From: Jerin Jacob <jerinjacobk@gmail.com>
To: huangdengdui <huangdengdui@huawei.com>
Cc: Thomas Monjalon <thomas@monjalon.net>,
Damodharam Ammepalli <damodharam.ammepalli@broadcom.com>,
Ferruh Yigit <ferruh.yigit@amd.com>,
dev@dpdk.org, aman.deep.singh@intel.com, yuying.zhang@intel.com,
andrew.rybchenko@oktetlabs.ru, liuyonglong@huawei.com,
fengchengwen@huawei.com, haijie1@huawei.com,
lihuisong@huawei.com
Subject: Re: [PATCH 0/3] support setting lanes
Date: Fri, 22 Mar 2024 10:08:34 +0530 [thread overview]
Message-ID: <CALBAE1PAr0W3=-nUGYZiO9iJcr1RDOD9EaZRYq387M=RA8Uw=Q@mail.gmail.com> (raw)
In-Reply-To: <6f93a427-303f-472b-862c-0a65ee7837c9@huawei.com>
On Fri, Mar 22, 2024 at 7:58 AM huangdengdui <huangdengdui@huawei.com> wrote:
>
>
>
> On 2024/3/21 16:28, Thomas Monjalon wrote:
> > 21/03/2024 03:02, huangdengdui:
> >>
> >> On 2024/3/20 20:31, Ferruh Yigit wrote:
> >>> On 3/18/2024 9:26 PM, Damodharam Ammepalli wrote:
> >>>> On Mon, Mar 18, 2024 at 7:56 AM Thomas Monjalon <thomas@monjalon.net> wrote:
> >>>>>
> >>>>> 12/03/2024 08:52, Dengdui Huang:
> >>>>>> Some speeds can be achieved with different number of lanes. For example,
> >>>>>> 100Gbps can be achieved using two lanes of 50Gbps or four lanes of 25Gbps.
> >>>>>> When use different lanes, the port cannot be up.
> >>>>>
> >>>>> I'm not sure what you are referring to.
> >>>>> I suppose it is not PCI lanes.
> >>>>> Please could you link to an explanation of how a port is split in lanes?
> >>>>> Which hardware does this?
> >>>>>
> >>>> This is a snapshot of 100Gb that the latest BCM576xx supports.
> >>>> 100Gb (NRZ: 25G per lane, 4 lanes) link speed
> >>>> 100Gb (PAM4-56: 50G per lane, 2 lanes) link speed
> >>>> 100Gb (PAM4-112: 100G per lane, 1 lane) link speed
> >>>>
> >>>> Let the user feed in lanes=< integer value> and the NIC driver decides
> >>>> the matching combination speed x lanes that works. In future if a new speed
> >>>> is implemented with more than 8 lanes, there wouldn't be a need
> >>>> to touch this speed command. Using separate lane command would
> >>>> be a better alternative to support already shipped products and only new
> >>>> drivers would consider this lanes configuration, if applicable.
> >>>>
> >>>
> >>> As far as I understand, lane is related to the physical layer of the
> >>> NIC, there are multiple copies of transmitter, receiver, modulator HW
> >>> block and each set called as a 'lane' and multiple lanes work together
> >>> to achieve desired speed. (please correct me if this is wrong).
> >>>
> >>> Why not just configuring the speed is not enough? Why user needs to know
> >>> the detail and configuration of the lanes?
> >>> Will it work if driver/device configure the "speed x lane" internally
> >>> for the requested speed?
> >>>
> >>> Is there a benefit to force specific lane count for a specific speed
> >>> (like power optimization, just a wild guess)?
> >>>
> >>>
> >>> And +1 for auto-negotiation if possible.
> >>
> >> As you said above,，multiple lanes work together to achieve desired speed.
> >> For example, the following solutions can be used to implement 100G:
> >> 1、Combines four 25G lanes
> >> 2、Combines two 50G lanes
> >> 3、A single 100G lane
> >>
> >> It is assumed that two ports are interconnected and the two ports support
> >> the foregoing three solutions. But, we just configured the speed to 100G and
> >> one port uses four 25G lanes by default and the other port uses two 50G lanes
> >> by default, the port cannot be up. In this case, we need to configure the
> >> two ports to use the same solutions (for example, uses two 50G lanes)
> >> so that the ports can be up.
> >
> > Why this config is not OK? How do we know?
> > Really I have a very bad feeling about this feature.
> >
> >
> Sorry, I don't quite understand your question.
> Are you asking why cannot be up when one port uses four 25G lanes and the other port uses two 50G lanes?
>
> 100GBASE-SR2 (two 50G lanes) and 100GBASE-SR4 (four 25G lanes) have different standards at the physical layer.[1]
> So it's not possible to communicate. Configuring lanes can help the driver choose the same standard.
Typically, low-level drivers like FW configure this.
For example, If FW configures, 100G port as 100GBASE-SR2 then two
ethdev(port 0 and port1) will show up.
Now, assume if we expose this API and Can end user configure port 1 as
25G lines if so,
a) What happens to port0 and it states?
b) Will port2, port3 will show up after issuing this API(As end user
configured 25Gx4 for 100G)? Will application needs to hotplug to get
use ports.
> https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9844436
next prev parent reply other threads:[~2024-03-22 4:39 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-12 7:52 Dengdui Huang
2024-03-12 7:52 ` [PATCH 1/3] ethdev: " Dengdui Huang
2024-03-19 3:02 ` Stephen Hemminger
2024-03-20 1:16 ` huangdengdui
2024-03-12 7:52 ` [PATCH 2/3] net/hns3: " Dengdui Huang
2024-03-12 7:52 ` [PATCH 3/3] app/testpmd: " Dengdui Huang
2024-03-15 21:47 ` Damodharam Ammepalli
2024-03-19 2:38 ` huangdengdui
2024-03-22 7:09 ` [PATCH v2 0/6] " Dengdui Huang
2024-03-22 7:09 ` [PATCH v2 1/6] ethdev: " Dengdui Huang
2024-03-22 13:58 ` Thomas Monjalon
2024-03-22 15:15 ` Ajit Khaparde
2024-03-22 17:32 ` Tyler Retzlaff
2024-03-22 22:30 ` Damodharam Ammepalli
2024-03-25 6:24 ` huangdengdui
2024-03-25 9:30 ` Thomas Monjalon
2024-03-25 21:14 ` Damodharam Ammepalli
2024-03-26 1:42 ` lihuisong (C)
2024-03-26 3:45 ` Ajit Khaparde
2024-03-26 10:30 ` Thomas Monjalon
2024-03-26 11:15 ` lihuisong (C)
2024-03-26 13:47 ` Ajit Khaparde
2024-03-26 18:11 ` Ajit Khaparde
2024-03-26 18:21 ` Damodharam Ammepalli
2024-03-30 11:38 ` huangdengdui
2024-04-01 20:07 ` Thomas Monjalon
2024-04-01 22:29 ` Damodharam Ammepalli
2024-04-02 8:37 ` huangdengdui
2024-04-02 15:28 ` Stephen Hemminger
2024-04-04 13:45 ` Ferruh Yigit
2024-03-29 3:25 ` lihuisong (C)
2024-03-22 7:09 ` [PATCH v2 2/6] test: updated UT for " Dengdui Huang
2024-03-22 7:09 ` [PATCH v2 3/6] ethdev: add function to parse link mode info Dengdui Huang
2024-03-22 7:09 ` [PATCH v2 4/6] net/hns3: use parse link mode info function Dengdui Huang
2024-03-22 7:09 ` [PATCH v2 5/6] net/hns3: support setting lanes Dengdui Huang
2024-03-22 7:09 ` [PATCH v2 6/6] app/testpmd: " Dengdui Huang
2024-04-04 13:58 ` [PATCH v2 0/6] " Ferruh Yigit
2024-05-16 12:48 ` huangdengdui
2024-03-18 14:56 ` [PATCH 0/3] " Thomas Monjalon
2024-03-18 21:26 ` Damodharam Ammepalli
2024-03-18 21:42 ` Stephen Hemminger
2024-03-18 22:55 ` Ajit Khaparde
2024-03-20 11:41 ` Thomas Monjalon
2024-03-20 12:31 ` Ferruh Yigit
2024-03-21 2:02 ` huangdengdui
2024-03-21 8:28 ` Thomas Monjalon
2024-03-22 2:28 ` huangdengdui
2024-03-22 4:38 ` Jerin Jacob [this message]
2024-03-22 5:25 ` Ajit Khaparde
2024-03-22 5:51 ` Jerin Jacob
2024-03-22 13:51 ` Thomas Monjalon
2024-03-25 14:04 ` Jerin Jacob
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