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Re: [PATCH 1/7] signals: reduce {setup,restore}_sigcontext sizes

To: "Ralf Baechle" <ralf@linux-mips.org>
Subject: Re: [PATCH 1/7] signals: reduce {setup,restore}_sigcontext sizes
From: "Franck Bui-Huu" <vagabon.xyz@gmail.com>
Date: Wed, 24 Jan 2007 13:25:27 +0100
Cc: linux-mips@linux-mips.org, "Franck Bui-Huu" <fbuihuu@gmail.com>
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On 1/23/07, Ralf Baechle <ralf@linux-mips.org> wrote:
On Tue, Jan 23, 2007 at 03:18:17PM +0100, Franck Bui-Huu wrote:

> From: Franck Bui-Huu <fbuihuu@gmail.com>
>
> This trivial change reduces considerably code size of these
> 2 functions callers. For instance, here is the figures for
> arch/kernel/signal.o objects:
>
>    text    data     bss     dec     hex filename
>   11972       0       0   11972    2ec4 arch/mips/kernel/signal.o~old
>    5380       0       0    5380    1504 arch/mips/kernel/signal.o~new

Have you ran any benchmarks on this?  Unrolling the loops used to make
a noticable difference.


OK, I ran a micro benchmark on setup_frame() which calls
setup_sigcontext(). I got the execution time of setup_frame() by
counting the number of cycles spent in it (by using cp0_count
register).

Without this patchset applied it takes about 14600 cycles for
setup_frame() execution whereas with this patchset applied it takes
10300 cycles. These figures are averages.

So it appears that this patchset has a positive impact on both size and speed.

thanks
--
              Franck

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