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Date: Tue, 22 Sep 2015 11:40:06 +0100
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From: Alejandro Lucero <alejandro.lucero@netronome.com>
To: Stephen Hemminger <stephen@networkplumber.org>
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Subject: Re: [dpdk-dev] rte_eth_rx_queue_count accuracy
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I can not see that code. Can you point out where is it?

Thanks

On Mon, Sep 21, 2015 at 11:41 PM, Stephen Hemminger <
stephen@networkplumber.org> wrote:

> On Fri, 18 Sep 2015 11:33:36 +0100
> Alejandro Lucero <alejandro.lucero@netronome.com> wrote:
>
> > I have seen the API definition says nothing about accuracy but some PMD
> > implementations sacrifice accuracy for the sake of performance. If I'm
> not
> > understanding the code wrongly  i40e and ixgbe check DD bit just for the
> > first descriptor in a group of 4, and they take all of them as used if
> the
> > first descriptor is used.
> >
> > By other hand, they do a "heavy" calculation when the descriptor ring
> wraps
> > which does not make sense (to me) if same performance goal is used.
> >
> > There are PMDs not supporting this option and I can not see any app or
> > example using it so I do not know how important is this function, its
> > accuracy and its performance impact. Can someone comment on this?
> >
> > Thanks
>
> I have version of this for virtio/vmxnet3
> It is useful when using the interrupt control mode.
>