net/rds: Use DMA memory pool allocation for rds_header

Currently, RDS calls ib_dma_alloc_coherent() to allocate a large piece
of contiguous DMA coherent memory to store struct rds_header for
sending/receiving packets.  The memory allocated is then partitioned
into struct rds_header.  This is not necessary and can be costly at
times when memory is fragmented.  Instead, RDS should use the DMA
memory pool interface to handle this.  The DMA addresses of the pre-
allocated headers are stored in an array.  At send/receive ring
initialization and refill time, this arrary is de-referenced to get
the DMA addresses.  This array is not accessed at send/receive packet
processing.

Suggested-by: Håkon Bugge <haakon.bugge@oracle.com>
Signed-off-by: Ka-Cheong Poon <ka-cheong.poon@oracle.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 6 deletions

diff --git a/net/rds/ib_send.c b/net/rds/ib_send.c
index 102c5c535977..d1cc1d7778d8 100644
--- a/net/rds/ib_send.c
+++ b/net/rds/ib_send.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2006, 2017 Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2006, 2019 Oracle and/or its affiliates. All rights reserved.
  *
  * This software is available to you under a choice of one of two
  * licenses.  You may choose to be licensed under the terms of the GNU
@@ -201,7 +201,8 @@ void rds_ib_send_init_ring(struct rds_ib_connection *ic)
 		send->s_wr.ex.imm_data = 0;
 
 		sge = &send->s_sge[0];
-		sge->addr = ic->i_send_hdrs_dma + (i * sizeof(struct rds_header));
+		sge->addr = ic->i_send_hdrs_dma[i];
+
 		sge->length = sizeof(struct rds_header);
 		sge->lkey = ic->i_pd->local_dma_lkey;
 
@@ -631,11 +632,13 @@ int rds_ib_xmit(struct rds_connection *conn, struct rds_message *rm,
 		send->s_queued = jiffies;
 		send->s_op = NULL;
 
-		send->s_sge[0].addr = ic->i_send_hdrs_dma
-			+ (pos * sizeof(struct rds_header));
+		send->s_sge[0].addr = ic->i_send_hdrs_dma[pos];
+
 		send->s_sge[0].length = sizeof(struct rds_header);
 
-		memcpy(&ic->i_send_hdrs[pos], &rm->m_inc.i_hdr, sizeof(struct rds_header));
+		memcpy(ic->i_send_hdrs[pos], &rm->m_inc.i_hdr,
+		       sizeof(struct rds_header));
+
 
 		/* Set up the data, if present */
 		if (i < work_alloc
@@ -674,7 +677,7 @@ int rds_ib_xmit(struct rds_connection *conn, struct rds_message *rm,
 			 &send->s_wr, send->s_wr.num_sge, send->s_wr.next);
 
 		if (ic->i_flowctl && adv_credits) {
-			struct rds_header *hdr = &ic->i_send_hdrs[pos];
+			struct rds_header *hdr = ic->i_send_hdrs[pos];
 
 			/* add credit and redo the header checksum */
 			hdr->h_credit = adv_credits;