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perf tools: Let a user specify a PMU event without any config terms

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This enables a PMU event to be specified in the form:

	pmu//

which is effectively the same as:

	pmu/config=0/

This patch is a precursor to defining default config for a PMU.

Further explanation extracted from lkml thread:

Imagine that the 'tsc' term did not exist.

Intel PT trace data would not contain TSC packets, and the decoder would
not know how to decode them.

Then imagine that a new version of the hardware adds 'tsc'.

It is such a useful feature that we want it by default, but older
versions of the tools don't know how to decode it, so the kernel cannot
turn it on by default.

It is similar to why the kernel does not select perf_event_attr.mmap2 by
default.

The kernel doesn't know whether the tool supports it.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1408129739-17368-6-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Adrian Hunter 2014-08-15 22:08:40 +03:00 committed by Arnaldo Carvalho de Melo
parent 6997af72e6
commit ad96227349
2 changed files with 16 additions and 0 deletions
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6
tools/perf/util/parse-events.c
View file

@ -645,6 +645,12 @@ int parse_events_add_pmu(struct list_head *list, int *idx,
memset(&attr, 0, sizeof(attr));
if (!head_config) {
attr.type = pmu->type;
evsel = __add_event(list, idx, &attr, NULL, pmu->cpus);
return evsel ? 0 : -ENOMEM;
}
if (perf_pmu__check_alias(pmu, head_config, &unit, &scale))
return -EINVAL;

10
tools/perf/util/parse-events.y
View file

@ -210,6 +210,16 @@ PE_NAME '/' event_config '/'
parse_events__free_terms($3);
$$ = list;
}
|
PE_NAME '/' '/'
{
struct parse_events_evlist *data = _data;
struct list_head *list;
ALLOC_LIST(list);
ABORT_ON(parse_events_add_pmu(list, &data->idx, $1, NULL));
$$ = list;
}
value_sym:
PE_VALUE_SYM_HW