netdev - Re: [PATCH net-next 1/1] [net] bonding: Add NUMA notice

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Date:   Fri, 6 Oct 2017 13:54:44 -0400
From:   Patrick Talbert <ptalbert@...hat.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH net-next 1/1] [net] bonding: Add NUMA notice

On Thu, Oct 5, 2017 at 5:46 PM, Andrew Lunn <andrew@...n.ch> wrote:
> On Thu, Oct 05, 2017 at 04:23:45PM -0400, Patrick Talbert wrote:
>> Network performance can suffer when a load balancing bond uses slave
>> interfaces which are in different NUMA domains.
>>
>> This compares the NUMA domain of a newly enslaved interface against any
>> existing enslaved interfaces and prints a warning if they do not match.
>
> Hi Patrick
>
> Is there a bonding mode which might actually want to do this? Send on
> the local domain, unless it is overloaded, in which case send it to
> the other domain?
>

I suppose there could theoretically be a bonding mode that could do
that, but currently no such mode exists.

> There is also this talk for netdev:
>
> https://netdevconf.org/2.2/session.html?shochat-devicemgmt-talk

>From reading the abstract there, it sounds like such a device driver
would want to abstract away the numa location of the underlying
devices from the "unified" net device it presents to the kernel.

>
>         Andrew

My goal with the patch is not to prevent some one from bonding
whichever interfaces they want, only to notify them that what they are
doing is *likely* to be less than ideal from a performance
perspective. Even if some theoretical load balancing bonding mode was
intelligent enough to consider NUMA when choosing a transmit
interface, it never has control over the interface traffic is received
on (excluding the strange balance-alb mode).

Patrick