[dpdk-dev] [PATCH v4 0/2] ethdev: add port speed capability
Nélio Laranjeiro
nelio.laranjeiro at 6wind.com
Wed Sep 9 11:29:13 CEST 2015
bitmap
Reply-To:
Shern <olgas at mellanox.com>, Adrien
Mazarguil <adrien.mazarguil at 6wind.com>
Bcc:
Subject: Re: [dpdk-dev] [PATCH v4 0/2] ethdev: add port speed capability bitmap
Reply-To:
In-Reply-To: <20150909090855.GC17463 at autoinstall.dev.6wind.com>
Marc,
On Tue, Sep 08, 2015 at 10:24:36PM +0200, Marc Sune wrote:
> Neilo,
>
> 2015-09-08 12:03 GMT+02:00 Nélio Laranjeiro <nelio.laranjeiro at 6wind.com>:
>
> On Mon, Sep 07, 2015 at 10:52:53PM +0200, Marc Sune wrote:
> > 2015-08-29 2:16 GMT+02:00 Marc Sune <marcdevel at gmail.com>:
> >
> > > The current rte_eth_dev_info abstraction does not provide any mechanism
> to
> > > get the supported speed(s) of an ethdev.
> > >
> > > For some drivers (e.g. ixgbe), an educated guess can be done based on
> the
> > > driver's name (driver_name in rte_eth_dev_info), see:
> > >
> > > http://dpdk.org/ml/archives/dev/2013-August/000412.html
> > >
> > > However, i) doing string comparisons is annoying, and can silently
> > > break existing applications if PMDs change their names ii) it does not
> > > provide all the supported capabilities of the ethdev iii) for some
> drivers
> > > it
> > > is impossible determine correctly the (max) speed by the application
> > > (e.g. in i40, distinguish between XL710 and X710).
> > >
> > > This small patch adds speed_capa bitmap in rte_eth_dev_info, which is
> > > filled
> > > by the PMDs according to the physical device capabilities.
> > >
> > > v2: rebase, converted speed_capa into 32 bits bitmap, fixed alignment
> > > (checkpatch).
> > >
> > > v3: rebase to v2.1. unified ETH_LINK_SPEED and ETH_SPEED_CAP into
> > > ETH_SPEED.
> > > Converted field speed in struct rte_eth_conf to speeds, to allow a
> > > bitmap
> > > for defining the announced speeds, as suggested by M. Brorup. Fixed
> > > spelling issues.
> > >
> > > v4: fixed errata in the documentation of field speeds of rte_eth_conf,
> and
> > > commit 1/2 message. rebased to v2.1.0. v3 was incorrectly based on
> > > ~2.1.0-rc1.
> > >
> >
> > Thomas,
> >
> > Since mostly you were commenting for v1 and v2; any opinion on this one?
> >
> > Regards
> > marc
>
> Hi Marc,
>
> I have read your patches, and there are a few mistakes, for instance mlx4
> (ConnectX-3 devices) does not support 100Gbps.
>
>
> When I circulated v1 and v2 I was kindly asking maintainers and reviewers of
> the drivers to fix any mistakes in SPEED capabilities, since I was taking the
> speeds from the online websites&catalogues. Some were fixed, but apparently
> some were still missing. I will remove 100Gbps. Please circulate any other
> error you have spotted.
>From Mellanox website:
- ConnectX-3 EN: 10/40/56Gb/s
- ConnectX-3 Pro EN 10GBASE-T: 10G/s
- ConnectX-3 Pro: EN 10/40/56GbE
- ConnectX-3 Pro Programmable: 10/40Gb/s
This PMD works with any of the ConnectX-3 adapters, so the announce speed
should be 10/40/56Gb/s.
> In addition, it seems your new bitmap does not support all kind of
> speeds, take a look at the header of Ethtool, in the Linux kernel
> (include/uapi/linux/ethtool.h) which already consumes 30bits without even
> managing speeds above 56Gbps.
>
>
> The bitmaps you are referring is SUPPORTED_ and ADVERTISED_. These bitmaps not
> only contain the speeds but PHY properties (e.g. BASE for ETH).
>
> The intention of this patch was to expose speed capabilities, similar to the
> bitmap SPEED_ in include/uapi/linux/ethtool.h, which as you see maps closely to
> ETH_SPEED_ proposed in this patch.
>
> I think the encoding of other things, like the exact model of the interface and
> its PHY details should go somewhere else. But I might be wrong here, so open to
> hear opinions.
I understand the need to have capability fields, but I don't understand
why you want to mix speeds and duplex mode in something which was
previously only handling speeds.
We now have redundant information in struct rte_eth_conf, whereas
that structure has a speed field which embeds the duplex mode and
a duplex field which does the same, which one should be used?
> It would be nice to keep the field to represent the real speed of the
> link, in case it is not represented by the bitmap, it could be also
> useful for aggregated links (bonding for instance). The current API
> already works this way, it just needs to be extended from 16 to 32 bit
> to manage speed above 64Gbps.
>
>
> This patch does not remove rte_eth_link_get() API. It just changes the encoding
> of speed in struct rte_eth_link, to have an homogeneous set of constants with
> the speed capabilities bitmap, as discussed previously in the thread (see
> Thomas comments). IOW, it returns now a single SPEED_ value in the struct
> rte_eth_link's link_speed field.
You change the coding of the speed field, but applications still expect
an integer, see port_infos_display function in app/test-pmd/config.c which
directly uses printf on rte_eth_link.speed field, there are other places
as well in PMDs (bn2x, bond, ...).
This patch currently expects that everything uses a bitmap but it is not
the case.
I don't understand the need to change the rte_eth_link.speed field
behavior to have the informations about the capability of the PHY, for
this are two distinct things:
- capability
- speed and duplex negotiated (or not).
I suggest to drop the part of the patch which changes the behavior of
link_speed in struct rte_eth_link.
PS: Sorry I did not sent the email as reply all.
--
Nélio Laranjeiro
6WIND
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