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From:   Eric Dumazet <edumazet@google.com>
Date:   Fri, 17 Sep 2021 10:15:08 -0700
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Subject: Re: [Linuxarm] Re: [PATCH net-next v2 3/3] skbuff: keep track of pp
 page when __skb_frag_ref() is called
To:     Yunsheng Lin <linyunsheng@huawei.com>
Cc:     Jesper Dangaard Brouer <jbrouer@redhat.com>,
        Ilias Apalodimas <ilias.apalodimas@linaro.org>,
        Jesper Dangaard Brouer <brouer@redhat.com>,
        Alexander Duyck <alexander.duyck@gmail.com>,
        David Miller <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        netdev <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>, linuxarm@openeuler.org,
        Jesper Dangaard Brouer <hawk@kernel.org>,
        Jonathan Lemon <jonathan.lemon@gmail.com>,
        Alexander Lobakin <alobakin@pm.me>,
        Willem de Bruijn <willemb@google.com>,
        Cong Wang <cong.wang@bytedance.com>,
        Paolo Abeni <pabeni@redhat.com>,
        Kevin Hao <haokexin@gmail.com>,
        Aleksandr Nogikh <nogikh@google.com>,
        Marco Elver <elver@google.com>, memxor@gmail.com,
        David Ahern <dsahern@gmail.com>
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On Wed, Sep 15, 2021 at 7:05 PM Yunsheng Lin <linyunsheng@huawei.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.