Re: [PATCH v7 0/7] mm: Hot page tracking and promotion infrastructure

[Gregory Price]

On Mon, May 11, 2026 at 04:07:16PM +0530, Bharata B Rao wrote:
> 
> The entire point of this patchset is not just about improving the performance.
> It is mainly about adding a new dedicated infrastructure for detecting and
> promoting hot pages. It is about having a subsystem that can act as a single
> source of truth page hotness in the kernel. Though we aren't there yet, we have
> started by having a minimal infrastructure that centralizes the hot page
> promotion and associated heuristics that currently sits in scheduler so that the
> same can be used with other page hotness sources as well.
> 

The goal of hotness tracking in general is to improve performance.

The goal of PGHot should be a reasonable baseline for the kernel to
course-correct LRU inversions across tiers over time, because LRU
threads only scan invidiual nodes and don't compare across nodes.

I would hazard against trying to wholesale state it "Shall be the single
source of truth", as we will inevitably discover some condition which is
not covered / cannot be captured / we will simply get it wrong.

Plus, intuitively, counter-balancing LRU/MGLRU aging is probably as good
good as we can get without having to inject per-workload information
into the system - at which point the users should use DAMON.

~Gregory