[PATCH 6.8 099/336] scsi: lpfc: Update lpfc_ramp_down_queue_handler() logic

Greg Kroah-Hartman
2024-05-14T10:31:31Z

From: Justin Tee <justin.tee@broadcom.com>

[ Upstream commit bb011631435c705cdeddca68d5c85fd40a4320f9 ]

Typically when an out of resource CQE status is detected, the
lpfc_ramp_down_queue_handler() logic is called to help reduce I/O load by
reducing an sdev's queue_depth.

However, the current lpfc_rampdown_queue_depth() logic does not help reduce
queue_depth. num_cmd_success is never updated and is always zero, which
means new_queue_depth will always be set to sdev->queue_depth. So,
new_queue_depth = sdev->queue_depth - new_queue_depth always sets
new_queue_depth to zero. And, scsi_change_queue_depth(sdev, 0) is
essentially a no-op.

Change the lpfc_ramp_down_queue_handler() logic to set new_queue_depth
equal to sdev->queue_depth subtracted from number of times num_rsrc_err was
incremented. If num_rsrc_err is >= sdev->queue_depth, then set
new_queue_depth equal to 1. Eventually, the frequency of Good_Status
frames will signal SCSI upper layer to auto increase the queue_depth back
to the driver default of 64 via scsi_handle_queue_ramp_up().

Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Link: https://lore.kernel.org/r/20240305200503.57317-5-justintee8345@gmail.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/scsi/lpfc/lpfc.h | 1 -
drivers/scsi/lpfc/lpfc_scsi.c | 13 ++++---------
2 files changed, 4 insertions(+), 10 deletions(-)

diff --git a/drivers/scsi/lpfc/lpfc.h b/drivers/scsi/lpfc/lpfc.h
index 04d608ea91060..be016732ab2ea 100644
--- a/drivers/scsi/lpfc/lpfc.h
+++ b/drivers/scsi/lpfc/lpfc.h
@@ -1325,7 +1325,6 @@ struct lpfc_hba {
struct timer_list fabric_block_timer;
unsigned long bit_flags;
atomic_t num_rsrc_err;
- atomic_t num_cmd_success;
unsigned long last_rsrc_error_time;
unsigned long last_ramp_down_time;
#ifdef CONFIG_SCSI_LPFC_DEBUG_FS
diff --git a/drivers/scsi/lpfc/lpfc_scsi.c b/drivers/scsi/lpfc/lpfc_scsi.c
index bf879d81846b6..cf506556f3b0b 100644
--- a/drivers/scsi/lpfc/lpfc_scsi.c
+++ b/drivers/scsi/lpfc/lpfc_scsi.c
@@ -167,11 +167,10 @@ lpfc_ramp_down_queue_handler(struct lpfc_hba *phba)
struct Scsi_Host *shost;
struct scsi_device *sdev;
unsigned long new_queue_depth;
- unsigned long num_rsrc_err, num_cmd_success;
+ unsigned long num_rsrc_err;
int i;

num_rsrc_err = atomic_read(&phba->num_rsrc_err);
- num_cmd_success = atomic_read(&phba->num_cmd_success);

/*
* The error and success command counters are global per
@@ -186,20 +185,16 @@ lpfc_ramp_down_queue_handler(struct lpfc_hba *phba)
for (i = 0; i <= phba->max_vports && vports[i] != NULL; i++) {
shost = lpfc_shost_from_vport(vports[i]);
shost_for_each_device(sdev, shost) {
- new_queue_depth =
- sdev->queue_depth * num_rsrc_err /
- (num_rsrc_err + num_cmd_success);
- if (!new_queue_depth)
- new_queue_depth = sdev->queue_depth - 1;
+ if (num_rsrc_err >= sdev->queue_depth)
+ new_queue_depth = 1;
else
new_queue_depth = sdev->queue_depth -
- new_queue_depth;
+ num_rsrc_err;
scsi_change_queue_depth(sdev, new_queue_depth);
}
}
lpfc_destroy_vport_work_array(phba, vports);
atomic_set(&phba->num_rsrc_err, 0);
- atomic_set(&phba->num_cmd_success, 0);
}

/**
--
2.43.0