Re: [PATCH v4 0/3] perf: add support for analyzing events for containers

[Hari Bathini]

Hi Alban,


On Friday 16 December 2016 05:44 PM, Alban Crequy wrote:
> Hi,
>
> > Currently, there is no trivial mechanism to analyze events based on
> > containers. perf -G can be used, but it will not filter events for the
> > containers created after perf is invoked, making it difficult to assess/
> > analyze performance issues of multiple containers at once.
> >
> > This patch-set overcomes this limitation by using cgroup identifier as
> > container unique identifier. A new PERF_RECORD_NAMESPACES event that
> > records namespaces related info is introduced, from which the cgroup
> > namespace's device & inode numbers are used as cgroup identifier. This
> > is based on the assumption that each container is created with it's own
> > cgroup namespace allowing assessment/analysis of multiple containers
> > using cgroup identifier.
> >
> > The first patch introduces PERF_RECORD_NAMESPACES in kernel while the
> > second patch makes the corresponding changes in perf tool to read this
> > PERF_RECORD_NAMESPACES events. The third patch adds a cgroup identifier
> > column in perf report, which contains the cgroup namespace's device and
> > inode numbers.
> I have a question for the pid namespace: does the new perf event gives
> the pid namespace of the task, or the pid_ns_for_children from the
> nsproxy? From my limited understanding, v4 seems to do the former, as
> opposed to v3.

Ah! How did I miss that?!

> When synthesizing events from /proc/$PID/ns/pid, it cannot take the
> pid_ns_for_children, so I wanted to make sure it is consistent.

So, eventually this version sounds like the right way of doing it..?

Thanks
Hari