Re: [RFC PATCH v4 1/1] mm/damon: add node_eligible_mem_bp and node_ineligible_mem_bp goal metrics

[Ravi Jonnalagadda]

On Sat, Mar 21, 2026 at 9:54 AM SeongJae Park <sj@xxxxxxxxxx> wrote:
>
> On Fri, 20 Mar 2026 12:04:53 -0700 Ravi Jonnalagadda <ravis.opensrc@xxxxxxxxx> wrote:
>
> > Add new quota goal metrics for memory tiering that track scheme-eligible
> > memory distribution across NUMA nodes:
> >
> > - DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP: ratio of eligible memory on a node
> > - DAMOS_QUOTA_NODE_INELIGIBLE_MEM_BP: ratio of eligible memory NOT on
> >   a node
>
> The description for the second metric should be "ratio of ineligible memory on
> a node".
>

Got it. Will fix the commit message.

> >
> > These complementary metrics enable push-pull migration schemes that
> > maintain a target memory distribution across different NUMA nodes
> > representing different memory tiers, based on access patterns defined
> > by each scheme.
> >
> > The metrics iterate scheme-eligible regions and use damon_get_folio()
> > to determine NUMA node placement of each folio, calculating the ratio
> > of eligible memory on the specified node versus total eligible memory.
> >
> > Suggested-by: SeongJae Park <sj@xxxxxxxxxx>
> > Signed-off-by: Ravi Jonnalagadda <ravis.opensrc@xxxxxxxxx>
> > ---
> >  include/linux/damon.h    |   6 ++
> >  mm/damon/core.c          | 158 ++++++++++++++++++++++++++++++++++++---
> >  mm/damon/sysfs-schemes.c |  12 +++
> >  3 files changed, 164 insertions(+), 12 deletions(-)
> >
> > diff --git a/include/linux/damon.h b/include/linux/damon.h
> > index b1d8fd88a0fc..490918804f85 100644
> > --- a/include/linux/damon.h
> > +++ b/include/linux/damon.h
> > @@ -193,6 +193,10 @@ enum damos_action {
> >   * @DAMOS_QUOTA_NODE_MEMCG_FREE_BP:  MemFree ratio of a node for a cgroup.
> >   * @DAMOS_QUOTA_ACTIVE_MEM_BP:               Active to total LRU memory ratio.
> >   * @DAMOS_QUOTA_INACTIVE_MEM_BP:     Inactive to total LRU memory ratio.
> > + * @DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP:        Scheme-eligible memory ratio of a
> > + *                                   node.
> > + * @DAMOS_QUOTA_NODE_INELIGIBLE_MEM_BP:      Scheme-ineligible memory ratio of a
> > + *                                   node.
> >   * @NR_DAMOS_QUOTA_GOAL_METRICS:     Number of DAMOS quota goal metrics.
> >   *
> >   * Metrics equal to larger than @NR_DAMOS_QUOTA_GOAL_METRICS are unsupported.
> > @@ -206,6 +210,8 @@ enum damos_quota_goal_metric {
> >       DAMOS_QUOTA_NODE_MEMCG_FREE_BP,
> >       DAMOS_QUOTA_ACTIVE_MEM_BP,
> >       DAMOS_QUOTA_INACTIVE_MEM_BP,
> > +     DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP,
> > +     DAMOS_QUOTA_NODE_INELIGIBLE_MEM_BP,
> >       NR_DAMOS_QUOTA_GOAL_METRICS,
> >  };
> >
> > diff --git a/mm/damon/core.c b/mm/damon/core.c
> > index b9e12865622c..3e0ac65e34a0 100644
> > --- a/mm/damon/core.c
> > +++ b/mm/damon/core.c
> > @@ -17,6 +17,8 @@
> >  #include <linux/string.h>
> >  #include <linux/string_choices.h>
> >
> > +#include "ops-common.h"
> > +
>
> I don't find a reason to include this, and I'd like to avoid including that in
> core.c unless it is really necessary.  Could you please remove this?
>

The include was added because the implementation uses damon_get_folio() to
determine NUMA node placement of folios when iterating eligible regions.
Would you prefer that I move the damon_get_folio() declaration to
include/linux/damon.h, or would you suggest a different approach such as
adding an ops callback for the node calculation?

> Below looks all good for RFC level code to move on to the next stage (dropping
> RFC tag). :)
>

Thank you, SJ! Will send v5 with fixes once I hear back on the above.

Best Regards,
Ravi.

>
> Thanks,
> SJ
>
> [...]