Re: [PATCH] perf script: Skip dummy event attr check

[Xing Zhengjun]

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@xxxxxxxxxx> 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@xxxxxx>
> > > Suggested-by: Namhyung Kim <namhyung@xxxxxxxxxx>
> > > Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> >
> > Acked-by: Ian Rogers <irogers@xxxxxxxxxx>
>
> 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@xxxxxxxxxxxxxxx>
---
 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