[dpdk-dev] [PATCH v2] examples/distributor: detect high frequency cores

[Burakov, Anatoly]

On 28-Mar-19 1:13 PM, David Hunt wrote:
> The distributor application is bottlenecked by the distributor core,
> so if we can give more frequency to this core, then the overall
> performance of the application may increase.
> 
> This patch uses the rte_power_get_capabilities() API to query the
> cores provided in the core mask, and if any high frequency cores are
> found (e.g. Turbo Boost is enabled), we will pin the distributor
> workload to that core.
> 
> Signed-off-by: Liang Ma <liang.j.ma at intel.com>
> Signed-off-by: David Hunt <david.hunt at intel.com>
> ---

<...>

> +	if (power_lib_initialised)
> +		rte_power_exit(rte_lcore_id());
>   	printf("\nCore %u exiting tx task.\n", rte_lcore_id());
>   	return 0;
>   }
> @@ -575,9 +582,35 @@ lcore_worker(struct lcore_params *p)
>   		if (num > 0)
>   			app_stats.worker_bursts[p->worker_id][num-1]++;
>   	}
> +	if (power_lib_initialised)
> +		rte_power_exit(rte_lcore_id());
> +	rte_free(p);
>   	return 0;
>   }
>   
> +static int
> +init_power_library(void)
> +{
> +	int ret = 0, lcore_id;
> +	RTE_LCORE_FOREACH_SLAVE(lcore_id) {
> +		if (rte_lcore_is_enabled(lcore_id)) {

Please correct me if i'm wrong, but RTE_LCORE_FOREACH_SLAVE already 
checks if the lcore is enabled.

<...>

>   
> +	if (power_lib_initialised) {
> +		/*
> +		 * Here we'll pre-assign lcore ids to the rx, tx and
> +		 * distributor workloads if there's higher frequency
> +		 * on those cores e.g. if Turbo Boost is enabled.
> +		 * It's also worth mentioning that it will assign cores in a
> +		 * specific order, so that if there's less than three
> +		 * available, the higher frequency cores will go to the
> +		 * distributor first, then rx, then tx.
> +		 */
> +		RTE_LCORE_FOREACH_SLAVE(lcore_id) {
> +
> +			rte_power_get_capabilities(lcore_id, &lcore_cap);
> +
> +			if (lcore_cap.turbo == 1) {
> +				priority_num++;
> +				switch (priority_num) {
> +				case 1:
> +					distr_core_id = lcore_id;
> +					printf("Distributor on priority core %d\n",
> +							lcore_id);
> +					break;
> +				case 2:
> +					rx_core_id = lcore_id;
> +					printf("Rx on priority core %d\n",
> +							lcore_id);
> +					break;
> +				case 3:
> +					tx_core_id = lcore_id;
> +					printf("Tx on priority core %d\n",
> +							lcore_id);
> +					break;
> +				default:
> +					break;
> +				}

This seems to be doing the same thing as right below (assigning lcore 
id's in order), yet in one case you use a switch, and in the other you 
use a simple loop. I don't see priority_num used anywhere else, so you 
might as well simplify this loop to be similar to what you have below, 
with "skip-if-not-turbo, if not assigned, assign-and-continue" type flow.

Once that is fixed,

Reviewed-by: Anatoly Burakov <anatoly.burakov at intel.com>

-- 
Thanks,
Anatoly