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SubjectRe: [PATCH v0 23/71] perf evlist: Add perf_evlist__to_front()
Em Wed, Dec 11, 2013 at 02:36:35PM +0200, Alexander Shishkin escreveu:
> From: Adrian Hunter <adrian.hunter@intel.com>

> 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.

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.

- Arnaldo

> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
> ---
> 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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