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 B17A31E481 for ; Thu, 31 Oct 2024 22:39:52 +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=1730414398; cv=none; b=kuNLTlAipySK4729OLsF2n8EWY0/NoYv3uAUbF1W/N0Md/oL9zw+8fpnt86dj9PbOij0INdWer0rJ1fdh1m+Ae/0FlfFuQO2E96DT8BT07aZMutO1i75ZeP+VC9a2aqyivhXH1h6eQ0RzcqiTUCIzMNxT483LQEkWprMShpNsgA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730414398; c=relaxed/simple; bh=1K+1EzPZRuDuWAazdL34ULZOOR+K2+dU7Cnwhnj3bHc=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=tVEZNooc/gQoImEym5xaGNTymcp15i/DKAXwCcjA1JEa49diqdjyep1wAENRyV7QKgrTP4j7VNnlrs+ts7NoS1kVQwGFiHgodGpHQBD4kb2SKS/iqeeUln1c3zJx3ikJxrKeWIGZcnI3DGiWvLTRCUT3upeV3DTrgyJ8j2uNYtw= 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=Tda9FmCH; 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="Tda9FmCH" Received: by mail-pf1-f201.google.com with SMTP id d2e1a72fcca58-71e8641f2a7so1568471b3a.2 for ; Thu, 31 Oct 2024 15:39:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1730414392; x=1731019192; 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=Tda9FmCHQADd+90H0/chEtVsoCbEAnKg0M0ML3FlySL7sj6BHFrw6u6i17kgxaCgQx 9zjNA4Sa96hqSAn+sD97usKHwr64ffrq2BHpZpFClvIBqGxopbmXwK7x6IcAv7ENnasM gymEtNOcWtRJScPibe5Of44MB9wElXiy93/CUPh6YlQ9hA7KPSCII7adyaCkzOoxGBbz qb4BqPWg6d5ipRMGazmoc1uWc3fyNTIDhU35NVaJ3mBWkYtHu3gIhYecKr+nFiJPYJxa kBxbjZAxQlDuwj/BGzXChJ2BPg/yLdEVxKEzm+eLDa2OjjeTrO+iTWSdwJV00qW3VSiJ re7A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1730414392; x=1731019192; 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=el9oasS0rKqxYbid5y4bHVKHwfhQ/FZqYwY42gboU+cPBL+xNPb4PgEa/J/VxtECKN bE9JUVgcbc8M8b2lo98YK/qGPDpSy32Xhri3+ji1TbQiyVZ5reByBEThuN8QLAGJhOXz Id1PpJdew5Es8+IwMrzycz+Ts8qj9k45tFKALnCdT/t6FoNdzwGOW1s3fxs0T02d2Eta citrvHGrlkDfXsCnwJPmJe80+AC8Mlry1Mcxj1GtfafCfw0iHZ/rBwH29oPchkPeZLJB CecVV2hS3NxWoz0c7WK+aj7UUptzqMfqa0W9RSbm1LaGmfsFn++MyzODqlZFTAsK0cDt pNXg== X-Forwarded-Encrypted: i=1; AJvYcCUsMY1IT7/PDpAb3ofiNKgnnuMKrzb92pYPyUm+N15libDz0fALb0sTh0Yh/cVl7goRHkluAV+cUki7hAma1m+I@vger.kernel.org X-Gm-Message-State: AOJu0YyMy6BXMEiHgICNfD5keTzxfddi55UDaW0TQqJuGVbYSkjdFdrM r/RdKbRxMsBCtm+2xutEHh35pE351Z0QSElPqCPy1HU4jkPk2Xz6XyqcRbecdchL/IbPNrHCnML 2oQ== 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-perf-users@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