Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Tue, 31 Aug 2021 16:16:57 -0300
From:   Arnaldo Carvalho de Melo <acme@kernel.org>
To:     Riccardo Mancini <rickyman7@gmail.com>
Cc:     Ian Rogers <irogers@google.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Jiri Olsa <jolsa@redhat.com>, linux-kernel@vger.kernel.org,
        linux-perf-users@vger.kernel.org
Subject: Re: [RFC PATCH v1 02/37] libperf cpumap: improve max function
Message-ID: <YS6AKamBroQIgG7r@kernel.org>
References: <cover.1629490974.git.rickyman7@gmail.com>
 <fb79f02e7b86ea8044d563adb1e9890c906f982f.1629490974.git.rickyman7@gmail.com>
 <YS55LhhuABId0ag7@kernel.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <YS55LhhuABId0ag7@kernel.org>
Precedence: bulk

Em Tue, Aug 31, 2021 at 03:47:10PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Sat, Aug 21, 2021 at 11:19:08AM +0200, Riccardo Mancini escreveu:
> > >From commit 7074674e7338863e ("perf cpumap: Maintain cpumaps ordered and
> > without dups"), perf_cpu_map elements are sorted in ascending order.
> > 
> > This patch improves the perf_cpu_map__max function by returning the last
> > element.
> > 
> > Signed-off-by: Riccardo Mancini <rickyman7@gmail.com>
> > ---
> >  tools/lib/perf/cpumap.c | 12 ++++--------
> >  1 file changed, 4 insertions(+), 8 deletions(-)
> > 
> > diff --git a/tools/lib/perf/cpumap.c b/tools/lib/perf/cpumap.c
> > index fb633272be3aaed9..80e03b2f0c60cce7 100644
> > --- a/tools/lib/perf/cpumap.c
> > +++ b/tools/lib/perf/cpumap.c
> > @@ -284,14 +284,10 @@ int perf_cpu_map__idx(struct perf_cpu_map *cpus, int cpu)
> >  
> >  int perf_cpu_map__max(struct perf_cpu_map *map)
> >  {
> > -	int i, max = -1;
> > -
> > -	for (i = 0; i < map->nr; i++) {
> > -		if (map->map[i] > max)
> > -			max = map->map[i];
> > -	}
> > -
> > -	return max;
> > +	if (map->nr > 0)
> > +		return map->map[map->nr-1];
> > +	else
> > +		return -1;
> 
> Applying, but adding spaces around the '-',

I ended up with this, ok?

+++ b/tools/lib/perf/cpumap.c
@@ -282,10 +282,8 @@ int perf_cpu_map__idx(struct perf_cpu_map *cpus, int cpu)

 int perf_cpu_map__max(struct perf_cpu_map *map)
 {
-       if (map->nr > 0)
-               return map->map[map->nr-1];
-       else
-               return -1;
+       // cpu_map__trim_new() qsort()s it, cpu_map__default_new() sorts it as well.
+       return map->nr > 0 ? map->map[map->nr - 1] : -1;
 }