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From:   Kal Cutter Conley <kal.conley@dectris.com>
Date:   Fri, 21 Apr 2023 17:27:33 +0200
Message-ID: <CAHApi-ngO=hYTL449hUuV_b4mAa4NVS6eE5Uya1dZM6fEE7rPA@mail.gmail.com>
Subject: Re: [PATCH bpf-next v3 1/3] xsk: Support UMEM chunk_size > PAGE_SIZE
To:     Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Cc:     =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= <toke@redhat.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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> Here is the comparison between multi-buffer and jumbo frames that I did
> for ZC ice driver. Configured MTU was 8192 as this is the frame size for
> aligned mode when working with huge pages. I am presenting plain numbers
> over here from xdpsock.
>
> Mbuf, packet size = 8192 - XDP_PACKET_HEADROOM
> 885,705pps - rxdrop frame_size=4096
> 806,307pps - l2fwd frame_size=4096
> 877,989pps - rxdrop frame_size=2048
> 773,331pps - l2fwd frame_size=2048
>
> Jumbo, packet size = 8192 - XDP_PACKET_HEADROOM
> 893,530pps - rxdrop frame_size=8192
> 841,860pps - l2fwd frame_size=8192

Thanks so much for sharing these initial results! Do you have similar
measurements for ~9000 byte packets in unaligned mode? We typically
receive packets larger than 8192 bytes.

>
> Kal might say that multi-buffer numbers are imaginary as these patches
> were never shown to the public ;) but now that we have extensive test
> suite I am fixing some last issues that stand out, so we are asking for
> some more patience over here... overall i was expecting that they will be
> much worse when compared to jumbo frames, but then again i believe this
> implementation is not ideal and can be improved. Nevertheless, jumbo
> frames support has its value.

You made me chuckle ;-) Any measurements people can provide are
helpful, even if they must be taken with a grain of salt. ;-). How
much of your test suite can be upstreamed in the future? My assumption
was the difference should be measurable, at least you have confirmed
that. :-)