[PATCH 1/3] tcp: Remove check in __tcp_push_pending_frames

[PATCH 1/3] tcp: Remove check in __tcp_push_pending_frames

[Krishna Kumar]

From: Krishna Kumar <krkumar2@in.ibm.com>

tcp_push checks tcp_send_head and calls __tcp_push_pending_frames,
which again checks tcp_send_head, and this unnecessary check is
done for every other caller of __tcp_push_pending_frames.

Remove tcp_send_head check in __tcp_push_pending_frames and add
the check to tcp_push_pending_frames. Other functions call
__tcp_push_pending_frames only when tcp_send_head would evaluate
to true.

Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
---
 include/net/tcp.h     |   16 +++++++++-------
 net/ipv4/tcp_output.c |    5 -----
 2 files changed, 9 insertions(+), 12 deletions(-)

diff -ruNp org/include/net/tcp.h new/include/net/tcp.h
--- org/include/net/tcp.h	2009-12-04 18:15:26.000000000 +0530
+++ new/include/net/tcp.h	2009-12-09 09:57:39.000000000 +0530
@@ -857,13 +857,6 @@ static inline void tcp_check_probe_timer
 					  icsk->icsk_rto, TCP_RTO_MAX);
 }
 
-static inline void tcp_push_pending_frames(struct sock *sk)
-{
-	struct tcp_sock *tp = tcp_sk(sk);
-
-	__tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
-}
-
 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
 {
 	tp->snd_wl1 = seq;
@@ -1366,6 +1359,15 @@ static inline int tcp_write_queue_empty(
 	return skb_queue_empty(&sk->sk_write_queue);
 }
 
+static inline void tcp_push_pending_frames(struct sock *sk)
+{
+	if (tcp_send_head(sk)) {
+		struct tcp_sock *tp = tcp_sk(sk);
+
+		__tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
+	}
+}
+
 /* Start sequence of the highest skb with SACKed bit, valid only if
  * sacked > 0 or when the caller has ensured validity by itself.
  */
diff -ruNp org/net/ipv4/tcp_output.c new/net/ipv4/tcp_output.c
--- org/net/ipv4/tcp_output.c	2009-12-04 18:16:00.000000000 +0530
+++ new/net/ipv4/tcp_output.c	2009-12-04 18:16:24.000000000 +0530
@@ -1799,11 +1799,6 @@ static int tcp_write_xmit(struct sock *s
 void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
 			       int nonagle)
 {
-	struct sk_buff *skb = tcp_send_head(sk);
-
-	if (!skb)
-		return;
-
 	/* If we are closed, the bytes will have to remain here.
 	 * In time closedown will finish, we empty the write queue and
 	 * all will be happy.

[PATCH 2/3] tcp: Remove unrequired operations in tcp_push()

[Krishna Kumar]

From: Krishna Kumar <krkumar2@in.ibm.com>

Remove unrequired operations in tcp_push()

Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
---
 net/ipv4/tcp.c |   15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff -ruNp org/net/ipv4/tcp.c new/net/ipv4/tcp.c
--- org/net/ipv4/tcp.c	2009-12-04 18:16:10.000000000 +0530
+++ new/net/ipv4/tcp.c	2009-12-09 10:01:35.000000000 +0530
@@ -536,8 +536,7 @@ static inline void skb_entail(struct soc
 		tp->nonagle &= ~TCP_NAGLE_PUSH;
 }
 
-static inline void tcp_mark_urg(struct tcp_sock *tp, int flags,
-				struct sk_buff *skb)
+static inline void tcp_mark_urg(struct tcp_sock *tp, int flags)
 {
 	if (flags & MSG_OOB)
 		tp->snd_up = tp->write_seq;
@@ -546,13 +545,15 @@ static inline void tcp_mark_urg(struct t
 static inline void tcp_push(struct sock *sk, int flags, int mss_now,
 			    int nonagle)
 {
-	struct tcp_sock *tp = tcp_sk(sk);
-
 	if (tcp_send_head(sk)) {
-		struct sk_buff *skb = tcp_write_queue_tail(sk);
-		if (!(flags & MSG_MORE) || forced_push(tp))
+		struct tcp_sock *tp = tcp_sk(sk);
+
+		if (!(flags & MSG_MORE) || forced_push(tp)) {
+			struct sk_buff *skb = tcp_write_queue_tail(sk);
+
 			tcp_mark_push(tp, skb);
-		tcp_mark_urg(tp, flags, skb);
+		}
+		tcp_mark_urg(tp, flags);
 		__tcp_push_pending_frames(sk, mss_now,
 					  (flags & MSG_MORE) ? TCP_NAGLE_CORK : nonagle);
 	}

[PATCH 3/3] tcp: Slightly optimize tcp_sendmsg

[Krishna Kumar]

From: Krishna Kumar <krkumar2@in.ibm.com>

Slightly optimize tcp_sendmsg since NETIF_F_SG is used many
times iteratively in the loop. The only other modification is
to change:
			} else if (i == MAX_SKB_FRAGS ||
				   (!i &&
				   !(sk->sk_route_caps & NETIF_F_SG))) {
	to:
			} else if (i == MAX_SKB_FRAGS || !sg) {

Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
---
 net/ipv4/tcp.c |   17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff -ruNp org/net/ipv4/tcp.c new/net/ipv4/tcp.c
--- org/net/ipv4/tcp.c	2009-12-09 10:01:35.000000000 +0530
+++ new/net/ipv4/tcp.c	2009-12-09 10:26:42.000000000 +0530
@@ -878,12 +878,12 @@ ssize_t tcp_sendpage(struct socket *sock
 #define TCP_PAGE(sk)	(sk->sk_sndmsg_page)
 #define TCP_OFF(sk)	(sk->sk_sndmsg_off)
 
-static inline int select_size(struct sock *sk)
+static inline int select_size(struct sock *sk, int sg)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	int tmp = tp->mss_cache;
 
-	if (sk->sk_route_caps & NETIF_F_SG) {
+	if (sg) {
 		if (sk_can_gso(sk))
 			tmp = 0;
 		else {
@@ -907,7 +907,7 @@ int tcp_sendmsg(struct kiocb *iocb, stru
 	struct sk_buff *skb;
 	int iovlen, flags;
 	int mss_now, size_goal;
-	int err, copied;
+	int sg, err, copied;
 	long timeo;
 
 	lock_sock(sk);
@@ -935,6 +935,8 @@ int tcp_sendmsg(struct kiocb *iocb, stru
 	if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
 		goto out_err;
 
+	sg = sk->sk_route_caps & NETIF_F_SG;
+
 	while (--iovlen >= 0) {
 		int seglen = iov->iov_len;
 		unsigned char __user *from = iov->iov_base;
@@ -960,8 +962,9 @@ new_segment:
 				if (!sk_stream_memory_free(sk))
 					goto wait_for_sndbuf;
 
-				skb = sk_stream_alloc_skb(sk, select_size(sk),
-						sk->sk_allocation);
+				skb = sk_stream_alloc_skb(sk,
+							  select_size(sk, sg),
+							  sk->sk_allocation);
 				if (!skb)
 					goto wait_for_memory;
 
@@ -998,9 +1001,7 @@ new_segment:
 					/* We can extend the last page
 					 * fragment. */
 					merge = 1;
-				} else if (i == MAX_SKB_FRAGS ||
-					   (!i &&
-					   !(sk->sk_route_caps & NETIF_F_SG))) {
+				} else if (i == MAX_SKB_FRAGS || !sg) {
 					/* Need to add new fragment and cannot
 					 * do this because interface is non-SG,
 					 * or because all the page slots are

Re: [PATCH 1/3] tcp: Remove check in __tcp_push_pending_frames

[Ilpo Järvinen]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 2437 bytes --]

On Wed, 9 Dec 2009, Krishna Kumar wrote:

> From: Krishna Kumar <krkumar2@in.ibm.com>
> 
> tcp_push checks tcp_send_head and calls __tcp_push_pending_frames,
> which again checks tcp_send_head, and this unnecessary check is
> done for every other caller of __tcp_push_pending_frames.
> 
> Remove tcp_send_head check in __tcp_push_pending_frames and add
> the check to tcp_push_pending_frames. Other functions call
> __tcp_push_pending_frames only when tcp_send_head would evaluate
> to true.
> 
> Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
> ---
>  include/net/tcp.h     |   16 +++++++++-------
>  net/ipv4/tcp_output.c |    5 -----
>  2 files changed, 9 insertions(+), 12 deletions(-)
> 
> diff -ruNp org/include/net/tcp.h new/include/net/tcp.h
> --- org/include/net/tcp.h	2009-12-04 18:15:26.000000000 +0530
> +++ new/include/net/tcp.h	2009-12-09 09:57:39.000000000 +0530
> @@ -857,13 +857,6 @@ static inline void tcp_check_probe_timer
>  					  icsk->icsk_rto, TCP_RTO_MAX);
>  }
>  
> -static inline void tcp_push_pending_frames(struct sock *sk)
> -{
> -	struct tcp_sock *tp = tcp_sk(sk);
> -
> -	__tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
> -}
> -
>  static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
>  {
>  	tp->snd_wl1 = seq;
> @@ -1366,6 +1359,15 @@ static inline int tcp_write_queue_empty(
>  	return skb_queue_empty(&sk->sk_write_queue);
>  }
>  
> +static inline void tcp_push_pending_frames(struct sock *sk)
> +{
> +	if (tcp_send_head(sk)) {
> +		struct tcp_sock *tp = tcp_sk(sk);
> +
> +		__tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
> +	}
> +}
> +
>  /* Start sequence of the highest skb with SACKed bit, valid only if
>   * sacked > 0 or when the caller has ensured validity by itself.
>   */
> diff -ruNp org/net/ipv4/tcp_output.c new/net/ipv4/tcp_output.c
> --- org/net/ipv4/tcp_output.c	2009-12-04 18:16:00.000000000 +0530
> +++ new/net/ipv4/tcp_output.c	2009-12-04 18:16:24.000000000 +0530
> @@ -1799,11 +1799,6 @@ static int tcp_write_xmit(struct sock *s
>  void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
>  			       int nonagle)
>  {
> -	struct sk_buff *skb = tcp_send_head(sk);
> -
> -	if (!skb)
> -		return;
> -
>  	/* If we are closed, the bytes will have to remain here.
>  	 * In time closedown will finish, we empty the write queue and
>  	 * all will be happy.

Acked-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>


-- 
 i.

Re: [PATCH 2/3] tcp: Remove unrequired operations in tcp_push()

[Ilpo Järvinen]

On Wed, 9 Dec 2009, Krishna Kumar wrote:

> From: Krishna Kumar <krkumar2@in.ibm.com>
> 
> Remove unrequired operations in tcp_push()
> 
> Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
> ---
>  net/ipv4/tcp.c |   15 ++++++++-------
>  1 file changed, 8 insertions(+), 7 deletions(-)
> 
> diff -ruNp org/net/ipv4/tcp.c new/net/ipv4/tcp.c
> --- org/net/ipv4/tcp.c	2009-12-04 18:16:10.000000000 +0530
> +++ new/net/ipv4/tcp.c	2009-12-09 10:01:35.000000000 +0530
> @@ -536,8 +536,7 @@ static inline void skb_entail(struct soc
>  		tp->nonagle &= ~TCP_NAGLE_PUSH;
>  }
>  
> -static inline void tcp_mark_urg(struct tcp_sock *tp, int flags,
> -				struct sk_buff *skb)
> +static inline void tcp_mark_urg(struct tcp_sock *tp, int flags)
>  {
>  	if (flags & MSG_OOB)
>  		tp->snd_up = tp->write_seq;
> @@ -546,13 +545,15 @@ static inline void tcp_mark_urg(struct t
>  static inline void tcp_push(struct sock *sk, int flags, int mss_now,
>  			    int nonagle)
>  {
> -	struct tcp_sock *tp = tcp_sk(sk);
> -
>  	if (tcp_send_head(sk)) {
> -		struct sk_buff *skb = tcp_write_queue_tail(sk);
> -		if (!(flags & MSG_MORE) || forced_push(tp))
> +		struct tcp_sock *tp = tcp_sk(sk);
> +
> +		if (!(flags & MSG_MORE) || forced_push(tp)) {
> +			struct sk_buff *skb = tcp_write_queue_tail(sk);
> +
>  			tcp_mark_push(tp, skb);

I suppose one could kill the temporary variable completely then?

> -		tcp_mark_urg(tp, flags, skb);
> +		}
> +		tcp_mark_urg(tp, flags);
>  		__tcp_push_pending_frames(sk, mss_now,
>  					  (flags & MSG_MORE) ? TCP_NAGLE_CORK : nonagle);
>  	}

-- 
 i.

Re: [PATCH 3/3] tcp: Slightly optimize tcp_sendmsg

[Ilpo Järvinen]

On Wed, 9 Dec 2009, Krishna Kumar wrote:

> From: Krishna Kumar <krkumar2@in.ibm.com>
> 
> Slightly optimize tcp_sendmsg since NETIF_F_SG is used many
> times iteratively in the loop. The only other modification is
> to change:
> 			} else if (i == MAX_SKB_FRAGS ||
> 				   (!i &&
> 				   !(sk->sk_route_caps & NETIF_F_SG))) {
> 	to:
> 			} else if (i == MAX_SKB_FRAGS || !sg) {

I can see that you make this change from the patch itself but could you 
give a justification on why dropping the !i is possible? ...I couldn't
see what would allow that.

> Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
> ---
>  net/ipv4/tcp.c |   17 +++++++++--------
>  1 file changed, 9 insertions(+), 8 deletions(-)
> 
> diff -ruNp org/net/ipv4/tcp.c new/net/ipv4/tcp.c
> --- org/net/ipv4/tcp.c	2009-12-09 10:01:35.000000000 +0530
> +++ new/net/ipv4/tcp.c	2009-12-09 10:26:42.000000000 +0530
> @@ -878,12 +878,12 @@ ssize_t tcp_sendpage(struct socket *sock
>  #define TCP_PAGE(sk)	(sk->sk_sndmsg_page)
>  #define TCP_OFF(sk)	(sk->sk_sndmsg_off)
>  
> -static inline int select_size(struct sock *sk)
> +static inline int select_size(struct sock *sk, int sg)
>  {
>  	struct tcp_sock *tp = tcp_sk(sk);
>  	int tmp = tp->mss_cache;
>  
> -	if (sk->sk_route_caps & NETIF_F_SG) {
> +	if (sg) {
>  		if (sk_can_gso(sk))
>  			tmp = 0;
>  		else {
> @@ -907,7 +907,7 @@ int tcp_sendmsg(struct kiocb *iocb, stru
>  	struct sk_buff *skb;
>  	int iovlen, flags;
>  	int mss_now, size_goal;
> -	int err, copied;
> +	int sg, err, copied;
>  	long timeo;
>  
>  	lock_sock(sk);
> @@ -935,6 +935,8 @@ int tcp_sendmsg(struct kiocb *iocb, stru
>  	if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
>  		goto out_err;
>  
> +	sg = sk->sk_route_caps & NETIF_F_SG;
> +
>  	while (--iovlen >= 0) {
>  		int seglen = iov->iov_len;
>  		unsigned char __user *from = iov->iov_base;
> @@ -960,8 +962,9 @@ new_segment:
>  				if (!sk_stream_memory_free(sk))
>  					goto wait_for_sndbuf;
>  
> -				skb = sk_stream_alloc_skb(sk, select_size(sk),
> -						sk->sk_allocation);
> +				skb = sk_stream_alloc_skb(sk,
> +							  select_size(sk, sg),
> +							  sk->sk_allocation);
>  				if (!skb)
>  					goto wait_for_memory;
>  
> @@ -998,9 +1001,7 @@ new_segment:
>  					/* We can extend the last page
>  					 * fragment. */
>  					merge = 1;
> -				} else if (i == MAX_SKB_FRAGS ||
> -					   (!i &&
> -					   !(sk->sk_route_caps & NETIF_F_SG))) {
> +				} else if (i == MAX_SKB_FRAGS || !sg) {
>  					/* Need to add new fragment and cannot
>  					 * do this because interface is non-SG,
>  					 * or because all the page slots are
> --
> To unsubscribe from this list: send the line "unsubscribe netdev" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

-- 
 i.

Re: [PATCH 2/3] tcp: Remove unrequired operations in tcp_push()

[Krishna Kumar2]

"Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi> wrote on 12/10/2009 01:40:51
PM:

> Re: [PATCH 2/3] tcp: Remove unrequired operations in tcp_push()
>
>
> >  static inline void tcp_push(struct sock *sk, int flags, int mss_now,
> >               int nonagle)
> >  {
> > -   struct tcp_sock *tp = tcp_sk(sk);
> > -
> >     if (tcp_send_head(sk)) {
> > -      struct sk_buff *skb = tcp_write_queue_tail(sk);
> > -      if (!(flags & MSG_MORE) || forced_push(tp))
> > +      struct tcp_sock *tp = tcp_sk(sk);
> > +
> > +      if (!(flags & MSG_MORE) || forced_push(tp)) {
> > +         struct sk_buff *skb = tcp_write_queue_tail(sk);
> > +
> >           tcp_mark_push(tp, skb);
>
> I suppose one could kill the temporary variable completely then?

I did consider that, but kept it this way for readability reasons.
Should I change it?

Thanks,

- KK

Re: [PATCH 2/3] tcp: Remove unrequired operations in tcp_push()

[Ilpo Järvinen]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 1212 bytes --]

On Thu, 10 Dec 2009, Krishna Kumar2 wrote:

> "Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi> wrote on 12/10/2009 01:40:51
> PM:
> 
> > Re: [PATCH 2/3] tcp: Remove unrequired operations in tcp_push()
> >
> >
> > >  static inline void tcp_push(struct sock *sk, int flags, int mss_now,
> > >               int nonagle)
> > >  {
> > > -   struct tcp_sock *tp = tcp_sk(sk);
> > > -
> > >     if (tcp_send_head(sk)) {
> > > -      struct sk_buff *skb = tcp_write_queue_tail(sk);
> > > -      if (!(flags & MSG_MORE) || forced_push(tp))
> > > +      struct tcp_sock *tp = tcp_sk(sk);
> > > +
> > > +      if (!(flags & MSG_MORE) || forced_push(tp)) {
> > > +         struct sk_buff *skb = tcp_write_queue_tail(sk);
> > > +
> > >           tcp_mark_push(tp, skb);
> >
> > I suppose one could kill the temporary variable completely then?
> 
> I did consider that, but kept it this way for readability reasons.
> Should I change it?

Honestly that doesn't look that fuzzy code even if you'd stick it into the 
tcp_mark_push line (nor should be even close to 80 limit). ...I was even 
thinking of getting totally rid of that skb arg of tcp_mark_push as I 
think it's always tcp_write_queue_tail(sk) that is put there.

-- 
 i.

Re: [PATCH 3/3] tcp: Slightly optimize tcp_sendmsg

[Krishna Kumar2]

Hi Ilpo,

"Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi> wrote on 12/10/2009 01:47:30
PM:

> Subject: Re: [PATCH 3/3] tcp: Slightly optimize tcp_sendmsg>
>
> > Slightly optimize tcp_sendmsg since NETIF_F_SG is used many
> > times iteratively in the loop. The only other modification is
> > to change:
> >          } else if (i == MAX_SKB_FRAGS ||
> >                (!i &&
> >                !(sk->sk_route_caps & NETIF_F_SG))) {
> >    to:
> >          } else if (i == MAX_SKB_FRAGS || !sg) {
>
> I can see that you make this change from the patch itself but could you
> give a justification on why dropping the !i is possible? ...I couldn't
> see what would allow that.

From what *I understood*, this code (other than the MAX_SKB_FRAGS case)
executes only due to the else part of "if (skb_tailroom(skb) > 0) {" -
there was no space in the skb to put the data inline. Hence SG is false
is a sufficient condition and there is no way to add a fragment (i == 0
since skb_fill_page_desc cannot be called when !SG).

thanks,

- KK

Re: [PATCH 3/3] tcp: Slightly optimize tcp_sendmsg

[Ilpo Järvinen]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 1409 bytes --]

On Thu, 10 Dec 2009, Krishna Kumar2 wrote:

> Hi Ilpo,
> 
> "Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi> wrote on 12/10/2009 01:47:30
> PM:
> 
> > Subject: Re: [PATCH 3/3] tcp: Slightly optimize tcp_sendmsg>
> >
> > > Slightly optimize tcp_sendmsg since NETIF_F_SG is used many
> > > times iteratively in the loop. The only other modification is
> > > to change:
> > >          } else if (i == MAX_SKB_FRAGS ||
> > >                (!i &&
> > >                !(sk->sk_route_caps & NETIF_F_SG))) {
> > >    to:
> > >          } else if (i == MAX_SKB_FRAGS || !sg) {
> >
> > I can see that you make this change from the patch itself but could you
> > give a justification on why dropping the !i is possible? ...I couldn't
> > see what would allow that.
> 
> From what *I understood*, this code (other than the MAX_SKB_FRAGS case)
> executes only due to the else part of "if (skb_tailroom(skb) > 0) {" -
> there was no space in the skb to put the data inline. Hence SG is false
> is a sufficient condition and there is no way to add a fragment (i == 0
> since skb_fill_page_desc cannot be called when !SG).

Please put this description into the patch description then :-). ...After 
some more thinking, reading and verification it seems right, however, it 
certainly wassn't immediately obvious from the code.

...You can add my Acked-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> for 
the resubmission.

-- 
 i.

Re: [PATCH 2/3] tcp: Remove unrequired operations in tcp_push()

[Krishna Kumar2]

"Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi> wrote on 12/10/2009 03:56:59
PM:

> Re: [PATCH 2/3] tcp: Remove unrequired operations in tcp_push()
>
> On Thu, 10 Dec 2009, Krishna Kumar2 wrote:
>
> > "Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi> wrote on 12/10/2009
01:40:51
> > PM:
> >
> > > Re: [PATCH 2/3] tcp: Remove unrequired operations in tcp_push()
> > >
> > >
> > > >  static inline void tcp_push(struct sock *sk, int flags, int
mss_now,
> > > >               int nonagle)
> > > >  {
> > > > -   struct tcp_sock *tp = tcp_sk(sk);
> > > > -
> > > >     if (tcp_send_head(sk)) {
> > > > -      struct sk_buff *skb = tcp_write_queue_tail(sk);
> > > > -      if (!(flags & MSG_MORE) || forced_push(tp))
> > > > +      struct tcp_sock *tp = tcp_sk(sk);
> > > > +
> > > > +      if (!(flags & MSG_MORE) || forced_push(tp)) {
> > > > +         struct sk_buff *skb = tcp_write_queue_tail(sk);
> > > > +
> > > >           tcp_mark_push(tp, skb);
> > >
> > > I suppose one could kill the temporary variable completely then?
> >
> > I did consider that, but kept it this way for readability reasons.
> > Should I change it?
>
> Honestly that doesn't look that fuzzy code even if you'd stick it into
the
> tcp_mark_push line (nor should be even close to 80 limit). ...I was even
> thinking of getting totally rid of that skb arg of tcp_mark_push as I
> think it's always tcp_write_queue_tail(sk) that is put there.

Yes, the skb is always the one at the tail. But in 4/5 cases, the
skb pointer is already available, so may be OK to pass the skb. I
will resubmit with the change you suggested (remove the temporary
variable).

Also, for the NETIF_F_SG patch, I will try to put a meaningful
explanation and resubmit.

Thanks for your review,

- KK

Re: [PATCH 2/3] tcp: Remove unrequired operations in tcp_push()

[Ilpo Järvinen]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 1842 bytes --]

On Thu, 10 Dec 2009, Krishna Kumar2 wrote:

> "Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi> wrote on 12/10/2009 03:56:59
> PM:
> 
> > Re: [PATCH 2/3] tcp: Remove unrequired operations in tcp_push()
> >
> > On Thu, 10 Dec 2009, Krishna Kumar2 wrote:
> >
> > > "Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi> wrote on 12/10/2009
> 01:40:51
> > > PM:
> > >
> > > > Re: [PATCH 2/3] tcp: Remove unrequired operations in tcp_push()
> > > >
> > > >
> > > > >  static inline void tcp_push(struct sock *sk, int flags, int
> mss_now,
> > > > >               int nonagle)
> > > > >  {
> > > > > -   struct tcp_sock *tp = tcp_sk(sk);
> > > > > -
> > > > >     if (tcp_send_head(sk)) {
> > > > > -      struct sk_buff *skb = tcp_write_queue_tail(sk);
> > > > > -      if (!(flags & MSG_MORE) || forced_push(tp))
> > > > > +      struct tcp_sock *tp = tcp_sk(sk);
> > > > > +
> > > > > +      if (!(flags & MSG_MORE) || forced_push(tp)) {
> > > > > +         struct sk_buff *skb = tcp_write_queue_tail(sk);
> > > > > +
> > > > >           tcp_mark_push(tp, skb);
> > > >
> > > > I suppose one could kill the temporary variable completely then?
> > >
> > > I did consider that, but kept it this way for readability reasons.
> > > Should I change it?
> >
> > Honestly that doesn't look that fuzzy code even if you'd stick it into
> the
> > tcp_mark_push line (nor should be even close to 80 limit). ...I was even
> > thinking of getting totally rid of that skb arg of tcp_mark_push as I
> > think it's always tcp_write_queue_tail(sk) that is put there.
> 
> Yes, the skb is always the one at the tail. But in 4/5 cases, the
> skb pointer is already available, so may be OK to pass the skb.

...which was exactly why I didn't immediately suggest it :-).

> Also, for the NETIF_F_SG patch, I will try to put a meaningful
> explanation and resubmit.

Thanks.

-- 
 i.

Re: [PATCH 1/3] tcp: Remove check in __tcp_push_pending_frames

[David Miller]

From: Krishna Kumar <krkumar2@in.ibm.com>
Date: Wed, 09 Dec 2009 13:56:13 +0530

> From: Krishna Kumar <krkumar2@in.ibm.com>
> 
> tcp_push checks tcp_send_head and calls __tcp_push_pending_frames,
> which again checks tcp_send_head, and this unnecessary check is
> done for every other caller of __tcp_push_pending_frames.
> 
> Remove tcp_send_head check in __tcp_push_pending_frames and add
> the check to tcp_push_pending_frames. Other functions call
> __tcp_push_pending_frames only when tcp_send_head would evaluate
> to true.
> 
> Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>

Applied.