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: Scott Benesh <scott.benesh@microchip.com>
Reviewed-by: Mike McGowen <mike.mcgowen@microchip.com>
Reviewed-by: Scott Teel <scott.teel@microchip.com>
Reviewed-by: Kevin Barnett <kevin.barnett@microchip.com>
Signed-off-by: Don Brace <don.brace@microchip.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/smartpqi/smartpqi.h b/drivers/scsi/smartpqi/smartpqi.h
index 6639432f3daba8df847dd5c67ff49d13cbf0c642..976bfd8c5192d1bdf56e3a6e442205518252e4b8 100644 (file)
--- a/drivers/scsi/smartpqi/smartpqi.h
+++ b/drivers/scsi/smartpqi/smartpqi.h
@@ -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;

diff --git a/drivers/scsi/smartpqi/smartpqi_init.c b/drivers/scsi/smartpqi/smartpqi_init.c
index 143bb7b64095309f6848546da46f374d17ca1e64..27bd3d9a3810a4a464af64ea2682125ac0a6e722 100644 (file)
--- a/drivers/scsi/smartpqi/smartpqi_init.c
+++ b/drivers/scsi/smartpqi/smartpqi_init.c
@@ -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;
@@ -5736,11 +5810,12 @@ 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 (rc == 0 || rc == SCSI_MLQUEUE_HOST_BUSY) {
-                               raid_bypassed = true;
-                               atomic_inc(&device->raid_bypass_cnt);
+                       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)