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From: "Paul E. McKenney" <paulmck@kernel.org>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Andrii Nakryiko <andriin@fb.com>, bpf <bpf@vger.kernel.org>,
	Networking <netdev@vger.kernel.org>,
	Alexei Starovoitov <ast@fb.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Kernel Team <kernel-team@fb.com>,
	Jonathan Lemon <jonathan.lemon@gmail.com>
Subject: Re: [PATCH v2 bpf-next 2/7] tools/memory-model: add BPF ringbuf MPSC litmus tests
Date: Mon, 25 May 2020 20:05:35 -0700
Message-ID: <20200526030535.GE2869@paulmck-ThinkPad-P72> (raw)
In-Reply-To: <CAEf4Bza9aRM+6EfXaokV8xfEj_hRoKhNd5vYKtpc61XFAiewsA@mail.gmail.com>

On Mon, May 25, 2020 at 04:33:15PM -0700, Andrii Nakryiko wrote:
> On Fri, May 22, 2020 at 11:51 AM Andrii Nakryiko
> <andrii.nakryiko@gmail.com> wrote:
> >
> > On Thu, May 21, 2020 at 5:34 PM Paul E. McKenney <paulmck@kernel.org> wrote:
> > >
> > > On Sun, May 17, 2020 at 12:57:22PM -0700, Andrii Nakryiko wrote:
> > > > Add 4 litmus tests for BPF ringbuf implementation, divided into two different
> > > > use cases.
> > > >
> > > > First, two unbounded case, one with 1 producer and another with
> > > > 2 producers, single consumer. All reservations are supposed to succeed.
> > > >
> > > > Second, bounded case with only 1 record allowed in ring buffer at any given
> > > > time. Here failures to reserve space are expected. Again, 1- and 2- producer
> > > > cases, single consumer, are validated.
> > > >
> > > > Just for the fun of it, I also wrote a 3-producer cases, it took *16 hours* to
> > > > validate, but came back successful as well. I'm not including it in this
> > > > patch, because it's not practical to run it. See output for all included
> > > > 4 cases and one 3-producer one with bounded use case.
> > > >
> > > > Each litmust test implements producer/consumer protocol for BPF ring buffer
> > > > implementation found in kernel/bpf/ringbuf.c. Due to limitations, all records
> > > > are assumed equal-sized and producer/consumer counters are incremented by 1.
> > > > This doesn't change the correctness of the algorithm, though.
> > >
> > > Very cool!!!
> > >
> > > However, these should go into Documentation/litmus-tests/bpf-rb or similar.
> > > Please take a look at Documentation/litmus-tests/ in -rcu, -tip, and
> > > -next, including the README file.
> > >
> > > The tools/memory-model/litmus-tests directory is for basic examples,
> > > not for the more complex real-world ones like these guys.  ;-)
> >
> > Oh, ok, I didn't realize there are more litmus tests under
> > Documentation/litmus-tests... Might have saved me some time (more
> > examples to learn from!) when I was writing mine :) Will check those
> > and move everything.
> 
> Ok, so Documentation/litmus-tests is not present in bpf-next, so I
> guess I'll have to split this patch out and post it separately. BTW,
> it's not in -rcu tree either, should I post this against linux-next
> tree directly?

It is on branch "dev" of -rcu, though yet not on branch "master".

							Thanx, Paul

  reply index

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-17 19:57 [PATCH v2 bpf-next 0/7] BPF ring buffer Andrii Nakryiko
2020-05-17 19:57 ` [PATCH v2 bpf-next 1/7] bpf: implement BPF ring buffer and verifier support for it Andrii Nakryiko
2020-05-19 12:57   ` kbuild test robot
2020-05-19 23:53   ` kbuild test robot
2020-05-22  0:25   ` Paul E. McKenney
2020-05-22 18:46     ` Andrii Nakryiko
2020-05-25 16:01       ` Paul E. McKenney
2020-05-25 18:45         ` Andrii Nakryiko
2020-05-22  1:07   ` Alexei Starovoitov
2020-05-22 18:48     ` Andrii Nakryiko
2020-05-25 20:34     ` Andrii Nakryiko
2020-05-17 19:57 ` [PATCH v2 bpf-next 2/7] tools/memory-model: add BPF ringbuf MPSC litmus tests Andrii Nakryiko
2020-05-22  0:34   ` Paul E. McKenney
2020-05-22 18:51     ` Andrii Nakryiko
2020-05-25 23:33       ` Andrii Nakryiko
2020-05-26  3:05         ` Paul E. McKenney [this message]
2020-05-17 19:57 ` [PATCH v2 bpf-next 3/7] bpf: track reference type in verifier Andrii Nakryiko
2020-05-22  1:13   ` Alexei Starovoitov
2020-05-22 18:53     ` Andrii Nakryiko
2020-05-17 19:57 ` [PATCH v2 bpf-next 4/7] libbpf: add BPF ring buffer support Andrii Nakryiko
2020-05-22  1:15   ` Alexei Starovoitov
2020-05-22 18:56     ` Andrii Nakryiko
2020-05-17 19:57 ` [PATCH v2 bpf-next 5/7] selftests/bpf: add BPF ringbuf selftests Andrii Nakryiko
2020-05-22  1:20   ` Alexei Starovoitov
2020-05-22 18:58     ` Andrii Nakryiko
2020-05-17 19:57 ` [PATCH v2 bpf-next 6/7] bpf: add BPF ringbuf and perf buffer benchmarks Andrii Nakryiko
2020-05-22  1:21   ` Alexei Starovoitov
2020-05-22 19:07     ` Andrii Nakryiko
2020-05-17 19:57 ` [PATCH v2 bpf-next 7/7] docs/bpf: add BPF ring buffer design notes Andrii Nakryiko
2020-05-22  1:23   ` Alexei Starovoitov
2020-05-22 19:08     ` Andrii Nakryiko
2020-05-25  9:59   ` Alban Crequy
2020-05-25 19:12     ` Andrii Nakryiko

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