From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1B85D4F7987; Wed, 16 Sep 2026 13:57:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789567055; cv=none; b=GB3mQ7iMtn01bU6fCdviykouGWTVS5XpuxuLHDSWVLeIsQSIVS7w5PLtNV7o92A3UD/dFtb9MzDCXCwtXrjl45Z4R8Jlf+9FWCmyMNam13o5QW3C/zUKoFnWN8wwYEreHBCs7td9OpmzB3L+1gRTdw1MWGjQsJvanYecvzixYGA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789567055; c=relaxed/simple; bh=t46hs0/GEgmiGgZp9Os84+OnNOORKYKQb8jdq05gkxs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=IQos4XNJOHRa/WGt2uVHnsCJwgTg5y1vNbo7BlR66OGKSxkN7LBvkJc6OvRX/Z5edMABLNRFmDdDF90mbMAwK9nvDNEEqIE8PJAMgvE1sFTriB+b2b97jk54+KCcPg40tOpwdPDaOFMUzjWxGyFrYLVgLAuGTGRECKdYpg7GfoM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=j28oebvK; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="j28oebvK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EDA561F000FF; Wed, 16 Sep 2026 13:57:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789567046; bh=+mvIy+ktfyCO7J35CXJ94gRBdKzmzDuLPLFeOqM1y24=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=j28oebvKbBFT/nU1bd70pbZcnAZWAMV3kmDAdf1VUu4h2xwujuol0OJ2oXG/aFsDq VCFYYL2aYxaodyPvbpHhTPv8footUbbq7HMxEEXasLhIAIYCa5/tL0YxYXJ5u2QoGy vBVHIqKdflCS6RxKL1o7fLdDoCpBm/FT+lCx8bowIlwctl+TbUq4BLKEKDhuf5/RKU LjrZmVWOj/h58DZHjxXa9KPahuW+Kf+Hl8RI8vA9H/gZEAkjuD17JsEVs8nHcYxZCM HqIXbiKTcAL7RqS3XiZi9vR10doSdiK7O8yd9PC0U5paxR5tDwMphwO8TwETbbOQLX jed7115szDXvg== Date: Wed, 16 Sep 2026 10:57:23 -0300 From: Arnaldo Carvalho de Melo To: Chun-Tse Shao 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 Subject: Re: [PATCH v9] perf evsel: Find process with busy PMUs for EBUSY Message-ID: References: <20260915204951.2935261-2-ctshao@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260915204951.2935261-2-ctshao@google.com> On Tue, Sep 15, 2026 at 01:49:51PM -0700, Chun-Tse Shao wrote: > 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. I'll apply this after addressing Sashiko's comments about missing headers for building on musl libc systems, thanks. - Arnaldo > 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