> -----Original Message-----
> From: Dmitry Eremin-Solenikov [mailto:dmitry.ereminsoleni...@linaro.org]
> Sent: Thursday, February 15, 2018 4:00 PM
> To: Savolainen, Petri (Nokia - FI/Espoo) <petri.savolai...@nokia.com>;
> Bill Fischofer <bill.fischo...@linaro.org>
> Cc: lng-odp-forward <lng-odp@lists.linaro.org>
> Subject: Re: [lng-odp] odp_packet_data() considered harmful
>
> On 15/02/18 16:32, Savolainen, Petri (Nokia - FI/Espoo) wrote:
>
> > odp_packet_offset() is more complex than the proposed
> odp_packet_data_seg_len(). Application mostly finds its data from the
> first segment, so it's important to keep the most common use case fast (==
> simple). We cannot and should not modify/remove current data() and
> offset() functions. But we can add another which combines data() +
> seg_len(), which is mostly enough for application. When application knows
> already that all (interesting) data is in the first segment, it can use
> data() which is the fastest and simplest function (to inline) to get
> access to the data.
>
> I'm fine with proposed odp_packet_data_seg_len() if that will allow us
> to drop odp_packet_data().
There's no need or possibility to remove data(). Documentation for data() may
be improved to be more explicit about possibility of multiple segments. The
function just returns pointer to current head of data, it does not promise
anything more. When application knows already how much data follows (and
usually all data follows), it does not need ask e.g. segment length over and
over again.
static inline void* odp_packet_data(pkt) {
return (pkt_desc_t)pkt->data_ptr;
}
static inline void* odp_packet_data_seg_len(pkt, *len) {
*len = (pkt_desc_t)pkt->seg_len;
return (pkt_desc_t)pkt->data_ptr;
}
The first is faster when application does not need to ask the segment length.
-Petri
