RE: [RFC PATCH v1 2/4] ethdev: add API for direct re-arm mode

["Morten Brørup" <mb@smartsharesystems.com>]

> From: Feifei Wang [mailto:Feifei.Wang2@arm.com]
> Sent: Sunday, 26 December 2021 10.50
> 
> > 发件人: Stephen Hemminger <stephen@networkplumber.org>
> > 发送时间: Saturday, December 25, 2021 3:38 AM
> >
> > On Sat, 25 Dec 2021 00:46:10 +0800
> > Feifei Wang <feifei.wang2@arm.com> wrote:
> >
> > > +rte_eth_direct_rxrearm_map(uint16_t rx_port_id, uint16_t
> rx_queue_id,
> > > +		uint16_t tx_port_id, uint16_t tx_queue_id) {
> > > +	struct rte_eth_dev *dev;
> > > +
> > > +	dev = &rte_eth_devices[rx_port_id];
> > > +	(*dev->dev_ops->rx_queue_direct_rearm_enable)(dev,
> > rx_queue_id);
> > > +	(*dev->dev_ops->rx_queue_direct_rearm_map)(dev, rx_queue_id,
> > > +			tx_port_id, tx_queue_id);
> > > +
> >
> > Indirect calls are expensive, maybe better to combine these?
> Thanks for your comment. I'm a little confused about this.
> 
> Whether 'expensive' is due to 'enable direct_rearm mode' and 'map
> queue' use
> different api, and we should combine them into the same API.
> If this, I think you are right, and just one api is enough to enable
> direct rearm mode and
> map queue.
> 

It's used in the control plane, so prefer readability over performance.

Also, the Ethdev API has separate _enable/_disable/_configure functions for many features like this. I would prefer the API to this feature to be similar, i.e. separate functions for enable and configure.

In other words: Disregard Stephen's comment about combining.