On Thu, Sep 03, 2020 at 10:58:45PM +0200, Lorenzo Bianconi wrote:
> Introduce multi-buffer bit (mb) in xdp_frame/xdp_buffer to specify
> if shared_info area has been properly initialized for non-linear
> xdp buffers
>
> Signed-off-by: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
> ---
> include/net/xdp.h | 8 ++++++--
> net/core/xdp.c | 1 +
> 2 files changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/include/net/xdp.h b/include/net/xdp.h
> index 3814fb631d52..42f439f9fcda 100644
> --- a/include/net/xdp.h
> +++ b/include/net/xdp.h
> @@ -72,7 +72,8 @@ struct xdp_buff {
> void *data_hard_start;
> struct xdp_rxq_info *rxq;
> struct xdp_txq_info *txq;
> - u32 frame_sz; /* frame size to deduce data_hard_end/reserved tailroom*/
> + u32 frame_sz:31; /* frame size to deduce data_hard_end/reserved tailroom*/
> + u32 mb:1; /* xdp non-linear buffer */
> };
>
> /* Reserve memory area at end-of data area.
> @@ -96,7 +97,8 @@ struct xdp_frame {
> u16 len;
> u16 headroom;
> u32 metasize:8;
> - u32 frame_sz:24;
> + u32 frame_sz:23;
> + u32 mb:1; /* xdp non-linear frame */
Hmm. Last time I checked compilers were generating ugly code with bitfields.
Not performant and not efficient.
frame_sz is used in the fast path.
I suspect the first hunk alone will cause performance degradation.
Could you use normal u8 or u32 flag field?
