| Message ID | 1541589617-1607-2-git-send-email-laoar.shao@gmail.com |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
| Series | [net-next] tcp: minor optimization in tcp ack fast path processing | expand |
On 11/07/2018 03:20 AM, Yafang Shao wrote: > Bitwise operation is a little faster. > So I replace after() with (flag & FLAG_SND_UNA_ADVANCED) as this flag is > already set before. > > Cc: Joe Perches <joe@perches.com> > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > --- > net/ipv4/tcp_input.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c > index 2868ef2..0167015 100644 > --- a/net/ipv4/tcp_input.c > +++ b/net/ipv4/tcp_input.c > @@ -3610,7 +3610,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) > if (flag & FLAG_UPDATE_TS_RECENT) > tcp_replace_ts_recent(tp, TCP_SKB_CB(skb)->seq); > > - if (!(flag & FLAG_SLOWPATH) && after(ack, prior_snd_una)) { > + if (!(flag & FLAG_SLOWPATH) && (flag & FLAG_SND_UNA_ADVANCED)) { > /* Window is constant, pure forward advance. > * No more checks are required. > * Note, we use the fact that SND.UNA>=SND.WL2. > What about reducing this to a single conditional jump ? if ((flag & (FLAG_SLOWPATH | FLAG_SND_UNA_ADVANCED)) == FLAG_SND_UNA_ADVANCED) {
On Wed, Nov 7, 2018 at 11:16 PM Eric Dumazet <eric.dumazet@gmail.com> wrote: > > > > On 11/07/2018 03:20 AM, Yafang Shao wrote: > > Bitwise operation is a little faster. > > > > So I replace after() with (flag & FLAG_SND_UNA_ADVANCED) as this flag is > > already set before. > > > > Cc: Joe Perches <joe@perches.com> > > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > > --- > > net/ipv4/tcp_input.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c > > index 2868ef2..0167015 100644 > > --- a/net/ipv4/tcp_input.c > > +++ b/net/ipv4/tcp_input.c > > @@ -3610,7 +3610,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) > > if (flag & FLAG_UPDATE_TS_RECENT) > > tcp_replace_ts_recent(tp, TCP_SKB_CB(skb)->seq); > > > > - if (!(flag & FLAG_SLOWPATH) && after(ack, prior_snd_una)) { > > + if (!(flag & FLAG_SLOWPATH) && (flag & FLAG_SND_UNA_ADVANCED)) { > > /* Window is constant, pure forward advance. > > * No more checks are required. > > * Note, we use the fact that SND.UNA>=SND.WL2. > > > > What about reducing this to a single conditional jump ? > > if ((flag & (FLAG_SLOWPATH | FLAG_SND_UNA_ADVANCED)) == FLAG_SND_UNA_ADVANCED) { > That's better. Will change it. Thanks Yafang
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 2868ef2..0167015 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -3610,7 +3610,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) if (flag & FLAG_UPDATE_TS_RECENT) tcp_replace_ts_recent(tp, TCP_SKB_CB(skb)->seq); - if (!(flag & FLAG_SLOWPATH) && after(ack, prior_snd_una)) { + if (!(flag & FLAG_SLOWPATH) && (flag & FLAG_SND_UNA_ADVANCED)) { /* Window is constant, pure forward advance. * No more checks are required. * Note, we use the fact that SND.UNA>=SND.WL2.
Bitwise operation is a little faster. So I replace after() with (flag & FLAG_SND_UNA_ADVANCED) as this flag is already set before. Cc: Joe Perches <joe@perches.com> Signed-off-by: Yafang Shao <laoar.shao@gmail.com> --- net/ipv4/tcp_input.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)