Commit c7ffedb3 authored by Don Brace's avatar Don Brace Committed by Martin K. Petersen
Browse files

scsi: smartpqi: Add stream detection 

Enhance performance by adding sequential stream detection for RAID5/RAID6
sequential write requests. Reduce stripe lock contention with full-stripe
write operations.

There is one common stripe lock for each RAID volume that can be set by
either the RAID engine or the AIO engine. The AIO path has I/O request
sizes well below the stripe size resulting in many Read-Modify-Write
operations.

Sending the request to the RAID engine allows for coalescing requests into
full stripe operations resulting in reduced Read-Modify-Write operations.

Link: https://lore.kernel.org/r/161549375693.25025.2962141451773219796.stgit@brunhilda


Reviewed-by: default avatarScott Benesh <scott.benesh@microchip.com>
Reviewed-by: default avatarMike McGowen <mike.mcgowen@microchip.com>
Reviewed-by: default avatarScott Teel <scott.teel@microchip.com>
Reviewed-by: default avatarKevin Barnett <kevin.barnett@microchip.com>
Signed-off-by: default avatarDon Brace <don.brace@microchip.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent 583891c9

drivers/scsi/smartpqi/smartpqi.h

+9 −0
Original line number Diff line number Diff line
@@ -1043,6 +1043,13 @@ struct pqi_scsi_dev_raid_map_data { 


#define RAID_CTLR_LUNID		"\0\0\0\0\0\0\0\0"



#define NUM_STREAMS_PER_LUN	8



struct pqi_stream_data {

	u64	next_lba;

	u32	last_accessed;

};



struct pqi_scsi_dev {

	int	devtype;		/* as reported by INQUIRY commmand */

	u8	device_type;		/* as reported by */
@@ -1097,6 +1104,7 @@ struct pqi_scsi_dev { 
	struct list_head add_list_entry;

	struct list_head delete_list_entry;



	struct pqi_stream_data stream_data[NUM_STREAMS_PER_LUN];

	atomic_t scsi_cmds_outstanding;

	atomic_t raid_bypass_cnt;

};
@@ -1296,6 +1304,7 @@ struct pqi_ctrl_info { 
	u8		enable_r5_writes : 1;

	u8		enable_r6_writes : 1;

	u8		lv_drive_type_mix_valid : 1;

	u8		enable_stream_detection : 1;



	u8		ciss_report_log_flags;

	u32		max_transfer_encrypted_sas_sata;

drivers/scsi/smartpqi/smartpqi_init.c

+81 −6
Original line number Diff line number Diff line
@@ -5688,8 +5688,82 @@ void pqi_prep_for_scsi_done(struct scsi_cmnd *scmd) 
	atomic_dec(&device->scsi_cmds_outstanding);

}



static int pqi_scsi_queue_command(struct Scsi_Host *shost,

static bool pqi_is_parity_write_stream(struct pqi_ctrl_info *ctrl_info,

	struct scsi_cmnd *scmd)

{

	u32 oldest_jiffies;

	u8 lru_index;

	int i;

	int rc;

	struct pqi_scsi_dev *device;

	struct pqi_stream_data *pqi_stream_data;

	struct pqi_scsi_dev_raid_map_data rmd;



	if (!ctrl_info->enable_stream_detection)

		return false;



	rc = pqi_get_aio_lba_and_block_count(scmd, &rmd);

	if (rc)

		return false;



	/* Check writes only. */

	if (!rmd.is_write)

		return false;



	device = scmd->device->hostdata;



	/* Check for RAID 5/6 streams. */

	if (device->raid_level != SA_RAID_5 && device->raid_level != SA_RAID_6)

		return false;



	/*

	 * If controller does not support AIO RAID{5,6} writes, need to send

	 * requests down non-AIO path.

	 */

	if ((device->raid_level == SA_RAID_5 && !ctrl_info->enable_r5_writes) ||

		(device->raid_level == SA_RAID_6 && !ctrl_info->enable_r6_writes))

		return true;



	lru_index = 0;

	oldest_jiffies = INT_MAX;

	for (i = 0; i < NUM_STREAMS_PER_LUN; i++) {

		pqi_stream_data = &device->stream_data[i];

		/*

		 * Check for adjacent request or request is within

		 * the previous request.

		 */

		if ((pqi_stream_data->next_lba &&

			rmd.first_block >= pqi_stream_data->next_lba) &&

			rmd.first_block <= pqi_stream_data->next_lba +

				rmd.block_cnt) {

			pqi_stream_data->next_lba = rmd.first_block +

				rmd.block_cnt;

			pqi_stream_data->last_accessed = jiffies;

			return true;

		}



		/* unused entry */

		if (pqi_stream_data->last_accessed == 0) {

			lru_index = i;

			break;

		}



		/* Find entry with oldest last accessed time. */

		if (pqi_stream_data->last_accessed <= oldest_jiffies) {

			oldest_jiffies = pqi_stream_data->last_accessed;

			lru_index = i;

		}

	}



	/* Set LRU entry. */

	pqi_stream_data = &device->stream_data[lru_index];

	pqi_stream_data->last_accessed = jiffies;

	pqi_stream_data->next_lba = rmd.first_block + rmd.block_cnt;



	return false;

}



static int pqi_scsi_queue_command(struct Scsi_Host *shost, struct scsi_cmnd *scmd)

{

	int rc;

	struct pqi_ctrl_info *ctrl_info;
@@ -5736,13 +5810,14 @@ static int pqi_scsi_queue_command(struct Scsi_Host *shost, 
		raid_bypassed = false;

		if (device->raid_bypass_enabled &&

			!blk_rq_is_passthrough(scmd->request)) {

			rc = pqi_raid_bypass_submit_scsi_cmd(ctrl_info, device,

				scmd, queue_group);

			if (!pqi_is_parity_write_stream(ctrl_info, scmd)) {

				rc = pqi_raid_bypass_submit_scsi_cmd(ctrl_info, device, scmd, queue_group);

				if (rc == 0 || rc == SCSI_MLQUEUE_HOST_BUSY) {

					raid_bypassed = true;

					atomic_inc(&device->raid_bypass_cnt);

				}

			}

		}

		if (!raid_bypassed)

			rc = pqi_raid_submit_scsi_cmd(ctrl_info, device, scmd, queue_group);

	} else {