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From: "Richardson, Bruce" <bruce.richardson@intel.com>
To: Stephen Hemminger <stephen@networkplumber.org>
Thread-Topic: [dpdk-dev] [RFC PATCH DRAFT 1/2] ethdev: add buffered single
 pkt TX function to API
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Date: Wed, 25 Jun 2014 00:02:18 +0000
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Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [RFC PATCH DRAFT 1/2] ethdev: add buffered single
 pkt TX function to API
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> -----Original Message-----
> From: Stephen Hemminger [mailto:stephen@networkplumber.org]
> Sent: Tuesday, June 24, 2014 4:07 PM
> To: Richardson, Bruce
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [RFC PATCH DRAFT 1/2] ethdev: add buffered single=
 pkt
> TX function to API
>=20
> On Tue, 24 Jun 2014 23:32:15 +0100
> Bruce Richardson <bruce.richardson@intel.com> wrote:
>=20
> > Many sample apps include internal buffering for single-packet-at-a-time
> > operation. Since this is such a common paradigm, this functionality is
> > better suited to being inside the core ethdev API.
> > The new APIs include three functions:
> > * rte_eth_tx_buffer - buffer up a single packet for future transmission
> > * rte_eth_tx_buffer_flush - flush any unsent buffered packets
> > * rte_eth_tx_buffer_set_err_callback - set up a callback to be called i=
n
> >   case transmitting a buffered burst fails. By default, we just free th=
e
> >   unsent packets
>=20
> This must be per-queue to be MP safe.
>=20
> Internally, we do something similar but it proved to be fastest to
> user per-cpu data in some cases.

The implementation is per-queue. If you look at the changes to the tx queue=
 setup function, we set up a buffer space for each TX queue inside the eth_=
dev_data structure that is then used for buffering that queue. The fact tha=
t it's handled per-queue inside the eth_dev means that it's as thread-safe =
as the existing tx_burst function, and also is completely driver agnostic.