Re: [PATCH v0 23/71] perf evlist: Add perf_evlist__to_front()

[Adrian Hunter]

On 11/12/13 21:38, Arnaldo Carvalho de Melo wrote:
> Em Wed, Dec 11, 2013 at 02:36:35PM +0200, Alexander Shishkin escreveu:
>> From: Adrian Hunter <adrian.hunter@xxxxxxxxx>
>  
>> Add a function to move a selected event to the front of the list.
>  
>> This is needed because it is not possible to use the
>> PERF_EVENT_IOC_SET_OUTPUT IOCTL from an Instruction Tracing event to a
>> non-Instruction Tracing event.  Thus the Instruction Tracing event
>> must come first.
> 
> 
> The description doesn't matches what the code is doing, as it is moving
> a _group_, not an event.

OK I will rename it

> 
> Also I wonder if you can't do this more effiently by finding where it
> starts, ends and then doing some more splice like operatins instead of
> moving member by member to a temp list. Setting the (next, prev) fields
> of the various sublists to the right places.
> 
> There is even list_cut_position() already in list.h, used with
> list_move() and list_splice() I think you can do it more efficiently,
> I think.

OK

> 
> - Arnaldo
>  
>> Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
>> ---
>>  tools/perf/util/evlist.c | 17 +++++++++++++++++
>>  tools/perf/util/evlist.h |  3 +++
>>  2 files changed, 20 insertions(+)
>>
>> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
>> index f9dbf5f..93683bc 100644
>> --- a/tools/perf/util/evlist.c
>> +++ b/tools/perf/util/evlist.c
>> @@ -1216,3 +1216,20 @@ int perf_evlist__strerror_open(struct perf_evlist *evlist __maybe_unused,
>>  
>>  	return 0;
>>  }
>> +
>> +void perf_evlist__to_front(struct perf_evlist *evlist,
>> +			   struct perf_evsel *move_evsel)
>> +{
>> +	struct perf_evsel *evsel, *n;
>> +	LIST_HEAD(move);
>> +
>> +	if (move_evsel == perf_evlist__first(evlist))
>> +		return;
>> +
>> +	list_for_each_entry_safe(evsel, n, &evlist->entries, node) {
>> +		if (evsel->leader == move_evsel->leader)
>> +			list_move_tail(&evsel->node, &move);
>> +	}
>> +
>> +	list_splice(&move, &evlist->entries);
>> +}
>> diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
>> index 8a04aae..9f64ede 100644
>> --- a/tools/perf/util/evlist.h
>> +++ b/tools/perf/util/evlist.h
>> @@ -194,5 +194,8 @@ static inline void perf_mmap__write_tail(struct perf_mmap *md,
>>  }
>>  
>>  bool perf_evlist__can_select_event(struct perf_evlist *evlist, const char *str);
>> +void perf_evlist__to_front(struct perf_evlist *evlist,
>> +			   struct perf_evsel *move_evsel);
>> +
>>  
>>  #endif /* __PERF_EVLIST_H */
>> -- 
>> 1.8.5.1
> 
> 

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