[PATCH v3 09/21] net/ena/base: use optimized memcpy version also on Arm

[Ferruh Yigit]

On 2/23/2022 12:19 PM, Michal Krawczyk wrote:
> As the default behavior for arm64 is to alias rte_memcpy as memcpy, ENA
> cannot redefine memcpy as rte_memcpy as it would cause nested
> declaration.
> 
> To make it possible to use optimized memcpy in the ena_com layer on Arm,

Out of curiosity, do you have any performance measurements for
the optimized memcpy usage?

> the driver now redefines memcpy when it is beneficial:
>    * For arm64 only when the flag RTE_ARCH_ARM64_MEMCPY was defined
>    * For arm only when the flag RTE_ARCH_ARM_NEON_MEMCPY was defined
> 
> Signed-off-by: Michal Krawczyk <mk at semihalf.com>
> Reviewed-by: Dawid Gorecki <dgr at semihalf.com>
> Reviewed-by: Shai Brandes <shaibran at amazon.com>
> ---
>   doc/guides/rel_notes/release_22_03.rst | 1 +
>   drivers/net/ena/base/ena_plat_dpdk.h   | 7 +++++--
>   2 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/doc/guides/rel_notes/release_22_03.rst b/doc/guides/rel_notes/release_22_03.rst
> index c8e38d4c70..92490afd60 100644
> --- a/doc/guides/rel_notes/release_22_03.rst
> +++ b/doc/guides/rel_notes/release_22_03.rst
> @@ -112,6 +112,7 @@ New Features
>     * Added new checksum related xstats: ``l3_csum_bad``, ``l4_csum_bad`` and
>       ``l4_csum_good``.
>     * Added support for the link status configuration.
> +  * Added optimized memcpy support for the ARM platforms.
>   
>   * **Updated Cisco enic driver.**
>   
> diff --git a/drivers/net/ena/base/ena_plat_dpdk.h b/drivers/net/ena/base/ena_plat_dpdk.h
> index 4e7f52881a..41db883c63 100644
> --- a/drivers/net/ena/base/ena_plat_dpdk.h
> +++ b/drivers/net/ena/base/ena_plat_dpdk.h
> @@ -66,8 +66,11 @@ typedef uint64_t dma_addr_t;
>   #define ENA_UDELAY(x) rte_delay_us_block(x)
>   
>   #define ENA_TOUCH(x) ((void)(x))
> -/* Avoid nested declaration on arm64, as it may define rte_memcpy as memcpy. */
> -#if defined(RTE_ARCH_X86)
> +/* Redefine memcpy with caution: rte_memcpy can be simply aliased to memcpy, so
> + * make the redefinition only if it's safe (and beneficial) to do so.
> + */
> +#if defined(RTE_ARCH_X86) || defined(RTE_ARCH_ARM64_MEMCPY) || \
> +	defined(RTE_ARCH_ARM_NEON_MEMCPY)
>   #undef memcpy
>   #define memcpy rte_memcpy
>   #endif

I can see there is 'ena_plat_dpdk.h', which seems like an osdep header,

it is possible to use 'ena_memcpy' in the code and in the 'ena_plat_dpdk.h'
define it as:
#define ena_memcpy rte_memcpy


This is just for your information if it helps, usage is up to you.