* [PATCH net-next] tcp: use tcp_flags in tcp_data_queue() @ 2014-09-24 10:35 Weiping Pan 2014-09-24 10:54 ` Eric Dumazet 0 siblings, 1 reply; 7+ messages in thread From: Weiping Pan @ 2014-09-24 10:35 UTC (permalink / raw) To: netdev; +Cc: edumazet Follow the idea in commit e11ecddf5128 (tcp: use TCP_SKB_CB(skb)->tcp_flags in input path), we can use tcp_flags to avoid cache miss. Signed-off-by: Weiping Pan <panweiping3@gmail.com> --- net/ipv4/tcp_input.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 13f3da4..85298c9 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4392,7 +4392,7 @@ queue_and_out: tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq; if (skb->len) tcp_event_data_recv(sk, skb); - if (th->fin) + if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) tcp_fin(sk); if (!skb_queue_empty(&tp->out_of_order_queue)) { -- 1.7.4 ^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH net-next] tcp: use tcp_flags in tcp_data_queue() 2014-09-24 10:35 [PATCH net-next] tcp: use tcp_flags in tcp_data_queue() Weiping Pan @ 2014-09-24 10:54 ` Eric Dumazet 2014-09-24 12:42 ` [PATCH net-next v2] " Weiping Pan 0 siblings, 1 reply; 7+ messages in thread From: Eric Dumazet @ 2014-09-24 10:54 UTC (permalink / raw) To: Weiping Pan; +Cc: netdev, edumazet On Wed, 2014-09-24 at 18:35 +0800, Weiping Pan wrote: > Follow the idea in commit e11ecddf5128 (tcp: use TCP_SKB_CB(skb)->tcp_flags in > input path), we can use tcp_flags to avoid cache miss. > > Signed-off-by: Weiping Pan <panweiping3@gmail.com> > --- > net/ipv4/tcp_input.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c > index 13f3da4..85298c9 100644 > --- a/net/ipv4/tcp_input.c > +++ b/net/ipv4/tcp_input.c > @@ -4392,7 +4392,7 @@ queue_and_out: > tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq; > if (skb->len) > tcp_event_data_recv(sk, skb); > - if (th->fin) > + if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) > tcp_fin(sk); > > if (!skb_queue_empty(&tp->out_of_order_queue)) { I thought of this, but my reasoning was that we needed th anyway, and th->fin had the same cost. But thinking more about this, its possible compiler can generate better code, as tcp_hdr() will only be needed at the very beginning of the function, and compiler no longer has to keep around th value. Could you go one step further maybe ? diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index f3f016a15c5a..1a399737802b 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4344,7 +4344,6 @@ err: static void tcp_data_queue(struct sock *sk, struct sk_buff *skb) { - const struct tcphdr *th = tcp_hdr(skb); struct tcp_sock *tp = tcp_sk(sk); int eaten = -1; bool fragstolen = false; @@ -4353,7 +4352,7 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb) goto drop; skb_dst_drop(skb); - __skb_pull(skb, th->doff * 4); + __skb_pull(skb, tcp_hdr(skb)->doff * 4); TCP_ECN_accept_cwr(tp, skb); @@ -4397,7 +4396,7 @@ queue_and_out: tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq; if (skb->len) tcp_event_data_recv(sk, skb); - if (th->fin) + if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) tcp_fin(sk); if (!skb_queue_empty(&tp->out_of_order_queue)) { ^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH net-next v2] tcp: use tcp_flags in tcp_data_queue() 2014-09-24 10:54 ` Eric Dumazet @ 2014-09-24 12:42 ` Weiping Pan 2014-09-24 13:22 ` Eric Dumazet 0 siblings, 1 reply; 7+ messages in thread From: Weiping Pan @ 2014-09-24 12:42 UTC (permalink / raw) To: netdev; +Cc: edumazet Follow the idea in commit e11ecddf5128 (tcp: use TCP_SKB_CB(skb)->tcp_flags in input path), we can use tcp_flags to avoid cache miss. v2: remove variable th Signed-off-by: Weiping Pan <panweiping3@gmail.com> --- net/ipv4/tcp_input.c | 5 ++--- 1 files changed, 2 insertions(+), 3 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 13f3da4..a51663f 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4339,7 +4339,6 @@ err: static void tcp_data_queue(struct sock *sk, struct sk_buff *skb) { - const struct tcphdr *th = tcp_hdr(skb); struct tcp_sock *tp = tcp_sk(sk); int eaten = -1; bool fragstolen = false; @@ -4348,7 +4347,7 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb) goto drop; skb_dst_drop(skb); - __skb_pull(skb, th->doff * 4); + __skb_pull(skb, tcp_hdr(skb)->doff * 4); TCP_ECN_accept_cwr(tp, skb); @@ -4392,7 +4391,7 @@ queue_and_out: tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq; if (skb->len) tcp_event_data_recv(sk, skb); - if (th->fin) + if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) tcp_fin(sk); if (!skb_queue_empty(&tp->out_of_order_queue)) { -- 1.7.4 ^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH net-next v2] tcp: use tcp_flags in tcp_data_queue() 2014-09-24 12:42 ` [PATCH net-next v2] " Weiping Pan @ 2014-09-24 13:22 ` Eric Dumazet 2014-09-24 14:17 ` [PATCH net-next v3] " Weiping Pan 0 siblings, 1 reply; 7+ messages in thread From: Eric Dumazet @ 2014-09-24 13:22 UTC (permalink / raw) To: Weiping Pan; +Cc: netdev, edumazet On Wed, 2014-09-24 at 20:42 +0800, Weiping Pan wrote: > Follow the idea in commit e11ecddf5128 (tcp: use TCP_SKB_CB(skb)->tcp_flags in > input path), we can use tcp_flags to avoid cache miss. > Well, there is no cache miss here. Lets try to have precise changelogs. We access tcp_hdr(skb)->doff right before, so the tcp header is in cpu cache. So this patch is a cleanup and a way to help compiler to reduce register pressure since skb->cb[] access is fast (skb is probably in a register) Thanks. ^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH net-next v3] tcp: use tcp_flags in tcp_data_queue() 2014-09-24 13:22 ` Eric Dumazet @ 2014-09-24 14:17 ` Weiping Pan 2014-09-26 12:38 ` Eric Dumazet 2014-09-28 20:38 ` David Miller 0 siblings, 2 replies; 7+ messages in thread From: Weiping Pan @ 2014-09-24 14:17 UTC (permalink / raw) To: netdev; +Cc: edumazet This patch is a cleanup which follows the idea in commit e11ecddf5128 (tcp: use TCP_SKB_CB(skb)->tcp_flags in input path), and it may reduce register pressure since skb->cb[] access is fast, bacause skb is probably in a register. v2: remove variable th v3: reword the changelog Signed-off-by: Weiping Pan <panweiping3@gmail.com> --- net/ipv4/tcp_input.c | 5 ++--- 1 files changed, 2 insertions(+), 3 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 13f3da4..a51663f 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4339,7 +4339,6 @@ err: static void tcp_data_queue(struct sock *sk, struct sk_buff *skb) { - const struct tcphdr *th = tcp_hdr(skb); struct tcp_sock *tp = tcp_sk(sk); int eaten = -1; bool fragstolen = false; @@ -4348,7 +4347,7 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb) goto drop; skb_dst_drop(skb); - __skb_pull(skb, th->doff * 4); + __skb_pull(skb, tcp_hdr(skb)->doff * 4); TCP_ECN_accept_cwr(tp, skb); @@ -4392,7 +4391,7 @@ queue_and_out: tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq; if (skb->len) tcp_event_data_recv(sk, skb); - if (th->fin) + if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN) tcp_fin(sk); if (!skb_queue_empty(&tp->out_of_order_queue)) { -- 1.7.4 ^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH net-next v3] tcp: use tcp_flags in tcp_data_queue() 2014-09-24 14:17 ` [PATCH net-next v3] " Weiping Pan @ 2014-09-26 12:38 ` Eric Dumazet 2014-09-28 20:38 ` David Miller 1 sibling, 0 replies; 7+ messages in thread From: Eric Dumazet @ 2014-09-26 12:38 UTC (permalink / raw) To: Weiping Pan; +Cc: netdev, edumazet On Wed, 2014-09-24 at 22:17 +0800, Weiping Pan wrote: > This patch is a cleanup which follows the idea in commit e11ecddf5128 (tcp: use > TCP_SKB_CB(skb)->tcp_flags in input path), > and it may reduce register pressure since skb->cb[] access is fast, > bacause skb is probably in a register. > > v2: remove variable th > v3: reword the changelog > > Signed-off-by: Weiping Pan <panweiping3@gmail.com> > --- Acked-by: Eric Dumazet <edumazet@google.com> ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH net-next v3] tcp: use tcp_flags in tcp_data_queue() 2014-09-24 14:17 ` [PATCH net-next v3] " Weiping Pan 2014-09-26 12:38 ` Eric Dumazet @ 2014-09-28 20:38 ` David Miller 1 sibling, 0 replies; 7+ messages in thread From: David Miller @ 2014-09-28 20:38 UTC (permalink / raw) To: panweiping3; +Cc: netdev, edumazet From: Weiping Pan <panweiping3@gmail.com> Date: Wed, 24 Sep 2014 22:17:02 +0800 > This patch is a cleanup which follows the idea in commit e11ecddf5128 (tcp: use > TCP_SKB_CB(skb)->tcp_flags in input path), > and it may reduce register pressure since skb->cb[] access is fast, > bacause skb is probably in a register. > > v2: remove variable th > v3: reword the changelog > > Signed-off-by: Weiping Pan <panweiping3@gmail.com> Applied, thanks. ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2014-09-28 20:38 UTC | newest] Thread overview: 7+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2014-09-24 10:35 [PATCH net-next] tcp: use tcp_flags in tcp_data_queue() Weiping Pan 2014-09-24 10:54 ` Eric Dumazet 2014-09-24 12:42 ` [PATCH net-next v2] " Weiping Pan 2014-09-24 13:22 ` Eric Dumazet 2014-09-24 14:17 ` [PATCH net-next v3] " Weiping Pan 2014-09-26 12:38 ` Eric Dumazet 2014-09-28 20:38 ` David Miller
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