFS_ATTR(, emulate_dpo);
CONFIGFS_ATTR(, emulate_fua_write);
@@ -1266,6 +1285,7 @@ CONFIGFS_ATTR(, unmap_zeroes_data);
CONFIGFS_ATTR(, max_write_same_len);
CONFIGFS_ATTR(, alua_support);
CONFIGFS_ATTR(, pgr_support);
+CONFIGFS_ATTR(, submit_type);
/*
* dev_attrib attributes for devices using the target core SBC/SPC
@@ -1308,6 +1328,7 @@ struct configfs_attribute *sbc_attrib_attrs[] = {
&attr_alua_support,
&attr_pgr_support,
&attr_emulate_rsoc,
+ &attr_submit_type,
NULL,
};
EXPORT_SYMBOL(sbc_attrib_attrs);
@@ -1325,6 +1346,7 @@ struct configfs_attribute *passthrough_attrib_attrs[] = {
&attr_emulate_pr,
&attr_alua_support,
&attr_pgr_support,
+ &attr_submit_type,
NULL,
};
EXPORT_SYMBOL(passthrough_attrib_attrs);
diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index b7ac60f4a219..0f3fd775fe6d 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -779,6 +779,7 @@ struct se_device *target_alloc_device(struct se_hba *hba, const char *name)
dev->dev_attrib.unmap_zeroes_data =
DA_UNMAP_ZEROES_DATA_DEFAULT;
dev->dev_attrib.max_write_same_len = DA_MAX_WRITE_SAME_LEN;
+ dev->dev_attrib.submit_type = TARGET_FABRIC_DEFAULT_SUBMIT;
xcopy_lun = &dev->xcopy_lun;
rcu_assign_pointer(xcopy_lun->lun_se_dev, dev);
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index d78f24c2dfcf..1fde18e1ef3f 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1576,14 +1576,7 @@ target_cmd_parse_cdb(struct se_cmd *cmd)
}
EXPORT_SYMBOL(target_cmd_parse_cdb);
-/**
- * target_submit - perform final initialization and submit cmd to LIO core
- * @cmd: command descriptor to submit
- *
- * target_submit_prep or something similar must have been called on the cmd,
- * and this must be called from process context.
- */
-int target_submit(struct se_cmd *cmd)
+static int __target_submit(struct se_cmd *cmd)
{
sense_reason_t ret;
@@ -1643,7 +1636,6 @@ int target_submit(struct se_cmd *cmd)
transport_generic_request_failure(cmd, ret);
return 0;
}
-EXPORT_SYMBOL_GPL(target_submit);
sense_reason_t
transport_generic_map_mem_to_cmd(struct se_cmd *cmd, struct scatterlist *sgl,
@@ -1905,7 +1897,7 @@ void target_queued_submit_work(struct work_struct *work)
se_plug = target_plug_device(se_dev);
}
- target_submit(se_cmd);
+ __target_submit(se_cmd);
}
if (se_plug)
@@ -1928,6 +1920,35 @@ void target_queue_submission(struct se_cmd *se_cmd)
}
EXPORT_SYMBOL_GPL(target_queue_submission);
+/**
+ * target_submit - perform final initialization and submit cmd to LIO core
+ * @cmd: command descriptor to submit
+ *
+ * target_submit_prep or something similar must have been called on the cmd,
+ * and this must be called from process context.
+ */
+int target_submit(struct se_cmd *se_cmd)
+{
+ const struct target_core_fabric_ops *tfo = se_cmd->se_sess->se_tpg->se_tpg_tfo;
+ struct se_dev_attrib *da = &se_cmd->se_dev->dev_attrib;
+ u8 submit_type;
+
+ if (da->submit_type == TARGET_FABRIC_DEFAULT_SUBMIT)
+ submit_type = tfo->default_submit_type;
+ else if (da->submit_type == TARGET_DIRECT_SUBMIT &&
+ tfo->direct_submit_supp)
+ submit_type = TARGET_DIRECT_SUBMIT;
+ else
+ submit_type = TARGET_QUEUE_SUBMIT;
+
+ if (submit_type == TARGET_DIRECT_SUBMIT)
+ return __target_submit(se_cmd);
+
+ target_queue_submission(se_cmd);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(target_submit);
+
static void target_complete_tmr_failure(struct work_struct *work)
{
struct se_cmd *se_cmd = container_of(work, struct se_cmd, work);
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index dc274463bdf0..4e3b2c25c721 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -909,7 +909,7 @@ static void vhost_scsi_target_queue_cmd(struct vhost_scsi_cmd *cmd)
cmd->tvc_prot_sgl_count, GFP_KERNEL))
return;
- target_queue_submission(se_cmd);
+ target_submit(se_cmd);
}
static void
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 401abdf8a9ef..97099a5e3f6c 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -726,6 +726,7 @@ struct se_dev_attrib {
u32 unmap_granularity;
u32 unmap_granularity_alignment;
u32 max_write_same_len;
+ u8 submit_type;
struct se_device *da_dev;
struct config_group da_group;
};
--
2.34.1
