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tcp: fill shinfo->gso_size at last moment

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In commit cd7d8498c9 ("tcp: change tcp_skb_pcount() location") we stored
gso_segs in a temporary cache hot location.

This patch does the same for gso_size.

This allows to save 2 cache line misses in tcp xmit path for
the last packet that is considered but not sent because of
various conditions (cwnd, tso defer, receiver window, TSQ...)

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2015-06-11 09:15:18 -07:00
committed by David S. Miller
parent 5bbb432c89
commit f69ad292cf
3 changed files with 16 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
net/ipv4/tcp_output.c
View File

@@ -402,8 +402,6 @@ static void tcp_ecn_send(struct sock *sk, struct sk_buff *skb,
*/
static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags)
{
struct skb_shared_info *shinfo = skb_shinfo(skb);
skb->ip_summed = CHECKSUM_PARTIAL;
skb->csum = 0;
@@ -411,7 +409,6 @@ static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags)
TCP_SKB_CB(skb)->sacked = 0;
tcp_skb_pcount_set(skb, 1);
shinfo->gso_size = 0;
TCP_SKB_CB(skb)->seq = seq;
if (flags & (TCPHDR_SYN | TCPHDR_FIN))
@@ -1028,8 +1025,9 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it,
tcp_skb_pcount(skb));
tp->segs_out += tcp_skb_pcount(skb);
/* OK, its time to fill skb_shinfo(skb)->gso_segs */
/* OK, its time to fill skb_shinfo(skb)->gso_{segs|size} */
skb_shinfo(skb)->gso_segs = tcp_skb_pcount(skb);
skb_shinfo(skb)->gso_size = tcp_skb_mss(skb);
/* Our usage of tstamp should remain private */
skb->tstamp.tv64 = 0;
@@ -1068,8 +1066,6 @@ static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb)
/* Initialize TSO segments for a packet. */
static void tcp_set_skb_tso_segs(struct sk_buff *skb, unsigned int mss_now)
{
struct skb_shared_info *shinfo = skb_shinfo(skb);
/* Make sure we own this skb before messing gso_size/gso_segs */
WARN_ON_ONCE(skb_cloned(skb));
@@ -1078,10 +1074,10 @@ static void tcp_set_skb_tso_segs(struct sk_buff *skb, unsigned int mss_now)
* non-TSO case.
*/
tcp_skb_pcount_set(skb, 1);
shinfo->gso_size = 0;
TCP_SKB_CB(skb)->tcp_gso_size = 0;
} else {
tcp_skb_pcount_set(skb, DIV_ROUND_UP(skb->len, mss_now));
shinfo->gso_size = mss_now;
TCP_SKB_CB(skb)->tcp_gso_size = mss_now;
}
}