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From: Thomas Monjalon <thomas@monjalon.net>
To: Olivier Matz <olivier.matz@6wind.com>,
	Andrew Rybchenko <arybchenko@solarflare.com>
Cc: Yongseok Koh <yskoh@mellanox.com>,
	wenzhuo.lu@intel.com, jingjing.wu@intel.com, dev@dpdk.org,
	konstantin.ananyev@intel.com, adrien.mazarguil@6wind.com,
	nelio.laranjeiro@6wind.com
Subject: Re: [dpdk-dev] [PATCH v4 1/2] mbuf: support attaching external buffer to mbuf
Date: Wed, 25 Apr 2018 00:15:39 +0200	[thread overview]
Message-ID: <1852150.zQNNKj7iQK@xps> (raw)
In-Reply-To: <20180424215340.GA88208@yongseok-MBP.local>

24/04/2018 23:53, Yongseok Koh:
> On Tue, Apr 24, 2018 at 10:22:45PM +0200, Thomas Monjalon wrote:
> > 24/04/2018 21:15, Olivier Matz:
> > > On Tue, Apr 24, 2018 at 09:21:00PM +0300, Andrew Rybchenko wrote:
> > > > On 04/24/2018 07:02 PM, Olivier Matz wrote:
> > > > > On Tue, Apr 24, 2018 at 03:28:33PM +0300, Andrew Rybchenko wrote:
> > > > > > On 04/24/2018 04:38 AM, Yongseok Koh wrote:
> > > > > > > + * Returns TRUE if given mbuf is cloned by mbuf indirection, or FALSE
> > > > > > > + * otherwise.
> > > > > > > + *
> > > > > > > + * If a mbuf has its data in another mbuf and references it by mbuf
> > > > > > > + * indirection, this mbuf can be defined as a cloned mbuf.
> > > > > > > + */
> > > > > > > +#define RTE_MBUF_CLONED(mb)     ((mb)->ol_flags & IND_ATTACHED_MBUF)
> > > > > > > +
> > > > > > > +/**
> > > > > > >     * Returns TRUE if given mbuf is indirect, or FALSE otherwise.
> > > > > > >     */
> > > > > > > -#define RTE_MBUF_INDIRECT(mb)   ((mb)->ol_flags & IND_ATTACHED_MBUF)
> > > > > > > +#define RTE_MBUF_INDIRECT(mb)   RTE_MBUF_CLONED(mb)
> > > > > > It is still confusing that INDIRECT != !DIRECT.
> > > > > > May be we have no good options right now, but I'd suggest to at least
> > > > > > deprecate
> > > > > > RTE_MBUF_INDIRECT() and completely remove it in the next release.
> > > > > Agree. I may have missed something, but is my previous suggestion
> > > > > not doable?
> > > > > 
> > > > > - direct = embeds its own data      (and indirect = !direct)
> > > > > - clone (or another name) = data is another mbuf
> > > > > - extbuf = data is in an external buffer
> > > > 
> > > > I guess the problem that it changes INDIRECT semantics since EXTBUF
> > > > is added as well. I think strictly speaking it is an API change.
> > > > Is it OK to make it without announcement?
> > > 
> > > In any case, there will be an ABI change, because an application
> > > compiled for 18.02 will not be able to handle these new kind of
> > > mbuf.
> > > 
> > > So unfortunatly yes, I think this kind of changes should first be
> > > announced.
> > > 
> > > Thomas, what do you think?
> > 
> > What is the impact for the application developer?
> > Is there something to change in the application after this patch?
> 
> Let me address two concerns discussed here.
> 
> 1) API breakage of RTE_MBUF_DIRECT()
> Previously, direct == !indirect but now direct == !indirect && !extbuf. But to
> set the new flag (EXT_ATTACHED_MBUF), the new API, rte_pktmbuf_attach_extbuf()
> should be used and it is experimental. If application isn't compiled without
> allowing experimental API or application doesn't use the new API, it is always
> true that direct == !indirect. It looks logically okay to me. And FYI, it passed
> the mbuf_autotest.
> 
> 2) ABI breakage of mlx5's new Multi-Packet RQ (a.k.a MPRQ) feature
> It's right that it could breadk ABI if the PMD delivers packets with external
> buffer attached. But, the MPRQ feature is disabled by default and it can be
> enabled only by the newly introduced PMD parameter (mprq_en). So, there's no
> possibility that 18.02-based application receives a mbuf having an external
> buffer. And, like Olivier mentioned, there's another ABI breakage by removing
> control mbuf anyway.
> 
> So, I don't think there's need for developers to change their application after
> this patch unless they want to use the new feature.

To summarize, this a feature addition, there is no breakage.
So I don't see what should be announced.

I think it could be integrated as experimental with a first
PMD implementation in 18.05. It will allow to test the feature
in the field, and have more feedbacks about how to improve the API.

  reply	other threads:[~2018-04-24 22:15 UTC|newest]

Thread overview: 86+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-10  1:25 [dpdk-dev] [PATCH v1 0/6] net/mlx5: add Multi-Packet Rx support Yongseok Koh
2018-03-10  1:25 ` [dpdk-dev] [PATCH v1 1/6] mbuf: add buffer offset field for flexible indirection Yongseok Koh
2018-03-10  1:25 ` [dpdk-dev] [PATCH v1 2/6] net/mlx5: separate filling Rx flags Yongseok Koh
2018-03-10  1:25 ` [dpdk-dev] [PATCH v1 3/6] net/mlx5: add a function to rdma-core glue Yongseok Koh
2018-03-12  9:13   ` Nélio Laranjeiro
2018-03-10  1:25 ` [dpdk-dev] [PATCH v1 4/6] net/mlx5: add Multi-Packet Rx support Yongseok Koh
2018-03-12  9:20   ` Nélio Laranjeiro
2018-03-10  1:25 ` [dpdk-dev] [PATCH v1 5/6] net/mlx5: release Tx queue resource earlier than Rx Yongseok Koh
2018-03-10  1:25 ` [dpdk-dev] [PATCH v1 6/6] app/testpmd: conserve mbuf indirection flag Yongseok Koh
2018-04-02 18:50 ` [dpdk-dev] [PATCH v2 0/6] net/mlx5: add Multi-Packet Rx support Yongseok Koh
2018-04-02 18:50   ` [dpdk-dev] [PATCH v2 1/6] mbuf: add buffer offset field for flexible indirection Yongseok Koh
2018-04-03  8:26     ` Olivier Matz
2018-04-04  0:12       ` Yongseok Koh
2018-04-09 16:04         ` Olivier Matz
2018-04-10  1:59           ` Yongseok Koh
2018-04-11  0:25             ` Ananyev, Konstantin
2018-04-11  5:33               ` Yongseok Koh
2018-04-11 11:39                 ` Ananyev, Konstantin
2018-04-11 14:02                   ` Andrew Rybchenko
2018-04-11 17:18                     ` Yongseok Koh
2018-04-11 17:08                   ` Yongseok Koh
2018-04-12 16:34                     ` Ananyev, Konstantin
2018-04-12 18:58                       ` Yongseok Koh
2018-04-02 18:50   ` [dpdk-dev] [PATCH v2 2/6] net/mlx5: separate filling Rx flags Yongseok Koh
2018-04-02 18:50   ` [dpdk-dev] [PATCH v2 3/6] net/mlx5: add a function to rdma-core glue Yongseok Koh
2018-04-02 18:50   ` [dpdk-dev] [PATCH v2 4/6] net/mlx5: add Multi-Packet Rx support Yongseok Koh
2018-04-02 18:50   ` [dpdk-dev] [PATCH v2 5/6] net/mlx5: release Tx queue resource earlier than Rx Yongseok Koh
2018-04-02 18:50   ` [dpdk-dev] [PATCH v2 6/6] app/testpmd: conserve mbuf indirection flag Yongseok Koh
2018-04-19  1:11 ` [dpdk-dev] [PATCH v3 1/2] mbuf: support attaching external buffer to mbuf Yongseok Koh
2018-04-19  1:11   ` [dpdk-dev] [PATCH v3 2/2] app/testpmd: conserve offload flags of mbuf Yongseok Koh
2018-04-23 11:53   ` [dpdk-dev] [PATCH v3 1/2] mbuf: support attaching external buffer to mbuf Ananyev, Konstantin
2018-04-24  2:04     ` Yongseok Koh
2018-04-25 13:16       ` Ananyev, Konstantin
2018-04-25 16:44         ` Yongseok Koh
2018-04-25 18:05           ` Ananyev, Konstantin
2018-04-23 16:18   ` Olivier Matz
2018-04-24  1:29     ` Yongseok Koh
2018-04-24 15:36       ` Olivier Matz
2018-04-24  1:38 ` [dpdk-dev] [PATCH v4 " Yongseok Koh
2018-04-24  1:38   ` [dpdk-dev] [PATCH v4 2/2] app/testpmd: conserve offload flags of mbuf Yongseok Koh
2018-04-24  5:01   ` [dpdk-dev] [PATCH v4 1/2] mbuf: support attaching external buffer to mbuf Stephen Hemminger
2018-04-24 11:47     ` Yongseok Koh
2018-04-24 12:28   ` Andrew Rybchenko
2018-04-24 16:02     ` Olivier Matz
2018-04-24 18:21       ` [dpdk-dev] ***Spam*** " Andrew Rybchenko
2018-04-24 19:15         ` [dpdk-dev] " Olivier Matz
2018-04-24 20:22           ` Thomas Monjalon
2018-04-24 21:53             ` Yongseok Koh
2018-04-24 22:15               ` Thomas Monjalon [this message]
2018-04-25  8:21               ` Olivier Matz
2018-04-25 15:06             ` Stephen Hemminger
2018-04-24 23:34           ` Yongseok Koh
2018-04-25 14:45             ` Andrew Rybchenko
2018-04-25 17:40               ` Yongseok Koh
2018-04-25  8:28       ` Olivier Matz
2018-04-25  9:08         ` Yongseok Koh
2018-04-25  9:19           ` Yongseok Koh
2018-04-25 20:00             ` Olivier Matz
2018-04-25 22:54               ` Yongseok Koh
2018-04-24 22:30     ` Yongseok Koh
2018-04-25  2:53 ` [dpdk-dev] [PATCH v5 " Yongseok Koh
2018-04-25  2:53   ` [dpdk-dev] [PATCH v5 2/2] app/testpmd: conserve offload flags of mbuf Yongseok Koh
2018-04-25 13:31   ` [dpdk-dev] [PATCH v5 1/2] mbuf: support attaching external buffer to mbuf Ananyev, Konstantin
2018-04-25 17:06     ` Yongseok Koh
2018-04-25 17:23       ` Ananyev, Konstantin
2018-04-25 18:02         ` Yongseok Koh
2018-04-25 18:22           ` Yongseok Koh
2018-04-25 18:30             ` Yongseok Koh
2018-04-26  1:10 ` [dpdk-dev] [PATCH v6 " Yongseok Koh
2018-04-26  1:10   ` [dpdk-dev] [PATCH v6 2/2] app/testpmd: conserve offload flags of mbuf Yongseok Koh
2018-04-26 11:39   ` [dpdk-dev] [PATCH v6 1/2] mbuf: support attaching external buffer to mbuf Ananyev, Konstantin
2018-04-26 16:05   ` Andrew Rybchenko
2018-04-26 16:10     ` Thomas Monjalon
2018-04-26 19:42       ` Olivier Matz
2018-04-26 19:58         ` Thomas Monjalon
2018-04-26 20:07           ` Olivier Matz
2018-04-26 20:24             ` Thomas Monjalon
2018-04-26 17:18     ` Yongseok Koh
2018-04-26 19:45       ` Olivier Matz
2018-04-27  0:01 ` [dpdk-dev] [PATCH v7 " Yongseok Koh
2018-04-27  0:01   ` [dpdk-dev] [PATCH v7 2/2] app/testpmd: conserve offload flags of mbuf Yongseok Koh
2018-04-27  8:00     ` Andrew Rybchenko
2018-04-27  7:22   ` [dpdk-dev] [PATCH v7 1/2] mbuf: support attaching external buffer to mbuf Andrew Rybchenko
2018-04-27 17:22 ` [dpdk-dev] [PATCH v8 " Yongseok Koh
2018-04-27 17:22   ` [dpdk-dev] [PATCH v8 2/2] app/testpmd: conserve offload flags of mbuf Yongseok Koh
2018-04-27 18:09   ` [dpdk-dev] [PATCH v8 1/2] mbuf: support attaching external buffer to mbuf Thomas Monjalon

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