Re: [PATCH v2] blk-cgroup: always display debug stats in io.stat

[Breno Leitao]

On Wed, Mar 04, 2026 at 06:48:17AM -1000, Tejun Heo wrote:
> Hello, Breno.
> 
> On Wed, Mar 04, 2026 at 01:56:43AM -0800, Breno Leitao wrote:
> > > Given that they haven't changed for a long time, maybe it's okay to expose
> > > them by default, but why? This is something which can be toggled on easily
> > > at any time.
> > 
> > My goal is to ship a kernel that exposes these detailed io stats by
> > default, without requiring any runtime configuration. The stats should
> > simply be available out of the box.
> 
> This is a pretty trivial patch to carry, right? Or just do it as a part of
> boot system config?

Yes, a very trivial one, but, which requires some work to be done at
every rebase. Mainly when trying to use pristine stable trees.

> > > What's the benefit of exposing these extra numbers which
> > > probably don't mean much for most people?
> > 
> > My original plan was to introduce a Kconfig option for this. In v1 (about a
> > month ago), Michal suggested removing the toggle entirely and always exposing
> > the stats, which seemed reasonable to me and received no objections, so I
> > went ahead with that approach.
> > 
> > To be clear: is your position that we should not support building a kernel
> > that always exposes the detailed stats in io.stat?
> 
> As a debug option maybe but I'd prefer if vendors (including us) that want
> to permanently enable these debug stats carried the patch in their trees.

That is fair, thanks for the direction!
--breno