[dpdk-dev] [PATCH v3 4/4] eal/arm: introduce CONFIG_RTE_ARCH_ARM_NEON_MEMCPY

Jan Viktorin viktorin at rehivetech.com
Mon Mar 21 13:21:31 CET 2016


On Mon, 21 Mar 2016 13:42:31 +0800
Jianbo Liu <jianbo.liu at linaro.org> wrote:

> On 20 March 2016 at 03:58, Jan Viktorin <viktorin at rehivetech.com> wrote:
> > The flag is used to enable memcpy optimizations in EAL. As it is not always
> > the performance benefit, the flag allows to disable it.
> >
> > Signed-off-by: Jan Viktorin <viktorin at rehivetech.com>
> > ---
> >  config/defconfig_arm-armv7a-linuxapp-gcc               | 1 +
> >  lib/librte_eal/common/include/arch/arm/rte_memcpy_32.h | 8 ++++++--
> >  2 files changed, 7 insertions(+), 2 deletions(-)
> >
> > diff --git a/config/defconfig_arm-armv7a-linuxapp-gcc b/config/defconfig_arm-armv7a-linuxapp-gcc
> > index 96c3343..2c60c2c 100644
> > --- a/config/defconfig_arm-armv7a-linuxapp-gcc
> > +++ b/config/defconfig_arm-armv7a-linuxapp-gcc
> > @@ -36,6 +36,7 @@ CONFIG_RTE_ARCH="arm"
> >  CONFIG_RTE_ARCH_ARM=y
> >  CONFIG_RTE_ARCH_ARMv7=y
> >  CONFIG_RTE_ARCH_ARM_TUNE="cortex-a9"
> > +CONFIG_RTE_ARCH_ARM_NEON_MEMCPY=y
> >  
> If it's not always benefit, why not disable here since it is common
> armv7a config, and enable in your or other user's own config file?

Jianbo, you are right. In that case, I'd just turn it off by default.
And when there is a new platform-specific defconfig, it can enable it.

Anyway, I am thinking of adding some comment into the rte_memcpy_32.h
file describing the potential of the NEON code. What about:

/* Enable in your defconfig to accelerate memcpy operations. Consider
   enabling this for Cortex-A15. For Cortex-A7 and Cortex-A9, It might
   accelerate short data copies (< 64 B). */

Thomas, do you consider this enough?

Jan

> 
> Thanks!
> Jianbo



-- 
   Jan Viktorin                  E-mail: Viktorin at RehiveTech.com
   System Architect              Web:    www.RehiveTech.com
   RehiveTech
   Brno, Czech Republic


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