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SubjectRE: [PATCH v4 3/3] perf tools: Add support to new style format of kernel PMU event
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> 
> On Tue, Sep 02, 2014 at 11:29:30AM -0400, kan.liang@intel.com wrote:
> > From: Kan Liang <kan.liang@intel.com>
>
> SNIP
>
> > }
> > +|
> > +PE_KERNEL_PMU_EVENT
> > +{
> > + struct parse_events_evlist *data = _data;
> > + struct list_head *head = malloc(sizeof(*head));
> > + struct parse_events_term *term;
> > + struct list_head *list;
> > +
> > + ABORT_ON(parse_events_term__num(&term,
> PARSE_EVENTS__TERM_TYPE_USER,
> > + $1, 1));
> > + ABORT_ON(!head);
> > + INIT_LIST_HEAD(head);
> > + list_add_tail(&term->list, head);
> > +
> > + ALLOC_LIST(list);
> > + ABORT_ON(parse_events_add_pmu(list, &data->idx, "cpu", head));
> > + parse_events__free_terms(head);
> > + $$ = list;
> > +}
> > +|
> > +PE_PMU_EVENT_PRE '-' PE_PMU_EVENT_SUF
>
> so, how about the event alias has more than 2 parts a-b-c ?
>

Currently, the patch only handle the format for "a-b" or "a". I think it's enough for current usage.
The event alias with more than 2 parts a-b-c are already handled by hardcode in the lexer.
So I don't think we really need to support a-b-c format now.

> if I remove 'stalled-cycles-frontend' from lexer (patch attached), I'll get error
> parsing it with this code:
>
> ---
> [jolsa@krava perf]$ ls -l /sys/devices/cpu/events/stalled-cycles-frontend
> -r--r--r-- 1 root root 4096 Sep 6 21:17 /sys/devices/cpu/events/stalled-
> cycles-frontend
> [jolsa@krava perf]$ ./perf record -e stalled-cycles-frontend ls invalid or
> unsupported event: 'stalled-cycles-frontend'
> Run 'perf list' for a list of valid events
>
> usage: perf record [<options>] [<command>]
> or: perf record [<options>] -- <command> [<options>]
>
> -e, --event <event> event selector. use 'perf list' to list available events
> ---
>
> and.. if we will actually handle this correctly, I think maybe we want to
> remove all the equivalents?

Yes, there will be error if 'stalled-cycles-frontend' from lexer is removed. It's because not only the unsupported a-b-c format but also the middle name cycles. (Cycles could be individual event name or prefix/suffix of many event names. Lexer cannot distinguish them.)
However, why we want to remove it?
The current codes work well. PERF_TYPE_HARDWARE events are seldom changed. So I think it's OK to keep them unchanged.
We only need to handle possible extended events. (Actually, the new PMU events are not frequently added. I think "a-b" format is enough.)

Thanks,
Kan


>
> thanks,
> jirka
>
>
> ---
> diff --git a/tools/perf/util/parse-events.l b/tools/perf/util/parse-events.l
> index 4dd7f0467dd1..c1a354f651ca 100644
> --- a/tools/perf/util/parse-events.l
> +++ b/tools/perf/util/parse-events.l
> @@ -176,8 +176,6 @@ branch_type { return term(yyscanner,
> PARSE_EVENTS__TERM_TYPE_BRANCH_SAMPLE_TYPE
> }
>
> cpu-cycles|cycles { return sym(yyscanner,
> PERF_TYPE_HARDWARE, PERF_COUNT_HW_CPU_CYCLES); }
> -stalled-cycles-frontend|idle-cycles-frontend { return sym(yyscanner,
> PERF_TYPE_HARDWARE, PERF_COUNT_HW_STALLED_CYCLES_FRONTEND); }
> -stalled-cycles-backend|idle-cycles-backend { return sym(yyscanner,
> PERF_TYPE_HARDWARE, PERF_COUNT_HW_STALLED_CYCLES_BACKEND); }
> instructions { return sym(yyscanner,
> PERF_TYPE_HARDWARE, PERF_COUNT_HW_INSTRUCTIONS); }
> cache-references { return sym(yyscanner,
> PERF_TYPE_HARDWARE, PERF_COUNT_HW_CACHE_REFERENCES); }
> cache-misses { return sym(yyscanner,
> PERF_TYPE_HARDWARE, PERF_COUNT_HW_CACHE_MISSES); }


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