On Mon, Oct 5, 2026 at 3:04 AM Kunwu Chan <[email protected]> wrote: > > > Hi Ravi, > > I agree with SJ that this would be more useful as a general quota-goal > tracepoint rather than being specific to NODE_ELIGIBLE_MEM_BP. The > target_value and current_value fields are not metric-specific.
Hi Kunwu, Thank you for the review. Agreed; I will make it a general quota goal tracepoint, as I wrote in my reply to SJ. > > On Sat, 3 Oct 2026 13:27:27 -0700 Ravi Jonnalagadda > <[email protected]> wrote: > > > Add a tracepoint for DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP quota goal > > evaluation. The tracepoint fires once per quota-score computation when > > the goal metric is DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP, exposing > > context_idx, scheme_idx, nid, target_value, and current_value. > > current_value is reported as the quota tuning sees it, after the goal's > > complement setting is applied. > > > > The DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP metric expresses node memory > > occupancy as basis points of eligible bytes. This information is not > > exposed through any existing external interface (perf stat, /proc, or > > sysfs), so the tracepoint is the only way for userspace to observe the > > target and current eligible-memory basis point values at quota-scoring > > time. > > > > Link: > > https://lore.kernel.org/linux-mm/[email protected]/ > > Signed-off-by: Ravi Jonnalagadda <[email protected]> > > --- > > include/trace/events/damon.h | 31 +++++++++++++++++++++++++++++++ > > mm/damon/core.c | 16 ++++++++++++++++ > > 2 files changed, 47 insertions(+) > > > > diff --git a/include/trace/events/damon.h b/include/trace/events/damon.h > > index 8851727ae162..2c7249cc7c88 100644 > > --- a/include/trace/events/damon.h > > +++ b/include/trace/events/damon.h > > @@ -74,6 +74,37 @@ TRACE_EVENT(damos_esz, > > __entry->esz) > > ); > > > > +/* Per-tick DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP goal evaluation. */ > > The comment says "Per-tick", but the event is emitted for each matching > goal in damos_quota_score(). "Per quota-goal evaluation" would be more > precise. Right, I will fix the comment. > > > +TRACE_EVENT(damos_node_eligible_mem_bp, > > + > > + TP_PROTO(unsigned int context_idx, unsigned int scheme_idx, > > + int nid, > > + unsigned long target_value, unsigned long current_value), > > + > > + TP_ARGS(context_idx, scheme_idx, nid, target_value, current_value), > > + > > + TP_STRUCT__entry( > > + __field(unsigned int, context_idx) > > + __field(unsigned int, scheme_idx) > > + __field(int, nid) > > + __field(unsigned long, target_value) > > + __field(unsigned long, current_value) > > Also, context_idx is currently always 0 here, since > damos_quota_score() only has struct damon_ctx * and no context index. > If this tracepoint is generalized, it may be worth considering how the > context/scheme are identified rather than introducing another tracepoint > field that is currently always 0. I kept context_idx for consistency with damos_esz and damos_before_apply, which carry the same field and also pass 0 today, since a kdamond runs one context. I will follow whatever SJ prefers for identifying the context in the generalized event. Thanks, Ravi. > > Thanks, > Kunwu > > > + ), > > + > > + TP_fast_assign( > > + __entry->context_idx = context_idx; > > + __entry->scheme_idx = scheme_idx; > > + __entry->nid = nid; > > + __entry->target_value = target_value; > > + __entry->current_value = current_value; > > + ), > > + > > + TP_printk("ctx_idx=%u scheme_idx=%u nid=%d target_value=%lu > > current_value=%lu", > > + __entry->context_idx, __entry->scheme_idx, > > + __entry->nid, > > + __entry->target_value, __entry->current_value) > > +); > > + > > TRACE_EVENT_CONDITION(damos_before_apply, > > > > TP_PROTO(unsigned int context_idx, unsigned int scheme_idx, > > diff --git a/mm/damon/core.c b/mm/damon/core.c > > index b63e60ef8990..6ddd15dc4f55 100644 > > --- a/mm/damon/core.c > > +++ b/mm/damon/core.c > > @@ -3294,6 +3294,22 @@ static unsigned long damos_quota_score(struct > > damon_ctx *c, struct damos *s) > > highest_score = max(highest_score, > > mult_frac(goal->current_value, 10000, > > goal->target_value)); > > + > > + if (goal->metric == DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP && > > + trace_damos_node_eligible_mem_bp_enabled()) { > > + unsigned int cidx = 0, sidx = 0; > > + struct damos *siter; > > + > > + damon_for_each_scheme(siter, c) { > > + if (siter == s) > > + break; > > + sidx++; > > + } > > + trace_damos_node_eligible_mem_bp(cidx, sidx, > > + goal->nid, > > + goal->target_value, > > + goal->current_value); > > + } > > } > > > > return highest_score; > > > > base-commit: 763ad0211c7b587344f03bc4d1299810aeb736f4 > > -- > > 2.54.0 (Apple Git-157) > > > > > > Sent using hkml (https://github.com/sjp38/hackermail)
