On Wed, Jul 31, 2019 at 8:24 AM James Smart <jsmart2...@gmail.com> wrote:
>
> 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.kenn...@broadcom.com>
> Signed-off-by: James Smart <jsmart2...@gmail.com>
> ---
> drivers/scsi/lpfc/lpfc.h | 1 +
> drivers/scsi/lpfc/lpfc_attr.c | 17 +++++++++++++++++
> drivers/scsi/lpfc/lpfc_init.c | 12 ++++++++----
> drivers/scsi/lpfc/lpfc_sli4.h | 5 +++++
> 4 files changed, 31 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/scsi/lpfc/lpfc.h b/drivers/scsi/lpfc/lpfc.h
> index 2c3bb8a966e5..bade2e025ecf 100644
> --- a/drivers/scsi/lpfc/lpfc.h
> +++ b/drivers/scsi/lpfc/lpfc.h
> @@ -824,6 +824,7 @@ 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 ea62322ffe2b..d267f57d1738 100644
> --- a/drivers/scsi/lpfc/lpfc_attr.c
> +++ b/drivers/scsi/lpfc/lpfc_attr.c
> @@ -5709,6 +5709,19 @@ LPFC_ATTR_RW(nvme_embed_cmd, 1, 0, 2,
> "Embed NVME Command in WQE");
>
> /*
> + * lpfc_fcp_mq_threshold: Set the number of Hardware Queues the driver
> + * will advertise it supports to the SCSI layer.
> + *
> + * 0 = Configure nr_hw_queues by the number of CPUs or HW queues.
> + * 1,128 = Manually specify nr_hw_queue value to be advertised,
> + *
> + * Value range is [0,128]. Default value is 4.
> + */
> +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");
Hi James,
Could the default hw queue count be set as numa node number? This way
should work
fine most of times.
Thanks,
Ming Lei
