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

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

> -----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
> >