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Open Source and information security mailing list archives
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Date: Wed, 9 Dec 2020 08:41:05 -0700 From: David Ahern <dsahern@...il.com> To: Jesper Dangaard Brouer <jbrouer@...hat.com>, Maciej Fijalkowski <maciej.fijalkowski@...el.com> Cc: John Fastabend <john.fastabend@...il.com>, Daniel Borkmann <daniel@...earbox.net>, Toke Høiland-Jørgensen <toke@...hat.com>, alardam@...il.com, magnus.karlsson@...el.com, bjorn.topel@...el.com, andrii.nakryiko@...il.com, kuba@...nel.org, ast@...nel.org, netdev@...r.kernel.org, davem@...emloft.net, hawk@...nel.org, jonathan.lemon@...il.com, bpf@...r.kernel.org, jeffrey.t.kirsher@...el.com, maciejromanfijalkowski@...il.com, intel-wired-lan@...ts.osuosl.org, Marek Majtyka <marekx.majtyka@...el.com> Subject: Re: [PATCH v2 bpf 1/5] net: ethtool: add xdp properties flag set On 12/9/20 4:52 AM, Jesper Dangaard Brouer wrote: >>> still load and either share queues across multiple cores or restirct >>> down to a subset of CPUs. >> >> And that's the missing piece of logic, I suppose. >> >>> Do you need 192 cores for a 10gbps nic, probably not. >> >> Let's hear from Jesper :p > > LOL - of-cause you don't need 192 cores. With XDP I will claim that > you only need 2 cores (with high GHz) to forward 10gbps wirespeed small > packets. You don't need 192 for 10G on Rx. However, if you are using XDP_REDIRECT from VM tap devices the next device (presumably the host NIC) does need to be able to handle the redirect. My personal experience with this one is mlx5/ConnectX4-LX with a limit of 63 queues and a server with 96 logical cpus. If the vhost thread for the tap device runs on a cpu that does not have an XDP TX Queue, the packet is dropped. This is a really bizarre case to debug as some packets go out fine while others are dropped.
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