Commit 97085cda authored by Brett Creeley's avatar Brett Creeley Committed by David S. Miller
Browse files

ionic: Shorten a Tx hotpath 



Perf was showing some hot spots in ionic_tx_descs_needed()
for TSO traffic.  Rework the function to return sooner where
possible.

Signed-off-by: default avatarBrett Creeley <brett.creeley@amd.com>
Signed-off-by: default avatarShannon Nelson <shannon.nelson@amd.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 4d140402

drivers/net/ethernet/pensando/ionic/ionic_txrx.c

+10 −5
Original line number Diff line number Diff line
@@ -1669,7 +1669,7 @@ static int ionic_tx(struct ionic_queue *q, struct sk_buff *skb) 


static int ionic_tx_descs_needed(struct ionic_queue *q, struct sk_buff *skb)

{

	struct ionic_tx_stats *stats = q_to_tx_stats(q);

	int nr_frags = skb_shinfo(skb)->nr_frags;

	bool too_many_frags = false;

	skb_frag_t *frag;

	int desc_bufs;
@@ -1685,17 +1685,20 @@ static int ionic_tx_descs_needed(struct ionic_queue *q, struct sk_buff *skb) 
	/* Each desc is mss long max, so a descriptor for each gso_seg */

	if (skb_is_gso(skb)) {

		ndescs = skb_shinfo(skb)->gso_segs;

		if (!nr_frags)

			return ndescs;

	} else {

		ndescs = 1;

		if (skb_shinfo(skb)->nr_frags > q->max_sg_elems) {

		if (!nr_frags)

			return ndescs;



		if (unlikely(nr_frags > q->max_sg_elems)) {

			too_many_frags = true;

			goto linearize;

		}

	}



	/* If non-TSO, or no frags to check, we're done */

	if (!skb_is_gso(skb) || !skb_shinfo(skb)->nr_frags)

		return ndescs;

	}



	/* We need to scan the skb to be sure that none of the MTU sized

	 * packets in the TSO will require more sgs per descriptor than we
@@ -1743,6 +1746,8 @@ static int ionic_tx_descs_needed(struct ionic_queue *q, struct sk_buff *skb) 


linearize:

	if (too_many_frags) {

		struct ionic_tx_stats *stats = q_to_tx_stats(q);



		err = skb_linearize(skb);

		if (err)

			return err;