Re: [dpdk-dev] [PATCH 25/33] app/testeventdev: perf queue: add worker functions

[Jerin Jacob <jerin.jacob@caviumnetworks.com>]

-----Original Message-----
> Date: Thu, 1 Jun 2017 21:04:15 +0000
> From: "Eads, Gage" <gage.eads@intel.com>
> To: Jerin Jacob <jerin.jacob@caviumnetworks.com>, "dev@dpdk.org"
>  <dev@dpdk.org>
> CC: "Richardson, Bruce" <bruce.richardson@intel.com>, "Van Haaren, Harry"
>  <harry.van.haaren@intel.com>, "hemant.agrawal@nxp.com"
>  <hemant.agrawal@nxp.com>, "nipun.gupta@nxp.com" <nipun.gupta@nxp.com>,
>  "Vangati, Narender" <narender.vangati@intel.com>, "Rao, Nikhil"
>  <nikhil.rao@intel.com>, "gprathyusha@caviumnetworks.com"
>  <gprathyusha@caviumnetworks.com>
> Subject: RE: [dpdk-dev] [PATCH 25/33] app/testeventdev: perf queue: add
>  worker functions
> 
> 
> 
> >  -----Original Message-----
> >  From: Jerin Jacob [mailto:jerin.jacob@caviumnetworks.com]
> >  Sent: Sunday, May 28, 2017 2:59 PM
> >  To: dev@dpdk.org
> >  Cc: Richardson, Bruce <bruce.richardson@intel.com>; Van Haaren, Harry
> >  <harry.van.haaren@intel.com>; hemant.agrawal@nxp.com; Eads, Gage
> >  <gage.eads@intel.com>; nipun.gupta@nxp.com; Vangati, Narender
> >  <narender.vangati@intel.com>; Rao, Nikhil <nikhil.rao@intel.com>;
> >  gprathyusha@caviumnetworks.com; Jerin Jacob
> >  <jerin.jacob@caviumnetworks.com>
> >  Subject: [dpdk-dev] [PATCH 25/33] app/testeventdev: perf queue: add worker
> >  functions
> >  
> >  Signed-off-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
> >  ---
> >   app/test-eventdev/test_perf_common.h |  60 +++++++++++++++  app/test-
> >  eventdev/test_perf_queue.c  | 137 +++++++++++++++++++++++++++++++++++
> >   2 files changed, 197 insertions(+)
> >  
> >  diff --git a/app/test-eventdev/test_perf_common.h b/app/test-
> >  eventdev/test_perf_common.h
> >  index f8246953a..9888e5078 100644
> >  --- a/app/test-eventdev/test_perf_common.h
> >  +++ b/app/test-eventdev/test_perf_common.h
> >  @@ -86,6 +86,66 @@ struct perf_elt {
> >   	uint64_t timestamp;
> >   } __rte_cache_aligned;
> >  
> >  +#define BURST_SIZE 16
> >  +
> >  +#define PERF_WORKER_INIT\
> >  +	struct worker_data *w  = arg;\
> >  +	struct test_perf *t = w->t;\
> >  +	struct evt_options *opt = t->opt;\
> >  +	const uint8_t dev = w->dev_id;\
> >  +	const uint8_t port = w->port_id;\
> >  +	uint8_t *const sched_type_list = &t->sched_type_list[0];\
> >  +	struct rte_mempool *const pool = t->pool;\
> >  +	const uint8_t nb_stages = t->opt->nb_stages;\
> >  +	const uint8_t laststage = nb_stages - 1;\
> >  +	uint8_t cnt = 0;\
> >  +	void *bufs[16] __rte_cache_aligned;\
> >  +	int const sz = RTE_DIM(bufs);\
> >  +	if (opt->verbose_level > 1)\
> >  +		printf("%s(): lcore %d dev_id %d port=%d\n", __func__,\
> >  +				rte_lcore_id(), dev, port)
> >  +
> >  +static inline __attribute__((always_inline)) int
> >  +perf_process_last_stage(struct rte_mempool *const pool,
> >  +		struct rte_event *const ev, struct worker_data *const w,
> >  +		void *bufs[], int const buf_sz, uint8_t count) {
> >  +	bufs[count++] = ev->event_ptr;
> >  +	w->processed_pkts++;
> >  +	rte_smp_wmb();
> >  +
> >  +	if (unlikely(count == buf_sz)) {
> >  +		count = 0;
> >  +		rte_mempool_put_bulk(pool, bufs, buf_sz);
> >  +	}
> >  +	return count;
> >  +}
> >  +
> >  +static inline __attribute__((always_inline)) uint8_t
> >  +perf_process_last_stage_latency(struct rte_mempool *const pool,
> >  +		struct rte_event *const ev, struct worker_data *const w,
> >  +		void *bufs[], int const buf_sz, uint8_t count) {
> >  +	uint64_t latency;
> >  +	struct perf_elt *const m = ev->event_ptr;
> >  +
> >  +	bufs[count++] = ev->event_ptr;
> >  +	w->processed_pkts++;
> >  +
> >  +	if (unlikely(count == buf_sz)) {
> >  +		count = 0;
> >  +		latency = rte_get_timer_cycles() - m->timestamp;
> >  +		rte_mempool_put_bulk(pool, bufs, buf_sz);
> >  +	} else {
> >  +		latency = rte_get_timer_cycles() - m->timestamp;
> >  +	}
> >  +
> >  +	w->latency += latency;
> >  +	rte_smp_wmb();
> >  +	return count;
> >  +}
> 
> What purpose does the store barrier serve in these two functions?

The master core(!worker core) reads w->latency and
w->processed_pkts periodically from all workers.