From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f201.google.com (mail-pf1-f201.google.com [209.85.210.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 157F81953AD for ; Thu, 31 Oct 2024 22:39:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730414399; cv=none; b=rufhBWs3wjzx+p2ESKnIWBHipn/dsA3XRN+ifCRaLbyKAZS0CFV5KzNxDvTRI/bcK0ceFGiFs4O38lvB6iuCZK8WeGcqbAxaUz0/K6ifKZ8WacNOoxGpoxK52uMkYFEKpK7se6BNA0+pa2xqDlyHYgT76hs5BxtVMs5M6vofZvA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730414399; c=relaxed/simple; bh=1K+1EzPZRuDuWAazdL34ULZOOR+K2+dU7Cnwhnj3bHc=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=lwDSiP2H4ET3JwxN4m5djXRst6v9OX3AOB4HZ8ttyhXuWyP3bmtUEhUruW/ex3w1qo9+NfdM9aA7sevNy5q0yMNMRwvZxvd4t73YdUwc1MQW1rDb3Z1D1ePrz7hW1H+kcp1EZshUAkek1Rb8D/2AdysgPUYpYIev2Bf8uF18R0w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--ctshao.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=I10qsQp7; arc=none smtp.client-ip=209.85.210.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--ctshao.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="I10qsQp7" Received: by mail-pf1-f201.google.com with SMTP id d2e1a72fcca58-71ec3392c25so1660935b3a.1 for ; Thu, 31 Oct 2024 15:39:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1730414393; x=1731019193; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=oWSTQrojMVMrsYh9AlNbCklcB9qjvy1WDWZ7XTJeoJ8=; b=I10qsQp7DoG6Q+ekBVxdugZvHc7YnpitHxQNWKSlC3DV2eLdU+ySLGm49BKVuBreBT 70tDGF871zOca2LaCRkusXQx+YnOCSkCozhF+eaTq61gCHu4Eg1rYFL2l3K/jAe730vR pkpelvIiNredJFxrBMXP8SFa9eihEaph19fgw9EHVftGqOM54o2nlPq4U48IRhGkWMUk rvpkIa3P5NKUzgpzrMFVxVbWr6snvS7EiIX4hv2U5EdASGcPjLX4/TSgfy7eMtjm00hH C2CRZMyhHEU5h5qrWG8INLk8+gXXE8Bu67BX0Fbu+b+oSYhLDboGmRP9PLDfXn1XjaUU v9LQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1730414393; x=1731019193; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=oWSTQrojMVMrsYh9AlNbCklcB9qjvy1WDWZ7XTJeoJ8=; b=Jikz+1FIQo+3cMqiXy13wNchwLUsLt53K9rDZvFcc55az8kMgYvp8zygoD5rQWTlu/ nlIErGnY04D/Iwhs94/wyzfg5vvU/s/ulOcSRnblZaj0ADmyMhCeLtSGwAhhgyk06Rg0 EOEtbgDC2mOH4BUP3mgHzCaxsElGflkvuNt6lwlsCiPN8PQoEg8mXVe2NkBVCpF4J8QS YGRs+I2bXkN08UnfXj70SZ4j1RXvwOS1T6RteV6s9KrJlGQY7op0zEaAWJ6CB0Cm4BP8 SxKAwi7/HgvQcZXfmPYXPsYl+CSL+juJerY852/Raz7N84nPw2QbMk7gAb2iKM8RxhyV q+NQ== X-Gm-Message-State: AOJu0YyrhHNCH9OkR//67Y6Ae2/hnxVW2B6ecy8XKW85zXj3PCOR7ex7 pttLn9cau7fXS7IUV1KsQ1hhIHs29FNOCePtmN1PIh1npzsjiiHPmKcpS52Tvya854TG3A2ZDrB 7/8ReLW+0mLbEHF66Cayp5bC6SVUkl5jVXFGIwCWpWuIfIJ2OsorqnE2O86qb5Yj1R8DYyhOnVw QBSubp5NPmU9vjhYfVhljF5fiuEVYV5cNLYWY2ShNM X-Google-Smtp-Source: AGHT+IE1yDy5/ekyNCt0cQuTHC9rjP5gdZ1iZnN2zHSFuCpS1ZZd2YFR1tYEu2/RWRUTfDsD7/TNpoJ0RIA= X-Received: from colette.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:ce7]) (user=ctshao job=sendgmr) by 2002:aa7:8758:0:b0:71e:5261:b156 with SMTP id d2e1a72fcca58-720c98a1a74mr2554b3a.2.1730414391614; Thu, 31 Oct 2024 15:39:51 -0700 (PDT) Date: Thu, 31 Oct 2024 22:39:43 +0000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.47.0.163.g1226f6d8fa-goog Message-ID: <20241031223948.4179222-1-ctshao@google.com> Subject: [PATCH 1/3] perf evsel: Improve the evsel__open_strerror for EBUSY From: Chun-Tse Shao To: linux-kernel@vger.kernel.org Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , Liang@google.com, Kan , Ze Gao , Chun-Tse Shao , Yang Jihong , Weilin Wang , linux-perf-users@vger.kernel.org Content-Type: text/plain; charset="UTF-8" From: Ian Rogers The existing EBUSY strerror message is: ``` The sys_perf_event_open() syscall returned with 16 (Device or resource busy) for event (intel_bts//). "dmesg | grep -i perf" may provide additional information. ``` The dmesg won't be useful. What is more useful is knowing what processes are potentially using the PMU, which some procfs scanning can reveal. When parallel testing tests/shell/stat_all_pmu.sh this yields: ``` Testing intel_bts// Error: The PMU intel_bts counters are busy and in use by another process. Possible processes: 2585882 perf list 2585902 perf list -j -o /tmp/__perf_test.list_output.json.KF9MY 2585904 perf list 2585911 perf record -e task-clock --filter period > 1 -o /dev/null --quiet true 2585912 perf list 2585915 perf list 2586042 /tmp/perf/perf record -asdg -e cpu-clock -o /tmp/perftool-testsuite_report.dIF/perf_report/perf.data -- sleep 2 2589078 perf record -g -e task-clock:u -o - perf test -w noploop 2589148 /tmp/perf/perf record --control=fifo:control,ack -e cpu-clock -m 1 sleep 10 2589379 perf --buildid-dir /tmp/perf.debug.Umx record --buildid-all -o /tmp/perf.data.YBm /tmp/perf.ex.MD5.ZQW 2589568 perf record -o /tmp/__perf_test.program.mtcZH/perf.data --branch-filter any,save_type,u -- perf test -w brstack 2589649 perf record --per-thread -o /tmp/__perf_test.perf.data.5d3dc perf test -w thloop 2589898 perf record -o /tmp/perf-test-script.BX2b27Dcnj/pp-perf.data --sample-cpu uname ``` Which gets a little closer to finding the issue. Signed-off-by: Ian Rogers --- tools/perf/util/evsel.c | 79 ++++++++++++++++++++++++++++++++++++++++- 1 file changed, 78 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index dbf9c8cee3c56..9a5b6a6f8d2e5 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -3286,6 +3286,78 @@ static bool find_process(const char *name) return ret ? false : true; } +static int dump_perf_event_processes(char *msg, size_t size) +{ + DIR *proc_dir; + struct dirent *proc_entry; + int printed = 0; + + proc_dir = opendir(procfs__mountpoint()); + if (!proc_dir) + return 0; + + /* Walk through the /proc directory. */ + while ((proc_entry = readdir(proc_dir)) != NULL) { + char path[PATH_MAX]; + DIR *fd_dir; + struct dirent *fd_entry; + int fd_dir_fd; + + if ((proc_entry->d_type != DT_DIR) || + !strcmp(".", proc_entry->d_name) || + !strcmp("..", proc_entry->d_name)) + continue; + + scnprintf(path, sizeof(path), "%s/fd", proc_entry->d_name); + fd_dir_fd = openat(dirfd(proc_dir), path, O_DIRECTORY); + if (fd_dir_fd == -1) + continue; + fd_dir = fdopendir(fd_dir_fd); + if (!fd_dir) { + close(fd_dir_fd); + continue; + } + while ((fd_entry = readdir(fd_dir)) != NULL) { + ssize_t link_size; + + if (fd_entry->d_type != DT_LNK) + continue; + link_size = readlinkat(fd_dir_fd, fd_entry->d_name, path, sizeof(path)); + if (link_size < 0) + continue; + /* Take care as readlink doesn't null terminate the string. */ + if (!strncmp(path, "anon_inode:[perf_event]", link_size)) { + int cmdline_fd; + ssize_t cmdline_size; + + scnprintf(path, sizeof(path), "%s/cmdline", proc_entry->d_name); + cmdline_fd = openat(dirfd(proc_dir), path, O_RDONLY); + if (cmdline_fd == -1) + continue; + cmdline_size = read(cmdline_fd, path, sizeof(path) - 1); + close(cmdline_fd); + if (cmdline_size < 0) + continue; + path[cmdline_size] = '\0'; + for (ssize_t i = 0; i < cmdline_size; i++) { + if (path[i] == '\0') + path[i] = ' '; + } + + if (printed == 0) + printed += scnprintf(msg, size, "Possible processes:\n"); + + printed += scnprintf(msg + printed, size - printed, + "%s %s\n", proc_entry->d_name, path); + break; + } + } + closedir(fd_dir); + } + closedir(proc_dir); + return printed; +} + int __weak arch_evsel__open_strerror(struct evsel *evsel __maybe_unused, char *msg __maybe_unused, size_t size __maybe_unused) @@ -3319,7 +3391,7 @@ int evsel__open_strerror(struct evsel *evsel, struct target *target, printed += scnprintf(msg, size, "No permission to enable %s event.\n\n", evsel__name(evsel)); - return scnprintf(msg + printed, size - printed, + return printed + scnprintf(msg + printed, size - printed, "Consider adjusting /proc/sys/kernel/perf_event_paranoid setting to open\n" "access to performance monitoring and observability operations for processes\n" "without CAP_PERFMON, CAP_SYS_PTRACE or CAP_SYS_ADMIN Linux capability.\n" @@ -3382,6 +3454,11 @@ int evsel__open_strerror(struct evsel *evsel, struct target *target, return scnprintf(msg, size, "The PMU counters are busy/taken by another profiler.\n" "We found oprofile daemon running, please stop it and try again."); + printed += scnprintf( + msg, size, + "The PMU %s counters are busy and in use by another process.\n", + evsel->pmu ? evsel->pmu->name : ""); + return printed + dump_perf_event_processes(msg + printed, size - printed); break; case EINVAL: if (evsel->core.attr.sample_type & PERF_SAMPLE_CODE_PAGE_SIZE && perf_missing_features.code_page_size) -- 2.47.0.163.g1226f6d8fa-goog