From: Segher Boessenkool <segher@kernel.crashing.org>
To: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] powerpc/32: Optimise __csum_partial()
Date: Thu, 24 May 2018 14:58:40 -0500 [thread overview]
Message-ID: <20180524195840.GF17342@gate.crashing.org> (raw)
In-Reply-To: <484bcfaccc1ec3d91b74aeaaa26a0ae66fe0955a.1527160868.git.christophe.leroy@c-s.fr>
On Thu, May 24, 2018 at 11:22:27AM +0000, Christophe Leroy wrote:
> Improve __csum_partial by interleaving loads and adds.
>
> On a 8xx, it brings neither improvement nor degradation.
> On a 83xx, it brings a 25% improvement.
Thanks! Looks fine to me.
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
> ---
> arch/powerpc/lib/checksum_32.S | 13 +++++++++++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/lib/checksum_32.S b/arch/powerpc/lib/checksum_32.S
> index d2238ea82209..aa224069f93a 100644
> --- a/arch/powerpc/lib/checksum_32.S
> +++ b/arch/powerpc/lib/checksum_32.S
> @@ -47,16 +47,25 @@ _GLOBAL(__csum_partial)
> bdnz 2b
> 21: srwi. r6,r4,4 /* # blocks of 4 words to do */
> beq 3f
> + lwz r0,4(r3)
> mtctr r6
> -22: lwz r0,4(r3)
> lwz r6,8(r3)
> + adde r5,r5,r0
> lwz r7,12(r3)
> + adde r5,r5,r6
> lwzu r8,16(r3)
> + adde r5,r5,r7
> + bdz 23f
> +22: lwz r0,4(r3)
> + adde r5,r5,r8
> + lwz r6,8(r3)
> adde r5,r5,r0
> + lwz r7,12(r3)
> adde r5,r5,r6
> + lwzu r8,16(r3)
> adde r5,r5,r7
> - adde r5,r5,r8
> bdnz 22b
> +23: adde r5,r5,r8
> 3: andi. r0,r4,2
> beq+ 4f
> lhz r0,4(r3)
> --
> 2.13.3
next prev parent reply other threads:[~2018-05-24 19:59 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-24 11:22 [PATCH] powerpc/32: Optimise __csum_partial() Christophe Leroy
2018-05-24 19:58 ` Segher Boessenkool [this message]
2018-06-04 14:11 ` Michael Ellerman
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