Re: [RFC PATCH 0/4] DAMOS access pattern supports selecting regions to apply a given

[SJ Park <sj@kernel.org>]

On Wed,  4 Nov 2026 07:36:39 -0800 SJ Park <sj@kernel.org> wrote:

I forgot adding a subject line.  As a result, first part of below paragraph was
added to the subject.  Sorry for inconvenience.  So, please read below
paragraph before the quoted followup paragraph to read the full intentional
cover letter message.

    DAMOS access pattern supports selecting regions to apply a given
    operation to, based on their age (access frequency stability).  The age
    is specified in the aggregation intervals unit.  The aggregation
    interval can be changed by users or intervals auto-tuning features.  If
    the intention is to specify the age in a deterministic way (e.g., 2
    minutes), it should be updated for each aggregation interval update.
    Doing so is cumbersome and challenging, particularly in the interval
    auto-tuning case.

> One straightforward solution is extending the DAMOS access pattern for
> specific deterministic time based age specification.  However, DAMOS
> core filter is a better option.  It is playing a similar role in a more
> flexible way.  It can be used for both accepting and rejecting regions
> based on if they matched or unmatched to a given criteria.  Multiple
> filters can also be combined for more flexible and detailed rules.
> 
> Extend DAMOS core filter to support milliseconds unit based age
> criteria.
> 
> Implement a new DAMOS core filter type, DAMOS_FILTER_TYPE_AGE_MS, in
> core layer and expose to DAMON API, via patch 1.  Add the support of the
> feature on DAMON sysfs ABI with patch 2.  Update the design and usage
> documents to explain the new features with patches 3 and 4,
> respectively.
> 
> SJ Park (4):
>   mm/damon/core: add DAMOS_FILTER_TYPE_AGE_MS
>   mm/damon/sysfs-schemes: support DAMOS_FILTER_TYPE_AGE_MS
>   Docs/mm/damon/design: update for age_ms damos core filter type
>   Docs/admin-guide/mm/damon/usage: update for age_ms damos core filter
> 
>  Documentation/admin-guide/mm/damon/usage.rst |  3 +++
>  Documentation/mm/damon/design.rst            |  3 +++
>  include/linux/damon.h                        | 16 ++++++++++------
>  mm/damon/core.c                              |  9 ++++++++-
>  mm/damon/sysfs-schemes.c                     |  5 +++++
>  5 files changed, 29 insertions(+), 7 deletions(-)
> 
> 
> base-commit: 32e967f279b24f952a5482e2c427894787848ee0
> -- 
> 2.47.3
> 
> 


Thanks,
SJ