Am Freitag, 9. Dezember 2005 02:46 schrieb Matt Mackall:
> On Tue, Dec 06, 2005 at 11:15:28PM +0100, Ingo Molnar wrote:
> >
> > * Jesper Juhl <[email protected]> wrote:
> >
> > > Ohh, and before I forget, besides the fact that this should speed
> > > things up a little bit it also has the added benefit of reducing the
> > > size of the generated code. The original kernel/exit.o file was 19604
> > > bytes in size, the patched one is 19508 bytes in size.
> >
> > nice. Just to underline your point, on x86, with gcc 4.0.2, i'm getting
> > this with your patch:
> >
> > text data bss dec hex filename
> > 11077 0 0 11077 2b45 exit.o.orig
> > 10997 0 0 10997 2af5 exit.o
> >
> > so 80 bytes shaved off. I think such patches also increase readability.
>
> Readability improved: good.
> 37 lines of patch for 80-100 bytes saved: not so good.
>
> So while this is a good style direction, I don't think it's worth the
> churn. And unlike kzalloc and the like, this particular optimization
> is perfectly doable by a compiler. So I'd rather wait for the compiler
> to get smarter than change code for such modest improvements.
How can the compiler do it? If a function call is between two evaluations
of a pointer chain, the compiler would have to make sure no pointer in
the chain is touched. For the case of a computed function call, it is
impossible in principle.
Regards
Oliver
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
