On Sun, Oct 4, 2026 at 1:01 AM SJ Park <[email protected]> wrote: > > Hi Ravi, > > 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. > > Thank you for this patch! > > We have damos_esz tracepoint. Have you considered using it? It doesn't > expose > the current value, though. I thought it wouldn't be real problem in most > cases, but I can show it could be problematic for node_eligible_mem_bp case, > as > the metric value is not straightforward to see without using DAMON.
Hi SJ, Yes, with the temporal goal tuner, damos_esz only tells whether the goal is met, not how close current_value is to target_value, and damo needs that to know when a step has settled. > > If you really need to know the current_value, I'm open to add a new > tracepoint. > But I think it has no reason to make it only eligible_mem_bp specific. How > about adding more general purpose tracepoint, and/or update the current_value > file [1] under the goal sysfs directory to show the current current_value for > all goal types? > Agreed, nothing in it needs to be specific to node_eligible_mem_bp. I will rework it as a general quota goal tracepoint, emitted for each goal evaluation with the goal's metric, target_value and current_value, the node id for the node metrics, and the memcg id for the memcg metrics. I would leave the current_value file as it is for now. It would need a stats update command or refresh_ms to stay current, and damo wants every evaluation as it happens, which the tracepoint gives it. Thanks, Ravi. > [1] > https://origin.kernel.org/doc/html/latest/admin-guide/mm/damon/usage.html#sysfs-schemes-quota-goals > > > Thanks, > SJ > > [...]
