Re: [PATCH v3 12/27] perf parse-events: Support no alias assigned event inside hybrid PMU

Jin, Yao
2021-04-15T14:58:28Z

Hi Jiri,

On 4/15/2021 10:11 PM, Jiri Olsa wrote:
> On Thu, Apr 15, 2021 at 09:36:16PM +0800, Jin, Yao wrote:
>
> SNIP
>
>>>> + int n = 0;
>>>> +
>>>> + list_for_each(pos, list)
>>>> + n++;
>>>> +
>>>> + return n;
>>>> +}
>>>> +
>>>> +static int parse_events__with_hybrid_pmu(struct parse_events_state *parse_state,
>>>> + const char *str, char *pmu_name,
>>>> + bool *found, struct list_head *list)
>>>> +{
>>>> + struct parse_events_state ps = {
>>>> + .list = LIST_HEAD_INIT(ps.list),
>>>> + .stoken = PE_START_EVENTS,
>>>> + .pmu_name = pmu_name,
>>>> + .idx = parse_state->idx,
>>>> + };
>>>
>>> could we add this pmu_name directly to __parse_events?
>>>
>>
>> Do you suggest we directly call __parse_events()?
>>
>> int __parse_events(struct evlist *evlist, const char *str,
>> struct parse_events_error *err, struct perf_pmu *fake_pmu)
>>
>> struct parse_events_state parse_state = {
>> .list = LIST_HEAD_INIT(parse_state.list),
>> .idx = evlist->core.nr_entries,
>> .error = err,
>> .evlist = evlist,
>> .stoken = PE_START_EVENTS,
>> .fake_pmu = fake_pmu,
>> };
>>
>> But for parse_events__with_hybrid_pmu, we don't have valid evlist. So if we
>> switch to __parse_events, evlist processing may be a problem.
>
> you should use parse_state->evlist no? but we can chec/make this
> change in next itaration.. it's already lot of changes
>
> jirka
>

With my current code,

static int parse_events__with_hybrid_pmu(struct parse_events_state *parse_state,
const char *str, char *pmu_name,
struct list_head *list)
{
struct parse_events_state ps = {
.list = LIST_HEAD_INIT(ps.list),
.stoken = PE_START_EVENTS,
.pmu_name = pmu_name,
.idx = parse_state->idx,
};
int ret;

ret = parse_events__scanner(str, &ps);
perf_pmu__parse_cleanup();

if (!ret) {
if (!list_empty(&ps.list)) {
list_splice(&ps.list, list);
parse_state->idx = ps.idx;
}
}

return ret;
}

The new created evsels are added to the tail of list (ps.list) and ps.list is joined to the list
(the parameter 'list').

If we want to reuse the __parse_events(), we may need to:

struct evlist *evlist = evlist__new();

__parse_events(evlist, str, NULL, NULL);
Add the evsels in evlist to the tail of list (the parameter 'list')
evlist__delete(evlist);

Is my understanding correct?

Yes, we have to change the interface of __parse_events() by adding a new parameter 'pmu_name', which
will bring much more changes. I agree to make this change in follow-up patches.

Thanks
Jin Yao