netdev - Re: [PATCH 2/3] tcp: Remove unrequired operations in tcp

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Message-ID: <alpine.DEB.2.00.0912101402590.7024@wel-95.cs.helsinki.fi>
Date:	Thu, 10 Dec 2009 14:03:58 +0200 (EET)
From:	"Ilpo Järvinen" <ilpo.jarvinen@...sinki.fi>
To:	Krishna Kumar2 <krkumar2@...ibm.com>
cc:	David Miller <davem@...emloft.net>, Netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH 2/3] tcp: Remove unrequired operations in tcp_push()

On Thu, 10 Dec 2009, Krishna Kumar2 wrote:

> "Ilpo Järvinen" <ilpo.jarvinen@...sinki.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@...sinki.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.