Hi Olivier,
> Hi Konstantin,
>
> On Mon, Jun 29, 2020 at 05:10:24PM +0100, Konstantin Ananyev wrote:
> > v2:
> > - update Release Notes (as per comments)
> >
> > Two new sync modes were introduced into rte_ring:
> > relaxed tail sync (RTS) and head/tail sync (HTS).
> > This change provides user with ability to select these
> > modes for ring based mempool via mempool ops API.
> >
> > Signed-off-by: Konstantin Ananyev <konstantin.anan...@intel.com>
> > Acked-by: Gage Eads <gage.e...@intel.com>
> > ---
> > doc/guides/rel_notes/release_20_08.rst | 6 ++
> > drivers/mempool/ring/rte_mempool_ring.c | 97 ++++++++++++++++++++++---
> > 2 files changed, 94 insertions(+), 9 deletions(-)
> >
> > diff --git a/doc/guides/rel_notes/release_20_08.rst
> > b/doc/guides/rel_notes/release_20_08.rst
> > index eaaf11c37..7bdcf3aac 100644
> > --- a/doc/guides/rel_notes/release_20_08.rst
> > +++ b/doc/guides/rel_notes/release_20_08.rst
> > @@ -84,6 +84,12 @@ New Features
> > * Dump ``rte_flow`` memory consumption.
> > * Measure packet per second forwarding.
> >
> > +* **Added support for new sync modes into mempool ring driver.**
> > +
> > + Added ability to select new ring synchronisation modes:
> > + ``relaxed tail sync (ring_mt_rts)`` and ``head/tail sync (ring_mt_hts)``
> > + via mempool ops API.
> > +
> >
> > Removed Items
> > -------------
> > diff --git a/drivers/mempool/ring/rte_mempool_ring.c
> > b/drivers/mempool/ring/rte_mempool_ring.c
> > index bc123fc52..15ec7dee7 100644
> > --- a/drivers/mempool/ring/rte_mempool_ring.c
> > +++ b/drivers/mempool/ring/rte_mempool_ring.c
> > @@ -25,6 +25,22 @@ common_ring_sp_enqueue(struct rte_mempool *mp, void *
> > const *obj_table,
> > obj_table, n, NULL) == 0 ? -ENOBUFS : 0;
> > }
> >
> > +static int
> > +rts_ring_mp_enqueue(struct rte_mempool *mp, void * const *obj_table,
> > + unsigned int n)
> > +{
> > + return rte_ring_mp_rts_enqueue_bulk(mp->pool_data,
> > + obj_table, n, NULL) == 0 ? -ENOBUFS : 0;
> > +}
> > +
> > +static int
> > +hts_ring_mp_enqueue(struct rte_mempool *mp, void * const *obj_table,
> > + unsigned int n)
> > +{
> > + return rte_ring_mp_hts_enqueue_bulk(mp->pool_data,
> > + obj_table, n, NULL) == 0 ? -ENOBUFS : 0;
> > +}
> > +
> > static int
> > common_ring_mc_dequeue(struct rte_mempool *mp, void **obj_table, unsigned
> > n)
> > {
> > @@ -39,17 +55,30 @@ common_ring_sc_dequeue(struct rte_mempool *mp, void
> > **obj_table, unsigned n)
> > obj_table, n, NULL) == 0 ? -ENOBUFS : 0;
> > }
> >
> > +static int
> > +rts_ring_mc_dequeue(struct rte_mempool *mp, void **obj_table, unsigned int
> > n)
> > +{
> > + return rte_ring_mc_rts_dequeue_bulk(mp->pool_data,
> > + obj_table, n, NULL) == 0 ? -ENOBUFS : 0;
> > +}
> > +
> > +static int
> > +hts_ring_mc_dequeue(struct rte_mempool *mp, void **obj_table, unsigned int
> > n)
> > +{
> > + return rte_ring_mc_hts_dequeue_bulk(mp->pool_data,
> > + obj_table, n, NULL) == 0 ? -ENOBUFS : 0;
> > +}
> > +
> > static unsigned
> > common_ring_get_count(const struct rte_mempool *mp)
> > {
> > return rte_ring_count(mp->pool_data);
> > }
> >
> > -
> > static int
> > -common_ring_alloc(struct rte_mempool *mp)
> > +ring_alloc(struct rte_mempool *mp, uint32_t rg_flags)
> > {
> > - int rg_flags = 0, ret;
> > + int ret;
> > char rg_name[RTE_RING_NAMESIZE];
> > struct rte_ring *r;
> >
> > @@ -60,12 +89,6 @@ common_ring_alloc(struct rte_mempool *mp)
> > return -rte_errno;
> > }
> >
> > - /* ring flags */
> > - if (mp->flags & MEMPOOL_F_SP_PUT)
> > - rg_flags |= RING_F_SP_ENQ;
> > - if (mp->flags & MEMPOOL_F_SC_GET)
> > - rg_flags |= RING_F_SC_DEQ;
> > -
> > /*
> > * Allocate the ring that will be used to store objects.
> > * Ring functions will return appropriate errors if we are
> > @@ -82,6 +105,40 @@ common_ring_alloc(struct rte_mempool *mp)
> > return 0;
> > }
> >
> > +static int
> > +common_ring_alloc(struct rte_mempool *mp)
> > +{
> > + uint32_t rg_flags;
> > +
> > + rg_flags = 0;
>
> Maybe it could go on the same line
>
> > +
> > + /* ring flags */
>
> Not sure we need to keep this comment
>
> > + if (mp->flags & MEMPOOL_F_SP_PUT)
> > + rg_flags |= RING_F_SP_ENQ;
> > + if (mp->flags & MEMPOOL_F_SC_GET)
> > + rg_flags |= RING_F_SC_DEQ;
> > +
> > + return ring_alloc(mp, rg_flags);
> > +}
> > +
> > +static int
> > +rts_ring_alloc(struct rte_mempool *mp)
> > +{
> > + if ((mp->flags & (MEMPOOL_F_SP_PUT | MEMPOOL_F_SC_GET)) != 0)
> > + return -EINVAL;
>
> Why do we need this? It is a problem to allow sc/sp in this mode (even
> if it's not optimal)?
These new sync modes (RTS, HTS) are for MT.
For SP/SC - there is simply no point to use MT sync modes.
I suppose there are few choices:
1. Make F_SP_PUT/F_SC_GET flags silently override expected ops behaviour
and create actual ring with ST sync mode for prod/cons.
2. Report an error.
3. Silently ignore these flags.
As I can see for "ring_mp_mc" ops, we doing #1,
while for "stack" we are doing #3.
For RTS/HTS I chosoe #2, as it seems cleaner to me.
Any thoughts from your side what preferable behaviour should be?
>
> > +
> > + return ring_alloc(mp, RING_F_MP_RTS_ENQ | RING_F_MC_RTS_DEQ);
> > +}
> > +
> > +static int
> > +hts_ring_alloc(struct rte_mempool *mp)
> > +{
> > + if ((mp->flags & (MEMPOOL_F_SP_PUT | MEMPOOL_F_SC_GET)) != 0)
> > + return -EINVAL;
> > +
> > + return ring_alloc(mp, RING_F_MP_HTS_ENQ | RING_F_MC_HTS_DEQ);
> > +}
> > +
> > static void
> > common_ring_free(struct rte_mempool *mp)
> > {
> > @@ -130,7 +187,29 @@ static const struct rte_mempool_ops ops_sp_mc = {
> > .get_count = common_ring_get_count,
> > };
> >
> > +/* ops for mempool with ring in MT_RTS sync mode */
> > +static const struct rte_mempool_ops ops_mt_rts = {
> > + .name = "ring_mt_rts",
> > + .alloc = rts_ring_alloc,
> > + .free = common_ring_free,
> > + .enqueue = rts_ring_mp_enqueue,
> > + .dequeue = rts_ring_mc_dequeue,
> > + .get_count = common_ring_get_count,
> > +};
> > +
> > +/* ops for mempool with ring in MT_HTS sync mode */
> > +static const struct rte_mempool_ops ops_mt_hts = {
> > + .name = "ring_mt_hts",
> > + .alloc = hts_ring_alloc,
> > + .free = common_ring_free,
> > + .enqueue = hts_ring_mp_enqueue,
> > + .dequeue = hts_ring_mc_dequeue,
> > + .get_count = common_ring_get_count,
> > +};
> > +
> > MEMPOOL_REGISTER_OPS(ops_mp_mc);
> > MEMPOOL_REGISTER_OPS(ops_sp_sc);
> > MEMPOOL_REGISTER_OPS(ops_mp_sc);
> > MEMPOOL_REGISTER_OPS(ops_sp_mc);
> > +MEMPOOL_REGISTER_OPS(ops_mt_rts);
> > +MEMPOOL_REGISTER_OPS(ops_mt_hts);
> Not really related to your patch, but I think we need a function to
> dump the name of available mempool ops. We could even add a description.
> The problem we have is that a user does not know on which criteria is
> should use a driver or another (except for platform drivers).
Agree, it will be usefull.
Though it probably subject for a separate patch.
