From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f200.google.com (mail-pl1-f200.google.com [209.85.214.200]) (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 9A1E736AB56 for ; Tue, 15 Sep 2026 20:51:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.200 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789505463; cv=none; b=IUlkAGnSbfEeS9BBQ95XEGIGJV/bGwG+lOwXP7wEY9SR9Wh9wzh4ZHrR33Ytc3No22SsLOdGU7b9zy6X/unR7MyLZquROBr0DOeoeBQ3zsZbFhqraLdYK0v+8bPN/+616IPI5XVJFWSTiSNGrg3KvjxeY8526GuBVxrVtMepyfI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789505463; c=relaxed/simple; bh=WekSfGriGt93pmZYw2hzEJz2kN7BGEHbUEL85lBDZTM=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=sgXRaW9Wub0dVruWNeu1vMb+YXAjhrBrl3k7IxndOpzgx79KKi9VhEkUvPot8+s6XWunL8miB3fiPd74gNZyAJHrBTG3jHXxjs18Shx7HAeO9I5nPpY2/fBC+J+vy4O+S6IVSWCH2xwRIDonhZH5dlpS1pb7Dv0tuzXLLA9ccxo= 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=sTtNQ+S+; arc=none smtp.client-ip=209.85.214.200 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="sTtNQ+S+" Received: by mail-pl1-f200.google.com with SMTP id d9443c01a7336-2dcfed75f77so72100915ad.2 for ; Tue, 15 Sep 2026 13:51:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1789505461; x=1790110261; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=KE/SmdG1WCHfb0EnIYsMzOMU1C1bEjt9QH54u0K4M7A=; b=sTtNQ+S+tV7g2JXS3lKmoCPeTc3O5JmoQDhlDxTFexcddDPdvEwHN7DH5BKGu1fSil I+qCZlcK5dwXwEBagSOYFwhfdxNb6pyLH2EoXbehfAHQsPYCSkOLcouCiPhXpkioIbki NCxhss88JwgrrvtFYOj3gC2SC2G274Kb1bJjVa6CdTueAQ5QAdm5GpXn+x/6IpWDaCLk ovbSxG+sS1u3cXfgJ8k0M3nrdEbGGPOZ0a4i5XC4exc47AX0QRrJgZmQzexmBGxsFuRC zwy5MS1gJsnlly0fxSdYsEw0zaVYfpkeVQkcPtuUnFUmsK+pTq4FsCEeTu/vtplIRP8h gXTw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1789505461; x=1790110261; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=KE/SmdG1WCHfb0EnIYsMzOMU1C1bEjt9QH54u0K4M7A=; b=FCiJtmyV6Vg/LqgKQIeOGNK11ZRM+pSgFyNligWvN84/QWzADgtUvglnppdubKNI/B JiQ4oi4FjGA+5m0FaJCGEsIV0dj5SjnZAndtRUJ8cDMQ5MoQ5qDrJZItn0JBKElP7wfG Kuhmm43gVpIRgIrktRWuy+OIdgaQ/eWSh+DlM5xADNYyoDq7CZvKXGIBHjFvlvGzlksZ pSmnUNHVxga4gnn8V3KetSnzwlRvmBBON0gMkco8y+mavIIK3CdbOYzzJ3uV8LN/IDY0 cSgsoSY/UkHJI4PdI/B0ysr9ovJJrTF5rHnSh2oGYZX13WhfUAP/EwVphCTX486+y6Wt JHyw== X-Forwarded-Encrypted: i=1; AKwUvBwWI1YkoHv3WslzmVN1s7ezzQzjbFLkdfUcQMdxkJYtQBJbxdufkgodtNe8yyBWVvJmssZu+zJBW03Fo0w=@vger.kernel.org X-Gm-Message-State: AFuF++lAlYwKZIoFqkfmnSRScRyI3UQX/uP1kavkRxp2ipZIzCjVDwoK CHOGdeU7K//LtKZ7+BR+U5GBvXOkdJ5yStxoHlH8CzPZi3Sbtdv4PkJrx/xWurVEsVq+mfojMtr vwBbHjQ== X-Received: from plgy12.prod.google.com ([2002:a17:903:22cc:b0:2dd:1daa:a60c]) (user=ctshao job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:22d0:b0:2d8:d4d3:da4d with SMTP id d9443c01a7336-2dd6c70ac50mr187737775ad.17.1789505460705; Tue, 15 Sep 2026 13:51:00 -0700 (PDT) Date: Tue, 15 Sep 2026 13:49:51 -0700 In-Reply-To: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: X-Mailer: git-send-email 2.55.0.1032.g73a4cd73de-goog Message-ID: <20260915204951.2935261-2-ctshao@google.com> Subject: [PATCH v9] perf evsel: Find process with busy PMUs for EBUSY From: Chun-Tse Shao To: Arnaldo Carvalho de Melo Cc: Ian Rogers , Namhyung Kim , Peter Zijlstra , Ingo Molnar , Mark Rutland , Alexander Shishkin , Jiri Olsa , Adrian Hunter , James Clark , Thomas Falcon , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Chun-Tse Shao Content-Type: text/plain; charset="UTF-8" It parses fdinfo with PMU type, comparing with the event which failed to open, and report the processes causing EBUSY error. Testing cycles and intel_pt// $ ./perf stat -e cycles & [1] 55569 $ ./perf stat -e intel_pt// & [2] 55683 $ ./perf stat -e intel_pt// Error: The PMU intel_pt counters are busy and in use by another process. Possible processes: 55683 ./perf stat -e intel_pt// Only perf with intel_pt was reported. Reviewed-by: Ian Rogers Signed-off-by: Chun-Tse Shao Assisted-by: Gemini:gemini-3.1-pro-preview --- v9: - Rebased onto perf-tools-next --- tools/perf/util/evsel.c | 69 ++++++++++++++++++++++++++++++++++++----- 1 file changed, 62 insertions(+), 7 deletions(-) diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index b44fd880d2d5..f3f5519d0d3d 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -4354,8 +4354,11 @@ static bool find_process(const char *name) return ret ? false : true; } -static int dump_perf_event_processes(char *msg, size_t size) +static int dump_perf_event_processes(const struct evsel *evsel, + char *msg, size_t size) { + const struct perf_event_attr *failed_attr = &evsel->core.attr; + u32 target_pmu_type = evsel->pmu ? evsel->pmu->type : UINT32_MAX; DIR *proc_dir; struct dirent *proc_entry; int printed = 0; @@ -4386,6 +4389,15 @@ static int dump_perf_event_processes(char *msg, size_t size) continue; } while ((fd_entry = readdir(fd_dir)) != NULL) { + const char *target_lnk = "anon_inode:[perf_event]"; + size_t target_lnk_len = sizeof("anon_inode:[perf_event]") - 1; + char fdinfo_buf[1024]; + int fdinfo_fd; + ssize_t fdinfo_size; + char *line; + char *saveptr; + u32 perf_event_type = UINT32_MAX; + u32 pmu_type = UINT32_MAX; ssize_t link_size; if (fd_entry->d_type != DT_LNK) @@ -4394,12 +4406,51 @@ static int dump_perf_event_processes(char *msg, size_t size) if (link_size < 0) continue; /* Take care as readlink doesn't null terminate the string. */ - if (!strncmp(buf, "anon_inode:[perf_event]", link_size)) { + if (link_size != (ssize_t)target_lnk_len || + strncmp(buf, target_lnk, target_lnk_len)) + continue; + + /* Let's check the PMU type reserved by this process */ + scnprintf(buf, sizeof(buf), "%s/fdinfo/%s", + proc_entry->d_name, fd_entry->d_name); + fdinfo_fd = openat(dirfd(proc_dir), buf, O_RDONLY | O_NONBLOCK); + if (fdinfo_fd == -1) + continue; + fdinfo_size = read(fdinfo_fd, fdinfo_buf, sizeof(fdinfo_buf) - 1); + close(fdinfo_fd); + if (fdinfo_size < 0) + continue; + fdinfo_buf[fdinfo_size] = '\0'; + + line = strtok_r(fdinfo_buf, "\n", &saveptr); + while (line) { + if (sscanf(line, + "perf_event_attr.type:\t%u", + &perf_event_type) == 1) { + /* continue parsing */ + } else if (sscanf(line, + "pmu_type:\t%u", + &pmu_type) == 1) { + /* continue parsing */ + } + line = strtok_r(NULL, "\n", &saveptr); + } + + /* Report the process which reserves the conflicted PMU. */ + /* If fdinfo does not contain PMU type, report it too. */ + if (perf_event_type == failed_attr->type || + pmu_type == failed_attr->type || + (target_pmu_type != UINT32_MAX && + pmu_type == target_pmu_type) || + (perf_event_type == UINT32_MAX && + pmu_type == UINT32_MAX)) { int cmdline_fd; ssize_t cmdline_size; - scnprintf(buf, sizeof(buf), "%s/cmdline", proc_entry->d_name); - cmdline_fd = openat(dirfd(proc_dir), buf, O_RDONLY); + scnprintf(buf, sizeof(buf), + "%s/cmdline", + proc_entry->d_name); + cmdline_fd = openat(dirfd(proc_dir), buf, O_RDONLY | O_NONBLOCK); if (cmdline_fd == -1) continue; cmdline_size = read(cmdline_fd, buf, sizeof(buf) - 1); @@ -4410,10 +4461,12 @@ static int dump_perf_event_processes(char *msg, size_t size) for (ssize_t i = 0; i < cmdline_size; i++) { if (buf[i] == '\0') buf[i] = ' '; + else if (!isprint((unsigned char)buf[i])) + buf[i] = '.'; } - if (printed == 0) - printed += scnprintf(msg, size, "Possible processes:\n"); + printed += scnprintf(msg, size, + "Possible processes:\n"); printed += scnprintf(msg + printed, size - printed, "%s %s\n", proc_entry->d_name, buf); @@ -4535,7 +4588,9 @@ int evsel__open_strerror(struct evsel *evsel, struct target *target, 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); + return printed + dump_perf_event_processes(evsel, + msg + printed, + size - printed); break; case EINVAL: if (evsel->core.attr.sample_type & PERF_SAMPLE_CODE_PAGE_SIZE && perf_missing_features.code_page_size) -- 2.55.0.1032.g73a4cd73de-goog