netdev - Re: [PATCH net-next] udp: under rx pressure, try to condense skbs

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Message-ID: <de654cac-fa3c-a4e1-a24a-27187456b8d7@hpe.com>
Date:   Thu, 8 Dec 2016 07:36:47 -0800
From:   Rick Jones <rick.jones2@....com>
To:     Eric Dumazet <eric.dumazet@...il.com>,
        Jesper Dangaard Brouer <brouer@...hat.com>
Cc:     David Miller <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>, Paolo Abeni <pabeni@...hat.com>
Subject: Re: [PATCH net-next] udp: under rx pressure, try to condense skbs

On 12/08/2016 07:30 AM, Eric Dumazet wrote:
> On Thu, 2016-12-08 at 10:46 +0100, Jesper Dangaard Brouer wrote:
>
>> Hmmm... I'm not thrilled to have such heuristics, that change memory
>> behavior when half of the queue size (sk->sk_rcvbuf) is reached.
>
> Well, copybreak drivers do that unconditionally, even under no stress at
> all, you really should complain then.

Isn't that behaviour based (in part?) on the observation/belief that it 
is fewer cycles to copy the small packet into a small buffer than to 
send the larger buffer up the stack and have to allocate and map a 
replacement?

rick jones