Re: [dpdk-dev] [PATCH] Add user defined tag calculation callback to librte_distributor.

[jigsaw <jigsaw@gmail.com>]

Hi Konstantin,

I agree with you. A callback is not necessary. Pls refer to my previous
mail, which proposed a not-at-all-intrusive patch.
Pls let me know your concern.

thx &
rgds,
-qinglai

On Wed, Nov 5, 2014 at 5:13 PM, Ananyev, Konstantin <
konstantin.ananyev@intel.com> wrote:

>
>
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Bruce Richardson
> > Sent: Wednesday, November 05, 2014 2:28 PM
> > To: Qinglai Xiao
> > Cc: dev@dpdk.org
> > Subject: Re: [dpdk-dev] [PATCH] Add user defined tag calculation
> callback to librte_distributor.
> >
> > On Wed, Nov 05, 2014 at 03:30:37PM +0200, Qinglai Xiao wrote:
> > > User defined tag calculation has access to mbuf.
> > > Default tag is RSS hash result.
> > >
> >
> > Interesting idea.
> > Did you investigate was there any performance improvement or regression
> comparing
> > whether the callback was called per-packet as packets were dequeued for
> distribution
> > (i.e. how you have things now in your patch), compared to calling
> > the callback in a loop to extract the tags for all packets initially? I
> suspect
> > there probably isn't much performance difference either way, but it may
> be worth
> > checking.
> > One other point, is that I think the callback to extract the tag should
> have
> > additional parameters - at least one, if not two. I would suggest that
> the
> > distributor pointer be passed in, as well as an arbitrary void * pointer.
>
>
> Just wonder, why do you need a call-back?
> Why not just make rte_distributor_process() to accept an extra parameter:
> array of tags?
>
> rte_distributor_process(struct rte_distributor *d,
>                 struct rte_mbuf **mbufs, uint32_t *mbuf_tags, unsigned
> num_mbufs)
>
> ?
>
>
> >
> > Regards,
> > /Bruce
> >
> > > Signed-off-by: Qinglai Xiao <jigsaw@gmail.com>
> > > ---
> > >  app/test/test_distributor.c              |    6 +++---
> > >  app/test/test_distributor_perf.c         |    2 +-
> > >  lib/librte_distributor/rte_distributor.c |   12 ++++++++++--
> > >  lib/librte_distributor/rte_distributor.h |    7 ++++++-
> > >  4 files changed, 20 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/app/test/test_distributor.c b/app/test/test_distributor.c
> > > index ce06436..6ea4943 100644
> > > --- a/app/test/test_distributor.c
> > > +++ b/app/test/test_distributor.c
> > > @@ -452,7 +452,7 @@ int test_error_distributor_create_name(void)
> > >     char *name = NULL;
> > >
> > >     d = rte_distributor_create(name, rte_socket_id(),
> > > -                   rte_lcore_count() - 1);
> > > +                   rte_lcore_count() - 1, NULL);
> > >     if (d != NULL || rte_errno != EINVAL) {
> > >             printf("ERROR: No error on create() with NULL name
> param\n");
> > >             return -1;
> > > @@ -467,7 +467,7 @@ int test_error_distributor_create_numworkers(void)
> > >  {
> > >     struct rte_distributor *d = NULL;
> > >     d = rte_distributor_create("test_numworkers", rte_socket_id(),
> > > -                   RTE_MAX_LCORE + 10);
> > > +                   RTE_MAX_LCORE + 10, NULL);
> > >     if (d != NULL || rte_errno != EINVAL) {
> > >             printf("ERROR: No error on create() with num_workers >
> MAX\n");
> > >             return -1;
> > > @@ -515,7 +515,7 @@ test_distributor(void)
> > >
> > >     if (d == NULL) {
> > >             d = rte_distributor_create("Test_distributor",
> rte_socket_id(),
> > > -                           rte_lcore_count() - 1);
> > > +                           rte_lcore_count() - 1, NULL);
> > >             if (d == NULL) {
> > >                     printf("Error creating distributor\n");
> > >                     return -1;
> > > diff --git a/app/test/test_distributor_perf.c
> b/app/test/test_distributor_perf.c
> > > index b04864c..507e446 100644
> > > --- a/app/test/test_distributor_perf.c
> > > +++ b/app/test/test_distributor_perf.c
> > > @@ -227,7 +227,7 @@ test_distributor_perf(void)
> > >
> > >     if (d == NULL) {
> > >             d = rte_distributor_create("Test_perf", rte_socket_id(),
> > > -                           rte_lcore_count() - 1);
> > > +                           rte_lcore_count() - 1, NULL);
> > >             if (d == NULL) {
> > >                     printf("Error creating distributor\n");
> > >                     return -1;
> > > diff --git a/lib/librte_distributor/rte_distributor.c
> b/lib/librte_distributor/rte_distributor.c
> > > index 585ff88..78c92bd 100644
> > > --- a/lib/librte_distributor/rte_distributor.c
> > > +++ b/lib/librte_distributor/rte_distributor.c
> > > @@ -97,6 +97,7 @@ struct rte_distributor {
> > >     union rte_distributor_buffer bufs[RTE_MAX_LCORE];
> > >
> > >     struct rte_distributor_returned_pkts returns;
> > > +   rte_distributor_tag_fn tag_cb;
> > >  };
> > >
> > >  TAILQ_HEAD(rte_distributor_list, rte_distributor);
> > > @@ -267,6 +268,7 @@ rte_distributor_process(struct rte_distributor *d,
> > >     struct rte_mbuf *next_mb = NULL;
> > >     int64_t next_value = 0;
> > >     uint32_t new_tag = 0;
> > > +   rte_distributor_tag_fn tag_cb = d->tag_cb;
> > >     unsigned ret_start = d->returns.start,
> > >                     ret_count = d->returns.count;
> > >
> > > @@ -282,7 +284,11 @@ rte_distributor_process(struct rte_distributor *d,
> > >                     next_mb = mbufs[next_idx++];
> > >                     next_value = (((int64_t)(uintptr_t)next_mb)
> > >                                     << RTE_DISTRIB_FLAG_BITS);
> > > -                   new_tag = (next_mb->hash.rss | 1);
> > > +                   if (tag_cb) {
> > > +                           new_tag = tag_cb(next_mb);
> > > +                   } else {
> > > +                           new_tag = (next_mb->hash.rss | 1);
> > > +                   }
> > >
> > >                     uint32_t match = 0;
> > >                     unsigned i;
> > > @@ -401,7 +407,8 @@ rte_distributor_clear_returns(struct
> rte_distributor *d)
> > >  struct rte_distributor *
> > >  rte_distributor_create(const char *name,
> > >             unsigned socket_id,
> > > -           unsigned num_workers)
> > > +           unsigned num_workers,
> > > +           rte_distributor_tag_fn tag_cb)
> > >  {
> > >     struct rte_distributor *d;
> > >     struct rte_distributor_list *distributor_list;
> > > @@ -435,6 +442,7 @@ rte_distributor_create(const char *name,
> > >     d = mz->addr;
> > >     snprintf(d->name, sizeof(d->name), "%s", name);
> > >     d->num_workers = num_workers;
> > > +   d->tag_cb = tag_cb;
> > >
> > >     rte_rwlock_write_lock(RTE_EAL_TAILQ_RWLOCK);
> > >     TAILQ_INSERT_TAIL(distributor_list, d, next);
> > > diff --git a/lib/librte_distributor/rte_distributor.h
> b/lib/librte_distributor/rte_distributor.h
> > > index ec0d74a..844d325 100644
> > > --- a/lib/librte_distributor/rte_distributor.h
> > > +++ b/lib/librte_distributor/rte_distributor.h
> > > @@ -52,6 +52,9 @@ extern "C" {
> > >
> > >  struct rte_distributor;
> > >
> > > +typedef uint32_t (*rte_distributor_tag_fn)(struct rte_mbuf *);
> > > +/**< User defined tag calculation function */
> > > +
> > >  /**
> > >   * Function to create a new distributor instance
> > >   *
> > > @@ -65,12 +68,14 @@ struct rte_distributor;
> > >   * @param num_workers
> > >   *   The maximum number of workers that will request packets from this
> > >   *   distributor
> > > + * @param tag_cb
> > > + *   The callback function for calculation of user defined tag.
> > >   * @return
> > >   *   The newly created distributor instance
> > >   */
> > >  struct rte_distributor *
> > >  rte_distributor_create(const char *name, unsigned socket_id,
> > > -           unsigned num_workers);
> > > +           unsigned num_workers, rte_distributor_tag_fn tag_cb);
> > >
> > >  /*  *** APIS to be called on the distributor lcore ***  */
> > >  /*
> > > --
> > > 1.7.1
> > >
>