Re: [PATCH v3 4/4] eal/arm: introduce CONFIG_RTE_ARCH_ARM_NEON_MEMCPY

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2016-03-21 13:21, Jan Viktorin:
> On Mon, 21 Mar 2016 13:42:31 +0800
> Jianbo Liu <jianbo.liu@linaro.org> wrote:
> 
> > On 20 March 2016 at 03:58, Jan Viktorin <viktorin@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@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?

Yes it is perfect.
Why not put it in defconfig_arm-armv7a-linuxapp-gcc?