linux-kernel - Re: [PATCH 03/31] perf tools: Enable passing bpf object file to --event

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Date:	Wed, 21 Oct 2015 10:01:05 +0800
From:	"Wangnan (F)" <wangnan0@...wei.com>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
CC:	<ast@...mgrid.com>, <brendan.d.gregg@...il.com>,
	<a.p.zijlstra@...llo.nl>, <daniel@...earbox.net>,
	<dsahern@...il.com>, <hekuang@...wei.com>, <jolsa@...nel.org>,
	<lizefan@...wei.com>, <masami.hiramatsu.pt@...achi.com>,
	<namhyung@...nel.org>, <paulus@...ba.org>,
	<linux-kernel@...r.kernel.org>, <pi3orama@....com>,
	<xiakaixu@...wei.com>
Subject: Re: [PATCH 03/31] perf tools: Enable passing bpf object file to --event



On 2015/10/20 23:42, Arnaldo Carvalho de Melo wrote:
> Em Tue, Oct 20, 2015 at 12:15:58PM -0300, Arnaldo Carvalho de Melo escreveu:
>> Em Tue, Oct 20, 2015 at 12:12:55PM -0300, Arnaldo Carvalho de Melo escreveu:
>>> Em Wed, Oct 14, 2015 at 12:41:14PM +0000, Wang Nan escreveu:
>>>
> Managed after running:
>
>   perf test LLVM
>
> copy'n'pasting the output of those "set env" lines, replacing it with
> export, etc to get to:
>
> [acme@...icio linux]$ echo '__attribute__((section("do_fork"), used)) int fork(void *ctx) {return 0;} char _license[] __attribute__((section("license"), used)) = "GPL";int _version __attribute__((section("version"), used)) = 0x40100;' | $CLANG_EXEC -D__KERNEL__ $CLANG_OPTIONS $KERNEL_INC_OPTIONS -Wno-unused-value -Wno-pointer-sign -working-directory $WORKING_DIR -c "$CLANG_SOURCE" -target bpf -O2 -o /tmp/foo.o
> [acme@...icio linux]$ file /tmp/foo.o
> /tmp/foo.o: ELF 64-bit LSB relocatable, no machine, version 1 (SYSV), not stripped
> [acme@...icio linux]$
>
> And finally:
>
>
> [acme@...icio linux]$ file /tmp/foo.o
> /tmp/foo.o: ELF 64-bit LSB relocatable, no machine, version 1 (SYSV), not stripped
> [acme@...icio linux]$ perf record --event /tmp/foo.o sleep 1
> [ perf record: Woken up 1 times to write data ]
> [ perf record: Captured and wrote 0.013 MB perf.data ]
> [acme@...icio linux]$ perf evlist  -v
> /tmp/foo.o: type: 1, size: 112, config: 0x9, { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|PERIOD, disabled: 1, inherit: 1, mmap: 1, comm: 1, freq: 1, enable_on_exec: 1, task: 1, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1
> [acme@...icio linux]$ perf evlist
> /tmp/foo.o
> [acme@...icio linux]$
>
> So, type 1 is PERF_TYPE_SOFTWARE, config 0x9 is PERF_COUNT_SW_DUMMY, ok.

You won't see this dummy event after patch 'perf tools: Collect perf_evsel
in BPF object files'. I use dummy event here so we can test basic parsing
and loading before that enabler patch to avoid enable too much code by
one patch.

Thank you, and glad to see you start working on this patch set again!

> And it behaves accordingly, no samples, etc.
>
> Added the sequence of testing with a non-existing file, with a normal ELF file
> and then with a valid eBPF ELF file as committer notes.
>
> Continuing.
>
> - Arnaldo


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