[PATCH 2/5] smartpqi: improve accuracy/performance of raid-bypass-counter.

Don Brace
2024-07-11T19:47:34Z

From: Kevin Barnett <kevin.barnett@microchip.com>

The original implementation of this counter used an atomic variable.
However, this implementation negatively impacted performance in some
configurations.

Switch to using per_cpu variables.

Reviewed-by: Scott Benesh <scott.benesh@microchip.com>
Reviewed-by: Scott Teel <scott.teel@microchip.com>
Reviewed-by: Mike McGowen <mike.mcgowen@microchip.com>
Co-developed-by: Mahesh Rajashekhara <mahesh.rajashekhara@microchip.com>
Signed-off-by: Mahesh Rajashekhara <mahesh.rajashekhara@microchip.com>
Signed-off-by: Kevin Barnett <kevin.barnett@microchip.com>
Signed-off-by: Don Brace <don.brace@microchip.com>
---
drivers/scsi/smartpqi/smartpqi.h | 2 +-
drivers/scsi/smartpqi/smartpqi_init.c | 30 +++++++++++++++++++++++----
2 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/smartpqi/smartpqi.h b/drivers/scsi/smartpqi/smartpqi.h
index cdedc271857a..023fbce04e7a 100644
--- a/drivers/scsi/smartpqi/smartpqi.h
+++ b/drivers/scsi/smartpqi/smartpqi.h
@@ -1158,7 +1158,7 @@ struct pqi_scsi_dev {

struct pqi_stream_data stream_data[NUM_STREAMS_PER_LUN];
atomic_t scsi_cmds_outstanding[PQI_MAX_LUNS_PER_DEVICE];
- unsigned int raid_bypass_cnt;
+ u64 __percpu *raid_bypass_cnt;

struct pqi_tmf_work tmf_work[PQI_MAX_LUNS_PER_DEVICE];
};
diff --git a/drivers/scsi/smartpqi/smartpqi_init.c b/drivers/scsi/smartpqi/smartpqi_init.c
index 9166dfa1fedc..eaebe3cc00aa 100644
--- a/drivers/scsi/smartpqi/smartpqi_init.c
+++ b/drivers/scsi/smartpqi/smartpqi_init.c
@@ -1508,6 +1508,12 @@ static int pqi_get_raid_map(struct pqi_ctrl_info *ctrl_info,
if (rc)
goto error;

+ device->raid_bypass_cnt = alloc_percpu(u64);
+ if (!device->raid_bypass_cnt) {
+ rc = -ENOMEM;
+ goto error;
+ }
+
device->raid_map = raid_map;

return 0;
@@ -2099,6 +2105,10 @@ static void pqi_scsi_update_device(struct pqi_ctrl_info *ctrl_info,
/* To prevent this from being freed later. */
new_device->raid_map = NULL;
}
+ if (new_device->raid_bypass_enabled && existing_device->raid_bypass_cnt == NULL) {
+ existing_device->raid_bypass_cnt = new_device->raid_bypass_cnt;
+ new_device->raid_bypass_cnt = NULL;
+ }
existing_device->raid_bypass_configured = new_device->raid_bypass_configured;
existing_device->raid_bypass_enabled = new_device->raid_bypass_enabled;
}
@@ -2121,6 +2131,7 @@ static void pqi_scsi_update_device(struct pqi_ctrl_info *ctrl_info,
static inline void pqi_free_device(struct pqi_scsi_dev *device)
{
if (device) {
+ free_percpu(device->raid_bypass_cnt);
kfree(device->raid_map);
kfree(device);
}
@@ -6007,6 +6018,7 @@ static int pqi_scsi_queue_command(struct Scsi_Host *shost, struct scsi_cmnd *scm
u16 hw_queue;
struct pqi_queue_group *queue_group;
bool raid_bypassed;
+ u64 *raid_bypass_cnt;
u8 lun;

scmd->host_scribble = PQI_NO_COMPLETION;
@@ -6053,7 +6065,8 @@ static int pqi_scsi_queue_command(struct Scsi_Host *shost, struct scsi_cmnd *scm
rc = pqi_raid_bypass_submit_scsi_cmd(ctrl_info, device, scmd, queue_group);
if (rc == 0 || rc == SCSI_MLQUEUE_HOST_BUSY) {
raid_bypassed = true;
- device->raid_bypass_cnt++;
+ raid_bypass_cnt = per_cpu_ptr(device->raid_bypass_cnt, smp_processor_id());
+ (*raid_bypass_cnt)++;
}
}
if (!raid_bypassed)
@@ -7350,7 +7363,9 @@ static ssize_t pqi_raid_bypass_cnt_show(struct device *dev,
struct scsi_device *sdev;
struct pqi_scsi_dev *device;
unsigned long flags;
- unsigned int raid_bypass_cnt;
+ u64 raid_bypass_cnt;
+ int cpu;
+ u64 *per_cpu_bypass_cnt_ptr;

sdev = to_scsi_device(dev);
ctrl_info = shost_to_hba(sdev->host);
@@ -7366,11 +7381,18 @@ static ssize_t pqi_raid_bypass_cnt_show(struct device *dev,
return -ENODEV;
}

- raid_bypass_cnt = device->raid_bypass_cnt;
+ raid_bypass_cnt = 0;
+
+ if (device->raid_bypass_cnt) {
+ for_each_online_cpu(cpu) {
+ per_cpu_bypass_cnt_ptr = per_cpu_ptr(device->raid_bypass_cnt, cpu);
+ raid_bypass_cnt += *per_cpu_bypass_cnt_ptr;
+ }
+ }

spin_unlock_irqrestore(&ctrl_info->scsi_device_list_lock, flags);

- return scnprintf(buffer, PAGE_SIZE, "0x%x\n", raid_bypass_cnt);
+ return scnprintf(buffer, PAGE_SIZE, "0x%llx\n", raid_bypass_cnt);
}

static ssize_t pqi_sas_ncq_prio_enable_show(struct device *dev,
--
2.45.2.827.g557ae147e6