netdev - Re: [PATCH 9/9] powerpc: optimise csum_partial() call when len is constant

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Date:	Thu, 22 Oct 2015 22:32:10 -0500
From:	Scott Wood <scottwood@...escale.com>
To:	Christophe Leroy <christophe.leroy@....fr>
CC:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	<linux-kernel@...r.kernel.org>, <linuxppc-dev@...ts.ozlabs.org>,
	<netdev@...r.kernel.org>
Subject: Re: [PATCH 9/9] powerpc: optimise csum_partial() call when len is
 constant

On Tue, 2015-09-22 at 16:34 +0200, Christophe Leroy wrote:
> csum_partial is often called for small fixed length packets
> for which it is suboptimal to use the generic csum_partial()
> function.
> 
> For instance, in my configuration, I got:
> * One place calling it with constant len 4
> * Seven places calling it with constant len 8
> * Three places calling it with constant len 14
> * One place calling it with constant len 20
> * One place calling it with constant len 24
> * One place calling it with constant len 32
> 
> This patch renames csum_partial() to __csum_partial() and
> implements csum_partial() as a wrapper inline function which
> * uses csum_add() for small 16bits multiple constant length
> * uses ip_fast_csum() for other 32bits multiple constant
> * uses __csum_partial() in all other cases
> 
> Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
> ---
>  arch/powerpc/include/asm/checksum.h | 80 ++++++++++++++++++++++++++--------
> ---
>  arch/powerpc/lib/checksum_32.S      |  4 +-
>  arch/powerpc/lib/checksum_64.S      |  4 +-
>  arch/powerpc/lib/ppc_ksyms.c        |  2 +-
>  4 files changed, 62 insertions(+), 28 deletions(-)

Benchmarks?

-Scott

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