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 17:38:27 +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

[...]
> > > > -		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()
> 
> Well, we (unfortunately) already have page_pool_put(), which is used
> for refcnt on the page_pool object itself.

__page_pool_put_page(pp, data, len, true) is a more generic version of
page_pool_recycle_direct where we can specify even the length. So what about:

- page_pool_recycle_len_direct
- page_pool_recycle_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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