From: Yosry Ahmed <yosryahmed@google.com> To: Tejun Heo <tj@kernel.org> Cc: 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>, Hao Luo <haoluo@google.com>, 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 Mailing List <linux-kernel@vger.kernel.org>, Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>, Cgroups <cgroups@vger.kernel.org> Subject: Re: [PATCH bpf-next v1 3/5] bpf: Introduce cgroup iter Date: Fri, 20 May 2022 00:58:52 -0700 [thread overview] Message-ID: <CAJD7tkbvMcMWESMcWi6TtdCKLr6keBNGgZTnqcHZvBrPa1qWPw@mail.gmail.com> (raw) In-Reply-To: <YodGI73xq8aIBrNM@slm.duckdns.org> On Fri, May 20, 2022 at 12:41 AM Tejun Heo <tj@kernel.org> wrote: > > On Fri, May 20, 2022 at 01:21:31AM +0000, Yosry Ahmed wrote: > > From: Hao Luo <haoluo@google.com> > > > > Introduce a new type of iter prog: cgroup. Unlike other bpf_iter, this > > iter doesn't iterate a set of kernel objects. Instead, it is supposed to > > be parameterized by a cgroup id and prints only that cgroup. So one > > needs to specify a target cgroup id when attaching this iter. The target > > cgroup's state can be read out via a link of this iter. > > > > Signed-off-by: Hao Luo <haoluo@google.com> > > Signed-off-by: Yosry Ahmed <yosryahmed@google.com> > > This could be me not understanding why it's structured this way but it keeps > bothering me that this is adding a cgroup iterator which doesn't iterate > cgroups. If all that's needed is extracting information from a specific > cgroup, why does this need to be an iterator? e.g. why can't I use > BPF_PROG_TEST_RUN which looks up the cgroup with the provided ID, flushes > rstat, retrieves whatever information necessary and returns that as the > result? I will let Hao and Yonghong reply here as they have a lot more context, and they had previous discussions about cgroup_iter. I just want to say that exposing the stats in a file is extremely convenient for userspace apps. It becomes very similar to reading stats from cgroupfs. It also makes migrating cgroup stats that we have implemented in the kernel to BPF a lot easier. AFAIK there are also discussions about using overlayfs to have links to the bpffs files in cgroupfs, which makes it even better. So I would really prefer keeping the approach we have here of reading stats through a file from userspace. As for how we go about this (and why a cgroup iterator doesn't iterate cgroups) I will leave this for Hao and Yonghong to explain the rationale behind it. Ideally we can keep the same functionality under a more descriptive name/type. > > Thanks. > > -- > tejun
WARNING: multiple messages have this Message-ID (diff)
From: Yosry Ahmed <yosryahmed@google.com> To: Tejun Heo <tj@kernel.org> Cc: 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>, Hao Luo <haoluo@google.com>, 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 Mailing List <linux-kernel@vger.kernel.org>, Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org> Subject: Re: [PATCH bpf-next v1 3/5] bpf: Introduce cgroup iter Date: Fri, 20 May 2022 00:58:52 -0700 [thread overview] Message-ID: <CAJD7tkbvMcMWESMcWi6TtdCKLr6keBNGgZTnqcHZvBrPa1qWPw@mail.gmail.com> (raw) In-Reply-To: <YodGI73xq8aIBrNM@slm.duckdns.org> On Fri, May 20, 2022 at 12:41 AM Tejun Heo <tj@kernel.org> wrote: > > On Fri, May 20, 2022 at 01:21:31AM +0000, Yosry Ahmed wrote: > > From: Hao Luo <haoluo@google.com> > > > > Introduce a new type of iter prog: cgroup. Unlike other bpf_iter, this > > iter doesn't iterate a set of kernel objects. Instead, it is supposed to > > be parameterized by a cgroup id and prints only that cgroup. So one > > needs to specify a target cgroup id when attaching this iter. The target > > cgroup's state can be read out via a link of this iter. > > > > Signed-off-by: Hao Luo <haoluo@google.com> > > Signed-off-by: Yosry Ahmed <yosryahmed@google.com> > > This could be me not understanding why it's structured this way but it keeps > bothering me that this is adding a cgroup iterator which doesn't iterate > cgroups. If all that's needed is extracting information from a specific > cgroup, why does this need to be an iterator? e.g. why can't I use > BPF_PROG_TEST_RUN which looks up the cgroup with the provided ID, flushes > rstat, retrieves whatever information necessary and returns that as the > result? I will let Hao and Yonghong reply here as they have a lot more context, and they had previous discussions about cgroup_iter. I just want to say that exposing the stats in a file is extremely convenient for userspace apps. It becomes very similar to reading stats from cgroupfs. It also makes migrating cgroup stats that we have implemented in the kernel to BPF a lot easier. AFAIK there are also discussions about using overlayfs to have links to the bpffs files in cgroupfs, which makes it even better. So I would really prefer keeping the approach we have here of reading stats through a file from userspace. As for how we go about this (and why a cgroup iterator doesn't iterate cgroups) I will leave this for Hao and Yonghong to explain the rationale behind it. Ideally we can keep the same functionality under a more descriptive name/type. > > Thanks. > > -- > tejun
next prev parent reply other threads:[~2022-05-20 7:59 UTC|newest] Thread overview: 110+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-05-20 1:21 [PATCH bpf-next v1 0/5] bpf: rstat: cgroup hierarchical stats Yosry Ahmed 2022-05-20 1:21 ` Yosry Ahmed 2022-05-20 1:21 ` [PATCH bpf-next v1 1/5] cgroup: bpf: add a hook for bpf progs to attach to rstat flushing Yosry Ahmed 2022-05-21 11:16 ` kernel test robot 2022-05-21 11:16 ` kernel test robot 2022-05-21 11:26 ` kernel test robot 2022-05-21 11:26 ` kernel test robot 2022-05-21 11:26 ` kernel test robot 2022-05-21 11:26 ` kernel test robot 2022-05-20 1:21 ` [PATCH bpf-next v1 2/5] cgroup: bpf: add cgroup_rstat_updated() and cgroup_rstat_flush() kfuncs Yosry Ahmed 2022-05-20 1:21 ` Yosry Ahmed 2022-05-20 7:24 ` Tejun Heo 2022-05-20 7:24 ` Tejun Heo 2022-05-20 9:13 ` Yosry Ahmed 2022-05-20 9:13 ` Yosry Ahmed 2022-05-20 9:36 ` Kumar Kartikeya Dwivedi 2022-05-20 9:36 ` Kumar Kartikeya Dwivedi 2022-05-20 11:16 ` Tejun Heo 2022-05-20 11:16 ` Tejun Heo 2022-05-20 16:06 ` Yosry Ahmed 2022-05-20 16:06 ` Yosry Ahmed 2022-05-20 15:14 ` Yonghong Song 2022-05-20 16:08 ` Yosry Ahmed 2022-05-20 16:08 ` Yosry Ahmed 2022-05-20 16:16 ` Yonghong Song 2022-05-20 16:16 ` Yonghong Song 2022-05-20 16:20 ` Yosry Ahmed 2022-05-20 16:20 ` Yosry Ahmed 2022-05-21 11:47 ` kernel test robot 2022-05-21 11:47 ` kernel test robot 2022-05-20 1:21 ` [PATCH bpf-next v1 3/5] bpf: Introduce cgroup iter Yosry Ahmed 2022-05-20 7:41 ` Tejun Heo 2022-05-20 7:41 ` Tejun Heo 2022-05-20 7:58 ` Yosry Ahmed [this message] 2022-05-20 7:58 ` Yosry Ahmed 2022-05-20 8:11 ` Tejun Heo 2022-05-20 8:11 ` Tejun Heo 2022-05-20 11:27 ` Tejun Heo 2022-05-20 11:27 ` Tejun Heo 2022-05-20 16:29 ` Yonghong Song 2022-05-20 16:29 ` Yonghong Song 2022-05-20 16:45 ` Tejun Heo 2022-05-20 16:45 ` Tejun Heo 2022-05-20 19:42 ` Hao Luo 2022-05-20 19:42 ` Hao Luo 2022-05-20 21:18 ` Yosry Ahmed 2022-05-20 21:18 ` Yosry Ahmed 2022-05-20 22:19 ` Alexei Starovoitov 2022-05-20 22:19 ` Alexei Starovoitov 2022-05-20 22:36 ` Yosry Ahmed 2022-05-20 22:36 ` Yosry Ahmed 2022-05-20 22:57 ` Tejun Heo 2022-05-20 22:57 ` Tejun Heo 2022-05-21 0:59 ` Yonghong Song 2022-05-21 0:59 ` Yonghong Song 2022-05-21 2:34 ` Hao Luo 2022-05-21 2:34 ` Hao Luo 2022-05-23 23:58 ` Andrii Nakryiko 2022-05-23 23:58 ` Andrii Nakryiko 2022-05-24 0:53 ` Hao Luo 2022-05-24 0:53 ` Hao Luo 2022-05-24 1:30 ` Andrii Nakryiko 2022-05-24 1:30 ` Andrii Nakryiko 2022-05-20 21:49 ` Hao Luo 2022-05-20 21:49 ` Hao Luo 2022-05-21 0:58 ` Yonghong Song 2022-05-21 0:58 ` Yonghong Song 2022-05-21 2:43 ` Hao Luo 2022-05-21 2:43 ` Hao Luo 2022-05-21 4:53 ` Tejun Heo 2022-05-21 4:53 ` Tejun Heo 2022-05-21 0:52 ` Yonghong Song 2022-05-21 0:52 ` Yonghong Song 2022-05-20 17:30 ` Hao Luo 2022-05-20 17:30 ` Hao Luo 2022-05-20 1:21 ` [PATCH bpf-next v1 4/5] selftests/bpf: extend cgroup helpers Yosry Ahmed 2022-05-20 1:21 ` [PATCH bpf-next v1 5/5] bpf: add a selftest for cgroup hierarchical stats collection Yosry Ahmed 2022-05-20 16:09 ` Yonghong Song 2022-05-20 16:18 ` Yosry Ahmed 2022-05-20 16:18 ` Yosry Ahmed 2022-05-24 0:01 ` Andrii Nakryiko 2022-05-24 0:01 ` Andrii Nakryiko 2022-05-24 2:35 ` Yosry Ahmed 2022-05-24 2:35 ` Yosry Ahmed 2022-06-03 16:23 ` Michal Koutný 2022-06-03 16:23 ` Michal Koutný 2022-06-03 19:52 ` Yosry Ahmed 2022-06-03 19:52 ` Yosry Ahmed 2022-06-06 12:32 ` Michal Koutný 2022-06-06 12:32 ` Michal Koutný 2022-06-06 19:41 ` Yosry Ahmed 2022-06-06 19:41 ` Yosry Ahmed 2022-06-07 12:12 ` Michal Koutný 2022-06-07 12:12 ` Michal Koutný 2022-06-07 17:43 ` Yosry Ahmed 2022-06-07 17:43 ` Yosry Ahmed 2022-06-08 11:17 ` Michal Koutný 2022-06-08 11:17 ` Michal Koutný 2022-06-03 16:22 ` [PATCH bpf-next v1 0/5] bpf: rstat: cgroup hierarchical stats Michal Koutný 2022-06-03 16:22 ` Michal Koutný 2022-06-03 19:47 ` Yosry Ahmed 2022-06-03 19:47 ` Yosry Ahmed 2022-06-06 12:32 ` Michal Koutný 2022-06-06 12:32 ` Michal Koutný 2022-06-06 19:32 ` Yosry Ahmed 2022-06-06 19:32 ` Yosry Ahmed 2022-06-06 19:54 ` Kumar Kartikeya Dwivedi 2022-06-06 19:54 ` Kumar Kartikeya Dwivedi 2022-06-06 20:00 ` Yosry Ahmed 2022-06-06 20:00 ` Yosry Ahmed
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