aboutsummaryrefslogtreecommitdiff
path: root/drivers
diff options
context:
space:
mode:
authorJames Smart2019-12-18 15:58:06 -0800
committerMartin K. Petersen2019-12-21 13:42:42 -0500
commit999fbbceb8312a764b318cf19510273291ec3575 (patch)
tree20b33b907b6d0dca74f48a11f7e680e4b0272ef8 /drivers
parent0b4391946da872e825efa3edfa932e44ae6e9cf9 (diff)
scsi: lpfc: Fix MDS Latency Diagnostics Err-drop rates
When running Cisco-MDS diagnostics which perform driver-level frame loop back, the switch is reporting errors. Diagnostic has a limit on latency that is not being met by the driver. The requirement of Latency frames is that they should be responded back by the host with a maximum delay of few hundreds of microseconds. If the switch doesn't get response frames within this time frame, it fails the test. Test is failing as the lpfc-wq workqueue was overwhelmed by the packet rate and in some cases, the work element yielded to other kernel elements. To resolve, reduce the outstanding load allowed by the adapter. This ensures the driver spends a reasonable amount of time doing loopback and can do so such that latency values can be met. Load is managed by reducing the number of receive buffers posted such that the link can be backpressured to reduce load. Link: https://lore.kernel.org/r/20191218235808.31922-9-jsmart2021@gmail.com Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com> Signed-off-by: James Smart <jsmart2021@gmail.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/scsi/lpfc/lpfc_sli.c13
1 files changed, 11 insertions, 2 deletions
diff --git a/drivers/scsi/lpfc/lpfc_sli.c b/drivers/scsi/lpfc/lpfc_sli.c
index 12319f63cb45..e660ee98ad8b 100644
--- a/drivers/scsi/lpfc/lpfc_sli.c
+++ b/drivers/scsi/lpfc/lpfc_sli.c
@@ -4918,8 +4918,17 @@ static int
lpfc_sli4_rb_setup(struct lpfc_hba *phba)
{
phba->hbq_in_use = 1;
- phba->hbqs[LPFC_ELS_HBQ].entry_count =
- lpfc_hbq_defs[LPFC_ELS_HBQ]->entry_count;
+ /**
+ * Specific case when the MDS diagnostics is enabled and supported.
+ * The receive buffer count is truncated to manage the incoming
+ * traffic.
+ **/
+ if (phba->cfg_enable_mds_diags && phba->mds_diags_support)
+ phba->hbqs[LPFC_ELS_HBQ].entry_count =
+ lpfc_hbq_defs[LPFC_ELS_HBQ]->entry_count >> 1;
+ else
+ phba->hbqs[LPFC_ELS_HBQ].entry_count =
+ lpfc_hbq_defs[LPFC_ELS_HBQ]->entry_count;
phba->hbq_count = 1;
lpfc_sli_hbqbuf_init_hbqs(phba, LPFC_ELS_HBQ);
/* Initially populate or replenish the HBQs */