linux-kernel - Re: [PATCH RFC V2 03/10] petf tools: using comm_str to replace comm in hist

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Date:   Mon, 18 Sep 2017 10:38:23 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Frédéric Weisbecker <fweisbec@...il.com>,
        kan.liang@...el.com, peterz@...radead.org, mingo@...hat.com,
        linux-kernel@...r.kernel.org, jolsa@...nel.org,
        namhyung@...nel.org, adrian.hunter@...el.com,
        lukasz.odzioba@...el.com, ak@...ux.intel.com
Subject: Re: [PATCH RFC V2 03/10] petf tools: using comm_str to replace comm
 in hist_entry

On Wed, Sep 13, 2017 at 12:21:56PM -0300, Arnaldo Carvalho de Melo wrote:
> Em Sun, Sep 10, 2017 at 07:23:16PM -0700, kan.liang@...el.com escreveu:
> > From: Kan Liang <kan.liang@...el.com>
> > 
> > For hist_entry, it only needs comm_str for cmp.
> 
> And thinking a bit more, isn't this even a bug fix, as at the time of
> that sample that was the comm string associated with that thread?
> 
> Frédéric, am I nutz?

I think it's ok, because struct comm holds just one comm string
which is 'correct/accurate' at the time the hist entry is created

this patch just seems to switch comm pointer with comm string pointer,
I'm guessing it's useful in follow up patches

jirka

> 
> - Arnaldo
>  
> > Signed-off-by: Kan Liang <kan.liang@...el.com>
> > ---
> >  tools/perf/util/hist.c | 4 ++--
> >  tools/perf/util/sort.c | 8 ++++----
> >  tools/perf/util/sort.h | 2 +-
> >  3 files changed, 7 insertions(+), 7 deletions(-)
> > 
> > diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
> > index e60d8d8..0f00dd9 100644
> > --- a/tools/perf/util/hist.c
> > +++ b/tools/perf/util/hist.c
> > @@ -587,7 +587,7 @@ __hists__add_entry(struct hists *hists,
> >  	struct namespaces *ns = thread__namespaces(al->thread);
> >  	struct hist_entry entry = {
> >  		.thread	= al->thread,
> > -		.comm = thread__comm(al->thread),
> > +		.comm_str = thread__comm_str(al->thread),
> >  		.cgroup_id = {
> >  			.dev = ns ? ns->link_info[CGROUP_NS_INDEX].dev : 0,
> >  			.ino = ns ? ns->link_info[CGROUP_NS_INDEX].ino : 0,
> > @@ -944,7 +944,7 @@ iter_add_next_cumulative_entry(struct hist_entry_iter *iter,
> >  		.hists = evsel__hists(evsel),
> >  		.cpu = al->cpu,
> >  		.thread = al->thread,
> > -		.comm = thread__comm(al->thread),
> > +		.comm_str = thread__comm_str(al->thread),
> >  		.ip = al->addr,
> >  		.ms = {
> >  			.map = al->map,
> > diff --git a/tools/perf/util/sort.c b/tools/perf/util/sort.c
> > index eb3ab90..99ab411 100644
> > --- a/tools/perf/util/sort.c
> > +++ b/tools/perf/util/sort.c
> > @@ -114,26 +114,26 @@ static int64_t
> >  sort__comm_cmp(struct hist_entry *left, struct hist_entry *right)
> >  {
> >  	/* Compare the addr that should be unique among comm */
> > -	return strcmp(comm__str(right->comm), comm__str(left->comm));
> > +	return strcmp(right->comm_str, left->comm_str);
> >  }
> >  
> >  static int64_t
> >  sort__comm_collapse(struct hist_entry *left, struct hist_entry *right)
> >  {
> >  	/* Compare the addr that should be unique among comm */
> > -	return strcmp(comm__str(right->comm), comm__str(left->comm));
> > +	return strcmp(right->comm_str, left->comm_str);
> >  }
> >  
> >  static int64_t
> >  sort__comm_sort(struct hist_entry *left, struct hist_entry *right)
> >  {
> > -	return strcmp(comm__str(right->comm), comm__str(left->comm));
> > +	return strcmp(right->comm_str, left->comm_str);
> >  }
> >  
> >  static int hist_entry__comm_snprintf(struct hist_entry *he, char *bf,
> >  				     size_t size, unsigned int width)
> >  {
> > -	return repsep_snprintf(bf, size, "%-*.*s", width, width, comm__str(he->comm));
> > +	return repsep_snprintf(bf, size, "%-*.*s", width, width, he->comm_str);
> >  }
> >  
> >  struct sort_entry sort_comm = {
> > diff --git a/tools/perf/util/sort.h b/tools/perf/util/sort.h
> > index f36dc49..861cbe7 100644
> > --- a/tools/perf/util/sort.h
> > +++ b/tools/perf/util/sort.h
> > @@ -96,7 +96,7 @@ struct hist_entry {
> >  	struct he_stat		*stat_acc;
> >  	struct map_symbol	ms;
> >  	struct thread		*thread;
> > -	struct comm		*comm;
> > +	const char		*comm_str;
> >  	struct namespace_id	cgroup_id;
> >  	u64			ip;
> >  	u64			transaction;
> > -- 
> > 2.5.5