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[23.116.43.216]) by smtp.gmail.com with ESMTPSA id 956f58d0204a3-66fb47a8b8fsm14316278d50.2.2026.09.10.10.16.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 10 Sep 2026 10:16:35 -0700 (PDT) From: Ravi Jonnalagadda To: sj@kernel.org, akinobu.mita@gmail.com, damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org Cc: akpm@linux-foundation.org, corbet@lwn.net, bijan311@gmail.com, ajayjoshi@micron.com, honggyu.kim@sk.com, yunjeong.mun@sk.com, ravis.opensrc@gmail.com, rientjes@google.com, weixugc@google.com, jic23@kernel.org, gourry@gourry.net Subject: [RFC PATCH v2 4/9] mm/damon: add damos_node_eligible_mem_bp tracepoint Date: Thu, 10 Sep 2026 10:16:18 -0700 Message-ID: <20260910171623.6638-5-ravis.opensrc@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260910171623.6638-1-ravis.opensrc@gmail.com> References: <20260910171623.6638-1-ravis.opensrc@gmail.com> Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add a per-tick tracepoint for DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP goal evaluation, exposing the goal target/current values for observability of the node-eligible-memory bandwidth quota loop. Bandwidth-feedback tiering loops read this goal metric to detect convergence. Signed-off-by: Ravi Jonnalagadda --- include/trace/events/damon.h | 32 ++++++++++++++++++++++++++++++++ mm/damon/core.c | 28 ++++++++++++++++++++++++++++ 2 files changed, 60 insertions(+) diff --git a/include/trace/events/damon.h b/include/trace/events/damon.h index 4dfc9467ea4b5..b2a472eb45d95 100644 --- a/include/trace/events/damon.h +++ b/include/trace/events/damon.h @@ -74,6 +74,38 @@ TRACE_EVENT(damos_esz, __entry->esz) ); +/* Per-tick DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP goal evaluation. */ +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) + ), + + 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 991ddb9a09414..6b56a3e961c4e 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -3461,6 +3461,34 @@ 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)); + + /* + * Per-tick visibility of NODE_ELIGIBLE_MEM_BP goal evaluation + * for userspace convergence-detection. + */ + if (goal->metric == DAMOS_QUOTA_NODE_ELIGIBLE_MEM_BP && + trace_damos_node_eligible_mem_bp_enabled()) { + /* + * cidx is hardcoded 0 because DAMON sysfs currently + * supports a single context per kdamond. Other DAMOS + * tracepoints (damos_before_apply, damos_esz, + * damos_stat_after_apply_interval) follow the same + * convention; once multi-ctx-per-kdamond lands the + * field becomes meaningful. + */ + 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; -- 2.43.0