On Sun, Jul 16, 2023 at 8:10 PM Yafang Shao <laoar.shao@xxxxxxxxx> wrote:
>
> This patch introduces cgroup_task iter, which allows for efficient
> iteration of tasks within a specific cgroup. For example, we can effiently
> get the nr_{running,blocked} of a container with this new feature.
>
> The cgroup_task iteration serves as an alternative to task_iter in
> container environments due to certain limitations associated with
> task_iter.
>
> - Firstly, task_iter only supports the 'current' pidns.
> However, since our data collector operates on the host, we may need to
> collect information from multiple containers simultaneously. Using
> task_iter would require us to fork the collector for each container,
> which is not ideal.
>
> - Additionally, task_iter is unable to collect task information from
> containers running in the host pidns.
> In our container environment, we have containers running in the host
> pidns, and we would like to collect task information from them as well.
>
> - Lastly, task_iter does not support multiple-container pods.
> In a Kubernetes environment, a single pod may contain multiple
> containers, all sharing the same pidns. However, we are only interested
> in iterating tasks within the main container, which is not possible with
> task_iter.
>
> To address the first issue, we could potentially extend task_iter to
> support specifying a pidns other than the current one. However, for the
> other two issues, extending task_iter would not provide a solution.
> Therefore, we believe it is preferable to introduce the cgroup_task iter to
> handle these scenarios effectively.
>
> Patch #1: Preparation
> Patch #2: Add cgroup_task iter
> Patch #3: Add support for cgroup_task iter in bpftool
> Patch #4: Selftests for cgroup_task iter
>
> Yafang Shao (4):
> bpf: Add __bpf_iter_attach_cgroup()
> bpf: Add cgroup_task iter
> bpftool: Add support for cgroup_task
> selftests/bpf: Add selftest for cgroup_task iter
>
> include/linux/btf_ids.h | 14 ++
> kernel/bpf/cgroup_iter.c | 181 ++++++++++++++--
> tools/bpf/bpftool/link.c | 3 +-
> .../bpf/prog_tests/cgroup_task_iter.c | 197 ++++++++++++++++++
> .../selftests/bpf/progs/cgroup_task_iter.c | 39 ++++
> 5 files changed, 419 insertions(+), 15 deletions(-)
> create mode 100644 tools/testing/selftests/bpf/prog_tests/cgroup_task_iter.c
> create mode 100644 tools/testing/selftests/bpf/progs/cgroup_task_iter.c
>
Just a kind reminder.
Anyone is interested in this idea ?
--
Regards
Yafang
