From patchwork Fri Aug 21 02:54:48 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrii Nakryiko X-Patchwork-Id: 1348803 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=reject dis=none) header.from=fb.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=fb.com header.i=@fb.com header.a=rsa-sha256 header.s=facebook header.b=HlFtQDwV; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4BXmMj6kRcz9sPC for ; Fri, 21 Aug 2020 12:54:57 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726983AbgHUCy4 (ORCPT ); Thu, 20 Aug 2020 22:54:56 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:37310 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726702AbgHUCyy (ORCPT ); Thu, 20 Aug 2020 22:54:54 -0400 Received: from pps.filterd (m0148461.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 07L2sBHq003787 for ; Thu, 20 Aug 2020 19:54:53 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding : content-type; s=facebook; bh=ujLsei6d9MTTvzOY59QeLLIkNuFkTD09Qg7i7E++HUs=; b=HlFtQDwVELFt/hkCB9es/4Uf/H6TMjUfmIQnootMg6ULFTOQ0+IywMHL3S74lZuPqnzR bfDQwxX1vMjKCSKrGF+/a4V6V+5aTKkJ+CSx33xiOimNtjMcb+0+3aIDJ0T0z5MisvKu FuJtOfPjs392aYb9VSg03iqjN578LNFW2A8= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com with ESMTP id 3304m3a8us-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Thu, 20 Aug 2020 19:54:53 -0700 Received: from intmgw001.03.ash8.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:82::d) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Thu, 20 Aug 2020 19:54:52 -0700 Received: by devbig012.ftw2.facebook.com (Postfix, from userid 137359) id 7C3192EC5F52; Thu, 20 Aug 2020 19:54:49 -0700 (PDT) Smtp-Origin-Hostprefix: devbig From: Andrii Nakryiko Smtp-Origin-Hostname: devbig012.ftw2.facebook.com To: , , , CC: , , Andrii Nakryiko Smtp-Origin-Cluster: ftw2c04 Subject: [PATCH bpf-next] libbpf: add perf_buffer APIs for better integration with outside epoll loop Date: Thu, 20 Aug 2020 19:54:48 -0700 Message-ID: <20200821025448.2087055-1-andriin@fb.com> X-Mailer: git-send-email 2.24.1 MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235,18.0.687 definitions=2020-08-21_03:2020-08-19,2020-08-21 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 mlxlogscore=999 impostorscore=0 mlxscore=0 bulkscore=0 suspectscore=25 spamscore=0 phishscore=0 lowpriorityscore=0 malwarescore=0 clxscore=1015 adultscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2008210026 X-FB-Internal: deliver Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Add a set of APIs to perf_buffer manage to allow applications to integrate perf buffer polling into existing epoll-based infrastructure. One example is applications using libevent already and wanting to plug perf_buffer polling, instead of relying on perf_buffer__poll() and waste an extra thread to do it. But perf_buffer is still extremely useful to set up and consume perf buffer rings even for such use cases. So to accomodate such new use cases, add three new APIs: - perf_buffer__buffer_cnt() returns number of per-CPU buffers maintained by given instance of perf_buffer manager; - perf_buffer__buffer_fd() returns FD of perf_event corresponding to a specified per-CPU buffer; this FD is then polled independently; - perf_buffer__consume_buffer() consumes data from single per-CPU buffer, identified by its slot index. These APIs allow for great flexiblity, but do not sacrifice general usability of perf_buffer. Also exercise and check new APIs in perf_buffer selftest. Signed-off-by: Andrii Nakryiko Reviewed-by: Alan Maguire --- tools/lib/bpf/libbpf.c | 51 ++++++++++++++- tools/lib/bpf/libbpf.h | 3 + tools/lib/bpf/libbpf.map | 7 +++ .../selftests/bpf/prog_tests/perf_buffer.c | 62 +++++++++++++++---- 4 files changed, 111 insertions(+), 12 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 0bc1fd813408..a6359d49aa9d 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -9390,6 +9390,55 @@ int perf_buffer__poll(struct perf_buffer *pb, int timeout_ms) return cnt < 0 ? -errno : cnt; } +/* Return number of PERF_EVENT_ARRAY map slots set up by this perf_buffer + * manager. + */ +size_t perf_buffer__buffer_cnt(const struct perf_buffer *pb) +{ + return pb->cpu_cnt; +} + +/* + * Return perf_event FD of a ring buffer in *buf_idx* slot of + * PERF_EVENT_ARRAY BPF map. This FD can be polled for new data using + * select()/poll()/epoll() Linux syscalls. + */ +int perf_buffer__buffer_fd(const struct perf_buffer *pb, size_t buf_idx) +{ + struct perf_cpu_buf *cpu_buf; + + if (buf_idx >= pb->cpu_cnt) + return -EINVAL; + + cpu_buf = pb->cpu_bufs[buf_idx]; + if (!cpu_buf) + return -ENOENT; + + return cpu_buf->fd; +} + +/* + * Consume data from perf ring buffer corresponding to slot *buf_idx* in + * PERF_EVENT_ARRAY BPF map without waiting/polling. If there is no data to + * consume, do nothing and return success. + * Returns: + * - 0 on success; + * - <0 on failure. + */ +int perf_buffer__consume_buffer(struct perf_buffer *pb, size_t buf_idx) +{ + struct perf_cpu_buf *cpu_buf; + + if (buf_idx >= pb->cpu_cnt) + return -EINVAL; + + cpu_buf = pb->cpu_bufs[buf_idx]; + if (!cpu_buf) + return -ENOENT; + + return perf_buffer__process_records(pb, cpu_buf); +} + int perf_buffer__consume(struct perf_buffer *pb) { int i, err; @@ -9402,7 +9451,7 @@ int perf_buffer__consume(struct perf_buffer *pb) err = perf_buffer__process_records(pb, cpu_buf); if (err) { - pr_warn("error while processing records: %d\n", err); + pr_warn("perf_buffer: failed to process records in buffer #%d: %d\n", i, err); return err; } } diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index 5ecb4069a9f0..15e02dcda2c7 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -590,6 +590,9 @@ perf_buffer__new_raw(int map_fd, size_t page_cnt, LIBBPF_API void perf_buffer__free(struct perf_buffer *pb); LIBBPF_API int perf_buffer__poll(struct perf_buffer *pb, int timeout_ms); LIBBPF_API int perf_buffer__consume(struct perf_buffer *pb); +LIBBPF_API int perf_buffer__consume_buffer(struct perf_buffer *pb, size_t buf_idx); +LIBBPF_API size_t perf_buffer__buffer_cnt(const struct perf_buffer *pb); +LIBBPF_API int perf_buffer__buffer_fd(const struct perf_buffer *pb, size_t buf_idx); typedef enum bpf_perf_event_ret (*bpf_perf_event_print_t)(struct perf_event_header *hdr, diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index e35bd6cdbdbf..77466958310a 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -299,3 +299,10 @@ LIBBPF_0.1.0 { btf__set_fd; btf__set_pointer_size; } LIBBPF_0.0.9; + +LIBBPF_0.2.0 { + global: + perf_buffer__buffer_cnt; + perf_buffer__buffer_fd; + perf_buffer__consume_buffer; +} LIBBPF_0.1.0; diff --git a/tools/testing/selftests/bpf/prog_tests/perf_buffer.c b/tools/testing/selftests/bpf/prog_tests/perf_buffer.c index c33ec180b3f2..add224ce17af 100644 --- a/tools/testing/selftests/bpf/prog_tests/perf_buffer.c +++ b/tools/testing/selftests/bpf/prog_tests/perf_buffer.c @@ -7,6 +7,8 @@ #include "test_perf_buffer.skel.h" #include "bpf/libbpf_internal.h" +static int duration; + /* AddressSanitizer sometimes crashes due to data dereference below, due to * this being mmap()'ed memory. Disable instrumentation with * no_sanitize_address attribute @@ -24,13 +26,31 @@ static void on_sample(void *ctx, int cpu, void *data, __u32 size) CPU_SET(cpu, cpu_seen); } +int trigger_on_cpu(int cpu) +{ + cpu_set_t cpu_set; + int err; + + CPU_ZERO(&cpu_set); + CPU_SET(cpu, &cpu_set); + + err = pthread_setaffinity_np(pthread_self(), sizeof(cpu_set), &cpu_set); + if (err && CHECK(err, "set_affinity", "cpu #%d, err %d\n", cpu, err)) + return err; + + usleep(1); + + return 0; +} + void test_perf_buffer(void) { - int err, on_len, nr_on_cpus = 0, nr_cpus, i, duration = 0; + int err, on_len, nr_on_cpus = 0, nr_cpus, i; struct perf_buffer_opts pb_opts = {}; struct test_perf_buffer *skel; - cpu_set_t cpu_set, cpu_seen; + cpu_set_t cpu_seen; struct perf_buffer *pb; + int last_fd = -1, fd; bool *online; nr_cpus = libbpf_num_possible_cpus(); @@ -71,16 +91,8 @@ void test_perf_buffer(void) continue; } - CPU_ZERO(&cpu_set); - CPU_SET(i, &cpu_set); - - err = pthread_setaffinity_np(pthread_self(), sizeof(cpu_set), - &cpu_set); - if (err && CHECK(err, "set_affinity", "cpu #%d, err %d\n", - i, err)) + if (trigger_on_cpu(i)) goto out_close; - - usleep(1); } /* read perf buffer */ @@ -92,6 +104,34 @@ void test_perf_buffer(void) "expect %d, seen %d\n", nr_on_cpus, CPU_COUNT(&cpu_seen))) goto out_free_pb; + if (CHECK(perf_buffer__buffer_cnt(pb) != nr_cpus, "buf_cnt", + "got %zu, expected %d\n", perf_buffer__buffer_cnt(pb), nr_cpus)) + goto out_close; + + for (i = 0; i < nr_cpus; i++) { + if (i >= on_len || !online[i]) + continue; + + fd = perf_buffer__buffer_fd(pb, i); + CHECK(last_fd == fd, "fd_check", "last fd %d == fd %d\n", last_fd, fd); + last_fd = fd; + + err = perf_buffer__consume_buffer(pb, i); + if (CHECK(err, "drain_buf", "cpu %d, err %d\n", i, err)) + goto out_close; + + CPU_CLR(i, &cpu_seen); + if (trigger_on_cpu(i)) + goto out_close; + + err = perf_buffer__consume_buffer(pb, i); + if (CHECK(err, "consume_buf", "cpu %d, err %d\n", i, err)) + goto out_close; + + if (CHECK(!CPU_ISSET(i, &cpu_seen), "cpu_seen", "cpu %d not seen\n", i)) + goto out_close; + } + out_free_pb: perf_buffer__free(pb); out_close: