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SubjectRe: [PATCH] perf script: Skip dummy event attr check
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Hi,

On 9/1/2022 12:23 AM, Arnaldo Carvalho de Melo wrote:
> Em Wed, Aug 31, 2022 at 09:02:46AM -0700, Ian Rogers escreveu:
>> On Wed, Aug 31, 2022 at 5:40 AM Jiri Olsa <jolsa@kernel.org> wrote:
>>>
>>> Hongtao Yu reported problem when displaying uregs in perf script
>>> for system wide perf.data:
>>>
>>> # perf script -F uregs | head -10
>>> Samples for 'dummy:HG' event do not have UREGS attribute set. Cannot print 'uregs' field.
>>>
>>> The problem is the extra dummy event added for system wide,
>>> which does not have proper sample_type setup.
>>>
>>> Skipping attr check completely for dummy event as suggested
>>> by Namhyung, because it does not have any samples anyway.
>>>
>>> Reported-by: Hongtao Yu <hoy@fb.com>
>>> Suggested-by: Namhyung Kim <namhyung@kernel.org>
>>> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
>>
>> Acked-by: Ian Rogers <irogers@google.com>
>
> Thanks, applied to perf/urgent.
>
> - Arnaldo

I have met a similar issue on hybrid systems such as ADL, I apply the
patch, and it works OK for the normal mode.
# ./perf record --intr-regs=di,r8,dx,cx -e
br_inst_retired.near_call:p -c 1000 --per-thread true
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.024 MB perf.data (25 samples) ]

# ./perf script -F iregs |head -5
ABI:2 CX:0xffff90e19d024ed8 DX:0x1 DI:0xffff90e19d024ed8
R8:0xffffba5e437e7b30
ABI:2 CX:0x7f5239783000 DX:0x80000000 DI:0xffff90e1801eea00
R8:0x71
ABI:2 CX:0x40 DX:0x60 DI:0xffffffff9fde5ab8 R8:0x40
ABI:2 CX:0x0 DX:0xffffffffffffffff DI:0xffff90e1877408e8
R8:0x1
ABI:2 CX:0xcc0 DX:0x1 DI:0xffff90e187d17c60 R8:0x40

But the issue still happened when running the test in the pipe mode. In
the pipe mode, it calls process_attr() which still checks the attr for
the dummy event, so the issue happened.

# ./perf record -o - --intr-regs=di,r8,dx,cx -e
br_inst_retired.near_call:p -c 1000 --per-thread true 2>/dev/null|./perf
script -F iregs |head -5
Samples for 'dummy:HG' event do not have IREGS attribute set. Cannot
print 'iregs' field.
0x120 [0x90]: failed to process type: 64

I have one test patch which can fix the pipe mode issue.

./perf record -o - --intr-regs=di,r8,dx,cx -e
br_inst_retired.near_call:p -c 1000 --per-thread true 2>/dev/null|./perf
script -F iregs |head -5
ABI:2 CX:0xffff90e18119e278 DX:0x0 DI:0xffff90e18119f858
R8:0xffff90e18119e278
ABI:2 CX:0x0 DX:0x1 DI:0xfffffa2844a91580 R8:0x402
ABI:2 CX:0x0 DX:0x0 DI:0x100cca R8:0x0
ABI:2 CX:0x0 DX:0x0 DI:0xffffffff9e997ca5 R8:0x0
ABI:2 CX:0x113ce8000 DX:0xffff90e198f46600
DI:0xffff90e189de8000 R8:0x290


Fixes: b91e5492f9d7 ("perf record: Add a dummy event on hybrid systems
to collect metadata records")
Signed-off-by: Zhengjun Xing <zhengjun.xing@linux.intel.com>
---
tools/perf/builtin-script.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 9152e3e45b69..2d863cdb19fe 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -2429,6 +2429,8 @@ static int process_attr(struct perf_tool *tool,
union perf_event *event,
}

if (evsel->core.attr.sample_type) {
+ if (evsel__is_dummy_event(evsel))
+ return 0;
err = evsel__check_attr(evsel, scr->session);
if (err)
return err;
--
2.25.1
--
Zhengjun Xing

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