From: Jay Vosburgh <jay.vosburgh@canonical.com>
To: Maor Gottlieb <maorg@mellanox.com>
Cc: Andy Gospodarek <andy@greyhouse.net>,
Jiri Pirko <jiri@resnulli.us>,
"vfalico@gmail.com" <vfalico@gmail.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
Saeed Mahameed <saeedm@mellanox.com>,
Jason Gunthorpe <jgg@mellanox.com>,
Leon Romanovsky <leonro@mellanox.com>,
Jiri Pirko <jiri@mellanox.com>,
Alex Rosenbaum <alexr@mellanox.com>,
"davem@davemloft.net" <davem@davemloft.net>,
Mark Zhang <markz@mellanox.com>,
Parav Pandit <parav@mellanox.com>
Subject: Re: Expose bond_xmit_hash function
Date: Thu, 16 Jan 2020 08:00:51 -0800 [thread overview]
Message-ID: <31666.1579190451@famine> (raw)
In-Reply-To: <8e90935b-7485-0969-6fe4-d802d259f778@mellanox.com>
Maor Gottlieb <maorg@mellanox.com> wrote:
>
>On 1/16/2020 4:42 PM, Andy Gospodarek wrote:
>> On Wed, Jan 15, 2020 at 03:15:35PM +0100, Jiri Pirko wrote:
>>> Wed, Jan 15, 2020 at 02:04:49PM CET, maorg@mellanox.com wrote:
>>>> On 1/15/2020 11:45 AM, Jiri Pirko wrote:
>>>>> Wed, Jan 15, 2020 at 09:01:43AM CET, maorg@mellanox.com wrote:
>>>>>> RDMA over Converged Ethernet (RoCE) is a standard protocol which enables
>>>>>> RDMA’s efficient data transfer over Ethernet networks allowing transport
>>>>>> offload with hardware RDMA engine implementation.
>>>>>> The RoCE v2 protocol exists on top of either the UDP/IPv4 or the
>>>>>> UDP/IPv6 protocol:
>>>>>>
>>>>>> --------------------------------------------------------------
>>>>>> | L2 | L3 | UDP |IB BTH | Payload| ICRC | FCS |
>>>>>> --------------------------------------------------------------
>>>>>>
>>>>>> When a bond LAG netdev is in use, we would like to have the same hash
>>>>>> result for RoCE packets as any other UDP packets, for this purpose we
>>>>>> need to expose the bond_xmit_hash function to external modules.
>>>>>> If no objection, I will push a patch that export this symbol.
>>>>> I don't think it is good idea to do it. It is an internal bond function.
>>>>> it even accepts "struct bonding *bond". Do you plan to push netdev
>>>>> struct as an arg instead? What about team? What about OVS bonding?
>>>> No, I am planning to pass the bond struct as an arg. Currently, team
>>> Hmm, that would be ofcourse wrong, as it is internal bonding driver
>>> structure.
>>>
>>>
>>>> bonding is not supported in RoCE LAG and I don't see how OVS is related.
>>> Should work for all. OVS is related in a sense that you can do bonding
>>> there too.
>>>
>>>
>>>>> Also, you don't really need a hash, you need a slave that is going to be
>>>>> used for a packet xmit.
>>>>>
>>>>> I think this could work in a generic way:
>>>>>
>>>>> struct net_device *master_xmit_slave_get(struct net_device *master_dev,
>>>>> struct sk_buff *skb);
>>>> The suggestion is to put this function in the bond driver and call it
>>>> instead of bond_xmit_hash? is it still necessary if I have the bond pointer?
>>> No. This should be in a generic code. No direct calls down to bonding
>>> driver please. Or do you want to load bonding module every time your
>>> module loads?
>>>
>>> I thinks this can be implemented with ndo with "master_xmit_slave_get()"
>>> as a wrapper. Masters that support this would just implement the ndo.
>> In general I think this is a good idea (though maybe not with an skb as
>> an arg so we can use it easily within BPF), but I'm not sure if solves
>> the problem that Maor et al were setting out to solve.
>>
>> Maor, if you did export bond_xmit_hash() to be used by another driver,
>> you would presumably have a check in place so if the RoCE and UDP
>> packets had a different hash function output you would make a change and
>> be sure that the UDP frames would go out on the same device that the
>> RoCE traffic would normally use. Is this correct? Would you also send
>> the frames directly on the interface using dev_queue_xmit() and bypass
>> the bonding driver completely?
>
>RoCE packets are UDP. The idea is that the same UDP header (RoCE as
>well) will get the same hash result so they will be transmitted from the
>same port.
>The frames will be sent by using the RDMA send API and bypass the
>bonding driver completely.
>Is it answer your question?
If the RDMA send bypasses bonding, how will you insure that the
same hash result maps to the same underlying interface for both bonding
and RDMA?
-J
>> I don't think I fundamentally have a problem with this, I just want to
>> make sure I understand your proposed code-flow.
>>
>> Thanks!
>>
---
-Jay Vosburgh, jay.vosburgh@canonical.com
next prev parent reply other threads:[~2020-01-16 16:01 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-15 8:01 Expose bond_xmit_hash function Maor Gottlieb
2020-01-15 9:45 ` Jiri Pirko
2020-01-15 13:04 ` Maor Gottlieb
2020-01-15 14:15 ` Jiri Pirko
2020-01-15 14:33 ` Leon Romanovsky
2020-01-15 16:48 ` Jiri Pirko
2020-01-15 17:34 ` David Ahern
2020-01-15 18:04 ` Jay Vosburgh
2020-01-15 18:12 ` David Ahern
2020-01-15 20:46 ` Jiri Pirko
2020-01-15 20:58 ` David Ahern
2020-01-16 14:42 ` Andy Gospodarek
2020-01-16 15:55 ` Maor Gottlieb
2020-01-16 16:00 ` Jay Vosburgh [this message]
2020-01-19 14:52 ` Maor Gottlieb
2020-01-20 18:43 ` Jay Vosburgh
2020-01-22 7:53 ` Maor Gottlieb
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