[SCSI] lpfc 8.3.33: Make I/O to hw queue distribution algorithm a mod…

…ule parameter

Signed-off-by: James Smart <james.smart@emulex.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/lpfc/lpfc.h

@@ -684,6 +684,7 @@ struct lpfc_hba {
 #define LPFC_FCF_FOV 1		/* Fast fcf failover */
 #define LPFC_FCF_PRIORITY 2	/* Priority fcf failover */
 	uint32_t cfg_fcf_failover_policy;
+	uint32_t cfg_fcp_io_sched;
 	uint32_t cfg_cr_delay;
 	uint32_t cfg_cr_count;
 	uint32_t cfg_multi_ring_support;

drivers/scsi/lpfc/lpfc_attr.c

@@ -3777,6 +3777,16 @@ static DEVICE_ATTR(lpfc_max_scsicmpl_time, S_IRUGO | S_IWUSR,
 */
 LPFC_ATTR_R(ack0, 0, 0, 1, "Enable ACK0 support");
 
+/*
+# lpfc_fcp_io_sched: Determine scheduling algrithmn for issuing FCP cmds
+# range is [0,1]. Default value is 0.
+# For [0], FCP commands are issued to Work Queues ina round robin fashion.
+# For [1], FCP commands are issued to a Work Queue associated with the
+#          current CPU.
+*/
+LPFC_ATTR_RW(fcp_io_sched, 0, 0, 1, "Determine scheduling algrithmn for "
+		"issuing commands [0] - Round Robin, [1] - Current CPU");
+
 /*
 # lpfc_cr_delay & lpfc_cr_count: Default values for I/O colaesing
 # cr_delay (msec) or cr_count outstanding commands. cr_delay can take
@@ -4001,6 +4011,7 @@ struct device_attribute *lpfc_hba_attrs[] = {
 	&dev_attr_lpfc_topology,
 	&dev_attr_lpfc_scan_down,
 	&dev_attr_lpfc_link_speed,
+	&dev_attr_lpfc_fcp_io_sched,
 	&dev_attr_lpfc_cr_delay,
 	&dev_attr_lpfc_cr_count,
 	&dev_attr_lpfc_multi_ring_support,
@@ -4990,6 +5001,7 @@ struct fc_function_template lpfc_vport_transport_functions = {
 void
 lpfc_get_cfgparam(struct lpfc_hba *phba)
 {
+	lpfc_fcp_io_sched_init(phba, lpfc_fcp_io_sched);
 	lpfc_cr_delay_init(phba, lpfc_cr_delay);
 	lpfc_cr_count_init(phba, lpfc_cr_count);
 	lpfc_multi_ring_support_init(phba, lpfc_multi_ring_support);

drivers/scsi/lpfc/lpfc_hw4.h

@@ -187,6 +187,10 @@ struct lpfc_sli_intf {
 /* Active interrupt test count */
 #define LPFC_ACT_INTR_CNT	4
 
+/* Algrithmns for scheduling FCP commands to WQs */
+#define	LPFC_FCP_SCHED_ROUND_ROBIN	0
+#define	LPFC_FCP_SCHED_BY_CPU		1
+
 /* Delay Multiplier constant */
 #define LPFC_DMULT_CONST       651042
 

drivers/scsi/lpfc/lpfc_sli.c

@@ -7816,7 +7816,11 @@ lpfc_sli4_scmd_to_wqidx_distr(struct lpfc_hba *phba)
 {
 	int i;
 
-	i = atomic_add_return(1, &phba->fcp_qidx);
+	if (phba->cfg_fcp_io_sched == LPFC_FCP_SCHED_BY_CPU)
+		i = smp_processor_id();
+	else
+		i = atomic_add_return(1, &phba->fcp_qidx);
+
 	i = (i % phba->cfg_fcp_io_channel);
 	return i;
 }