Re: [tip:perf/urgent] perf evlist: Open event on evsel cpus and threads

[Arnaldo Carvalho de Melo]

Em Thu, Sep 03, 2015 at 07:23:43PM +0300, Adrian Hunter escreveu:
> On 3/09/2015 6:27 p.m., Arnaldo Carvalho de Melo wrote:
> >Em Thu, Sep 03, 2015 at 04:34:24PM +0300, Adrian Hunter escreveu:
> >>On 01/09/15 11:31, tip-bot for Kan Liang wrote:
> >>>Commit-ID:  d988d5ee647861706bc7a391ddbc29429b50f00e
> >>>Gitweb:     http://git.kernel.org/tip/d988d5ee647861706bc7a391ddbc29429b50f00e
> >>>Author:     Kan Liang <kan.liang@xxxxxxxxx>
> >>>AuthorDate: Fri, 21 Aug 2015 02:23:14 -0400
> >>>Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> >>>CommitDate: Mon, 31 Aug 2015 17:28:01 -0300
> >>>
> >>>perf evlist: Open event on evsel cpus and threads
> >>>
> >>>An evsel may have different cpus and threads than the evlist it is in.
> >>>
> >>>Use it's own cpus and threads, when opening the evsel in 'perf record'.
> >>>
> >>>Signed-off-by: Kan Liang <kan.liang@xxxxxxxxx>
> >>>Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> >>>Link: http://lkml.kernel.org/r/1440138194-17001-1-git-send-email-kan.liang@xxxxxxxxx
> >>>Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> >>
> >>Just noticed this breaks Intel PT.  Will have to investigate further.
> >
> >What kind of breakage?
> 
> Can't open the sched_switch event
> 
> >
> >It all should be equivalent to before, its just that it uses
> >evsel->{threads,cpus} while before it was using evlist->{threads,cpus},
> >but that should point to the same thing if that
> >perf_evlist__propagate_maps() method was called, so I assume this is
> >some segfault?
> 
> I think maybe it doesn't consider evsels added later

A-ha, so when using perf_evlist__add() we need to do this, i.e. if
evsel->{threads||cpus} is not set, fill it in with the evlist-> member?
 
> >
> >Something we could catch in a 'test' entry? Even if that required Intel
> >PT hardware that would be something important to have, all this stuff is
> >growing in complexity, we need those tests...
> 
> There is "Test tracking with sched_switch" but you need to expose it
> to the same issue i.e.

Sure, Kan and Jiri were talking about the need to go doing these
changes, Jiri? Kan?

- Arnaldo
 
> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> index d51a520..6aeffdd 100644
> --- a/tools/perf/util/evlist.c
> +++ b/tools/perf/util/evlist.c
> @@ -1433,7 +1433,7 @@ int perf_evlist__open(struct perf_evlist *evlist)
>  	perf_evlist__update_id_pos(evlist);
> 
>  	evlist__for_each(evlist, evsel) {
> -		err = perf_evsel__open(evsel, evlist->cpus, evlist->threads);
> +		err = perf_evsel__open(evsel, evsel->cpus, evsel->threads);
>  		if (err < 0)
>  			goto out_err;
>  	}
> 
> 
> 
> >
> >- Arnaldo
> >
> >>>---
> >>>  tools/perf/builtin-record.c | 2 +-
> >>>  tools/perf/util/evlist.c    | 4 ++++
> >>>  2 files changed, 5 insertions(+), 1 deletion(-)
> >>>
> >>>diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> >>>index a660022..1d14f38 100644
> >>>--- a/tools/perf/builtin-record.c
> >>>+++ b/tools/perf/builtin-record.c
> >>>@@ -279,7 +279,7 @@ static int record__open(struct record *rec)
> >>>
> >>>  	evlist__for_each(evlist, pos) {
> >>>  try_again:
> >>>-		if (perf_evsel__open(pos, evlist->cpus, evlist->threads) < 0) {
> >>>+		if (perf_evsel__open(pos, pos->cpus, pos->threads) < 0) {
> >>>  			if (perf_evsel__fallback(pos, errno, msg, sizeof(msg))) {
> >>>  				if (verbose)
> >>>  					ui__warning("%s\n", msg);
> >>>diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> >>>index 8d00039..d51a520 100644
> >>>--- a/tools/perf/util/evlist.c
> >>>+++ b/tools/perf/util/evlist.c
> >>>@@ -1181,6 +1181,10 @@ int perf_evlist__apply_filters(struct perf_evlist *evlist, struct perf_evsel **e
> >>>  		if (evsel->filter == NULL)
> >>>  			continue;
> >>>
> >>>+		/*
> >>>+		 * filters only work for tracepoint event, which doesn't have cpu limit.
> >>>+		 * So evlist and evsel should always be same.
> >>>+		 */
> >>>  		err = perf_evsel__apply_filter(evsel, ncpus, nthreads, evsel->filter);
> >>>  		if (err) {
> >>>  			*err_evsel = evsel;
> >>>
--
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