scsi: qla2xxx: edif: Reduce memory usage during low I/O

For edif, each I/O requires a secondary buffer to carry the FCP
cmnd. During high traffic time, these buffers are cached in the qpair. As
traffic dies down, these buffers will be trimmed as needed. If traffic is
reduced to none over 2 consecutive intervals, then these buffers will be
further trimmed.

Free FCP cmnd buffers to reduce memory usage during slow I/O time.

Signed-off-by: Quinn Tran <qutran@marvell.com>
Signed-off-by: Nilesh Javali <njavali@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/qla2xxx/qla_def.h

@@ -3735,7 +3735,10 @@ struct  qla_buf_pool {
 	u16 num_bufs;
 	u16 num_active;
 	u16 max_used;
-	u16 reserved;
+	u16 num_alloc;
+	u16 prev_max;
+	u16 pad;
+	uint32_t take_snapshot:1;
 	unsigned long *buf_map;
 	void **buf_array;
 	dma_addr_t *dma_array;
@@ -4874,6 +4877,7 @@ typedef struct scsi_qla_host {
 #define LOOP_READY	5
 #define LOOP_DEAD	6
 
+	unsigned long   buf_expired;
 	unsigned long   relogin_jif;
 	unsigned long   dpc_flags;
 #define RESET_MARKER_NEEDED	0	/* Send marker to ISP. */

drivers/scsi/qla2xxx/qla_gbl.h

@@ -293,6 +293,7 @@ extern void qla2x00_alert_all_vps(struct rsp_que *, uint16_t *);
 extern void qla2x00_async_event(scsi_qla_host_t *, struct rsp_que *,
 	uint16_t *);
 extern int  qla2x00_vp_abort_isp(scsi_qla_host_t *);
+void qla_adjust_buf(struct scsi_qla_host *);
 
 /*
  * Global Function Prototypes in qla_iocb.c source file.

drivers/scsi/qla2xxx/qla_mid.c

@@ -1170,6 +1170,7 @@ again:
 
 		dsc->buf = qp->buf_pool.buf_array[tag] = buf;
 		dsc->buf_dma = qp->buf_pool.dma_array[tag] = buf_dma;
+		qp->buf_pool.num_alloc++;
 	} else {
 		dsc->buf = qp->buf_pool.buf_array[tag];
 		dsc->buf_dma = qp->buf_pool.dma_array[tag];
@@ -1185,14 +1186,107 @@ again:
 	return 0;
 }
 
+void qla_trim_buf(struct qla_qpair *qp, u16 trim)
+{
+	int i, j;
+	struct qla_hw_data *ha = qp->vha->hw;
+
+	if (!trim)
+		return;
+
+	for (i = 0; i < trim; i++) {
+		j = qp->buf_pool.num_alloc - 1;
+		if (test_bit(j, qp->buf_pool.buf_map)) {
+			ql_dbg(ql_dbg_io + ql_dbg_verbose, qp->vha, 0x300b,
+			       "QP id(%d): trim active buf[%d]. Remain %d bufs\n",
+			       qp->id, j, qp->buf_pool.num_alloc);
+			return;
+		}
+
+		if (qp->buf_pool.buf_array[j]) {
+			dma_pool_free(ha->fcp_cmnd_dma_pool, qp->buf_pool.buf_array[j],
+				      qp->buf_pool.dma_array[j]);
+			qp->buf_pool.buf_array[j] = NULL;
+			qp->buf_pool.dma_array[j] = 0;
+		}
+		qp->buf_pool.num_alloc--;
+		if (!qp->buf_pool.num_alloc)
+			break;
+	}
+	ql_dbg(ql_dbg_io + ql_dbg_verbose, qp->vha, 0x3010,
+	       "QP id(%d): trimmed %d bufs. Remain %d bufs\n",
+	       qp->id, trim, qp->buf_pool.num_alloc);
+}
+
+void __qla_adjust_buf(struct qla_qpair *qp)
+{
+	u32 trim;
+
+	qp->buf_pool.take_snapshot = 0;
+	qp->buf_pool.prev_max = qp->buf_pool.max_used;
+	qp->buf_pool.max_used = qp->buf_pool.num_active;
+
+	if (qp->buf_pool.prev_max > qp->buf_pool.max_used &&
+	    qp->buf_pool.num_alloc > qp->buf_pool.max_used) {
+		/* down trend */
+		trim = qp->buf_pool.num_alloc - qp->buf_pool.max_used;
+		trim  = (trim * 10) / 100;
+		trim = trim ? trim : 1;
+		qla_trim_buf(qp, trim);
+	} else if (!qp->buf_pool.prev_max  && !qp->buf_pool.max_used) {
+		/* 2 periods of no io */
+		qla_trim_buf(qp, qp->buf_pool.num_alloc);
+	}
+}
 
 /* it is assume qp->qp_lock is held at this point */
 void qla_put_buf(struct qla_qpair *qp, struct qla_buf_dsc *dsc)
 {
 	if (dsc->tag == TAG_FREED)
 		return;
+	lockdep_assert_held(qp->qp_lock_ptr);
 
 	clear_bit(dsc->tag, qp->buf_pool.buf_map);
 	qp->buf_pool.num_active--;
 	dsc->tag = TAG_FREED;
+
+	if (qp->buf_pool.take_snapshot)
+		__qla_adjust_buf(qp);
+}
+
+#define EXPIRE (60 * HZ)
+void qla_adjust_buf(struct scsi_qla_host *vha)
+{
+	unsigned long flags;
+	int i;
+	struct qla_qpair *qp;
+
+	if (vha->vp_idx)
+		return;
+
+	if (!vha->buf_expired) {
+		vha->buf_expired = jiffies + EXPIRE;
+		return;
+	}
+	if (time_before(jiffies, vha->buf_expired))
+		return;
+
+	vha->buf_expired = jiffies + EXPIRE;
+
+	for (i = 0; i < vha->hw->num_qpairs; i++) {
+		qp = vha->hw->queue_pair_map[i];
+		if (!qp)
+			continue;
+		if (!qp->buf_pool.num_alloc)
+			continue;
+
+		if (qp->buf_pool.take_snapshot) {
+			/* no io has gone through in the last EXPIRE period */
+			spin_lock_irqsave(qp->qp_lock_ptr, flags);
+			__qla_adjust_buf(qp);
+			spin_unlock_irqrestore(qp->qp_lock_ptr, flags);
+		} else {
+			qp->buf_pool.take_snapshot = 1;
+		}
+	}
 }

drivers/scsi/qla2xxx/qla_os.c

@@ -7522,6 +7522,7 @@ qla2x00_timer(struct timer_list *t)
 		set_bit(SET_ZIO_THRESHOLD_NEEDED, &vha->dpc_flags);
 		start_dpc++;
 	}
+	qla_adjust_buf(vha);
 
 	/* borrowing w to signify dpc will run */
 	w = 0;