> -----Original Message----- > From: David Laight [mailto:david.lai...@aculab.com] > Sent: Friday, June 09, 2017 10:28 AM > To: 'David Miller' <da...@davemloft.net>; Mintz, Yuval > <yuval.mi...@cavium.com> > Cc: netdev@vger.kernel.org; linux-r...@vger.kernel.org; Kalderon, Michal > <michal.kalde...@cavium.com> > Subject: RE: [PATCH net-next 1/8] qed: LL2 to use packed information for tx > > From: David Miller > > Sent: 09 June 2017 00:24 > > > > From: Yuval Mintz <yuval.mi...@cavium.com> > > Date: Thu, 8 Jun 2017 19:13:16 +0300 > > > > > @@ -67,6 +79,21 @@ struct qed_ll2_stats { > > > u64 sent_bcast_pkts; > > > }; > > > > > > +struct qed_ll2_tx_pkt_info { > > > + u8 num_of_bds; > > > + u16 vlan; > > > + u8 bd_flags; > > > + u16 l4_hdr_offset_w; /* from start of packet */ > > > + enum qed_ll2_tx_dest tx_dest; > > > + enum qed_ll2_roce_flavor_type qed_roce_flavor; > > > + dma_addr_t first_frag; > > > + u16 first_frag_len; > > > + bool enable_ip_cksum; > > > + bool enable_l4_cksum; > > > + bool calc_ip_len; > > > + void *cookie; > > > +}; > > > + > > > > This layout is extremely inefficient, with lots of padding in between > > struct members. > > > > Group small u8 members and u16 members together so that they consume > > full 32-bit areas so you can eliminate all of the padding. > > I'd also query the use of u16 sizes/lengths, any arithmetic on u16 (and u8) > variables is likely to generate extra code (on non-x86). > You are using 32 bits for the 'enum' - I bet the values fit in 8 bits, so > aren't > really worried about size. > > If size did matter you can easily get the above down to 32 bytes.
You're right, and that's exactly the point - since this is not data-path critical I don't see why the size/efficiency should matter [greatly].
