[PATCH v1 03/13] graph: add macro to walk on graph circular buffer

[Yan, Zhirun]

> -----Original Message-----
> From: Jerin Jacob <jerinjacobk at gmail.com>
> Sent: Monday, February 20, 2023 9:45 PM
> To: Yan, Zhirun <zhirun.yan at intel.com>
> Cc: dev at dpdk.org; jerinj at marvell.com; kirankumark at marvell.com;
> ndabilpuram at marvell.com; Liang, Cunming <cunming.liang at intel.com>; Wang,
> Haiyue <haiyue.wang at intel.com>
> Subject: Re: [PATCH v1 03/13] graph: add macro to walk on graph circular buffer
> 
> On Thu, Nov 17, 2022 at 10:40 AM Zhirun Yan <zhirun.yan at intel.com> wrote:
> >
> > It is common to walk on graph circular buffer and use macro to make it
> > reusable for other worker models.
> >
> > Signed-off-by: Haiyue Wang <haiyue.wang at intel.com>
> > Signed-off-by: Cunming Liang <cunming.liang at intel.com>
> > Signed-off-by: Zhirun Yan <zhirun.yan at intel.com>
> > ---
> >  lib/graph/rte_graph_model_rtc.h     | 23 ++---------------------
> >  lib/graph/rte_graph_worker_common.h | 23 +++++++++++++++++++++++
> >  2 files changed, 25 insertions(+), 21 deletions(-)
> 
> > +/**
> > + * Macro to walk on the source node(s) ((cir_start - head) ->
> > +cir_start)
> > + * and then on the pending streams
> > + * (cir_start -> (cir_start + mask) -> cir_start)
> > + * in a circular buffer fashion.
> > + *
> > + *     +-----+ <= cir_start - head [number of source nodes]
> > + *     |     |
> > + *     | ... | <= source nodes
> > + *     |     |
> > + *     +-----+ <= cir_start [head = 0] [tail = 0]
> > + *     |     |
> > + *     | ... | <= pending streams
> > + *     |     |
> > + *     +-----+ <= cir_start + mask
> > + */
> > +#define rte_graph_walk_node(graph, head, node)                                         \
> > +       for ((node) = RTE_PTR_ADD((graph), (graph)->cir_start[(int32_t)(head)]);
> \
> > +            likely((head) != (graph)->tail);                                           \
> > +            (head)++,                                                                  \
> > +            (node) = RTE_PTR_ADD((graph), (graph)->cir_start[(int32_t)(head)]),
> \
> 
> This is an additional assignment compare to original while() based version. Right?
> No need to generalize with performance impact.
Yes, you are right. I will change the macro to use the original while loop.

> 
> 
> > +            (head) = likely((int32_t)(head) > 0) ? (head) &
> > + (graph)->cir_mask : (head))
> > +
> >  /**
> >   * @internal
> >   *
> > --
> > 2.25.1
> >