From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751255AbeAPHs0 (ORCPT + 1 other); Tue, 16 Jan 2018 02:48:26 -0500 Received: from mga04.intel.com ([192.55.52.120]:31461 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750765AbeAPHsX (ORCPT ); Tue, 16 Jan 2018 02:48:23 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.46,367,1511856000"; d="scan'208";a="22667279" From: Jin Yao To: acme@kernel.org, jolsa@kernel.org, peterz@infradead.org, mingo@redhat.com, alexander.shishkin@linux.intel.com Cc: Linux-kernel@vger.kernel.org, ak@linux.intel.com, kan.liang@intel.com, yao.jin@intel.com, Jin Yao Subject: [PATCH] perf stat: Ignore error thread when enabling system-wide --per-thread Date: Tue, 16 Jan 2018 23:43:08 +0800 Message-Id: <1516117388-10120-1-git-send-email-yao.jin@linux.intel.com> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: If we execute 'perf stat --per-thread' with non-root account (even set kernel.perf_event_paranoid = -1 yet), it reports the error: jinyao@skl:~$ perf stat --per-thread Error: You may not have permission to collect system-wide stats. Consider tweaking /proc/sys/kernel/perf_event_paranoid, which controls use of the performance events system by unprivileged users (without CAP_SYS_ADMIN). The current value is 2: -1: Allow use of (almost) all events by all users Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK >= 0: Disallow ftrace function tracepoint by users without CAP_SYS_ADMIN Disallow raw tracepoint access by users without CAP_SYS_ADMIN >= 1: Disallow CPU event access by users without CAP_SYS_ADMIN >= 2: Disallow kernel profiling by users without CAP_SYS_ADMIN To make this setting permanent, edit /etc/sysctl.conf too, e.g.: kernel.perf_event_paranoid = -1 Perhaps the ptrace rule doesn't allow to trace some processes. But anyway the global --per-thread mode had better ignore such errors and continue working on other threads. This patch will record the index of error thread in perf_evsel__open() and remove this thread before retrying. For example (run with non-root, kernel.perf_event_paranoid isn't set): jinyao@skl:~$ perf stat --per-thread ^C Performance counter stats for 'system wide': vmstat-3458 6.171984 cpu-clock:u (msec) # 0.000 CPUs utilized perf-3670 0.515599 cpu-clock:u (msec) # 0.000 CPUs utilized vmstat-3458 1,163,643 cycles:u # 0.189 GHz perf-3670 40,881 cycles:u # 0.079 GHz vmstat-3458 1,410,238 instructions:u # 1.21 insn per cycle perf-3670 3,536 instructions:u # 0.09 insn per cycle vmstat-3458 288,937 branches:u # 46.814 M/sec perf-3670 936 branches:u # 1.815 M/sec vmstat-3458 15,195 branch-misses:u # 5.26% of all branches perf-3670 76 branch-misses:u # 8.12% of all branches 12.651675247 seconds time elapsed Signed-off-by: Jin Yao --- tools/perf/builtin-stat.c | 14 +++++++++++++- tools/perf/util/evsel.c | 3 +++ tools/perf/util/thread_map.c | 1 + tools/perf/util/thread_map.h | 1 + 4 files changed, 18 insertions(+), 1 deletion(-) diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c index 98bf9d3..bcdb47c 100644 --- a/tools/perf/builtin-stat.c +++ b/tools/perf/builtin-stat.c @@ -632,7 +632,19 @@ static int __run_perf_stat(int argc, const char **argv) if (verbose > 0) ui__warning("%s\n", msg); goto try_again; - } + } else if (target__has_per_thread(&target) && + evsel_list->threads && + evsel_list->threads->err_thread != -1) { + /* + * For global --per-thread case, skip current + * error thread. + */ + if (!thread_map__remove(evsel_list->threads, + evsel_list->threads->err_thread)) { + evsel_list->threads->err_thread = -1; + goto try_again; + } + } perf_evsel__open_strerror(counter, &target, errno, msg, sizeof(msg)); diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index a4d256e..12f8733 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -1899,6 +1899,9 @@ int perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus, goto fallback_missing_features; } out_close: + if (err) + threads->err_thread = thread; + do { while (--thread >= 0) { close(FD(evsel, cpu, thread)); diff --git a/tools/perf/util/thread_map.c b/tools/perf/util/thread_map.c index 3e1038f..870cb0c 100644 --- a/tools/perf/util/thread_map.c +++ b/tools/perf/util/thread_map.c @@ -32,6 +32,7 @@ static void thread_map__reset(struct thread_map *map, int start, int nr) size_t size = (nr - start) * sizeof(map->map[0]); memset(&map->map[start], 0, size); + map->err_thread = -1; } static struct thread_map *thread_map__realloc(struct thread_map *map, int nr) diff --git a/tools/perf/util/thread_map.h b/tools/perf/util/thread_map.h index 0a806b9..ac6baf1 100644 --- a/tools/perf/util/thread_map.h +++ b/tools/perf/util/thread_map.h @@ -14,6 +14,7 @@ struct thread_map_data { struct thread_map { refcount_t refcnt; int nr; + int err_thread; struct thread_map_data map[]; }; -- 2.7.4