netdev - Re: [Linuxarm] Re: [PATCH net-next v2 3/3] skbuff: keep track of pp page when __skb_frag

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Message-ID: <CANn89iLWo_03b=9WYi1401gFCLXnNrjeFJJaZXJkh0E2Bw-yYQ@mail.gmail.com>
Date:   Fri, 17 Sep 2021 10:15:08 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     Yunsheng Lin <linyunsheng@...wei.com>
Cc:     Jesper Dangaard Brouer <jbrouer@...hat.com>,
        Ilias Apalodimas <ilias.apalodimas@...aro.org>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Alexander Duyck <alexander.duyck@...il.com>,
        David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>, linuxarm@...neuler.org,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        Jonathan Lemon <jonathan.lemon@...il.com>,
        Alexander Lobakin <alobakin@...me>,
        Willem de Bruijn <willemb@...gle.com>,
        Cong Wang <cong.wang@...edance.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Kevin Hao <haokexin@...il.com>,
        Aleksandr Nogikh <nogikh@...gle.com>,
        Marco Elver <elver@...gle.com>, memxor@...il.com,
        David Ahern <dsahern@...il.com>
Subject: Re: [Linuxarm] Re: [PATCH net-next v2 3/3] skbuff: keep track of pp
 page when __skb_frag_ref() is called

On Wed, Sep 15, 2021 at 7:05 PM Yunsheng Lin <linyunsheng@...wei.com> wrote:

> As memtioned before, Tx recycling is based on page_pool instance per socket.
> it shares the page_pool instance with rx.
>
> Anyway, based on feedback from edumazet and dsahern, I am still trying to
> see if the page pool is meaningful for tx.
>

It is not for generic linux TCP stack, but perhaps for benchmarks.

Unless you dedicate one TX/RX pair per TCP socket ?

Most high performance TCP flows are using zerocopy, I am really not
sure why we would
need to 'optimize' the path that is wasting cpu cycles doing
user->kernel copies anyway,
at the cost of insane complexity.