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Message-ID: <1438082255-60683-1-git-send-email-xiakaixu@huawei.com>
Date: Tue, 28 Jul 2015 11:17:31 +0000
From: Kaixu Xia <xiakaixu@...wei.com>
To: <ast@...mgrid.com>, <davem@...emloft.net>, <acme@...nel.org>,
<mingo@...hat.com>, <a.p.zijlstra@...llo.nl>,
<masami.hiramatsu.pt@...achi.com>, <jolsa@...nel.org>,
<daniel@...earbox.net>
CC: <xiakaixu@...wei.com>, <wangnan0@...wei.com>,
<linux-kernel@...r.kernel.org>, <pi3orama@....com>,
<hekuang@...wei.com>
Subject: [PATCH v4 0/4] bpf: Introduce the new ability of eBPF programs to access hardware PMU counter
Previous patch v3 url:
https://lkml.org/lkml/2015/7/23/203
changes in V4:
- make the bpf_prog_array_map more generic;
- fix the bug of event refcnt leak;
- use more useful errno in bpf_perf_event_read();
changes in V3:
- collapse V2 patches 1-3 into one;
- drop the function map->ops->map_traverse_elem() and release
the struct perf_event in map_free;
- only allow to access bpf_perf_event_read() from programs;
- update the perf_event_array_map elem via xchg();
- pass index directly to bpf_perf_event_read() instead of
MAP_KEY;
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 4/4 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
...
syslog-ng-548 [000] d..1 76.905673: : CPU-0 681765271
syslog-ng-548 [000] d..1 76.905690: : CPU-0 681787855
syslog-ng-548 [000] d..1 76.905707: : CPU-0 681810504
syslog-ng-548 [000] d..1 76.905725: : CPU-0 681834771
syslog-ng-548 [000] d..1 76.905745: : CPU-0 681859519
syslog-ng-548 [000] d..1 76.905766: : CPU-0 681890419
syslog-ng-548 [000] d..1 76.905783: : CPU-0 681914045
syslog-ng-548 [000] d..1 76.905800: : CPU-0 681935950
syslog-ng-548 [000] d..1 76.905816: : CPU-0 681958299
ls-690 [005] d..1 82.241308: : CPU-5 3138451
sh-691 [004] d..1 82.244570: : CPU-4 7324988
<...>-699 [007] d..1 99.961387: : CPU-7 3194027
<...>-695 [003] d..1 99.961474: : CPU-3 288901
<...>-695 [003] d..1 99.961541: : CPU-3 383145
<...>-695 [003] d..1 99.961591: : CPU-3 450365
<...>-695 [003] d..1 99.961639: : CPU-3 515751
<...>-695 [003] d..1 99.961686: : CPU-3 579047
...
The detail of patches is as follow:
Patch 1/4 rewrites part of the bpf_prog_array map code and make it
more generic;
Patch 2/4 introduces a new bpf map type. This map only stores the
pointer to struct perf_event;
Patch 3/4 implements function bpf_perf_event_read() that get the
selected hardware PMU conuter;
Patch 4/4 gives a simple example.
Kaixu Xia (3):
bpf: Add new bpf map type to store the pointer to struct perf_event
bpf: Implement function bpf_perf_event_read() that get the selected
hardware PMU conuter
samples/bpf: example of get selected PMU counter value
Wang Nan (1):
bpf: Make the bpf_prog_array_map more generic
include/linux/bpf.h | 8 ++-
include/linux/perf_event.h | 5 +-
include/uapi/linux/bpf.h | 2 +
kernel/bpf/arraymap.c | 161 ++++++++++++++++++++++++++++++++++++---------
kernel/bpf/helpers.c | 36 ++++++++++
kernel/bpf/syscall.c | 4 +-
kernel/bpf/verifier.c | 15 +++++
kernel/events/core.c | 21 +++++-
kernel/trace/bpf_trace.c | 2 +
samples/bpf/Makefile | 4 ++
samples/bpf/bpf_helpers.h | 2 +
samples/bpf/tracex6_kern.c | 26 ++++++++
samples/bpf/tracex6_user.c | 67 +++++++++++++++++++
13 files changed, 316 insertions(+), 37 deletions(-)
create mode 100644 samples/bpf/tracex6_kern.c
create mode 100644 samples/bpf/tracex6_user.c
--
1.8.3.4
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