staging/rdma/hfi1: Thread the receive interrupt.

When under heavy load, the receive interrupt handler can run too long with IRQs
disabled.  Add a mixed-mode threading scheme.  Initially process packets in the
handler for quick responses (latency).  If there are too many packets to
process move to a thread to continue (bandwidth).

Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Dean Luick <dean.luick@intel.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 41 insertions, 31 deletions

diff --git a/drivers/staging/rdma/hfi1/driver.c b/drivers/staging/rdma/hfi1/driver.c
index ee4a01f71e8d..ce69141b56cb 100644
--- a/drivers/staging/rdma/hfi1/driver.c
+++ b/drivers/staging/rdma/hfi1/driver.c
@@ -427,8 +427,7 @@ static inline void init_packet(struct hfi1_ctxtdata *rcd,
 	packet->rcd = rcd;
 	packet->updegr = 0;
 	packet->etail = -1;
-	packet->rhf_addr = (__le32 *) rcd->rcvhdrq + rcd->head +
-			   rcd->dd->rhf_offset;
+	packet->rhf_addr = get_rhf_addr(rcd);
 	packet->rhf = rhf_to_cpu(packet->rhf_addr);
 	packet->rhqoff = rcd->head;
 	packet->numpkt = 0;
@@ -619,10 +618,7 @@ next:
 }
 #endif /* CONFIG_PRESCAN_RXQ */
 
-#define RCV_PKT_OK 0x0
-#define RCV_PKT_MAX 0x1
-
-static inline int process_rcv_packet(struct hfi1_packet *packet)
+static inline int process_rcv_packet(struct hfi1_packet *packet, int thread)
 {
 	int ret = RCV_PKT_OK;
 
@@ -664,9 +660,13 @@ static inline int process_rcv_packet(struct hfi1_packet *packet)
 	if (packet->rhqoff >= packet->maxcnt)
 		packet->rhqoff = 0;
 
-	if (packet->numpkt == MAX_PKT_RECV) {
-		ret = RCV_PKT_MAX;
-		this_cpu_inc(*packet->rcd->dd->rcv_limit);
+	if (unlikely((packet->numpkt & (MAX_PKT_RECV - 1)) == 0)) {
+		if (thread) {
+			cond_resched();
+		} else {
+			ret = RCV_PKT_LIMIT;
+			this_cpu_inc(*packet->rcd->dd->rcv_limit);
+		}
 	}
 
 	packet->rhf_addr = (__le32 *) packet->rcd->rcvhdrq + packet->rhqoff +
@@ -743,57 +743,63 @@ static inline void process_rcv_qp_work(struct hfi1_packet *packet)
 /*
  * Handle receive interrupts when using the no dma rtail option.
  */
-void handle_receive_interrupt_nodma_rtail(struct hfi1_ctxtdata *rcd)
+int handle_receive_interrupt_nodma_rtail(struct hfi1_ctxtdata *rcd, int thread)
 {
 	u32 seq;
-	int last = 0;
+	int last = RCV_PKT_OK;
 	struct hfi1_packet packet;
 
 	init_packet(rcd, &packet);
 	seq = rhf_rcv_seq(packet.rhf);
-	if (seq != rcd->seq_cnt)
+	if (seq != rcd->seq_cnt) {
+		last = RCV_PKT_DONE;
 		goto bail;
+	}
 
 	prescan_rxq(&packet);
 
-	while (!last) {
-		last = process_rcv_packet(&packet);
+	while (last == RCV_PKT_OK) {
+		last = process_rcv_packet(&packet, thread);
 		seq = rhf_rcv_seq(packet.rhf);
 		if (++rcd->seq_cnt > 13)
 			rcd->seq_cnt = 1;
 		if (seq != rcd->seq_cnt)
-			last = 1;
+			last = RCV_PKT_DONE;
 		process_rcv_update(last, &packet);
 	}
 	process_rcv_qp_work(&packet);
 bail:
 	finish_packet(&packet);
+	return last;
 }
 
-void handle_receive_interrupt_dma_rtail(struct hfi1_ctxtdata *rcd)
+int handle_receive_interrupt_dma_rtail(struct hfi1_ctxtdata *rcd, int thread)
 {
 	u32 hdrqtail;
-	int last = 0;
+	int last = RCV_PKT_OK;
 	struct hfi1_packet packet;
 
 	init_packet(rcd, &packet);
 	hdrqtail = get_rcvhdrtail(rcd);
-	if (packet.rhqoff == hdrqtail)
+	if (packet.rhqoff == hdrqtail) {
+		last = RCV_PKT_DONE;
 		goto bail;
+	}
 	smp_rmb();  /* prevent speculative reads of dma'ed hdrq */
 
 	prescan_rxq(&packet);
 
-	while (!last) {
-		last = process_rcv_packet(&packet);
+	while (last == RCV_PKT_OK) {
+		last = process_rcv_packet(&packet, thread);
+		hdrqtail = get_rcvhdrtail(rcd);
 		if (packet.rhqoff == hdrqtail)
-			last = 1;
+			last = RCV_PKT_DONE;
 		process_rcv_update(last, &packet);
 	}
 	process_rcv_qp_work(&packet);
 bail:
 	finish_packet(&packet);
-
+	return last;
 }
 
 static inline void set_all_nodma_rtail(struct hfi1_devdata *dd)
@@ -821,12 +827,11 @@ static inline void set_all_dma_rtail(struct hfi1_devdata *dd)
  * Called from interrupt handler for errors or receive interrupt.
  * This is the slow path interrupt handler.
  */
-void handle_receive_interrupt(struct hfi1_ctxtdata *rcd)
+int handle_receive_interrupt(struct hfi1_ctxtdata *rcd, int thread)
 {
-
 	struct hfi1_devdata *dd = rcd->dd;
 	u32 hdrqtail;
-	int last = 0, needset = 1;
+	int last = RCV_PKT_OK, needset = 1;
 	struct hfi1_packet packet;
 
 	init_packet(rcd, &packet);
@@ -834,19 +839,23 @@ void handle_receive_interrupt(struct hfi1_ctxtdata *rcd)
 	if (!HFI1_CAP_IS_KSET(DMA_RTAIL)) {
 		u32 seq = rhf_rcv_seq(packet.rhf);
 
-		if (seq != rcd->seq_cnt)
+		if (seq != rcd->seq_cnt) {
+			last = RCV_PKT_DONE;
 			goto bail;
+		}
 		hdrqtail = 0;
 	} else {
 		hdrqtail = get_rcvhdrtail(rcd);
-		if (packet.rhqoff == hdrqtail)
+		if (packet.rhqoff == hdrqtail) {
+			last = RCV_PKT_DONE;
 			goto bail;
+		}
 		smp_rmb();  /* prevent speculative reads of dma'ed hdrq */
 	}
 
 	prescan_rxq(&packet);
 
-	while (!last) {
+	while (last == RCV_PKT_OK) {
 
 		if (unlikely(dd->do_drop && atomic_xchg(&dd->drop_packet,
 			DROP_PACKET_OFF) == DROP_PACKET_ON)) {
@@ -860,7 +869,7 @@ void handle_receive_interrupt(struct hfi1_ctxtdata *rcd)
 			packet.rhf = rhf_to_cpu(packet.rhf_addr);
 
 		} else {
-			last = process_rcv_packet(&packet);
+			last = process_rcv_packet(&packet, thread);
 		}
 
 		if (!HFI1_CAP_IS_KSET(DMA_RTAIL)) {
@@ -869,7 +878,7 @@ void handle_receive_interrupt(struct hfi1_ctxtdata *rcd)
 			if (++rcd->seq_cnt > 13)
 				rcd->seq_cnt = 1;
 			if (seq != rcd->seq_cnt)
-				last = 1;
+				last = RCV_PKT_DONE;
 			if (needset) {
 				dd_dev_info(dd,
 					"Switching to NO_DMA_RTAIL\n");
@@ -878,7 +887,7 @@ void handle_receive_interrupt(struct hfi1_ctxtdata *rcd)
 			}
 		} else {
 			if (packet.rhqoff == hdrqtail)
-				last = 1;
+				last = RCV_PKT_DONE;
 			if (needset) {
 				dd_dev_info(dd,
 					    "Switching to DMA_RTAIL\n");
@@ -898,6 +907,7 @@ bail:
 	 * if no packets were processed.
 	 */
 	finish_packet(&packet);
+	return last;
 }
 
 /*