On Mon, 26 Oct 2015 18:23:07 -0700 (PDT), David Miller wrote:
> From: Jakub Kicinski <jakub.kicin...@netronome.com>
> Date: Fri, 23 Oct 2015 19:58:11 +0100
>
> > +struct nfp_net_tx_buf {
> > + struct sk_buff *skb;
> > + dma_addr_t dma_addr;
> > + short int fidx;
> > + u16 pkt_cnt;
> > + u32 real_len;
> > +};
>
> This packs very poorly, and has a lot of padding holes. Better ordering
> would be:
>
> struct nfp_net_tx_buf {
> struct sk_buff *skb;
> dma_addr_t dma_addr;
> u32 real_len;
> short int fidx;
> u16 pkt_cnt;
> };
Seems to pack fine on x86:
struct nfp_net_tx_buf {
struct sk_buff * skb; /* 0 8 */
dma_addr_t dma_addr; /* 8 8 */
short int fidx; /* 16 2 */
u16 pkt_cnt; /* 18 2 */
u32 real_len; /* 20 4 */
/* size: 24, cachelines: 1, members: 5 */
/* last cacheline: 24 bytes */
};
Are my packing skills deceiving me? Maybe I'll try to build the driver
for more esoteric architectures.
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