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Sat, 30 May 2026 12:59:53 -0700 (PDT) Received: from archlinux ([205.254.163.119]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-c85772df0fasm5178148a12.30.2026.05.30.12.59.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 30 May 2026 12:59:53 -0700 (PDT) From: Suchit Karunakaran To: peterz@infradead.org, mingo@redhat.com, acme@kernel.org, namhyung@kernel.org Cc: mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, irogers@google.com, adrian.hunter@intel.com, james.clark@linaro.org, tycho@kernel.org, suchitkarunakaran@gmail.com, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org Subject: [PATCH v2 RESEND] perf/lock: enable end-timestamp accounting for cgroup aggregation Date: Sun, 31 May 2026 01:29:40 +0530 Message-ID: <20260530195940.78700-1-suchitkarunakaran@gmail.com> X-Mailer: git-send-email 2.54.0 Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit update_lock_stat() handles lock contentions that start but never reach a contention_end event (e.g., locks still held when profiling stops), but previously treated LOCK_AGGR_CGROUP as a no-op due to missing cgroup context in userspace. Fix this by adding a cgroup_id field to struct tstamp_data, recording it at contention_begin using get_current_cgroup_id() when aggr_mode is LOCK_AGGR_CGROUP. Capturing it at contention_begin is semantically correct, the contention cost is incurred by the task that had to wait, not by whatever task happens to be running at contention_end. It is also preferable from a performance standpoint, as contention_end runs just before the task enters the critical section. Update contention_end to use pelem->cgroup_id instead of calling get_current_cgroup_id() dynamically, ensuring both complete and incomplete contention events attribute the wait time to the cgroup at wait-start time consistently. Signed-off-by: Suchit Karunakaran --- tools/perf/util/bpf_lock_contention.c | 4 ++-- tools/perf/util/bpf_skel/lock_contention.bpf.c | 4 +++- tools/perf/util/bpf_skel/lock_data.h | 1 + 3 files changed, 6 insertions(+), 3 deletions(-) diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c index cbd7435579fe..1a5bd2ff8ee4 100644 --- a/tools/perf/util/bpf_lock_contention.c +++ b/tools/perf/util/bpf_lock_contention.c @@ -463,8 +463,8 @@ static void update_lock_stat(int map_fd, int pid, u64 end_ts, stat_key.lock_addr_or_cgroup = ts_data->lock; break; case LOCK_AGGR_CGROUP: - /* TODO */ - return; + stat_key.lock_addr_or_cgroup = ts_data->cgroup_id; + break; default: return; } diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c index 96e7d853b9ed..139199811020 100644 --- a/tools/perf/util/bpf_skel/lock_contention.bpf.c +++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c @@ -536,6 +536,8 @@ int contention_begin(u64 *ctx) pelem->timestamp = bpf_ktime_get_ns(); pelem->lock = (__u64)ctx[0]; pelem->flags = (__u32)ctx[1]; + if (aggr_mode == LOCK_AGGR_CGROUP) + pelem->cgroup_id = get_current_cgroup_id(); if (needs_callstack) { u32 i = 0; @@ -771,7 +773,7 @@ int contention_end(u64 *ctx) key.stack_id = pelem->stack_id; break; case LOCK_AGGR_CGROUP: - key.lock_addr_or_cgroup = get_current_cgroup_id(); + key.lock_addr_or_cgroup = pelem->cgroup_id; break; default: /* should not happen */ diff --git a/tools/perf/util/bpf_skel/lock_data.h b/tools/perf/util/bpf_skel/lock_data.h index 28c5e5aced7f..652e114e6b87 100644 --- a/tools/perf/util/bpf_skel/lock_data.h +++ b/tools/perf/util/bpf_skel/lock_data.h @@ -13,6 +13,7 @@ struct owner_tracing_data { struct tstamp_data { u64 timestamp; u64 lock; + u64 cgroup_id; u32 flags; s32 stack_id; }; -- 2.54.0