netdev - Re: [net-next 2/7] igb: add rx drop enable attribute

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Message-ID: <20191016165531.26854b0e@cakuba.netronome.com>
Date:   Wed, 16 Oct 2019 16:55:31 -0700
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Cc:     davem@...emloft.net, Robert Beckett <bob.beckett@...labora.com>,
        netdev@...r.kernel.org, nhorman@...hat.com, sassmann@...hat.com,
        Aaron Brown <aaron.f.brown@...el.com>
Subject: Re: [net-next 2/7] igb: add rx drop enable attribute

On Wed, 16 Oct 2019 16:47:06 -0700, Jeff Kirsher wrote:
> From: Robert Beckett <bob.beckett@...labora.com>
> 
> To allow userland to enable or disable dropping packets when descriptor
> ring is exhausted, add RX_DROP_EN private flag.
> 
> This can be used in conjunction with flow control to mitigate packet storms
> (e.g. due to network loop or DoS) by forcing the network adapter to send
> pause frames whenever the ring is close to exhaustion.
> 
> By default this will maintain previous behaviour of enabling dropping of
> packets during ring buffer exhaustion.
> Some use cases prefer to not drop packets upon exhaustion, but instead
> use flow control to limit ingress rates and ensure no dropped packets.
> This is useful when the host CPU cannot keep up with packet delivery,
> but data delivery is more important than throughput via multiple queues.
> 
> Userland can set this flag to 0 via ethtool to disable packet dropping.
> 
> Signed-off-by: Robert Beckett <bob.beckett@...labora.com>
> Tested-by: Aaron Brown <aaron.f.brown@...el.com>
> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@...el.com>

How is this different than enabling/disabling flow control..

ethtool -a/-A