netdev - Re: [PATCH bpf-next 0/9] bpf: cpumap: enable GRO for XDP

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Message-ID: <20240903135158.7031a3ab@kernel.org>
Date: Tue, 3 Sep 2024 13:51:58 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Alexander Lobakin <aleksander.lobakin@...el.com>
Cc: Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann
 <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>, Lorenzo
 Bianconi <lorenzo@...nel.org>, Daniel Xu <dxu@...uu.xyz>, John Fastabend
 <john.fastabend@...il.com>, Jesper Dangaard Brouer <hawk@...nel.org>,
 Martin KaFai Lau <martin.lau@...ux.dev>, "David S. Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Paolo Abeni
 <pabeni@...hat.com>, bpf@...r.kernel.org, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH bpf-next 0/9] bpf: cpumap: enable GRO for XDP_PASS
 frames

On Fri, 30 Aug 2024 18:24:59 +0200 Alexander Lobakin wrote:
> * patch 4: switch cpumap from a custom kthread to a CPU-pinned
>   threaded NAPI;

Could you try to use the backlog NAPI? Allocating a fake netdev and
using NAPI as a threading abstraction feels like an abuse. Maybe try
to factor out the necessary bits? What we want is using the per-cpu 
caches, and feeding GRO. None of the IRQ related NAPI functionality
fits in here.