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From:   Kal Cutter Conley <kal.conley@dectris.com>
Date:   Thu, 13 Apr 2023 14:43:32 +0200
Message-ID: <CAHApi-m4gu8SX_1rBtUwrw+1-Q3ERFEX-HPMcwcCK1OceirwuA@mail.gmail.com>
Subject: Re: [PATCH bpf-next v3 1/3] xsk: Support UMEM chunk_size > PAGE_SIZE
To:     =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= <toke@redhat.com>
Cc:     Maciej Fijalkowski <maciej.fijalkowski@intel.com>,
        =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= <bjorn@kernel.org>,
        Magnus Karlsson <magnus.karlsson@intel.com>,
        Jonathan Lemon <jonathan.lemon@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Jesper Dangaard Brouer <hawk@kernel.org>,
        John Fastabend <john.fastabend@gmail.com>,
        netdev@vger.kernel.org, bpf@vger.kernel.org,
        linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org
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> Well, you mentioned yourself that:
>
> > The disadvantage of this patchset is requiring the user to allocate
> > HugeTLB pages which is an extra complication.

It's a small extra complication *for the user*. However, users that
need this feature are willing to allocate hugepages. We are one such
user. For us, having to deal with packets split into disjoint buffers
(from the XDP multi-buffer paradigm) is a significantly more annoying
complication than allocating hugepages (particularly on the RX side).