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

["Wangnan (F)" <wangnan0@huawei.com>]

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@felicio 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@felicio linux]$ file /tmp/foo.o
> /tmp/foo.o: ELF 64-bit LSB relocatable, no machine, version 1 (SYSV), not stripped
> [acme@felicio linux]$
>
> And finally:
>
>
> [acme@felicio linux]$ file /tmp/foo.o
> /tmp/foo.o: ELF 64-bit LSB relocatable, no machine, version 1 (SYSV), not stripped
> [acme@felicio 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@felicio 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@felicio linux]$ perf evlist
> /tmp/foo.o
> [acme@felicio 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