From: "Wangnan (F)" <wangnan0@huawei.com>
To: Arnaldo Carvalho de Melo <acme@kernel.org>,
Peter Zijlstra <peterz@infradead.org>
Cc: "Alexei Starovoitov" <ast@kernel.org>,
"Arnaldo Carvalho de Melo" <acme@redhat.com>,
"Brendan Gregg" <brendan.d.gregg@gmail.com>,
"Adrian Hunter" <adrian.hunter@intel.com>,
"Cody P Schafer" <dev@codyps.com>,
"David S. Miller" <davem@davemloft.net>,
"He Kuang" <hekuang@huawei.com>,
"Jérémie Galarneau" <jeremie.galarneau@efficios.com>,
"Jiri Olsa" <jolsa@kernel.org>,
"Kirill Smelkov" <kirr@nexedi.com>,
"Li Zefan" <lizefan@huawei.com>,
"Masami Hiramatsu" <masami.hiramatsu.pt@hitachi.com>,
"Namhyung Kim" <namhyung@kernel.org>,
pi3orama@163.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 10/48] perf tools: Introduce bpf-output event
Date: Wed, 24 Feb 2016 13:03:40 +0800 [thread overview]
Message-ID: <56CD39AC.5020909@huawei.com> (raw)
In-Reply-To: <56CD2B98.4040009@huawei.com>
On 2016/2/24 12:03, Wangnan (F) wrote:
>
>
> On 2016/2/24 10:04, Wangnan (F) wrote:
>>
>>
>> On 2016/2/24 9:58, Wangnan (F) wrote:
>>>
[SNIP]
>>> So, there is something strange here:
>>>>
>>>> if (unlikely(event->oncpu != smp_processor_id()))
>>>> return -EOPNOTSUPP;
>>>>
>>>
>>
>> All failures have 'event->oncpu == -1' here. I guess we should
>> suppress warning in
>> this case. But why event->oncpu becomes -1?
>>
>
> For this specific test it is not surprising to see these error
> messages. In this test
> we create bpf-output channel on 'ls' process only, but the BPF script
> is triggered
> on all procs (BPF triggering is not related to perf event scheduling).
> Trying to
> output data through 'ls' specific bpf-output channel should fail if
> this 'sys_write'
> is not issued by 'ls' or its children. So it is a correct behavior.
>
> However, I also see them in system wide channel:
>
> # echo "" > /sys/kernel/debug/tracing/trace
> # ./perf record -a -e bpf-output/no-inherit,name=evt/ \
> -e ./test_bpf_output.c/map:channel.event=evt/
> -a
> ^C[ perf record: Woken up 0 times to write data ]
> [ perf record: Captured and wrote 17.534 MB perf.data (264326 samples) ]
> # cat /sys/kernel/debug/tracing/trace | tail
> rs:main Q:Reg-582 [000] d..2 4858.711225: : Error: failed to
> output: -95
> rs:main Q:Reg-582 [000] d..2 4858.711241: : Error: failed to
> output: -95
> gmain-1858 [003] d..2 4858.711436: : Error: failed to
> output: -95
> gmain-1858 [003] d..2 4858.711441: : Error: failed to
> output: -95
> gmain-1858 [003] d..2 4858.711473: : Error: failed to
> output: -95
> rs:main Q:Reg-582 [002] d..2 4858.712215: : Error: failed to
> output: -95
> rs:main Q:Reg-582 [002] d..2 4858.712224: : Error: failed to
> output: -95
> gmain-1858 [003] d..2 4858.712230: : Error: failed to
> output: -95
> rs:main Q:Reg-582 [002] d..2 4858.712235: : Error: failed to
> output: -95
> rs:main Q:Reg-582 [002] d..2 4858.712239: : Error: failed to
> output: -95
>
> System wide events can also be scheduled in and out. If the bpf-output
> events
> are scheduled out, trying to output data through it causes the above
> failure.
> I don't think it is a problem.
>
> Peter, Could you please give some infomation? In which case a system wide
> bpf output channel would be scheduled out?
>
Sorry, I think my brain is not quite well. Actually this is a easy question:
all ENOTSUPP results are generated before PERF_EVENT_IOC_ENABLE or after
PERF_EVENT_IOC_DISABLE. You saw so many failure messages because it is
sys_write,
and perf itself needs it.
So you can simply ignore these messages.
Thank you.
next prev parent reply other threads:[~2016-02-24 5:06 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-22 9:10 [PATCH 00/48] perf tools: Bugfix, BPF improvements and overwrite ring buffer support Wang Nan
2016-02-22 9:10 ` [PATCH 01/48] perf tools: Record text offset in dso to calculate objdump address Wang Nan
2016-02-22 9:10 ` [PATCH 02/48] perf tools: Adjust symbol for shared objects Wang Nan
2016-02-22 9:10 ` [PATCH 03/48] perf bpf: Add API to set values to map entries in a bpf object Wang Nan
2016-02-25 5:39 ` [tip:perf/core] " tip-bot for Wang Nan
2016-02-22 9:10 ` [PATCH 04/48] perf tools: Enable BPF object configure syntax Wang Nan
2016-02-25 5:39 ` [tip:perf/core] " tip-bot for Wang Nan
2016-02-22 9:10 ` [PATCH 05/48] perf record: Apply config to BPF objects before recording Wang Nan
2016-02-25 5:39 ` [tip:perf/core] " tip-bot for Wang Nan
2016-02-22 9:10 ` [PATCH 06/48] perf tools: Enable passing event to BPF object Wang Nan
2016-02-25 5:40 ` [tip:perf/core] " tip-bot for Wang Nan
2016-02-22 9:10 ` [PATCH 07/48] perf tools: Support setting different slots in a BPF map separately Wang Nan
2016-02-25 5:40 ` [tip:perf/core] " tip-bot for Wang Nan
2016-02-22 9:10 ` [PATCH 08/48] perf tools: Enable indices setting syntax for BPF map Wang Nan
2016-02-25 5:40 ` [tip:perf/core] " tip-bot for Wang Nan
2016-02-22 9:10 ` [PATCH 09/48] perf tools: Pass tracepoint options to BPF script Wang Nan
2016-02-25 5:41 ` [tip:perf/core] perf tools: Apply tracepoint event definition " tip-bot for Wang Nan
2016-02-22 9:10 ` [PATCH 10/48] perf tools: Introduce bpf-output event Wang Nan
2016-02-23 17:45 ` Arnaldo Carvalho de Melo
2016-02-24 1:58 ` Wangnan (F)
2016-02-24 2:04 ` Wangnan (F)
2016-02-24 4:03 ` Wangnan (F)
2016-02-24 5:03 ` Wangnan (F) [this message]
2016-02-24 13:36 ` Arnaldo Carvalho de Melo
2016-02-25 5:41 ` [tip:perf/core] " tip-bot for Wang Nan
2016-02-22 9:10 ` [PATCH 11/48] perf data: Support converting data from bpf_perf_event_output() Wang Nan
2016-02-23 16:14 ` Arnaldo Carvalho de Melo
2016-02-23 17:23 ` Jiri Olsa
2016-02-23 17:24 ` Jiri Olsa
2016-02-23 19:22 ` Jiri Olsa
2016-02-22 9:10 ` [PATCH 12/48] perf data: Explicitly set byte order for integer types Wang Nan
2016-02-22 9:10 ` [PATCH 13/48] perf core: Introduce new ioctl options to pause and resume ring buffer Wang Nan
2016-02-22 9:10 ` [PATCH 14/48] perf core: Set event's default overflow_handler Wang Nan
2016-02-22 9:10 ` [PATCH 15/48] perf core: Prepare writing into ring buffer from end Wang Nan
2016-02-22 9:10 ` [PATCH 16/48] perf core: Add backward attribute to perf event Wang Nan
2016-02-24 13:08 ` Jiri Olsa
2016-02-24 13:21 ` Jiri Olsa
2016-02-22 9:10 ` [PATCH 17/48] perf core: Reduce perf event output overhead by new overflow handler Wang Nan
2016-02-22 9:10 ` [PATCH 18/48] perf tools: Only validate is_pos for tracking evsels Wang Nan
2016-02-24 14:21 ` Jiri Olsa
2016-02-22 9:10 ` [PATCH 19/48] perf tools: Print write_backward value in perf_event_attr__fprintf Wang Nan
2016-02-22 9:10 ` [PATCH 20/48] perf tools: Make ordered_events reusable Wang Nan
2016-02-24 14:18 ` Jiri Olsa
2016-02-22 9:10 ` [PATCH 21/48] perf record: Extract synthesize code to record__synthesize() Wang Nan
2016-02-24 14:29 ` Jiri Olsa
2016-02-22 9:10 ` [PATCH 22/48] perf tools: Add perf_data_file__switch() helper Wang Nan
2016-02-24 14:34 ` Jiri Olsa
2016-02-22 9:10 ` [PATCH 23/48] perf record: Turns auxtrace_snapshot_enable into 3 states Wang Nan
2016-02-24 14:43 ` Jiri Olsa
2016-02-22 9:10 ` [PATCH 24/48] perf record: Introduce record__finish_output() to finish a perf.data Wang Nan
2016-02-22 9:10 ` [PATCH 25/48] perf record: Add '--timestamp-filename' option to append timestamp to output filename Wang Nan
2016-02-22 9:10 ` [PATCH 26/48] perf record: Split output into multiple files via '--switch-output' Wang Nan
2016-02-22 9:10 ` [PATCH 27/48] perf record: Force enable --timestamp-filename when --switch-output is provided Wang Nan
2016-02-22 9:10 ` [PATCH 28/48] perf record: Disable buildid cache options by default in switch output mode Wang Nan
2016-02-22 9:10 ` [PATCH 29/48] perf record: Re-synthesize tracking events after output switching Wang Nan
2016-02-24 14:57 ` Jiri Olsa
2016-02-22 9:10 ` [PATCH 30/48] perf record: Generate tracking events for process forked by perf Wang Nan
2016-02-24 15:01 ` Jiri Olsa
2016-02-22 9:10 ` [PATCH 31/48] perf record: Ensure return non-zero rc when mmap fail Wang Nan
2016-02-22 9:10 ` [PATCH 32/48] perf record: Prevent reading invalid data in record__mmap_read Wang Nan
2016-02-22 9:11 ` [PATCH 33/48] perf tools: Add evlist channel helpers Wang Nan
2016-02-22 9:11 ` [PATCH 34/48] perf tools: Automatically add new channel according to evlist Wang Nan
2016-02-22 9:11 ` [PATCH 35/48] perf tools: Operate multiple channels Wang Nan
2016-02-22 9:11 ` [PATCH 36/48] perf tools: Squash overwrite setting into channel Wang Nan
2016-02-22 9:11 ` [PATCH 37/48] perf record: Don't read from and poll overwrite channel Wang Nan
2016-02-22 9:11 ` [PATCH 38/48] perf record: Don't poll on " Wang Nan
2016-02-22 9:11 ` [PATCH 39/48] perf tools: Detect avalibility of write_backward Wang Nan
2016-02-22 9:11 ` [PATCH 40/48] perf tools: Enable overwrite settings Wang Nan
2016-02-22 9:11 ` [PATCH 41/48] perf tools: Set write_backward attribut bit for overwrite events Wang Nan
2016-02-22 9:11 ` [PATCH 42/48] perf tools: Record fd into perf_mmap Wang Nan
2016-02-22 9:11 ` [PATCH 43/48] perf tools: Add API to pause a channel Wang Nan
2016-02-22 9:11 ` [PATCH 44/48] perf record: Toggle overwrite ring buffer for reading Wang Nan
2016-02-22 9:11 ` [PATCH 45/48] perf record: Rename variable to make code clear Wang Nan
2016-02-22 9:11 ` [PATCH 46/48] perf record: Read from backward ring buffer Wang Nan
2016-02-22 9:11 ` [PATCH 47/48] perf record: Allow generate tracking events at the end of output Wang Nan
2016-02-22 9:11 ` [PATCH 48/48] perf tools: Don't warn about out of order event if write_backward is used Wang Nan
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