Re: [RFC PATCH v0] Docs/mm/damon/design: document data attributes report infra design (beyond page table accessed-bit milestone 2)

[SJ Park <sj@kernel.org>]

On Wed, 11 Nov 2026 10:54:11 -0800 SJ Park <sj@kernel.org> wrote:

> Hi Aveline,
> 
> On Wed, 11 Nov 2026 18:35:52 +1100 Aveline Noir <jm5905938@gmail.com> wrote:
> 
> > Hi SJ,
> > 
> > On Sat, 17 Oct 2026 12:57:45 -0700 SJ Park wrote:
> > 
> > > +The data attribute probe supports the reports.  The probes can be configured to
> > > +hit for a given memory region depending on the existence of specific types of
> > > +reports that associated with the memory region in given report buffers.
> > 
> > I'm wondering how this would interact with the region size.  If each
> > page of a region is reported with probability q, a region of s pages
> > would hit with probability 1 - (1 - q)^s, so a large region may hit
> > more often than a small region of the same access density.
> 
> Thank you for sharing this finding.  Seems this theory assumes the probe will
> hit for report of any byte of the region exists in the report buffers.  Under
> the assumption, that makes sense.
> 
> But I'd say the assumed implementation is not realistic.  That's because DAMON
> design does probing for only single sampling byte of the region, not the entire
> bytes of the region.  In a real implementation that is aligned with the design,
> the probe will hit if a report associated with the sampling byte exists.

I will rephrase the document in the next spin to make this be more clear.
E.g., The probes can be configured to hit for existence of specific types of
reports that associated with the probing memory in the report buffers.


Thanks,
SJ

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