netdev - Re: [PATCH v4 net-next 3/3] net: mvneta: get rid of huge dma sync in mvneta_rx

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Date:   Tue, 19 Nov 2019 14:19:11 +0200
From:   Lorenzo Bianconi <lorenzo.bianconi@...hat.com>
To:     Jesper Dangaard Brouer <brouer@...hat.com>
Cc:     Lorenzo Bianconi <lorenzo@...nel.org>, netdev@...r.kernel.org,
        davem@...emloft.net, ilias.apalodimas@...aro.org,
        mcroce@...hat.com, jonathan.lemon@...il.com
Subject: Re: [PATCH v4 net-next 3/3] net: mvneta: get rid of huge dma sync in
 mvneta_rx_refill

> On Mon, 18 Nov 2019 15:33:46 +0200
> Lorenzo Bianconi <lorenzo@...nel.org> wrote:
> 
> > diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
> > index f7713c2c68e1..a06d109c9e80 100644
> > --- a/drivers/net/ethernet/marvell/mvneta.c
> > +++ b/drivers/net/ethernet/marvell/mvneta.c
> [...]
> > @@ -2097,8 +2093,10 @@ mvneta_run_xdp(struct mvneta_port *pp, struct mvneta_rx_queue *rxq,
> >  		err = xdp_do_redirect(pp->dev, xdp, prog);
> >  		if (err) {
> >  			ret = MVNETA_XDP_DROPPED;
> > -			page_pool_recycle_direct(rxq->page_pool,
> > -						 virt_to_head_page(xdp->data));
> > +			__page_pool_put_page(rxq->page_pool,
> > +					virt_to_head_page(xdp->data),
> > +					xdp->data_end - xdp->data_hard_start,
> > +					true);
> >  		} else {
> >  			ret = MVNETA_XDP_REDIR;
> >  		}
> > @@ -2107,8 +2105,10 @@ mvneta_run_xdp(struct mvneta_port *pp, struct mvneta_rx_queue *rxq,
> >  	case XDP_TX:
> >  		ret = mvneta_xdp_xmit_back(pp, xdp);
> >  		if (ret != MVNETA_XDP_TX)
> > -			page_pool_recycle_direct(rxq->page_pool,
> > -						 virt_to_head_page(xdp->data));
> > +			__page_pool_put_page(rxq->page_pool,
> > +					virt_to_head_page(xdp->data),
> > +					xdp->data_end - xdp->data_hard_start,
> > +					true);
> >  		break;
> >  	default:
> >  		bpf_warn_invalid_xdp_action(act);
> > @@ -2117,8 +2117,10 @@ mvneta_run_xdp(struct mvneta_port *pp, struct mvneta_rx_queue *rxq,
> >  		trace_xdp_exception(pp->dev, prog, act);
> >  		/* fall through */
> >  	case XDP_DROP:
> > -		page_pool_recycle_direct(rxq->page_pool,
> > -					 virt_to_head_page(xdp->data));
> > +		__page_pool_put_page(rxq->page_pool,
> > +				     virt_to_head_page(xdp->data),
> > +				     xdp->data_end - xdp->data_hard_start,
> > +				     true);
> 
> This does beg for the question: Should we create an API wrapper for
> this in the header file?
> 
> But what to name it?
> 
> I know Jonathan doesn't like the "direct" part of the  previous function
> name page_pool_recycle_direct.  (I do considered calling this 'napi'
> instead, as it would be inline with networking use-cases, but it seemed
> limited if other subsystem end-up using this).
> 
> Does is 'page_pool_put_page_len' sound better?
> 
> But I want also want hide the bool 'allow_direct' in the API name.
> (As it makes it easier to identify users that uses this from softirq)
> 
> Going for 'page_pool_put_page_len_napi' starts to be come rather long.

What about removing the second 'page'? Something like:
- page_pool_put_len_napi()

Regards,
Lorenzo

> 
> -- 
> Best regards,
>   Jesper Dangaard Brouer
>   MSc.CS, Principal Kernel Engineer at Red Hat
>   LinkedIn: http://www.linkedin.com/in/brouer
> 

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