diff options
| author | Eric Dumazet <dada1@cosmosbay.com> | 2007-02-22 03:20:44 -0800 |
|---|---|---|
| committer | David S. Miller <davem@sunset.davemloft.net> | 2007-04-25 22:23:21 -0700 |
| commit | 54287cc178cf85dbae0decec8b4dc190bff757ad (patch) | |
| tree | 44dedf7be5ac37fae65718d359ff598902247753 | |
| parent | cf4c6bf83d0fa070f60b1ba8124dfe0e65fbfbcc (diff) | |
| download | linux-54287cc178cf85dbae0decec8b4dc190bff757ad.tar.bz2 | |
[TCP]: Keep copied_seq, rcv_wup and rcv_next together.
I noticed in oprofile study a cache miss in tcp_rcv_established() to read
copied_seq.
ffffffff80400a80 <tcp_rcv_established>: /* tcp_rcv_established total: 4034293
2.0400 */
55493 0.0281 :ffffffff80400bc9: mov 0x4c8(%r12),%eax copied_seq
543103 0.2746 :ffffffff80400bd1: cmp 0x3e0(%r12),%eax rcv_nxt
if (tp->copied_seq == tp->rcv_nxt &&
len - tcp_header_len <= tp->ucopy.len) {
In this function, the cache line 0x4c0 -> 0x500 is used only for this
reading 'copied_seq' field.
rcv_wup and copied_seq should be next to rcv_nxt field, to lower number of
active cache lines in hot paths. (tcp_rcv_established(), tcp_poll(), ...)
As you suggested, I changed tcp_create_openreq_child() so that these fields
are changed together, to avoid adding a new store buffer stall.
Patch is 64bit friendly (no new hole because of alignment constraints)
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | include/linux/tcp.h | 4 | ||||
| -rw-r--r-- | net/ipv4/tcp_minisocks.c | 6 |
2 files changed, 4 insertions, 6 deletions
diff --git a/include/linux/tcp.h b/include/linux/tcp.h index 29d3089038ab..415193e171e4 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -242,6 +242,8 @@ struct tcp_sock { * See RFC793 and RFC1122. The RFC writes these in capitals. */ u32 rcv_nxt; /* What we want to receive next */ + u32 copied_seq; /* Head of yet unread data */ + u32 rcv_wup; /* rcv_nxt on last window update sent */ u32 snd_nxt; /* Next sequence we send */ u32 snd_una; /* First byte we want an ack for */ @@ -307,10 +309,8 @@ struct tcp_sock { struct sk_buff_head out_of_order_queue; /* Out of order segments go here */ u32 rcv_wnd; /* Current receiver window */ - u32 rcv_wup; /* rcv_nxt on last window update sent */ u32 write_seq; /* Tail(+1) of data held in tcp send buffer */ u32 pushed_seq; /* Last pushed seq, required to talk to windows */ - u32 copied_seq; /* Head of yet unread data */ /* SACKs data */ struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */ diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c index 6b5c64f3c925..706932726a11 100644 --- a/net/ipv4/tcp_minisocks.c +++ b/net/ipv4/tcp_minisocks.c @@ -387,8 +387,8 @@ struct sock *tcp_create_openreq_child(struct sock *sk, struct request_sock *req, /* Now setup tcp_sock */ newtp = tcp_sk(newsk); newtp->pred_flags = 0; - newtp->rcv_nxt = treq->rcv_isn + 1; - newtp->snd_nxt = newtp->snd_una = newtp->snd_sml = treq->snt_isn + 1; + newtp->rcv_wup = newtp->copied_seq = newtp->rcv_nxt = treq->rcv_isn + 1; + newtp->snd_sml = newtp->snd_una = newtp->snd_nxt = treq->snt_isn + 1; tcp_prequeue_init(newtp); @@ -422,10 +422,8 @@ struct sock *tcp_create_openreq_child(struct sock *sk, struct request_sock *req, tcp_set_ca_state(newsk, TCP_CA_Open); tcp_init_xmit_timers(newsk); skb_queue_head_init(&newtp->out_of_order_queue); - newtp->rcv_wup = treq->rcv_isn + 1; newtp->write_seq = treq->snt_isn + 1; newtp->pushed_seq = newtp->write_seq; - newtp->copied_seq = treq->rcv_isn + 1; newtp->rx_opt.saw_tstamp = 0; |