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Message-ID: <CAJ+HfNiH4KUO-MXm3L8pka3dECC1S6rHUJ9NoMfyrhPD+9s9nw@mail.gmail.com> Date: Wed, 11 Dec 2019 13:38:01 +0100 From: Björn Töpel <bjorn.topel@...il.com> To: Toke Høiland-Jørgensen <toke@...hat.com> Cc: Netdev <netdev@...r.kernel.org>, Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, bpf <bpf@...r.kernel.org>, Magnus Karlsson <magnus.karlsson@...il.com>, "Karlsson, Magnus" <magnus.karlsson@...el.com>, Jonathan Lemon <jonathan.lemon@...il.com>, Edward Cree <ecree@...arflare.com>, Toke Høiland-Jørgensen <thoiland@...hat.com>, Andrii Nakryiko <andrii.nakryiko@...il.com> Subject: Re: [PATCH bpf-next v3 0/6] Introduce the BPF dispatcher On Mon, 9 Dec 2019 at 18:42, Björn Töpel <bjorn.topel@...il.com> wrote: > [...] > > You mentioned in the earlier version that this would impact the time it > > takes to attach an XDP program. Got any numbers for this? > > > > Ah, no, I forgot to measure that. I'll get back with that. So, when a > new program is entered or removed from dispatcher, it needs to be > re-jited, but more importantly -- a text poke is needed. I don't know > if this is a concern or not, but let's measure it. > Toke, I tried to measure the impact, but didn't really get anything useful out. :-( My concern was mainly that text-poking is a point of contention, and it messes with the icache. As for contention, we're already synchronized around the rtnl-lock. As for the icache-flush effects... well... I'm open to suggestions how to measure the impact in a useful way. > > Björn > > > -Toke > >
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