From: James Smart jsmart2021@gmail.com
[ Upstream commit 77ffd3465ba837e9dc714e17b014e77b2eae765a ]
When SCSI-MQ is enabled, the SCSI-MQ layers will do pre-allocation of MQ resources based on shost values set by the driver. In newer cases of the driver, which attempts to set nr_hw_queues to the cpu count, the multipliers become excessive, with a single shost having SCSI-MQ pre-allocation reaching into the multiple GBytes range. NPIV, which creates additional shosts, only multiply this overhead. On lower-memory systems, this can exhaust system memory very quickly, resulting in a system crash or failures in the driver or elsewhere due to low memory conditions.
After testing several scenarios, the situation can be mitigated by limiting the value set in shost->nr_hw_queues to 4. Although the shost values were changed, the driver still had per-cpu hardware queues of its own that allowed parallelization per-cpu. Testing revealed that even with the smallish number for nr_hw_queues for SCSI-MQ, performance levels remained near maximum with the within-driver affiinitization.
A module parameter was created to allow the value set for the nr_hw_queues to be tunable.
Signed-off-by: Dick Kennedy dick.kennedy@broadcom.com Signed-off-by: James Smart jsmart2021@gmail.com Reviewed-by: Ming Lei ming.lei@redhat.com Reviewed-by: Ewan D. Milne emilne@redhat.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_attr.c | 15 +++++++++++++++ drivers/scsi/lpfc/lpfc_init.c | 10 ++++++---- drivers/scsi/lpfc/lpfc_sli4.h | 5 +++++ 4 files changed, 27 insertions(+), 4 deletions(-)
diff --git a/drivers/scsi/lpfc/lpfc.h b/drivers/scsi/lpfc/lpfc.h index aafcffaa25f71..4604e1bc334c0 100644 --- a/drivers/scsi/lpfc/lpfc.h +++ b/drivers/scsi/lpfc/lpfc.h @@ -822,6 +822,7 @@ struct lpfc_hba { uint32_t cfg_cq_poll_threshold; uint32_t cfg_cq_max_proc_limit; uint32_t cfg_fcp_cpu_map; + uint32_t cfg_fcp_mq_threshold; uint32_t cfg_hdw_queue; uint32_t cfg_irq_chann; uint32_t cfg_suppress_rsp; diff --git a/drivers/scsi/lpfc/lpfc_attr.c b/drivers/scsi/lpfc/lpfc_attr.c index d4c65e2109e2f..353da12d797ba 100644 --- a/drivers/scsi/lpfc/lpfc_attr.c +++ b/drivers/scsi/lpfc/lpfc_attr.c @@ -5640,6 +5640,19 @@ LPFC_ATTR_RW(nvme_oas, 0, 0, 1, LPFC_ATTR_RW(nvme_embed_cmd, 1, 0, 2, "Embed NVME Command in WQE");
+/* + * lpfc_fcp_mq_threshold: Set the maximum number of Hardware Queues + * the driver will advertise it supports to the SCSI layer. + * + * 0 = Set nr_hw_queues by the number of CPUs or HW queues. + * 1,128 = Manually specify the maximum nr_hw_queue value to be set, + * + * Value range is [0,128]. Default value is 8. + */ +LPFC_ATTR_R(fcp_mq_threshold, LPFC_FCP_MQ_THRESHOLD_DEF, + LPFC_FCP_MQ_THRESHOLD_MIN, LPFC_FCP_MQ_THRESHOLD_MAX, + "Set the number of SCSI Queues advertised"); + /* * lpfc_hdw_queue: Set the number of Hardware Queues the driver * will advertise it supports to the NVME and SCSI layers. This also @@ -5961,6 +5974,7 @@ struct device_attribute *lpfc_hba_attrs[] = { &dev_attr_lpfc_cq_poll_threshold, &dev_attr_lpfc_cq_max_proc_limit, &dev_attr_lpfc_fcp_cpu_map, + &dev_attr_lpfc_fcp_mq_threshold, &dev_attr_lpfc_hdw_queue, &dev_attr_lpfc_irq_chann, &dev_attr_lpfc_suppress_rsp, @@ -7042,6 +7056,7 @@ lpfc_get_cfgparam(struct lpfc_hba *phba) /* Initialize first burst. Target vs Initiator are different. */ lpfc_nvme_enable_fb_init(phba, lpfc_nvme_enable_fb); lpfc_nvmet_fb_size_init(phba, lpfc_nvmet_fb_size); + lpfc_fcp_mq_threshold_init(phba, lpfc_fcp_mq_threshold); lpfc_hdw_queue_init(phba, lpfc_hdw_queue); lpfc_irq_chann_init(phba, lpfc_irq_chann); lpfc_enable_bbcr_init(phba, lpfc_enable_bbcr); diff --git a/drivers/scsi/lpfc/lpfc_init.c b/drivers/scsi/lpfc/lpfc_init.c index eaaef682de251..2fd8f15f99975 100644 --- a/drivers/scsi/lpfc/lpfc_init.c +++ b/drivers/scsi/lpfc/lpfc_init.c @@ -4308,10 +4308,12 @@ lpfc_create_port(struct lpfc_hba *phba, int instance, struct device *dev) shost->max_cmd_len = 16;
if (phba->sli_rev == LPFC_SLI_REV4) { - if (phba->cfg_fcp_io_sched == LPFC_FCP_SCHED_BY_HDWQ) - shost->nr_hw_queues = phba->cfg_hdw_queue; - else - shost->nr_hw_queues = phba->sli4_hba.num_present_cpu; + if (!phba->cfg_fcp_mq_threshold || + phba->cfg_fcp_mq_threshold > phba->cfg_hdw_queue) + phba->cfg_fcp_mq_threshold = phba->cfg_hdw_queue; + + shost->nr_hw_queues = min_t(int, 2 * num_possible_nodes(), + phba->cfg_fcp_mq_threshold);
shost->dma_boundary = phba->sli4_hba.pc_sli4_params.sge_supp_len-1; diff --git a/drivers/scsi/lpfc/lpfc_sli4.h b/drivers/scsi/lpfc/lpfc_sli4.h index 8e4fd1a98023c..986594ec40e2a 100644 --- a/drivers/scsi/lpfc/lpfc_sli4.h +++ b/drivers/scsi/lpfc/lpfc_sli4.h @@ -44,6 +44,11 @@ #define LPFC_HBA_HDWQ_MAX 128 #define LPFC_HBA_HDWQ_DEF 0
+/* FCP MQ queue count limiting */ +#define LPFC_FCP_MQ_THRESHOLD_MIN 0 +#define LPFC_FCP_MQ_THRESHOLD_MAX 128 +#define LPFC_FCP_MQ_THRESHOLD_DEF 8 + /* Common buffer size to accomidate SCSI and NVME IO buffers */ #define LPFC_COMMON_IO_BUF_SZ 768