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Commit 1d2024f6 authored by Alexander Duyck's avatar Alexander Duyck Committed by Jeff Kirsher
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ixgbe: Address fact that RSC was not setting GSO size for incoming frames 



This patch is meant to address the fact that RSC has not been setting the
gso_size value on the skb.  As a result performance on lossy TCP
connections was negatively impacted.  This change resolves the issue by
setting gso_size to the average size for incoming packets.

Signed-off-by: default avatarAlexander Duyck <alexander.h.duyck@intel.com>
Tested-by: default avatarStephen Ko <stephen.s.ko@intel.com>
Signed-off-by: default avatarJeff Kirsher <jeffrey.t.kirsher@intel.com>
parent 4c1975d7

drivers/net/ethernet/intel/ixgbe/ixgbe_main.c

+125 −5
Original line number Diff line number Diff line
@@ -1276,6 +1276,104 @@ static inline bool ixgbe_close_active_frag_list(struct sk_buff *head) 
	return true;

}



/**

 * ixgbe_get_headlen - determine size of header for RSC/LRO/GRO/FCOE

 * @data: pointer to the start of the headers

 * @max_len: total length of section to find headers in

 *

 * This function is meant to determine the length of headers that will

 * be recognized by hardware for LRO, GRO, and RSC offloads.  The main

 * motivation of doing this is to only perform one pull for IPv4 TCP

 * packets so that we can do basic things like calculating the gso_size

 * based on the average data per packet.

 **/

static unsigned int ixgbe_get_headlen(unsigned char *data,

				      unsigned int max_len)

{

	union {

		unsigned char *network;

		/* l2 headers */

		struct ethhdr *eth;

		struct vlan_hdr *vlan;

		/* l3 headers */

		struct iphdr *ipv4;

	} hdr;

	__be16 protocol;

	u8 nexthdr = 0;	/* default to not TCP */

	u8 hlen;



	/* this should never happen, but better safe than sorry */

	if (max_len < ETH_HLEN)

		return max_len;



	/* initialize network frame pointer */

	hdr.network = data;



	/* set first protocol and move network header forward */

	protocol = hdr.eth->h_proto;

	hdr.network += ETH_HLEN;



	/* handle any vlan tag if present */

	if (protocol == __constant_htons(ETH_P_8021Q)) {

		if ((hdr.network - data) > (max_len - VLAN_HLEN))

			return max_len;



		protocol = hdr.vlan->h_vlan_encapsulated_proto;

		hdr.network += VLAN_HLEN;

	}



	/* handle L3 protocols */

	if (protocol == __constant_htons(ETH_P_IP)) {

		if ((hdr.network - data) > (max_len - sizeof(struct iphdr)))

			return max_len;



		/* access ihl as a u8 to avoid unaligned access on ia64 */

		hlen = (hdr.network[0] & 0x0F) << 2;



		/* verify hlen meets minimum size requirements */

		if (hlen < sizeof(struct iphdr))

			return hdr.network - data;



		/* record next protocol */

		nexthdr = hdr.ipv4->protocol;

		hdr.network += hlen;

#ifdef CONFIG_FCOE

	} else if (protocol == __constant_htons(ETH_P_FCOE)) {

		if ((hdr.network - data) > (max_len - FCOE_HEADER_LEN))

			return max_len;

		hdr.network += FCOE_HEADER_LEN;

#endif

	} else {

		return hdr.network - data;

	}



	/* finally sort out TCP */

	if (nexthdr == IPPROTO_TCP) {

		if ((hdr.network - data) > (max_len - sizeof(struct tcphdr)))

			return max_len;



		/* access doff as a u8 to avoid unaligned access on ia64 */

		hlen = (hdr.network[12] & 0xF0) >> 2;



		/* verify hlen meets minimum size requirements */

		if (hlen < sizeof(struct tcphdr))

			return hdr.network - data;



		hdr.network += hlen;

	}



	/*

	 * If everything has gone correctly hdr.network should be the

	 * data section of the packet and will be the end of the header.

	 * If not then it probably represents the end of the last recognized

	 * header.

	 */

	if ((hdr.network - data) < max_len)

		return hdr.network - data;

	else

		return max_len;

}



static void ixgbe_get_rsc_cnt(struct ixgbe_ring *rx_ring,

			      union ixgbe_adv_rx_desc *rx_desc,

			      struct sk_buff *skb)
@@ -1299,6 +1397,32 @@ static void ixgbe_get_rsc_cnt(struct ixgbe_ring *rx_ring, 
	IXGBE_CB(skb)->append_cnt += rsc_cnt - 1;

}



static void ixgbe_set_rsc_gso_size(struct ixgbe_ring *ring,

				   struct sk_buff *skb)

{

	u16 hdr_len = ixgbe_get_headlen(skb->data, skb_headlen(skb));



	/* set gso_size to avoid messing up TCP MSS */

	skb_shinfo(skb)->gso_size = DIV_ROUND_UP((skb->len - hdr_len),

						 IXGBE_CB(skb)->append_cnt);

}



static void ixgbe_update_rsc_stats(struct ixgbe_ring *rx_ring,

				   struct sk_buff *skb)

{

	/* if append_cnt is 0 then frame is not RSC */

	if (!IXGBE_CB(skb)->append_cnt)

		return;



	rx_ring->rx_stats.rsc_count += IXGBE_CB(skb)->append_cnt;

	rx_ring->rx_stats.rsc_flush++;



	ixgbe_set_rsc_gso_size(rx_ring, skb);



	/* gso_size is computed using append_cnt so always clear it last */

	IXGBE_CB(skb)->append_cnt = 0;

}



static bool ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector,

			       struct ixgbe_ring *rx_ring,

			       int budget)
@@ -1437,11 +1561,7 @@ static bool ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector, 
			goto next_desc;

		}



		if (IXGBE_CB(skb)->append_cnt) {

			rx_ring->rx_stats.rsc_count +=

					IXGBE_CB(skb)->append_cnt;

			rx_ring->rx_stats.rsc_flush++;

		}

		ixgbe_update_rsc_stats(rx_ring, skb);



		/* ERR_MASK will only have valid bits if EOP set */

		if (unlikely(staterr & IXGBE_RXDADV_ERR_FRAME_ERR_MASK)) {