From: Stanislav Fomichev <sdf@google.com>
To: Pavel Begunkov <asml.silence@gmail.com>
Cc: Martin KaFai Lau <kafai@fb.com>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Song Liu <songliubraving@fb.com>,
linux-kernel@vger.kernel.org
Subject: Re: [BPF PATCH for-next] cgroup/bpf: fast path for not loaded skb BPF filtering
Date: Tue, 14 Dec 2021 10:04:27 -0800 [thread overview]
Message-ID: <CAKH8qBvRG3Zdpo0ZK_Mkji52HqMa=i9ftzMykZLQB5bnz1YAPA@mail.gmail.com> (raw)
In-Reply-To: <5e2bc4bc-e844-9a8c-2a95-0f55645b4392@gmail.com>
On Tue, Dec 14, 2021 at 10:00 AM Pavel Begunkov <asml.silence@gmail.com> wrote:
>
> On 12/14/21 17:54, sdf@google.com wrote:
> > On 12/11, Pavel Begunkov wrote:
> >> On 12/11/21 01:56, Martin KaFai Lau wrote:
> >> > On Sat, Dec 11, 2021 at 01:15:05AM +0000, Pavel Begunkov wrote:
> >> > > That was the first idea, but it's still heavier than I'd wish. 0.3%-0.7%
> >> > > in profiles, something similar in reqs/s. rcu_read_lock/unlock() pair is
> >> > > cheap but anyway adds 2 barrier()s, and with bitmasks we can inline
> >> > > the check.
> >> > It sounds like there is opportunity to optimize
> >> > __cgroup_bpf_prog_array_is_empty().
> >> >
> >> > How about using rcu_access_pointer(), testing with &empty_prog_array.hdr,
> >> > and then inline it? The cgroup prog array cannot be all
> >> > dummy_bpf_prog.prog. If that could be the case, it should be replaced
> >> > with &empty_prog_array.hdr earlier, so please check.
> >
> >> I'd need to expose and export empty_prog_array, but that should do.
> >> Will try it out, thanks
> >
> > Note that we already use __cgroup_bpf_prog_array_is_empty in
> > __cgroup_bpf_run_filter_setsockopt/__cgroup_bpf_run_filter_getsockopt
> > for exactly the same purpose. If you happen to optimize it, pls
> > update these places as well.
>
> Just like it's already done in the patch? Or maybe you mean something else?
Ah, you already did it, looks good! I didn't scroll all the way to the
bottom and got distracted by Martin's comment about
__cgroup_bpf_prog_array_is_empty :-[
prev parent reply other threads:[~2021-12-14 18:04 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-10 2:23 [BPF PATCH for-next] cgroup/bpf: fast path for not loaded skb BPF filtering Pavel Begunkov
2021-12-11 0:38 ` Martin KaFai Lau
2021-12-11 1:15 ` Pavel Begunkov
2021-12-11 1:56 ` Martin KaFai Lau
2021-12-11 2:20 ` Pavel Begunkov
2021-12-14 17:54 ` sdf
2021-12-14 18:00 ` Pavel Begunkov
2021-12-14 18:04 ` Stanislav Fomichev [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAKH8qBvRG3Zdpo0ZK_Mkji52HqMa=i9ftzMykZLQB5bnz1YAPA@mail.gmail.com' \
--to=sdf@google.com \
--cc=andrii@kernel.org \
--cc=asml.silence@gmail.com \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=kafai@fb.com \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=songliubraving@fb.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).