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| author | James Smart <jsmart2021@gmail.com> | 2019-08-15 19:36:49 -0700 |
|---|---|---|
| committer | Martin K. Petersen <martin.petersen@oracle.com> | 2019-08-19 22:14:10 -0400 |
| commit | 77ffd3465ba837e9dc714e17b014e77b2eae765a (patch) | |
| tree | e7600f3b593e0dc5019efb7b013cd15785319d6c /drivers/scsi/lpfc/lpfc_attr.c | |
| parent | 7c7cfdcf7f1777c7376fc9a239980de04b6b5ea1 (diff) | |
| download | linux-77ffd3465ba837e9dc714e17b014e77b2eae765a.tar.bz2 | |
scsi: lpfc: Mitigate high memory pre-allocation by SCSI-MQ
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>
Diffstat (limited to 'drivers/scsi/lpfc/lpfc_attr.c')
| -rw-r--r-- | drivers/scsi/lpfc/lpfc_attr.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/drivers/scsi/lpfc/lpfc_attr.c b/drivers/scsi/lpfc/lpfc_attr.c index ea62322ffe2b..8d8c495b5b60 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 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 * will map to the number of CQ/WQ pairs the driver will create. @@ -6030,6 +6043,7 @@ 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, @@ -7112,6 +7126,7 @@ 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); |