Eric Lee / smarc-ti-linux-kernel

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Commit f69ad292cfd13aa7ee00847320c6bb9ba2154e87

Authored by Eric Dumazet
Committed by David S. Miller
1 parent 5bbb432c89
Exists in smarct4x-processor-sdk-linux-03.00.00.04 and in 4 other branches dlt-processor-sdk-linux-03.00.00.04, smarct3x-processor-sdk-04.01.00.06, smarct3x-processor-sdk-linux-03.00.00.04, smarct4x-processor-sdk-04.01.00.06

tcp: fill shinfo->gso_size at last moment 

In commit cd7d8498c9a5 ("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>

Showing 3 changed files with 16 additions and 17 deletions Side-by-side Diff

... ... @@ -730,11 +730,14 @@
730 730 /* Note : tcp_tw_isn is used in input path only
731 731 * (isn chosen by tcp_timewait_state_process())
732 732 *
733   - * tcp_gso_segs is used in write queue only,
734   - * cf tcp_skb_pcount()
  733 + * tcp_gso_segs/size are used in write queue only,
  734 + * cf tcp_skb_pcount()/tcp_skb_mss()
735 735 */
736 736 __u32 tcp_tw_isn;
737   - __u32 tcp_gso_segs;
  737 + struct {
  738 + u16 tcp_gso_segs;
  739 + u16 tcp_gso_size;
  740 + };
738 741 };
739 742 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
740 743  
741 744  
... ... @@ -790,10 +793,10 @@
790 793 TCP_SKB_CB(skb)->tcp_gso_segs += segs;
791 794 }
792 795  
793   -/* This is valid iff tcp_skb_pcount() > 1. */
  796 +/* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */
794 797 static inline int tcp_skb_mss(const struct sk_buff *skb)
795 798 {
796   - return skb_shinfo(skb)->gso_size;
  799 + return TCP_SKB_CB(skb)->tcp_gso_size;
797 800 }
798 801  
799 802 /* Events passed to congestion control interface */
net/ipv4/tcp_input.c
Diff comments   View file @ f69ad29
... ... @@ -1316,12 +1316,12 @@
1316 1316 * code can come after this skb later on it's better to keep
1317 1317 * setting gso_size to something.
1318 1318 */
1319   - if (!skb_shinfo(prev)->gso_size)
1320   - skb_shinfo(prev)->gso_size = mss;
  1319 + if (!TCP_SKB_CB(prev)->tcp_gso_size)
  1320 + TCP_SKB_CB(prev)->tcp_gso_size = mss;
1321 1321  
1322 1322 /* CHECKME: To clear or not to clear? Mimics normal skb currently */
1323 1323 if (tcp_skb_pcount(skb) <= 1)
1324   - skb_shinfo(skb)->gso_size = 0;
  1324 + TCP_SKB_CB(skb)->tcp_gso_size = 0;
1325 1325  
1326 1326 /* Difference in this won't matter, both ACKed by the same cumul. ACK */
1327 1327 TCP_SKB_CB(prev)->sacked |= (TCP_SKB_CB(skb)->sacked & TCPCB_EVER_RETRANS);
... ... @@ -2248,7 +2248,7 @@
2248 2248 (oldcnt >= packets))
2249 2249 break;
2250 2250  
2251   - mss = skb_shinfo(skb)->gso_size;
  2251 + mss = tcp_skb_mss(skb);
2252 2252 err = tcp_fragment(sk, skb, (packets - oldcnt) * mss,
2253 2253 mss, GFP_ATOMIC);
2254 2254 if (err < 0)
net/ipv4/tcp_output.c
Diff comments   View file @ f69ad29
... ... @@ -402,8 +402,6 @@
402 402 */
403 403 static void tcp_init_nondata_skb(struct sk_buff *skb, u32 seq, u8 flags)
404 404 {
405   - struct skb_shared_info *shinfo = skb_shinfo(skb);
406   -
407 405 skb->ip_summed = CHECKSUM_PARTIAL;
408 406 skb->csum = 0;
409 407  
... ... @@ -411,7 +409,6 @@
411 409 TCP_SKB_CB(skb)->sacked = 0;
412 410  
413 411 tcp_skb_pcount_set(skb, 1);
414   - shinfo->gso_size = 0;
415 412  
416 413 TCP_SKB_CB(skb)->seq = seq;
417 414 if (flags & (TCPHDR_SYN | TCPHDR_FIN))
418 415  
... ... @@ -1028,8 +1025,9 @@
1028 1025 tcp_skb_pcount(skb));
1029 1026  
1030 1027 tp->segs_out += tcp_skb_pcount(skb);
1031   - /* OK, its time to fill skb_shinfo(skb)->gso_segs */
  1028 + /* OK, its time to fill skb_shinfo(skb)->gso_{segs|size} */
1032 1029 skb_shinfo(skb)->gso_segs = tcp_skb_pcount(skb);
  1030 + skb_shinfo(skb)->gso_size = tcp_skb_mss(skb);
1033 1031  
1034 1032 /* Our usage of tstamp should remain private */
1035 1033 skb->tstamp.tv64 = 0;
... ... @@ -1068,8 +1066,6 @@
1068 1066 /* Initialize TSO segments for a packet. */
1069 1067 static void tcp_set_skb_tso_segs(struct sk_buff *skb, unsigned int mss_now)
1070 1068 {
1071   - struct skb_shared_info *shinfo = skb_shinfo(skb);
1072   -
1073 1069 /* Make sure we own this skb before messing gso_size/gso_segs */
1074 1070 WARN_ON_ONCE(skb_cloned(skb));
1075 1071  
1076 1072  
... ... @@ -1078,10 +1074,10 @@
1078 1074 * non-TSO case.
1079 1075 */
1080 1076 tcp_skb_pcount_set(skb, 1);
1081   - shinfo->gso_size = 0;
  1077 + TCP_SKB_CB(skb)->tcp_gso_size = 0;
1082 1078 } else {
1083 1079 tcp_skb_pcount_set(skb, DIV_ROUND_UP(skb->len, mss_now));
1084   - shinfo->gso_size = mss_now;
  1080 + TCP_SKB_CB(skb)->tcp_gso_size = mss_now;
1085 1081 }
1086 1082 }
1087 1083