netdev - Re: [PATCH bpf-next 0/6] ice: post-mbuf fixes

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Message-ID: <87fsbd75pz.fsf@toke.dk>
Date:   Fri, 10 Feb 2023 19:09:12 +0100
From:   Toke Høiland-Jørgensen <toke@...hat.com>
To:     Alexander Lobakin <alexandr.lobakin@...el.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>
Cc:     Alexander Lobakin <alexandr.lobakin@...el.com>,
        Maciej Fijalkowski <maciej.fijalkowski@...el.com>,
        Magnus Karlsson <magnus.karlsson@...el.com>,
        Martin KaFai Lau <martin.lau@...ux.dev>,
        Song Liu <song@...nel.org>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        Jakub Kicinski <kuba@...nel.org>, bpf@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH bpf-next 0/6] ice: post-mbuf fixes

Alexander Lobakin <alexandr.lobakin@...el.com> writes:

> The set grew from the poor performance of %BPF_F_TEST_XDP_LIVE_FRAMES
> when the ice-backed device is a sender. Initially there were around
> 3.3 Mpps / thread, while I have 5.5 on skb-based pktgen...
>
> After fixing 0005 (0004 is a prereq for it) first (strange thing nobody
> noticed that earlier), I started catching random OOMs. This is how 0002
> (and partially 0001) appeared.
> 0003 is a suggestion from Maciej to not waste time on refactoring dead
> lines. 0006 is a "cherry on top" to get away with the final 6.7 Mpps.
> 4.5 of 6 are fixes, but only the first three are tagged, since it then
> starts being tricky. I may backport them manually later on.
>
> TL;DR for the series is that shortcuts are good, but only as long as
> they don't make the driver miss important things. %XDP_TX is purely
> driver-local, however .ndo_xdp_xmit() is not, and sometimes assumptions
> can be unsafe there.
>
> With that series and also one core code patch[0], "live frames" and
> xdp-trafficgen are now safe'n'fast on ice (probably more to come).

Nice speedup! And cool to see that you're playing around with
xdp-trafficgen :)

-Toke