Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <CAM9d7cjQ20a01YoZi=o-_7HT6TzR0TZgtpscKNvRrMq2yqV1Og@mail.gmail.com>
 <20220922041435.709119-1-namhyung@kernel.org> <YzdjHenrJpooKMjv@krava>
In-Reply-To: <YzdjHenrJpooKMjv@krava>
From:   Namhyung Kim <namhyung@kernel.org>
Date:   Fri, 30 Sep 2022 14:56:40 -0700
Message-ID: <CAM9d7cjKaZvWQUwGwoTLNzAgHS7ndL_V_5+O+WqMUvuHJ7cWNg@mail.gmail.com>
Subject: Re: [PATCH] perf stat: Support old kernels for bperf cgroup counting
To:     Jiri Olsa <olsajiri@gmail.com>
Cc:     Tejun Heo <tj@kernel.org>, Zefan Li <lizefan.x@bytedance.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        cgroups <cgroups@vger.kernel.org>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-perf-users <linux-perf-users@vger.kernel.org>,
        Song Liu <songliubraving@fb.com>, bpf <bpf@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Hi Jiri,

On Fri, Sep 30, 2022 at 2:44 PM Jiri Olsa <olsajiri@gmail.com> wrote:
>
> On Wed, Sep 21, 2022 at 09:14:35PM -0700, Namhyung Kim wrote:
> > The recent change in the cgroup will break the backward compatiblity in
> > the BPF program.  It should support both old and new kernels using BPF
> > CO-RE technique.
> >
> > Like the task_struct->__state handling in the offcpu analysis, we can
> > check the field name in the cgroup struct.
> >
> > Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> > ---
> > Arnaldo, I think this should go through the cgroup tree since it depends
> > on the earlier change there.  I don't think it'd conflict with other
> > perf changes but please let me know if you see any trouble, thanks!
>
> could you please paste the cgroup tree link?

Do you mean this?

  https://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git

Thanks,.
Namhyung