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From: Tobias Waldekranz <tobias@waldekranz.com>
To: Marek Behun <marek.behun@nic.cz>
Cc: "Vladimir Oltean" <olteanv@gmail.com>,
	"Ansuel Smith" <ansuelsmth@gmail.com>,
	netdev@vger.kernel.org, "David S. Miller" <davem@davemloft.net>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Andrew Lunn" <andrew@lunn.ch>,
	"Vivien Didelot" <vivien.didelot@gmail.com>,
	"Florian Fainelli" <f.fainelli@gmail.com>,
	"Alexei Starovoitov" <ast@kernel.org>,
	"Daniel Borkmann" <daniel@iogearbox.net>,
	"Andrii Nakryiko" <andriin@fb.com>,
	"Eric Dumazet" <edumazet@google.com>,
	"Wei Wang" <weiwan@google.com>,
	"Cong Wang" <cong.wang@bytedance.com>,
	"Taehee Yoo" <ap420073@gmail.com>,
	"Björn Töpel" <bjorn@kernel.org>,
	"zhang kai" <zhangkaiheb@126.com>,
	"Weilong Chen" <chenweilong@huawei.com>,
	"Roopa Prabhu" <roopa@cumulusnetworks.com>,
	"Di Zhu" <zhudi21@huawei.com>,
	"Francis Laniel" <laniel_francis@privacyrequired.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC net-next 0/3] Multi-CPU DSA support
Date: Tue, 13 Apr 2021 20:16:24 +0200	[thread overview]
Message-ID: <87fszujbif.fsf@waldekranz.com> (raw)
In-Reply-To: <20210413171443.1b2b2f88@thinkpad>

On Tue, Apr 13, 2021 at 17:14, Marek Behun <marek.behun@nic.cz> wrote:
> On Tue, 13 Apr 2021 16:46:32 +0200
> Tobias Waldekranz <tobias@waldekranz.com> wrote:
>
>> On Tue, Apr 13, 2021 at 02:27, Marek Behun <marek.behun@nic.cz> wrote:
>> > On Tue, 13 Apr 2021 01:54:50 +0200
>> > Marek Behun <marek.behun@nic.cz> wrote:
>> >  
>> >> I will look into this, maybe ask some follow-up questions.  
>> >
>> > Tobias,
>> >
>> > it seems that currently the LAGs in mv88e6xxx driver do not use the
>> > HashTrunk feature (which can be enabled via bit 11 of the
>> > MV88E6XXX_G2_TRUNK_MAPPING register).  
>> 
>> This should be set at the bottom of mv88e6xxx_lag_sync_masks.
>> 
>> > If we used this feature and if we knew what hash function it uses, we
>> > could write a userspace tool that could recompute new MAC
>> > addresses for the CPU ports in order to avoid the problem I explained
>> > previously...
>> >
>> > Or the tool can simply inject frames into the switch and try different
>> > MAC addresses for the CPU ports until desired load-balancing is reached.
>> >
>> > What do you think?  
>> 
>> As you concluded in your followup, not being able to have a fixed MAC
>> for the CPU seems weird.
>> 
>> Maybe you could do the inverse? Allow userspace to set the masks for an
>> individual bond/team port in a hash-based LAG, then you can offload that
>> to DSA. 
>
> What masks?

The table defined in Global2/Register7.

When a frame is mapped to a LAG (e.g. by an ATU lookup), all member
ports will added to the frame's destination vector. The mask table is
the block that then filters the vector to only include a single
member.

By modifying that table, you can choose which buckets are assigned to
which member ports. This includes assigning 7 buckets to one member and
1 to the other for example.

At the moment, mv88e6xxx will statically determine this mapping (in
mv88e6xxx_lag_set_port_mask), by trying to spread the buckets as evenly
as possible. It will also rebalance the assignments whenever a link goes
down, or is "detached" in LACP terms.

You could imagine a different mode in which the DSA driver would receive
the bucket allocation from the bond/team driver (which in turn could
come all the way from userspace). Userspace could then implement
whatever strategy it wants to maximize utilization, though still bound
by the limitations of the hardware in terms of fields considered during
hashing of course.

  reply	other threads:[~2021-04-13 18:16 UTC|newest]

Thread overview: 68+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-10 13:34 [PATCH RFC net-next 0/3] Multi-CPU DSA support Ansuel Smith
2021-04-10 13:34 ` [PATCH RFC net-next 1/3] net: dsa: allow for multiple CPU ports Ansuel Smith
2021-04-12  3:35   ` DENG Qingfang
2021-04-12  4:41     ` Ansuel Smith
2021-04-12 15:30       ` DENG Qingfang
2021-04-12 16:17         ` Frank Wunderlich
2021-04-10 13:34 ` [PATCH RFC net-next 2/3] net: add ndo for setting the iflink property Ansuel Smith
2021-04-10 13:34 ` [PATCH RFC net-next 3/3] net: dsa: implement ndo_set_netlink for chaning port's CPU port Ansuel Smith
2021-04-10 13:34 ` [PATCH RFC iproute2-next] iplink: allow to change iplink value Ansuel Smith
2021-04-11 17:04   ` Stephen Hemminger
2021-04-11 17:09     ` Vladimir Oltean
2021-04-11 18:01 ` [PATCH RFC net-next 0/3] Multi-CPU DSA support Marek Behun
2021-04-11 18:08   ` Ansuel Smith
2021-04-11 18:39   ` Andrew Lunn
2021-04-12  2:07     ` Florian Fainelli
2021-04-12  4:53     ` Ansuel Smith
2021-04-11 18:50   ` Vladimir Oltean
2021-04-11 23:53     ` Vladimir Oltean
2021-04-12  2:10       ` Florian Fainelli
2021-04-12  5:04     ` Ansuel Smith
2021-04-12 12:46     ` Tobias Waldekranz
2021-04-12 14:35       ` Vladimir Oltean
2021-04-12 21:06         ` Tobias Waldekranz
2021-04-12 19:30       ` Marek Behun
2021-04-12 21:22         ` Tobias Waldekranz
2021-04-12 21:34           ` Vladimir Oltean
2021-04-12 21:49             ` Tobias Waldekranz
2021-04-12 21:56               ` Marek Behun
2021-04-12 22:06               ` Vladimir Oltean
2021-04-12 22:26                 ` Tobias Waldekranz
2021-04-12 22:48                   ` Vladimir Oltean
2021-04-12 23:04                     ` Marek Behun
2021-04-12 21:50           ` Marek Behun
2021-04-12 22:05             ` Tobias Waldekranz
2021-04-12 22:55               ` Marek Behun
2021-04-12 23:09                 ` Tobias Waldekranz
2021-04-12 23:13                   ` Tobias Waldekranz
2021-04-12 23:54                     ` Marek Behun
2021-04-13  0:27                       ` Marek Behun
2021-04-13  0:31                         ` Marek Behun
2021-04-13 14:46                         ` Tobias Waldekranz
2021-04-13 15:14                           ` Marek Behun
2021-04-13 18:16                             ` Tobias Waldekranz [this message]
2021-04-14 15:14                               ` Marek Behun
2021-04-14 18:39                                 ` Tobias Waldekranz
2021-04-14 23:39                                   ` Vladimir Oltean
2021-04-15  9:20                                     ` Tobias Waldekranz
2021-04-13 14:40                       ` Tobias Waldekranz
2021-04-12 15:00     ` DENG Qingfang
2021-04-12 16:32       ` Vladimir Oltean
2021-04-12 22:04         ` Marek Behun
2021-04-12 22:17           ` Vladimir Oltean
2021-04-12 22:47             ` Marek Behun
  -- strict thread matches above, loose matches on Subject: below --
2019-08-24  2:42 Marek Behún
2019-08-24 15:24 ` Andrew Lunn
2019-08-24 17:45   ` Marek Behun
2019-08-24 17:54     ` Andrew Lunn
2019-08-25  4:19   ` Marek Behun
2019-08-24 15:40 ` Vladimir Oltean
2019-08-24 15:44   ` Vladimir Oltean
2019-08-24 17:55     ` Marek Behun
2019-08-24 15:56   ` Andrew Lunn
2019-08-24 17:58     ` Marek Behun
2019-08-24 20:04 ` Florian Fainelli
2019-08-24 21:01   ` Marek Behun
2019-08-25  4:08     ` Marek Behun
2019-08-25  7:13   ` Marek Behun
2019-08-25 15:00     ` Florian Fainelli

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