From: Tejun Heo <tj@kernel.org>
To: Hao Luo <haoluo@google.com>
Cc: Yosry Ahmed <yosryahmed@google.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@kernel.org>, Zefan Li <lizefan.x@bytedance.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Shuah Khan <shuah@kernel.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
Michal Hocko <mhocko@kernel.org>,
Stanislav Fomichev <sdf@google.com>,
David Rientjes <rientjes@google.com>,
Greg Thelen <gthelen@google.com>,
Shakeel Butt <shakeelb@google.com>,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
bpf@vger.kernel.org, cgroups@vger.kernel.org
Subject: Re: [RFC PATCH bpf-next 8/9] bpf: Introduce cgroup iter
Date: Tue, 10 May 2022 12:07:44 -1000 [thread overview]
Message-ID: <YnriMPYyOP9ibskc@slm.duckdns.org> (raw)
In-Reply-To: <CA+khW7girnNwap1ABN1a4XuvkEEnmkztTV+fsuC3MsxNeB08Yg@mail.gmail.com>
Hello,
On Tue, May 10, 2022 at 02:12:16PM -0700, Hao Luo wrote:
> > Is there a reason why this can't be a proper iterator which supports
> > lseek64() to locate a specific cgroup?
> >
>
> There are two reasons:
>
> - Bpf_iter assumes no_llseek. I haven't looked closely on why this is
> so and whether we can add its support.
>
> - Second, the name 'iter' in this patch is misleading. What this patch
> really does is reusing the functionality of dumping in bpf_iter.
> 'Dumper' is a better name. We want to create one file in bpffs for
> each cgroup. We are essentially just iterating a set of one single
> element.
I see. I'm just shooting in the dark without context but at least in
principle there's no reason why cgroups wouldn't be iterable, so it might be
something worth at least thinking about before baking in the interface.
Thanks.
--
tejun
next prev parent reply other threads:[~2022-05-10 22:07 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-10 0:17 [RFC PATCH bpf-next 0/9] bpf: cgroup hierarchical stats collection Yosry Ahmed
2022-05-10 0:17 ` [RFC PATCH bpf-next 1/9] bpf: introduce CGROUP_SUBSYS_RSTAT program type Yosry Ahmed
2022-05-10 18:07 ` Yosry Ahmed
2022-05-10 19:21 ` Yosry Ahmed
2022-05-10 18:44 ` Tejun Heo
2022-05-10 19:34 ` Yosry Ahmed
2022-05-10 19:59 ` Tejun Heo
2022-05-10 20:43 ` Yosry Ahmed
2022-05-10 21:01 ` Tejun Heo
2022-05-10 21:55 ` Yosry Ahmed
2022-05-10 22:09 ` Tejun Heo
2022-05-10 22:10 ` Yosry Ahmed
2022-05-10 0:18 ` [RFC PATCH bpf-next 2/9] cgroup: bpf: flush bpf stats on rstat flush Yosry Ahmed
2022-05-10 18:45 ` Tejun Heo
2022-05-10 0:18 ` [RFC PATCH bpf-next 3/9] libbpf: Add support for rstat progs and links Yosry Ahmed
2022-05-10 0:18 ` [RFC PATCH bpf-next 4/9] bpf: add bpf rstat helpers Yosry Ahmed
2022-05-10 0:18 ` [RFC PATCH bpf-next 5/9] bpf: add bpf_map_lookup_percpu_elem() helper Yosry Ahmed
2022-05-10 0:18 ` [RFC PATCH bpf-next 6/9] cgroup: add v1 support to cgroup_get_from_id() Yosry Ahmed
2022-05-10 18:33 ` Tejun Heo
2022-05-10 18:36 ` Yosry Ahmed
2022-05-10 0:18 ` [RFC PATCH bpf-next 7/9] cgroup: Add cgroup_put() in !CONFIG_CGROUPS case Yosry Ahmed
2022-05-10 18:25 ` Hao Luo
2022-05-10 0:18 ` [RFC PATCH bpf-next 8/9] bpf: Introduce cgroup iter Yosry Ahmed
2022-05-10 18:25 ` Hao Luo
2022-05-10 18:54 ` Tejun Heo
2022-05-10 21:12 ` Hao Luo
2022-05-10 22:07 ` Tejun Heo [this message]
2022-05-10 22:49 ` Hao Luo
2022-05-10 0:18 ` [RFC PATCH bpf-next 9/9] selftest/bpf: add a selftest for cgroup hierarchical stats Yosry Ahmed
2022-05-13 7:16 ` [RFC PATCH bpf-next 0/9] bpf: cgroup hierarchical stats collection Yosry Ahmed
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