Re: [PATCH] reorder: improve buffer structure layout

[Bruce Richardson <bruce.richardson@intel.com>]

On Fri, Apr 14, 2023 at 10:43:43AM +0200, Volodymyr Fialko wrote:
> Rearrange the reorder buffer structure to prevent padding to extra one
> cache line.
> 
> Current layout:
> struct rte_reorder_buffer {
>         char name[RTE_REORDER_NAMESIZE];
>         uint32_t min_seqn;
>         unsigned int memsize;
> // -> padding to cache align (cir_buffer is also cache aligned)
>         struct cir_buffer ready_buf;
>         struct cir_buffer order_buf;
>         int is_initialized;
> // -> padding to cache align, eat whole line
> };
> 
> New layout:
> struct rte_reorder_buffer {
>         char name[RTE_REORDER_NAMESIZE];
>         uint32_t min_seqn;
>         unsigned int memsize;
>         int is_initialized;
> // -> padding to cache align (cir_buffer is also cache aligned)
>         struct cir_buffer ready_buf;
>         struct cir_buffer order_buf;
> // -> no padding
> };
> 
> Signed-off-by: Volodymyr Fialko <vfialko@marvell.com>
> ---

Acked-by: Bruce Richardson <bruce.richardson@intel.com>

>  lib/reorder/rte_reorder.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/reorder/rte_reorder.c b/lib/reorder/rte_reorder.c
> index f55f383700..7418202b04 100644
> --- a/lib/reorder/rte_reorder.c
> +++ b/lib/reorder/rte_reorder.c
> @@ -46,9 +46,10 @@ struct rte_reorder_buffer {
>  	char name[RTE_REORDER_NAMESIZE];
>  	uint32_t min_seqn;  /**< Lowest seq. number that can be in the buffer */
>  	unsigned int memsize; /**< memory area size of reorder buffer */
> +	int is_initialized; /**< flag indicates that buffer was initialized */
> +

Since we are moving it, it might be an opportunity to change it from "int"
to "bool".

>  	struct cir_buffer ready_buf; /**< temp buffer for dequeued entries */
>  	struct cir_buffer order_buf; /**< buffer used to reorder entries */
> -	int is_initialized;
>  } __rte_cache_aligned;
>  
>  static void
> -- 
> 2.34.1
>