netdev - Re: 802.1q HW filter spammage in 3.7.2+ kernels.

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Date:	Wed, 16 Jan 2013 06:03:04 -0800
From:	Ben Greear <greearb@...delatech.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	David Miller <davem@...emloft.net>, netdev <netdev@...r.kernel.org>
Subject: Re: 802.1q HW filter spammage in 3.7.2+ kernels.

On 01/15/2013 10:01 PM, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@...gle.com>
>
> On Tue, 2013-01-15 at 17:36 -0800, Ben Greear wrote:
>> My kernel logs are full of this (I have 2000 macvlans).
>
> Are you using 2000 macvlans on the same device ? Interesting...

Well, in this case, we have 1000 mac-vlans on each of 2 1G
Ethernet ports, but 2000 on a single device has been used
as well.

>
> I am wondering how multicast/broadcast messages don't generate a huge
> load and packet drops, since we clone packets for every macvlan, and
> queue then to netif_rx()
>

I have added ARP patches to do a random retry timer to help spread
out the ARP requests a bit, at least.  The system is still sluggish
at times, but it does function.  With a fixed-interval ARP timer, things
can get into very bad patterns.

http://patchwork.ozlabs.org/patch/9301/

My test cases often require SO_BINDTODEVICE to function with full features,
with one traffic-application per interface, so mac-vlans seems the easiest
way to scale.

> I guess you dont use IPv6 on these macvlans ?

I have...but many use cases use far fewer (virtual) interfaces.

Thanks,
Ben

-- 
Ben Greear <greearb@...delatech.com>
Candela Technologies Inc  http://www.candelatech.com

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