Re: [LSF/MM/BPF TOPIC] Memory profiling using code tagging

[Kent Overstreet <kent.overstreet@linux.dev>]

On Tue, Mar 28, 2023 at 06:28:21PM +0200, Vlastimil Babka wrote:
> On 2/22/23 20:31, Suren Baghdasaryan wrote:
> > We would like to continue the discussion about code tagging use for
> > memory allocation profiling. The code tagging framework [1] and its
> > applications were posted as an RFC [2] and discussed at LPC 2022. It
> > has many applications proposed in the RFC but we would like to focus
> > on its application for memory profiling. It can be used as a
> > low-overhead solution to track memory leaks, rank memory consumers by
> > the amount of memory they use, identify memory allocation hot paths
> > and possible other use cases.
> > Kent Overstreet and I worked on simplifying the solution, minimizing
> > the overhead and implementing features requested during RFC review.
> 
> IIRC one large objection was the use of page_ext, I don't recall if you
> found another solution to that?

No, page_ext is really the thing that makes the most sense here. It's
per-page allocation information, so the only other place it could go is
in struct page itself - but that doesn't make any sense with the boot
time option we've got now, page_ext works perfectly with that.