Re: Getting the latest and greatest Linux perf features on every Debian kernel

From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Ian Rogers <irogers@google.com>
Cc: debian-kernel@lists.debian.org,
	linux-perf-users <linux-perf-users@vger.kernel.org>,
	ben@decadent.org.uk, Jiri Olsa <jolsa@kernel.org>,
	Namhyung Kim <namhyung@kernel.org>
Subject: Re: Getting the latest and greatest Linux perf features on every Debian kernel
Date: Fri, 12 Nov 2021 11:39:05 -0300	[thread overview]
Message-ID: <YY58idSor+lJ84KF@kernel.org> (raw)
In-Reply-To: <CAP-5=fW7La9ZNv8Z6LHRRNXne4+dWK6dR1ye2P=zETFELtK=fg@mail.gmail.com>

Em Thu, Nov 11, 2021 at 10:34:33PM -0800, Ian Rogers escreveu:
> Hi,

> Debian currently tries to match the Linux perf tool to the version of
> the kernel that it is being run upon. Reaching out to Ben Hutchings,
> he explained to me that this was done back in 2010 due to kernel and
> Linux perf incompatibilities. This was likely the case, but it was a
> bug in the Linux perf tool that should have been fixed. It is the goal
> of the tool to be backward compatible. A problem with matching the
> tool to the kernel version is that users miss out on new features and
> fixes (this topic came up in a recent interview of the maintainer
> Arnaldo Carvalho de Melo [1]).

> Ben Hutchings informs me that making it so that Debian ships the
> latest Linux perf tool requires updates both to the linux-base and
> linux source packages. The Linux perf tool also has many other often
> optional dependencies, like libunwind, libbpf, libpfm4, libtraceevent,
> etc. In general, having the dependency will unlock more features.
> Linux tools has its own copies of libbpf and libtraceevent, and so
> these may pose some versioning issues.

We can use LIBBPF_DYNAMIC=1 to use the distro libbpf-dev package, which
currently is going thru some growing pains as libbpf is 0.x, with
several APIs being deprecated, others renamed, and that has been a
source of friction, but should be past us with v1.0. Till then the perf
codebase is being adjusted to allow it to be seamlessly built with the
in-kernel version and with whatever libbpf-devel the distro has.

> I think it'd be great to get Debian shipping the latest version of
> Linux perf for its users. Hopefully we can agree to change how Debian
> packages perf currently and then work out the best way to package and
> keep it up-to-date. I look forward to everyone's help and input.

I also keep the tarballs available at:

https://mirrors.edge.kernel.org/pub/linux/kernel/tools/perf/

Where there are instructions on how to build this detached tarball.

I regularly build perf on lots of distros, including:

  debian:9                      : Ok   gcc (Debian 6.3.0-18+deb9u1) 6.3.0 20170516 , clang version 3.8.1-24 (tags/RELEASE_381/final)
  debian:10                     : Ok   gcc (Debian 8.3.0-6) 8.3.0 , clang version 7.0.1-8+deb10u2 (tags/RELEASE_701/final)
  debian:11                     : Ok   gcc (Debian 10.2.1-6) 10.2.1 20210110 , Debian clang version 11.0.1-2
  debian:experimental           : Ok   gcc (Debian 11.2.0-10) 11.2.0 , Debian clang version 11.1.0-4
  debian:experimental-x-arm64   : Ok   aarch64-linux-gnu-gcc (Debian 11.2.0-9) 11.2.0
  debian:experimental-x-mips    : Ok   mips-linux-gnu-gcc (Debian 10.2.1-6) 10.2.1 20210110
  debian:experimental-x-mips64  : Ok   mips64-linux-gnuabi64-gcc (Debian 10.2.1-6) 10.2.1 20210110
  debian:experimental-x-mipsel  : Ok   mipsel-linux-gnu-gcc (Debian 11.2.0-9) 11.2.0

Ditto for ubuntu.

A complete list can be found in each pull request I send to Linus, see
in the last one:

  https://lore.kernel.org/all/20211107204947.1394255-1-acme@kernel.org/

Search for BUILD_TARBALL.

There is also the output for 'make -C tools/perf build-test' that tests
building with lots of combinations of optional libraries, for instance,
with LIBBPF_DYNAMIC=1, etc.

- Arnaldo