From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (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 9DFFD1E0DEB for ; Fri, 1 Nov 2024 21:18:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730495894; cv=none; b=GwBw2F6IQYyHRSJ/jOAv/g8msLgbai9KxJ1xAbi+qpmaLNcSeZriabjNa5TZKebqjuEG92enboK2qGrTTV55aYIOzlhvk/IlJ7XwtSAsC22HevPwzXBfHxwVojpe4964tMokpHeTK7PfR3wJWEvGPKEuJYBmYR6Hd1D+stL/niE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730495894; c=relaxed/simple; bh=1K+1EzPZRuDuWAazdL34ULZOOR+K2+dU7Cnwhnj3bHc=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=F7V9bBOYbbvplfRJR2DyNUtBLUoPy8XBaxRNTNu5ucGCxHmW2pR0HtxHCXsBztYVkLyOAGxxXb4wDKjjGiREtmIAN9O/juBpuKj1fj2sy5y1RNnTiQDtsoF2mIZJiHrX7g4DojzZF8Vg2ioc+XxBEisqUfuvv67g8ogEjl5NAvo= 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=A3DG/N9E; arc=none smtp.client-ip=209.85.216.74 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="A3DG/N9E" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-2e2cc47ce63so2369590a91.3 for ; Fri, 01 Nov 2024 14:18:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1730495891; x=1731100691; 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=A3DG/N9EDSnYjveH0bu0Fp484nJ4JhDfXkmPduno66CkRDJ9vj9nkQxabH1gFhRtaG rv7WwFRUTkNHbEg7oLZVdOVhtyCzYgIKKytW2K7jEzDYVpo8SzhtTi5QAN1nf446MeDj KnvflbkqdkNceNkSrWgr/Y/OHaP6FTje+SiRpsCCfApAcpQmxoadS+DJTLpwY2Snha+O 9lSVJbEJfkAWcP7SI+rc8xgyVM4X429zNrmXvjncT+GaxtUr1nLUObL5KIM0cA7bpFZx QxVm6ETY0oCqeRD+qXHM6X+XPmzlrkUzFNtOdoCbokaF9QFy4qnamE/JzNktQhfZAL+J 2yoA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1730495891; x=1731100691; 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=BoylscKONqhWaBFK+mo51rCuZrX0lrNR6NDXXC4Lofj24Ue1bxI4STb3IUmXKJ7Lbv XSFYJCrhkmSzHoPQ2BC6q4D7T/pgsPjeuUiV7N7H17TjFd1S+Jhs9tbcQ2cqZMw3i51J MKGYSbzucdOdd1HQ28VK0TOiHrT/iAp1R/N+MeBkFRtJ2FySQif9SYAd4vX2kue4ZQBW gaCHbcGKQPkZChJf25EuwdzaKO7ePjk5zg+bYD1eAzzBDJihuNNo8CM8wB4aFV0StAFj L17fjiZOhxzHHRbhwsS/vgU2BUyFgaWC4jOUSQOZrMjtf039D+TCkamTlem5uY2erIhd oUDw== X-Gm-Message-State: AOJu0Yw2a+KnGj+/bM0WTSPnd1oX+GlHmZK4wkuHS6KH0TEh8e7DZ/vg hf+NOmurJP+oECPrmCqm6yqQIdNJtvoO+N5NHzExIyY02pLruMd9bzEmuLyQbtGaMliaTAeYMSi ZDZDucveYAkAOzpIKhWS9gUEtvtgOayAjhGu43tOUzbzsDWLwIwn0n7jZiQxnEy9fNkHJadzQ+P o2tAMKr11U3wSxnLgg4oKq9KqK4rw5/2SE+1GcZ5Ac X-Google-Smtp-Source: AGHT+IGcrF9Nd0YKeNbT2/fZ8v29QoHtRzjzJ4lx7/d1D79YvtfH9TY9JNSjSTEP6wS5SGZQViK95MsJ3Aw= X-Received: from colette.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:ce7]) (user=ctshao job=sendgmr) by 2002:a17:90b:4a0a:b0:2e2:da81:40c6 with SMTP id 98e67ed59e1d1-2e8f0f4e144mr40997a91.2.1730495889950; Fri, 01 Nov 2024 14:18:09 -0700 (PDT) Date: Fri, 1 Nov 2024 21:17:55 +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: <20241101211757.824743-1-ctshao@google.com> Subject: [PATCH v2 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 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