Re: [PATCH liburing v1 1/2] examples/zcrx: Use PAGE_SIZE for ring refill alignment

[Jens Axboe <axboe@kernel.dk>]

On 4/19/25 3:57 AM, Haiyue Wang wrote:
> According to the 'Create refill ring' section in [1], use the macro
> PAGE_SIZE instead of 4096 hard code number.
> 
> [1]: https://www.kernel.org/doc/html/latest/networking/iou-zcrx.html
> 
> Signed-off-by: Haiyue Wang <haiyuewa@163.com>
> ---
>  examples/zcrx.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/examples/zcrx.c b/examples/zcrx.c
> index 8393cfe..c96bbfe 100644
> --- a/examples/zcrx.c
> +++ b/examples/zcrx.c
> @@ -66,7 +66,7 @@ static inline size_t get_refill_ring_size(unsigned int rq_entries)
>  	ring_size = rq_entries * sizeof(struct io_uring_zcrx_rqe);
>  	/* add space for the header (head/tail/etc.) */
>  	ring_size += PAGE_SIZE;
> -	return T_ALIGN_UP(ring_size, 4096);
> +	return T_ALIGN_UP(ring_size, PAGE_SIZE);
>  }
>  
>  static void setup_zcrx(struct io_uring *ring)

Well, in that same file:

#define PAGE_SIZE (4096)         

so this won't really fix anything. Examples or test code
should use:

sysconf(_SC_PAGESIZE)

to get the page size at runtime.

-- 
Jens Axboe