From 8d34a59caecda9a7ce0cad108ee64c37aa0c9812 Mon Sep 17 00:00:00 2001 From: James Smart Date: Wed, 14 Aug 2019 16:56:35 -0700 Subject: scsi: lpfc: Fix failure to clear non-zero eq_delay after io rate reduction Unusually high IO latency can be observed with little IO in progress. The latency may remain high regardless of amount of IO and can only be cleared by forcing lpfc_fcp_imax values to non-zero and then back to zero. The driver's eq_delay mechanism that scales the interrupt coalescing based on io completion load failed to reduce or turn off coalescing when load decreased. Specifically, if no io completed on a cpu within an eq_delay polling window, the eq delay processing was skipped and no change was made to the coalescing values. This left the coalescing values set when they were no longer applicable. Fix by always clearing the percpu counters for each time period and always run the eq_delay calculations if an eq has a non-zero coalescing value. Signed-off-by: Dick Kennedy Signed-off-by: James Smart Signed-off-by: Martin K. Petersen --- drivers/scsi/lpfc/lpfc_init.c | 32 +++++++++++++++++++++----------- 1 file changed, 21 insertions(+), 11 deletions(-) (limited to 'drivers/scsi/lpfc/lpfc_init.c') diff --git a/drivers/scsi/lpfc/lpfc_init.c b/drivers/scsi/lpfc/lpfc_init.c index f9986efa0aa3..d04d00dea901 100644 --- a/drivers/scsi/lpfc/lpfc_init.c +++ b/drivers/scsi/lpfc/lpfc_init.c @@ -1262,6 +1262,7 @@ lpfc_hb_eq_delay_work(struct work_struct *work) unsigned char *eqcnt = NULL; uint32_t usdelay; int i; + bool update = false; if (!phba->cfg_auto_imax || phba->pport->load_flag & FC_UNLOADING) return; @@ -1275,20 +1276,29 @@ lpfc_hb_eq_delay_work(struct work_struct *work) if (!eqcnt) goto requeue; - /* Loop thru all IRQ vectors */ - for (i = 0; i < phba->cfg_irq_chann; i++) { - /* Get the EQ corresponding to the IRQ vector */ - eq = phba->sli4_hba.hba_eq_hdl[i].eq; - if (eq && eqcnt[eq->last_cpu] < 2) - eqcnt[eq->last_cpu]++; - continue; - } + if (phba->cfg_irq_chann > 1) { + /* Loop thru all IRQ vectors */ + for (i = 0; i < phba->cfg_irq_chann; i++) { + /* Get the EQ corresponding to the IRQ vector */ + eq = phba->sli4_hba.hba_eq_hdl[i].eq; + if (!eq) + continue; + if (eq->q_mode) { + update = true; + break; + } + if (eqcnt[eq->last_cpu] < 2) + eqcnt[eq->last_cpu]++; + } + } else + update = true; for_each_present_cpu(i) { - if (phba->cfg_irq_chann > 1 && eqcnt[i] < 2) - continue; - eqi = per_cpu_ptr(phba->sli4_hba.eq_info, i); + if (!update && eqcnt[i] < 2) { + eqi->icnt = 0; + continue; + } usdelay = (eqi->icnt / LPFC_IMAX_THRESHOLD) * LPFC_EQ_DELAY_STEP; -- cgit v1.2.3-59-g8ed1b