Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933334AbbGVIL4 (ORCPT ); Wed, 22 Jul 2015 04:11:56 -0400 Received: from szxga01-in.huawei.com ([58.251.152.64]:36804 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756130AbbGVIJ7 (ORCPT ); Wed, 22 Jul 2015 04:09:59 -0400 From: Kaixu Xia To: , , , , , , CC: , , , , Subject: [PATCH v2 0/5] bpf: Introduce the new ability of eBPF programs to access hardware PMU counter Date: Wed, 22 Jul 2015 08:09:27 +0000 Message-ID: <1437552572-84748-1-git-send-email-xiakaixu@huawei.com> X-Mailer: git-send-email 1.8.3.4 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.107.193.250] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4513 Lines: 100 Previous patch v1 url: https://lkml.org/lkml/2015/7/17/287 This patchset allows user read PMU events in the following way: 1. Open the PMU using perf_event_open() (for each CPUs or for each processes he/she'd like to watch); 2. Create a BPF_MAP_TYPE_PERF_EVENT_ARRAY BPF map; 3. Insert FDs into the map with some key-value mapping scheme (i.e. cpuid -> event on that CPU); 4. Load and attach eBPF programs as usual; 5. In eBPF program, get the perf_event_map_fd and key (i.e. cpuid get from bpf_get_smp_processor_id()) then use bpf_perf_event_read() to read from it. 6. Do anything he/her want. changes in V2: - put atomic_long_inc_not_zero() between fdget() and fdput(); - limit the event type to PERF_TYPE_RAW and PERF_TYPE_HARDWARE; - Only read the event counter on current CPU or on current process; - add new map type BPF_MAP_TYPE_PERF_EVENT_ARRAY to store the pointer to the struct perf_event; - according to the perf_event_map_fd and key, the function bpf_perf_event_read() can get the Hardware PMU counter value; Patch 5/5 is a simple example and shows how to use this new eBPF programs ability. The PMU counter data can be found in /sys/kernel/debug/tracing/trace(trace_pipe).(the cycles PMU value when 'kprobe/sys_write' sampling) $ cat /sys/kernel/debug/tracing/trace_pipe $ ./tracex6 ... cat-677 [002] d..1 210.299270: : bpf count: CPU-2 5316659 cat-677 [002] d..1 210.299316: : bpf count: CPU-2 5378639 cat-677 [002] d..1 210.299362: : bpf count: CPU-2 5440654 cat-677 [002] d..1 210.299408: : bpf count: CPU-2 5503211 cat-677 [002] d..1 210.299454: : bpf count: CPU-2 5565438 cat-677 [002] d..1 210.299500: : bpf count: CPU-2 5627433 cat-677 [002] d..1 210.299547: : bpf count: CPU-2 5690033 cat-677 [002] d..1 210.299593: : bpf count: CPU-2 5752184 cat-677 [002] d..1 210.299639: : bpf count: CPU-2 5814543 <...>-548 [009] d..1 210.299667: : bpf count: CPU-9 605418074 <...>-548 [009] d..1 210.299692: : bpf count: CPU-9 605452692 cat-677 [002] d..1 210.299700: : bpf count: CPU-2 5896319 <...>-548 [009] d..1 210.299710: : bpf count: CPU-9 605477824 <...>-548 [009] d..1 210.299728: : bpf count: CPU-9 605501726 <...>-548 [009] d..1 210.299745: : bpf count: CPU-9 605525279 <...>-548 [009] d..1 210.299762: : bpf count: CPU-9 605547817 <...>-548 [009] d..1 210.299778: : bpf count: CPU-9 605570433 <...>-548 [009] d..1 210.299795: : bpf count: CPU-9 605592743 ... The detail of patches is as follow: Patch 1/5 introduces a new bpf map type. This map only stores the pointer to struct perf_event; Patch 2/5 introduces a map_traverse_elem() function for further use; Patch 3/5 convets event file descriptors into perf_event structure when add new element to the map; Patch 4/5 implement function bpf_perf_event_read() that get the selected hardware PMU conuter; Patch 5/5 give a simple example. Kaixu Xia (5): bpf: Add new bpf map type to store the pointer to struct perf_event bpf: Add function map->ops->map_traverse_elem() to traverse map elems bpf: Save the pointer to struct perf_event to map bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU conuter samples/bpf: example of get selected PMU counter value include/linux/bpf.h | 6 +++ include/linux/perf_event.h | 5 ++- include/uapi/linux/bpf.h | 3 ++ kernel/bpf/arraymap.c | 110 +++++++++++++++++++++++++++++++++++++++++++++ kernel/bpf/helpers.c | 42 +++++++++++++++++ kernel/bpf/syscall.c | 26 +++++++++++ kernel/events/core.c | 30 ++++++++++++- kernel/trace/bpf_trace.c | 2 + samples/bpf/Makefile | 4 ++ samples/bpf/bpf_helpers.h | 2 + samples/bpf/tracex6_kern.c | 27 +++++++++++ samples/bpf/tracex6_user.c | 67 +++++++++++++++++++++++++++ 12 files changed, 321 insertions(+), 3 deletions(-) create mode 100644 samples/bpf/tracex6_kern.c create mode 100644 samples/bpf/tracex6_user.c -- 1.8.3.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/