Re: rte_mbuf library likely()/unlikely()

[Stephen Hemminger <stephen@networkplumber.org>]

On Mon, 23 Jul 2018 15:53:42 +0200
Morten Brørup <mb@smartsharesystems.com> wrote:

> Hi Olivier,
> 
>  
> 
> I noticed that __rte_pktmbuf_read() could do with an unlikely(), so I went through the entire library. Here are my suggested modifications.
> 
>  
> 
>  
> 
> diff -bu rte_mbuf.c.orig rte_mbuf.c
> 
> --- rte_mbuf.c.orig     2018-07-23 15:13:22.000000000 +0200
> 
> +++ rte_mbuf.c  2018-07-23 15:32:53.000000000 +0200
> 
> @@ -173,19 +173,19 @@
> 
> {
> 
>         unsigned int nb_segs, pkt_len;
> 
>  
> 
> -       if (m == NULL)
> 
> +       if (unlikely(m == NULL))
> 
>                 rte_panic("mbuf is NULL\n");
> 
>  

Adding is unlikely is not necessary since rte_panic is marked with cold attribute
which has the same effect.