Re: [dpdk-dev] [PATCH] config: set cache line as 128B in the generic arm64 config

[santosh <santosh.shukla@caviumnetworks.com>]

Hi Jerin,

On Wednesday 26 April 2017 09:59 PM, Jerin Jacob wrote:

> armv8 implementations may have 64B or 128B cache line.
> Setting to the maximum available cache line size in generic config to
> address minimum DMA alignment across all arm64 implementations.
>
> Increasing the cacheline size has no negative impact to cache invalidation
> on systems with a smaller cache line.
>
> The need for the minimum DMA alignment has impact on functional aspects
> of the platform so default config should cater the functional aspects.
>
> There is an impact on memory usage with this scheme, but that's not too
> important for the single image arm64 distribution use case.
>
> The arm64 linux kernel followed the similar approach for single
> arm64 image use case.
> http://lxr.free-electrons.com/source/arch/arm64/include/asm/cache.h
>
> Signed-off-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
> ---
>  config/defconfig_arm64-armv8a-linuxapp-gcc | 5 +++++
>  config/defconfig_arm64-dpaa2-linuxapp-gcc  | 1 +
>  config/defconfig_arm64-xgene1-linuxapp-gcc | 1 +
>  3 files changed, 7 insertions(+)
>
> diff --git a/config/defconfig_arm64-armv8a-linuxapp-gcc b/config/defconfig_arm64-armv8a-linuxapp-gcc
> index 65888cef1..0faa2d3a3 100644
> --- a/config/defconfig_arm64-armv8a-linuxapp-gcc
> +++ b/config/defconfig_arm64-armv8a-linuxapp-gcc
> @@ -42,6 +42,11 @@ CONFIG_RTE_FORCE_INTRINSICS=y
>  CONFIG_RTE_TOOLCHAIN="gcc"
>  CONFIG_RTE_TOOLCHAIN_GCC=y
>  
> +#Maximum available cache line size in arm64 implementations. Setting to maximum
> +#available cache line size in generic config to address minimum DMA alignment
> +#across all arm64 implementations.
> +CONFIG_RTE_CACHE_LINE_SIZE=128
> +
>  CONFIG_RTE_EAL_IGB_UIO=n
>  
>  CONFIG_RTE_LIBRTE_FM10K_PMD=n
> diff --git a/config/defconfig_arm64-dpaa2-linuxapp-gcc b/config/defconfig_arm64-dpaa2-linuxapp-gcc
> index 010cb8092..314a0eceb 100644
> --- a/config/defconfig_arm64-dpaa2-linuxapp-gcc
> +++ b/config/defconfig_arm64-dpaa2-linuxapp-gcc
> @@ -41,6 +41,7 @@ CONFIG_RTE_ARCH_ARM_TUNE="cortex-a57+fp+simd"
>  #
>  CONFIG_RTE_MAX_LCORE=8
>  CONFIG_RTE_MAX_NUMA_NODES=1
> +CONFIG_RTE_CACHE_LINE_SIZE=64
>  
>  CONFIG_RTE_PKTMBUF_HEADROOM=256
>  
> diff --git a/config/defconfig_arm64-xgene1-linuxapp-gcc b/config/defconfig_arm64-xgene1-linuxapp-gcc
> index f096166b7..d8e544728 100644
> --- a/config/defconfig_arm64-xgene1-linuxapp-gcc
> +++ b/config/defconfig_arm64-xgene1-linuxapp-gcc
> @@ -32,3 +32,4 @@
>  #include "defconfig_arm64-armv8a-linuxapp-gcc"
>  
>  CONFIG_RTE_MACHINE="xgene1"
> +CONFIG_RTE_CACHE_LINE_SIZE=64

Acked-by : Santosh Shukla <santosh.shukla@caviumnetworks.com>

Thanks,!