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From: "John W. Linville" <linville@tuxdriver.com>
To: Thomas Monjalon <thomas.monjalon@6wind.com>
Cc: dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH v2 07/11 1/2] vdev: new registration API
Date: Mon, 14 Apr 2014 09:20:54 -0400	[thread overview]
Message-ID: <20140414132053.GA27324@tuxdriver.com> (raw)
In-Reply-To: <24514389.3vY1j6NNAg@x220>

On Sat, Apr 12, 2014 at 08:05:22AM +0200, Thomas Monjalon wrote:
> Hi Bruce,
> 
> 11/04/2014 20:08, Richardson, Bruce :
> > From: Neil Horman
> > > On Fri, Apr 11, 2014 at 06:18:08PM +0200, Thomas Monjalon wrote:
> > > > It seems that your patch is not removing
> > > > rte_eth_ring_pair_create/rte_eth_ring_pair_attach so I'm not sure you
> > > > can dynamically change the PMD in this case.
> > > 
> > > Ew, I had missed those calls.  Yes, those should be encapsulated as some
> > > driver ops or some such.  I'll look at that when I rebase.  Regardless
> > > however, I didn't mean to state that pmds could be switched while
> > > running, only that the pmd to use could be specified at run time. 
> > > Though, you're correct, pmd_ring doesn't seem to hold in line with the
> > > other pmds in their isolation.
> > 
> > The ring PMD is probably best treated separately from the other PMDs as it's
> > not really a device poll-mode driver. Instead, it's a general library that
> > presents an API to make a ring, or set of rings, appear as a poll-mode
> > driver ethdev. The EAL command to have one created at startup time was just
> > an addon after-the-fact in case someone might find it useful :-). However,
> > it's primary purpose was to allow applications to be written which could
> > use physical NICs or rings interchangeably. For example, an app with
> > multiple stages in a pipeline, where each stage just reads from an ethdev
> > without caring if it's actually reading from a port or from packets sent
> > from another lcore/function etc. Another example might be where an
> > application wishes to sometimes loop packets back to itself, in this case
> > it uses the C API to create an additional ring ethdev which it uses as
> > output port for any packets it wants looped back - no special handling
> > needed, everything is an ethdev to it on which it calls rx_burst or
> > tx_burst. It's also likely that in future we will develop other libraries
> > which wish to present their functionality via rx_burst/tx_burst functions
> > i.e. as an ethdev.
> 
> I think you are describing a vdev and you want to be able to instantiate this 
> vdev in your application code. Right?
> So why not make a generic API to be able to instantiate a vdev?

Treating vdevs as something inherently different from the
hardware-backed PMDs continues to be the wrong approach.

Ordinarily the whole point of having an abstraction that looks like
a hardware device is so that applications can use either hardware
or that abstraction without having to know the difference.  Forcing
applications to be vdev-aware defeats the whole purpose of wrapping
those constructs inside a PMD in the first place.

John
-- 
John W. Linville		Someday the world will need a hero, and you
linville@tuxdriver.com			might be all we have.  Be ready.

  parent reply	other threads:[~2014-04-14 13:30 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-02-28 17:25 [dpdk-dev] [PATCH 00/11] eal: allow virtual pmd drivers as shared lib Olivier Matz
2014-02-28 17:25 ` [dpdk-dev] [PATCH 01/11] mk: use whole-archive option when creating dpdk binaries Olivier Matz
2014-04-10 13:58   ` Thomas Monjalon
2014-02-28 17:25 ` [dpdk-dev] [PATCH 02/11] devices-args: introduce rte_devargs in eal Olivier Matz
2014-02-28 21:39   ` Stephen Hemminger
2014-03-01 12:02     ` Olivier MATZ
2014-03-01 12:14       ` [dpdk-dev] [PATCH v2 " Olivier Matz
2014-04-10 13:59         ` Thomas Monjalon
2014-02-28 17:25 ` [dpdk-dev] [PATCH 03/11] devices-args: use rte_devargs and remove old whitelist code Olivier Matz
2014-03-01 12:14   ` [dpdk-dev] [PATCH v2 " Olivier Matz
2014-04-10 14:01     ` Thomas Monjalon
2014-02-28 17:25 ` [dpdk-dev] [PATCH 04/11] devices-args: add a dump_devargs command in basic test application Olivier Matz
2014-04-10 14:02   ` Thomas Monjalon
2014-02-28 17:25 ` [dpdk-dev] [PATCH 05/11] pci: rename device_list as pci_device_list Olivier Matz
2014-04-10 14:03   ` Thomas Monjalon
2014-02-28 17:25 ` [dpdk-dev] [PATCH 06/11] vdev: rename eal_common_nonpci_devs.c as eal_common_vdev.c Olivier Matz
2014-04-10 14:39   ` Thomas Monjalon
2014-04-11  7:36     ` [dpdk-dev] [PATCH v2 06/11] vdev: rename nonpci_devs as vdev Olivier Matz
2014-04-11 11:25       ` Thomas Monjalon
2014-04-11 11:45         ` [dpdk-dev] [PATCH v3 " Olivier Matz
2014-04-11 12:37           ` Thomas Monjalon
2014-02-28 17:25 ` [dpdk-dev] [PATCH 07/11] vdev: allow external registration of virtual device drivers Olivier Matz
2014-04-10 14:55   ` Thomas Monjalon
2014-04-11  7:36     ` [dpdk-dev] [PATCH v2 07/11 1/2] vdev: new registration API Olivier Matz
2014-04-11  7:36       ` [dpdk-dev] [PATCH v2 07/11 2/2] vdev: allow external registration of virtual device drivers Olivier Matz
2014-04-11 14:31         ` Thomas Monjalon
2014-04-11 10:49       ` [dpdk-dev] [PATCH v2 07/11 1/2] vdev: new registration API Neil Horman
2014-04-11 13:11         ` Thomas Monjalon
2014-04-11 15:50           ` Neil Horman
2014-04-11 16:18             ` Thomas Monjalon
2014-04-11 17:44               ` Neil Horman
2014-04-11 20:08                 ` Richardson, Bruce
2014-04-12  6:05                   ` Thomas Monjalon
2014-04-12 11:03                     ` Neil Horman
2014-04-12 11:23                       ` Richardson, Bruce
2014-04-12 14:06                         ` Neil Horman
2014-04-14 13:20                     ` John W. Linville [this message]
2014-04-14 13:45                       ` Thomas Monjalon
2014-04-14 13:54                         ` Neil Horman
2014-04-14 14:10                         ` John W. Linville
2014-04-14 14:39                           ` Thomas Monjalon
2014-04-11 14:31       ` Thomas Monjalon
2014-02-28 17:25 ` [dpdk-dev] [PATCH 08/11] device-args: use a comma instead of semicolon to separate key/values Olivier Matz
2014-04-10 14:05   ` Thomas Monjalon
2014-02-28 17:25 ` [dpdk-dev] [PATCH 09/11] device-args: replace use-device eal option by pci-whitelist and vdev Olivier Matz
2014-03-01 12:14   ` [dpdk-dev] [PATCH v2 " Olivier Matz
2014-04-10 14:06     ` Thomas Monjalon
2014-03-03 17:14   ` [dpdk-dev] [PATCH " Richardson, Bruce
2014-03-04 13:09     ` Olivier MATZ
2014-03-04 13:14       ` Richardson, Bruce
2014-03-24 22:39         ` Thomas Monjalon
2014-02-28 17:25 ` [dpdk-dev] [PATCH 10/11] device-args: allow to provide per pci device command line arguments Olivier Matz
2014-03-01 12:14   ` [dpdk-dev] [PATCH v2 " Olivier Matz
2014-04-10 14:06     ` Thomas Monjalon
2014-02-28 17:25 ` [dpdk-dev] [PATCH 11/11] testpmd: add several dump commands, useful for debug Olivier Matz
2014-03-01 12:15   ` [dpdk-dev] [PATCH v2 " Olivier Matz
2014-04-10 14:08     ` Thomas Monjalon

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