[dpdk-dev] [PATCH] Add user defined tag calculation callback to librte_distributor.
Bruce Richardson
bruce.richardson at intel.com
Wed Nov 5 17:36:55 CET 2014
On Wed, Nov 05, 2014 at 05:11:51PM +0200, jigsaw wrote:
> Hi Bruce,
>
> Thanks for reply.
> The idea is triggered by real life use case, where the flow id is buried in
> L3 payload. Deep packet inspection is one of the scenarios, tunneled pkts
> is another.
> However, only functionality is verified. Performance impact has not been
> checked yet.
>
> To add distributor and another void * as params is nice.
>
> Your advice of extract tags in a row inspired me another solution, which is
> to change the union hash inside rte_mbuf:
>
> diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
> index e8f9bfc..5b13c0b 100644
> --- a/lib/librte_mbuf/rte_mbuf.h
> +++ b/lib/librte_mbuf/rte_mbuf.h
> @@ -185,6 +185,7 @@ struct rte_mbuf {
> uint16_t id;
> } fdir; /**< Filter identifier if FDIR enabled */
> uint32_t sched; /**< Hierarchical scheduler */
> + uint32_t user; /**< User defined hash tag */
> } hash; /**< hash information */
>
> /* second cache line - fields only used in slow path or on TX */
>
> The new union field user is actually for documentation purpose only, coz
> user application can set hash.rss value and have the same result.
> Therefore, the user application is free to calculate the tag in burst mode
> before calling rte_distributor_process.
>
> Then rte_distributor_process needs to read next_mb->hash.user.
> Does it sounds better?
What you propose is the exact original intent, though I did not try to add
a new union member purely for documentation purposes. I had planned, but
perhaps did not explain well enough, that the application would itself set up
the tag as it thought best before passing packets to the distributor. I suspect
that overloading the RSS field for this impeded that idea geting through.
/Bruce
>
> I have another question: why the logical OR 1 is added to new_tag?
>
> thx &
> rgds,
> -qinglai
>
>
>
>
>
>
>
> On Wed, Nov 5, 2014 at 4:27 PM, Bruce Richardson <bruce.richardson at intel.com
> > wrote:
>
> > 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.
> >
> > Regards,
> > /Bruce
> >
> > > Signed-off-by: Qinglai Xiao <jigsaw at 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
> > >
> >
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