Re: [dpdk-dev] [PATCH v6 08/10] examples/l2fwd-event: add eventdev main loop

[Pavan Nikhilesh Bhagavatula <pbhagavatula@marvell.com>]

Hi Vipin,

>HI Pavan,
>
>snipped
>> Add event dev main loop based on enabled l2fwd options and
>eventdev
>> capabilities.
>>
>> Signed-off-by: Pavan Nikhilesh <pbhagavatula@marvell.com>
>> ---
>> +	if (rsrc->event_mode) {
>> +		port_conf.rxmode.mq_mode = ETH_MQ_RX_RSS;
>> +		port_conf.rx_adv_conf.rss_conf.rss_key = NULL;
>> +		port_conf.rx_adv_conf.rss_conf.rss_hf = ETH_RSS_IP;
>> +	}
>Question, is RSS hash configured for generating flow id for Eventdev?
>As my understanding. RSS for single RX port-queue pair does not
>require the same.
>snipped

In case of SW event device i.e. vdev=event_sw0 the software Rx adapter requires mbuf::rss:hash 
to distribute packets else it has to calculate rss.

@see lib/librte_eventdev/rte_event_eth_rx_adapter.c +817
'
                rss = do_rss ?
                        rxa_do_softrss(m, rx_adapter->rss_key_be) :
                        m->hash.rss;
'

>> +		if (is_master && timer_period > 0) {
>> +			cur_tsc = rte_rdtsc();
>> +			diff_tsc = cur_tsc - prev_tsc;
>> +
>> +			/* advance the timer */
>> +			timer_tsc += diff_tsc;
>> +
>> +			/* if timer has reached its timeout */
>> +			if (unlikely(timer_tsc >= timer_period)) {
>> +				print_stats(rsrc);
>> +				/* reset the timer */
>> +				timer_tsc = 0;
>> +			}
>> +			prev_tsc = cur_tsc;
>> +		}
>Is it possible to move the print_stats to service core, as 'CALL_MASTER'
>is enabled in remote_launch making this a potential worker?
>

Since not every eventdevice requires Service core user might not pass service core mask.
Instead we could do SKIP_MASTER and prints stats here.

>> +
>> +		/* Read packet from eventdev */
>> +		if (!rte_event_dequeue_burst(event_d_id, port_id,
>&ev, 1, 0))
>> +			continue;
>Is not this unlikely `nb_burst == 0`
>

Not necessarily refer
https://mails.dpdk.org/archives/dev/2018-July/108610.html 

>> +
>> +		l2fwd_event_fwd(rsrc, &ev, tx_q_id, timer_period,
>flags);
>> +
>> +		if (flags & L2FWD_EVENT_TX_ENQ) {
>> +			while (rte_event_enqueue_burst(event_d_id,
>port_id,
>> +						       &ev, 1) &&
>> +					!rsrc->force_quit)
>> +				;
>Can we place a `continue` as we are not expecting `
>L2FWD_EVENT_TX_DIRECT`?
>> +		}
>
>> +
>> +		if (flags & L2FWD_EVENT_TX_DIRECT) {
>> +			while
>> (!rte_event_eth_tx_adapter_enqueue(event_d_id,
>> +								port_id,
>> +								&ev, 1,
>0) &&
>> +					!rsrc->force_quit)
>> +				;
>> +		}
>> +	}
>snipped
>> +
>> +	while (!rsrc->force_quit) {
>> +		/* if timer is enabled */
>> +		if (is_master && timer_period > 0) {
>> +			cur_tsc = rte_rdtsc();
>> +			diff_tsc = cur_tsc - prev_tsc;
>> +
>> +			/* advance the timer */
>> +			timer_tsc += diff_tsc;
>> +
>> +			/* if timer has reached its timeout */
>> +			if (unlikely(timer_tsc >= timer_period)) {
>> +				print_stats(rsrc);
>> +				/* reset the timer */
>> +				timer_tsc = 0;
>> +			}
>> +			prev_tsc = cur_tsc;
>> +		}
>Can we move `print_stats` logic to service core?
>
>> +
>> +		/* Read packet from eventdev */
>> +		nb_rx = rte_event_dequeue_burst(event_d_id,
>port_id, ev,
>> +						deq_len, 0);
>> +		if (nb_rx == 0)
>Can we use `unlikely`?

Not necessarily refer
https://mails.dpdk.org/archives/dev/2018-July/108610.html

>> +			continue;
>> +
>> +		for (i = 0; i < nb_rx; i++) {
>> +			l2fwd_event_fwd(rsrc, &ev[i], tx_q_id,
>timer_period,
>> +					flags);
>> +		}
>> +
>> +		if (flags & L2FWD_EVENT_TX_ENQ) {
>> +			nb_tx =
>rte_event_enqueue_burst(event_d_id, port_id,
>> +							ev, nb_rx);
>> +			while (nb_tx < nb_rx && !rsrc->force_quit)
>> +				nb_tx +=
>> rte_event_enqueue_burst(event_d_id,
>> +						port_id, ev + nb_tx,
>> +						nb_rx - nb_tx);
>Can we use `continue` as we do not transmit from the same worker int
>his case?

I'm not sure I follow what you meant here. We are trying to transmit the work 
present on the worker till we succeed, if we do a continue then we would loose
the untransmitted packets. 

@see examples/eventdev_pipeline/pipeline_worker_generic.c +109

>> +		}
>> +
>snipped