scsi: fnic: Impose upper limit on max. # of CQs processed per intr

Impose an upper limit on the max number of CQ entries (corresponding to the
copy wq) processed in an interrupt.  Use module parameter to set the limit.
Signed-off-by: Satish Kharat <satishkh@cisco.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/fnic/fnic.h

@@ -128,6 +128,7 @@
 	__fnic_set_state_flags(fnicp, st_flags, 1)
 
 extern unsigned int fnic_log_level;
+extern unsigned int io_completions;
 
 #define FNIC_MAIN_LOGGING 0x01
 #define FNIC_FCS_LOGGING 0x02
@@ -196,6 +197,7 @@ enum fnic_state {
 #define FNIC_WQ_MAX 1
 #define FNIC_RQ_MAX 1
 #define FNIC_CQ_MAX (FNIC_WQ_COPY_MAX + FNIC_WQ_MAX + FNIC_RQ_MAX)
+#define FNIC_DFLT_IO_COMPLETIONS 256
 
 struct mempool;
 

drivers/scsi/fnic/fnic_isr.c

@@ -51,7 +51,7 @@ static irqreturn_t fnic_isr_legacy(int irq, void *data)
 	}
 
 	if (pba & (1 << FNIC_INTX_WQ_RQ_COPYWQ)) {
-		work_done += fnic_wq_copy_cmpl_handler(fnic, -1);
+		work_done += fnic_wq_copy_cmpl_handler(fnic, io_completions);
 		work_done += fnic_wq_cmpl_handler(fnic, -1);
 		work_done += fnic_rq_cmpl_handler(fnic, -1);
 
@@ -72,7 +72,7 @@ static irqreturn_t fnic_isr_msi(int irq, void *data)
 	fnic->fnic_stats.misc_stats.last_isr_time = jiffies;
 	atomic64_inc(&fnic->fnic_stats.misc_stats.isr_count);
 
-	work_done += fnic_wq_copy_cmpl_handler(fnic, -1);
+	work_done += fnic_wq_copy_cmpl_handler(fnic, io_completions);
 	work_done += fnic_wq_cmpl_handler(fnic, -1);
 	work_done += fnic_rq_cmpl_handler(fnic, -1);
 
@@ -125,7 +125,7 @@ static irqreturn_t fnic_isr_msix_wq_copy(int irq, void *data)
 	fnic->fnic_stats.misc_stats.last_isr_time = jiffies;
 	atomic64_inc(&fnic->fnic_stats.misc_stats.isr_count);
 
-	wq_copy_work_done = fnic_wq_copy_cmpl_handler(fnic, -1);
+	wq_copy_work_done = fnic_wq_copy_cmpl_handler(fnic, io_completions);
 	vnic_intr_return_credits(&fnic->intr[FNIC_MSIX_WQ_COPY],
 				 wq_copy_work_done,
 				 1 /* unmask intr */,

drivers/scsi/fnic/fnic_main.c

@@ -69,6 +69,11 @@ unsigned int fnic_log_level;
 module_param(fnic_log_level, int, S_IRUGO|S_IWUSR);
 MODULE_PARM_DESC(fnic_log_level, "bit mask of fnic logging levels");
 
+
+unsigned int io_completions = FNIC_DFLT_IO_COMPLETIONS;
+module_param(io_completions, int, S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(io_completions, "Max CQ entries to process at a time");
+
 unsigned int fnic_trace_max_pages = 16;
 module_param(fnic_trace_max_pages, uint, S_IRUGO|S_IWUSR);
 MODULE_PARM_DESC(fnic_trace_max_pages, "Total allocated memory pages "
@@ -503,7 +508,7 @@ static int fnic_cleanup(struct fnic *fnic)
 	}
 
 	/* Clean up completed IOs and FCS frames */
-	fnic_wq_copy_cmpl_handler(fnic, -1);
+	fnic_wq_copy_cmpl_handler(fnic, io_completions);
 	fnic_wq_cmpl_handler(fnic, -1);
 	fnic_rq_cmpl_handler(fnic, -1);