[PATCH] Decrease number of pointer derefs in nf_conntrack_core.c

[PATCH] Decrease number of pointer derefs in nf_conntrack_core.c

[Jesper Juhl]

Hi,

Here's a small patch to decrease the number of pointer derefs in
net/netfilter/nf_conntrack_core.c

Benefits of the patch:
 - Fewer pointer dereferences should make the code slightly faster.
 - Size of generated code is smaller
 - improved readability

Please consider applying.


Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
---


 net/netfilter/nf_conntrack_core.c |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)

orig:
   text    data     bss     dec     hex filename
  12636      49     760   13445    3485 net/netfilter/nf_conntrack_core.o

patched:
   text    data     bss     dec     hex filename
  11825     183     632   12640    3160 net/netfilter/nf_conntrack_core.o

--- linux-2.6.15-rc5-git1-orig/net/netfilter/nf_conntrack_core.c	2005-12-04 18:48:58.000000000 +0100
+++ linux-2.6.15-rc5-git1/net/netfilter/nf_conntrack_core.c	2005-12-08 20:13:03.000000000 +0100
@@ -1129,6 +1129,7 @@ static inline int refresh_timer(struct n
 int nf_conntrack_expect_related(struct nf_conntrack_expect *expect)
 {
 	struct nf_conntrack_expect *i;
+	struct nf_conn *master = expect->master;
 	int ret;
 
 	DEBUGP("nf_conntrack_expect_related %p\n", related_to);
@@ -1149,9 +1150,9 @@ int nf_conntrack_expect_related(struct n
 		}
 	}
 	/* Will be over limit? */
-	if (expect->master->helper->max_expected && 
-	    expect->master->expecting >= expect->master->helper->max_expected)
-		evict_oldest_expect(expect->master);
+	if (master->helper->max_expected && 
+	    master->expecting >= master->helper->max_expected)
+		evict_oldest_expect(master);
 
 	nf_conntrack_expect_insert(expect);
 	nf_conntrack_expect_event(IPEXP_NEW, expect);

Re: [netfilter-core] [PATCH] Decrease number of pointer derefs in nf_conntrack_core.c

[Harald Welte]

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On Thu, Dec 08, 2005 at 11:36:19PM +0100, Jesper Juhl wrote:
> Here's a small patch to decrease the number of pointer derefs in
> net/netfilter/nf_conntrack_core.c

thanks, looks fine.

Patrick: please merge into your queue, too.

-- 
- Harald Welte <laforge@netfilter.org>                 http://netfilter.org/
============================================================================
  "Fragmentation is like classful addressing -- an interesting early
   architectural error that shows how much experimentation was going
   on while IP was being designed."                    -- Paul Vixie

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Re: [PATCH] Decrease number of pointer derefs in nf_conntrack_core.c

[Jesper Juhl]

On 12/9/05, Ingo Molnar <mingo@elte.hu> wrote:
>
> * Jesper Juhl <jesper.juhl@gmail.com> wrote:
>
> > orig:
> >    text    data     bss     dec     hex filename
> >   12636      49     760   13445    3485 net/netfilter/nf_conntrack_core.o
> >
> > patched:
> >    text    data     bss     dec     hex filename
> >   11825     183     632   12640    3160 net/netfilter/nf_conntrack_core.o
>
> just a question - are you sure the measurements are accurate in this
> case? The patch looks too small to shave more than 800 bytes off .text!
> If it's real then something really wrong is going on in gcc-land ...
>
I did all this with an allyesconfig kernel source and then did :
   make net/netfilter/nf_conntrack_core.o
   size net/netfilter/nf_conntrack_core.o
   rm net/netfilter/nf_conntrack_core.o
then applied the patch and redid
   make net/netfilter/nf_conntrack_core.o
   size net/netfilter/nf_conntrack_core.o

So I believe the numbers should be correct, but I'm not at home atm,
so I can't verify right now. I won't have a chance to look at it until
tomorrow, but then I'll double-check.

--
Jesper Juhl <jesper.juhl@gmail.com>
Don't top-post  http://www.catb.org/~esr/jargon/html/T/top-post.html
Plain text mails only, please      http://www.expita.com/nomime.html

Re: [PATCH] Decrease number of pointer derefs in nf_conntrack_core.c

[Tim Schmielau]

On Fri, 9 Dec 2005, Jesper Juhl wrote:

> On 12/9/05, Ingo Molnar <mingo@elte.hu> wrote:
> >
> > * Jesper Juhl <jesper.juhl@gmail.com> wrote:
> >
> > > orig:
> > >    text    data     bss     dec     hex filename
> > >   12636      49     760   13445    3485 net/netfilter/nf_conntrack_core.o
> > >
> > > patched:
> > >    text    data     bss     dec     hex filename
> > >   11825     183     632   12640    3160 net/netfilter/nf_conntrack_core.o
> >
> > just a question - are you sure the measurements are accurate in this
> > case? The patch looks too small to shave more than 800 bytes off .text!
> > If it's real then something really wrong is going on in gcc-land ...
> >
> I did all this with an allyesconfig kernel source and then did :
>    make net/netfilter/nf_conntrack_core.o
>    size net/netfilter/nf_conntrack_core.o
>    rm net/netfilter/nf_conntrack_core.o
> then applied the patch and redid
>    make net/netfilter/nf_conntrack_core.o
>    size net/netfilter/nf_conntrack_core.o
> 
> So I believe the numbers should be correct, but I'm not at home atm,
> so I can't verify right now. I won't have a chance to look at it until
> tomorrow, but then I'll double-check.


I get
orig:
   text    data     bss     dec     hex filename
  11745      67     728   12540    30fc net/netfilter/nf_conntrack_core.o

patched:
   text    data     bss     dec     hex filename
  11681      67     728   12476    30bc net/netfilter/nf_conntrack_core.o

> gcc --version
gcc (GCC) 4.0.2 20050901 (prerelease) (SUSE Linux)

Tim

Re: [PATCH] Decrease number of pointer derefs in nf_conntrack_core.c

[Ingo Molnar]

* Jesper Juhl <jesper.juhl@gmail.com> wrote:

> orig:
>    text    data     bss     dec     hex filename
>   12636      49     760   13445    3485 net/netfilter/nf_conntrack_core.o
> 
> patched:
>    text    data     bss     dec     hex filename
>   11825     183     632   12640    3160 net/netfilter/nf_conntrack_core.o

just a question - are you sure the measurements are accurate in this 
case? The patch looks too small to shave more than 800 bytes off .text!  
If it's real then something really wrong is going on in gcc-land ...

	Ingo

Re: [PATCH] Decrease number of pointer derefs in nf_conntrack_core.c

[Ingo Molnar]

* Tim Schmielau <tim@physik3.uni-rostock.de> wrote:

> I get
> orig:
>    text    data     bss     dec     hex filename
>   11745      67     728   12540    30fc net/netfilter/nf_conntrack_core.o
> 
> patched:
>    text    data     bss     dec     hex filename
>   11681      67     728   12476    30bc net/netfilter/nf_conntrack_core.o

yeah, that's OK and in the expected range.

	Ingo

Re: [PATCH] Decrease number of pointer derefs in nf_conntrack_core.c

[Jesper Juhl]

On 12/9/05, Ingo Molnar <mingo@elte.hu> wrote:
>
> * Tim Schmielau <tim@physik3.uni-rostock.de> wrote:
>
> > I get
> > orig:
> >    text    data     bss     dec     hex filename
> >   11745      67     728   12540    30fc net/netfilter/nf_conntrack_core.o
> >
> > patched:
> >    text    data     bss     dec     hex filename
> >   11681      67     728   12476    30bc net/netfilter/nf_conntrack_core.o
>
> yeah, that's OK and in the expected range.
>
Ingo, Tim, you are correct. I did screw up the size measurements for
that one patch. Sorry about that.

--
Jesper Juhl <jesper.juhl@gmail.com>
Don't top-post  http://www.catb.org/~esr/jargon/html/T/top-post.html
Plain text mails only, please      http://www.expita.com/nomime.html

Re: [netfilter-core] [PATCH] Decrease number of pointer derefs in nf_conntrack_core.c

[Patrick McHardy]

Jesper Juhl wrote:
> Here's a small patch to decrease the number of pointer derefs in
> net/netfilter/nf_conntrack_core.c
> 
> Benefits of the patch:
>  - Fewer pointer dereferences should make the code slightly faster.
>  - Size of generated code is smaller
>  - improved readability
> 
> Please consider applying.

I've added both patches to my 2.6.16 queue, thanks Jesper.