netdev - Re: [net-next, RFC, 4/8] net: core: add recycle capabilities on skbs via page

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Date:   Sat, 8 Dec 2018 04:34:15 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Florian Westphal <fw@...len.de>,
        Jesper Dangaard Brouer <brouer@...hat.com>
Cc:     netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
        Toke Høiland-Jørgensen <toke@...e.dk>,
        ard.biesheuvel@...aro.org, Jason Wang <jasowang@...hat.com>,
        ilias.apalodimas@...aro.org,
        BjörnTöpel <bjorn.topel@...el.com>, w@....eu,
        Saeed Mahameed <saeedm@...lanox.com>,
        mykyta.iziumtsev@...il.com,
        Daniel Borkmann <borkmann@...earbox.net>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Tariq Toukan <tariqt@...lanox.com>
Subject: Re: [net-next, RFC, 4/8] net: core: add recycle capabilities on skbs
 via page_pool API



On 12/08/2018 04:29 AM, Eric Dumazet wrote:
> 

> But I do not get why the patch is needed.
> 
> Adding extra cost for each skb destruction is costly.
> 
> I though XDP was all about _not_ having skbs.
> 
> Please let's do not slow down the non XDP stack only to make XDP more appealing.
> 

I have a similar concern with napi_consume_skb() :

This added a cost for locally generated TCP traffic, since most TX packets are fast clones.