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

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Message-ID: <1507313288.14419.21.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Fri, 06 Oct 2017 11:08:08 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Patrick Talbert <ptalbert@...hat.com>
Cc:     Andrew Lunn <andrew@...n.ch>, netdev@...r.kernel.org
Subject: Re: [PATCH net-next 1/1] [net] bonding: Add NUMA notice

On Fri, 2017-10-06 at 13:54 -0400, Patrick Talbert wrote:

> 
> 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).

Note that following the NUMA node of current process would lead to
reordering for TCP flows.

XPS makes sure we stick to one TXQ to avoid reorders.

I am not sure your patch will really help, since you do not warn if a
process from another NUMA node tries to send packet to a bonding driver
using slaves on another NUMA node.