Re: [PATCHSET 0/9] perf: Improve cgroup profiling (v3)

[Vince Weaver <vincent.weaver@maine.edu>]

On Thu, 26 Dec 2019, Arnaldo Carvalho de Melo wrote:

> Em Tue, Dec 24, 2019 at 09:40:04AM +0900, Namhyung Kim escreveu:
> > On Tue, Dec 24, 2019 at 2:35 AM Vince Weaver <vincent.weaver@maine.edu> wrote:
> > > On Mon, 23 Dec 2019, Namhyung Kim wrote:
> > > > This work is to improve cgroup profiling in perf.  Currently it only
> > > > supports profiling tasks in a specific cgroup and there's no way to
> > > > identify which cgroup the current sample belongs to.  So I added
> > > > PERF_SAMPLE_CGROUP to add cgroup id into each sample.  It's a 64-bit
> > > > integer having file handle of the cgroup.  And kernel also generates
> > > > PERF_RECORD_CGROUP event for new groups to correlate the cgroup id and
> > > > cgroup name (path in the cgroup filesystem).  The cgroup id can be
> > > > read from userspace by name_to_handle_at() system call so it can
> > > > synthesize the CGROUP event for existing groups.
> 
> > > so is there a patch to the manpage that describes this new behavior in
> > > perf_event_open()?
> 
> > Not yet.  I'll cook a patch once it's merged to the Linus' tree.
> 
> Vince, was it ever considered to carry the man page in the kernel
> sources and then make it so that new features need to come with the
> respective changes to the man page? I think that would be a good move,
> you would be the maintainer for that file, what do you think?

While I do a lot of work on the perf_event_open() manpage,  it's part of 
the linux man-pages project so I don't really control where it is 
maintained.

I personally do not think it would help much merging into the kernel tree.
I still think the idea of moving everything into linux-git (such as the  
"perf" tool) isn't always the best idea and can make it harder for people
who aren't kernel developers to work on things.

Vince