From e2f4ea40138e16d1dfd768f2dead8f3f75a85673 Mon Sep 17 00:00:00 2001 From: Mike Christie Date: Wed, 27 Sep 2023 21:09:05 -0500 Subject: [PATCH] scsi: target: Allow userspace to request direct submissions 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 an NVMe drive and vhost-scsi with direct submission we see around a 20% improvement in 4K I/Os: 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 I/Os for other LUs. Signed-off-by: Mike Christie Link: https://lore.kernel.org/r/20230928020907.5730-6-michael.christie@oracle.com Signed-off-by: Martin K. Petersen --- 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 936e5ff1b209..f7eaf17e9050 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 6c8f6055fc1e..f1fab7e0ea3d 100644 --- a/drivers/target/target_core_transport.c +++ b/drivers/target/target_core_transport.c @@ -1575,14 +1575,7 @@ 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; @@ -1642,7 +1635,6 @@ 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, @@ -1904,7 +1896,7 @@ 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) @@ -1927,6 +1919,35 @@ 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; };