From patchwork Wed Feb 28 05:33:35 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Namhyung Kim X-Patchwork-Id: 13574896 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D81791EEFC; Wed, 28 Feb 2024 05:33:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709098418; cv=none; b=Fm67iPeZnAY7o1/ncRIbcFHJXHzkLASUPuLU0t1N/HLre0KwVFi03dM4usVWAU24aecLM8+vF0aPrFKPmnE4KacytpAxwhckN5l4WfBW5WonEzll6P3c1cHiUJPz6LdxG6KiwNKPc/YsteRdyY+g82QeLePkJMod2swLz3W1kgc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709098418; c=relaxed/simple; bh=SG51VYH9JEUGEW6hnzOW/IFg0lpQP3pfUJCNA/WYd58=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=oB+hsXFT8hj/DE11RCDFihAjSBSmE8B4CpOV6GD//kdWwsCVOB6adbbZ8KK3GOop9qu0mLWvuKKLvHSs9FUodVexLxQ08/R2zUarL2a4UTMj8+u8qq5pHlVGGLUTyT3dEoKxO0Xok4fBTBKwpcO77DkdYF9ZLkVE3I1yeUi6oZE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HZL1DB1C; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="HZL1DB1C" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0067AC433F1; Wed, 28 Feb 2024 05:33:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1709098417; bh=SG51VYH9JEUGEW6hnzOW/IFg0lpQP3pfUJCNA/WYd58=; h=From:To:Cc:Subject:Date:From; b=HZL1DB1CnQH4Q3Vc5pionsBT0KLxSYcuTOGSZA6/0MHpfcQRvefBX6K9FMqDg2SVC MBpJjwuoTu0DK9Owt6CghzhCd2SDrFwlLG+Hbql/pnhQIC7vCW5Xg1wRd5Q75TpYrb giCUPqCLpKN4DNEHQNKfIVbSyMTx8eQh2feiQGAeo9ih9rxYmQdJwo3dCsESjqjRMS 9s7ecG2rUzj6cjdkLdJmN+yNnHk6u7/kAxdI++c8q7E6/Xneq7vcrSzfhGREc+DFL0 fA3CYcUB1ylQfQgCuguezZKgDb0Yim55orJ8KqREnGfYzB7bZ6QU9v37CkYQfViVSn W+EDNzx3d8nVQ== From: Namhyung Kim To: Arnaldo Carvalho de Melo , Ian Rogers Cc: Jiri Olsa , Adrian Hunter , Peter Zijlstra , Ingo Molnar , LKML , linux-perf-users@vger.kernel.org, Song Liu , bpf@vger.kernel.org Subject: [PATCH v2] perf lock contention: Account contending locks too Date: Tue, 27 Feb 2024 21:33:35 -0800 Message-ID: <20240228053335.312776-1-namhyung@kernel.org> X-Mailer: git-send-email 2.44.0.rc1.240.g4c46232300-goog Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Currently it accounts the contention using delta between timestamps in lock:contention_begin and lock:contention_end tracepoints. But it means the lock should see the both events during the monitoring period. Actually there are 4 cases that happen with the monitoring: monitoring period / \ | | 1: B------+-----------------------+--------E 2: B----+-------------E | 3: | B-----------+----E 4: | B-------------E | | | t0 t1 where B and E mean contention BEGIN and END, respectively. So it only accounts the case 4 for now. It seems there's no way to handle the case 1. The case 2 might be handled if it saved the timestamp (t0), but it lacks the information from the B notably the flags which shows the lock types. Also it could be a nested lock which it currently ignores. So I think we should ignore the case 2. However we can handle the case 3 if we save the timestamp (t1) at the end of the period. And then it can iterate the map entries in the userspace and update the lock stat accordinly. Signed-off-by: Namhyung Kim Reviewed-by: Ian Rogers --- v2: add a comment on mark_end_timestamp (Ian) tools/perf/util/bpf_lock_contention.c | 120 ++++++++++++++++++ .../perf/util/bpf_skel/lock_contention.bpf.c | 16 ++- tools/perf/util/bpf_skel/lock_data.h | 7 + 3 files changed, 136 insertions(+), 7 deletions(-) diff --git a/tools/perf/util/bpf_lock_contention.c b/tools/perf/util/bpf_lock_contention.c index 31ff19afc20c..9af76c6b2543 100644 --- a/tools/perf/util/bpf_lock_contention.c +++ b/tools/perf/util/bpf_lock_contention.c @@ -179,6 +179,123 @@ int lock_contention_prepare(struct lock_contention *con) return 0; } +/* + * Run the BPF program directly using BPF_PROG_TEST_RUN to update the end + * timestamp in ktime so that it can calculate delta easily. + */ +static void mark_end_timestamp(void) +{ + DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts, + .flags = BPF_F_TEST_RUN_ON_CPU, + ); + int prog_fd = bpf_program__fd(skel->progs.end_timestamp); + + bpf_prog_test_run_opts(prog_fd, &opts); +} + +static void update_lock_stat(int map_fd, int pid, u64 end_ts, + enum lock_aggr_mode aggr_mode, + struct tstamp_data *ts_data) +{ + u64 delta; + struct contention_key stat_key = {}; + struct contention_data stat_data; + + if (ts_data->timestamp >= end_ts) + return; + + delta = end_ts - ts_data->timestamp; + + switch (aggr_mode) { + case LOCK_AGGR_CALLER: + stat_key.stack_id = ts_data->stack_id; + break; + case LOCK_AGGR_TASK: + stat_key.pid = pid; + break; + case LOCK_AGGR_ADDR: + stat_key.lock_addr_or_cgroup = ts_data->lock; + break; + case LOCK_AGGR_CGROUP: + /* TODO */ + return; + default: + return; + } + + if (bpf_map_lookup_elem(map_fd, &stat_key, &stat_data) < 0) + return; + + stat_data.total_time += delta; + stat_data.count++; + + if (delta > stat_data.max_time) + stat_data.max_time = delta; + if (delta < stat_data.min_time) + stat_data.min_time = delta; + + bpf_map_update_elem(map_fd, &stat_key, &stat_data, BPF_EXIST); +} + +/* + * Account entries in the tstamp map (which didn't see the corresponding + * lock:contention_end tracepoint) using end_ts. + */ +static void account_end_timestamp(struct lock_contention *con) +{ + int ts_fd, stat_fd; + int *prev_key, key; + u64 end_ts = skel->bss->end_ts; + int total_cpus; + enum lock_aggr_mode aggr_mode = con->aggr_mode; + struct tstamp_data ts_data, *cpu_data; + + /* Iterate per-task tstamp map (key = TID) */ + ts_fd = bpf_map__fd(skel->maps.tstamp); + stat_fd = bpf_map__fd(skel->maps.lock_stat); + + prev_key = NULL; + while (!bpf_map_get_next_key(ts_fd, prev_key, &key)) { + if (bpf_map_lookup_elem(ts_fd, &key, &ts_data) == 0) { + int pid = key; + + if (aggr_mode == LOCK_AGGR_TASK && con->owner) + pid = ts_data.flags; + + update_lock_stat(stat_fd, pid, end_ts, aggr_mode, + &ts_data); + } + + prev_key = &key; + } + + /* Now it'll check per-cpu tstamp map which doesn't have TID. */ + if (aggr_mode == LOCK_AGGR_TASK || aggr_mode == LOCK_AGGR_CGROUP) + return; + + total_cpus = cpu__max_cpu().cpu; + ts_fd = bpf_map__fd(skel->maps.tstamp_cpu); + + cpu_data = calloc(total_cpus, sizeof(*cpu_data)); + if (cpu_data == NULL) + return; + + prev_key = NULL; + while (!bpf_map_get_next_key(ts_fd, prev_key, &key)) { + if (bpf_map_lookup_elem(ts_fd, &key, cpu_data) < 0) + goto next; + + for (int i = 0; i < total_cpus; i++) { + update_lock_stat(stat_fd, -1, end_ts, aggr_mode, + &cpu_data[i]); + } + +next: + prev_key = &key; + } + free(cpu_data); +} + int lock_contention_start(void) { skel->bss->enabled = 1; @@ -188,6 +305,7 @@ int lock_contention_start(void) int lock_contention_stop(void) { skel->bss->enabled = 0; + mark_end_timestamp(); return 0; } @@ -301,6 +419,8 @@ int lock_contention_read(struct lock_contention *con) if (stack_trace == NULL) return -1; + account_end_timestamp(con); + if (con->aggr_mode == LOCK_AGGR_TASK) { struct thread *idle = __machine__findnew_thread(machine, /*pid=*/0, diff --git a/tools/perf/util/bpf_skel/lock_contention.bpf.c b/tools/perf/util/bpf_skel/lock_contention.bpf.c index 95cd8414f6ef..fb54bd38e7d0 100644 --- a/tools/perf/util/bpf_skel/lock_contention.bpf.c +++ b/tools/perf/util/bpf_skel/lock_contention.bpf.c @@ -19,13 +19,6 @@ #define LCB_F_PERCPU (1U << 4) #define LCB_F_MUTEX (1U << 5) -struct tstamp_data { - __u64 timestamp; - __u64 lock; - __u32 flags; - __s32 stack_id; -}; - /* callstack storage */ struct { __uint(type, BPF_MAP_TYPE_STACK_TRACE); @@ -140,6 +133,8 @@ int perf_subsys_id = -1; /* determine the key of lock stat */ int aggr_mode; +__u64 end_ts; + /* error stat */ int task_fail; int stack_fail; @@ -559,4 +554,11 @@ int BPF_PROG(collect_lock_syms) return 0; } +SEC("raw_tp/bpf_test_finish") +int BPF_PROG(end_timestamp) +{ + end_ts = bpf_ktime_get_ns(); + return 0; +} + char LICENSE[] SEC("license") = "Dual BSD/GPL"; diff --git a/tools/perf/util/bpf_skel/lock_data.h b/tools/perf/util/bpf_skel/lock_data.h index 08482daf61be..36af11faad03 100644 --- a/tools/perf/util/bpf_skel/lock_data.h +++ b/tools/perf/util/bpf_skel/lock_data.h @@ -3,6 +3,13 @@ #ifndef UTIL_BPF_SKEL_LOCK_DATA_H #define UTIL_BPF_SKEL_LOCK_DATA_H +struct tstamp_data { + u64 timestamp; + u64 lock; + u32 flags; + u32 stack_id; +}; + struct contention_key { u32 stack_id; u32 pid;