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From:   Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Date:   Mon, 2 Sep 2019 10:57:10 -0300
To:     Jiri Olsa <jolsa@kernel.org>
Cc:     lkml <linux-kernel@vger.kernel.org>,
        Ingo Molnar <mingo@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Michael Petlan <mpetlan@redhat.com>,
        Joe Mario <jmario@redhat.com>,
        Kan Liang <kan.liang@linux.intel.com>,
        Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH 2/3] perf tools: Add perf_env__numa_node function
Message-ID: <20190902135710.GB8396@kernel.org>
References: <20190902121255.536-1-jolsa@kernel.org>
 <20190902121255.536-3-jolsa@kernel.org>
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Em Mon, Sep 02, 2019 at 02:12:54PM +0200, Jiri Olsa escreveu:
> To speed up cpu to node lookup, adding perf_env__numa_node
> function, that creates cpu array on the first lookup, that
> holds numa nodes for each stored cpu.
> 
> Link: http://lkml.kernel.org/n/tip-qqwxklhissf3yjyuaszh6480@git.kernel.org
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
>  tools/perf/util/env.c | 35 +++++++++++++++++++++++++++++++++++
>  tools/perf/util/env.h |  6 ++++++
>  2 files changed, 41 insertions(+)
> 
> diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c
> index 3baca06786fb..6385961e45df 100644
> --- a/tools/perf/util/env.c
> +++ b/tools/perf/util/env.c
> @@ -179,6 +179,7 @@ void perf_env__exit(struct perf_env *env)
>  	zfree(&env->sibling_threads);
>  	zfree(&env->pmu_mappings);
>  	zfree(&env->cpu);
> +	zfree(&env->numa_map);
>  
>  	for (i = 0; i < env->nr_numa_nodes; i++)
>  		perf_cpu_map__put(env->numa_nodes[i].map);
> @@ -338,3 +339,37 @@ const char *perf_env__arch(struct perf_env *env)
>  
>  	return normalize_arch(arch_name);
>  }
> +
> +
> +int perf_env__numa_node(struct perf_env *env, int cpu)
> +{
> +	if (!env->nr_numa_map) {
> +		struct numa_node *nn;
> +		int i, nr = 0;
> +
> +		for (i = 0; i < env->nr_numa_nodes; i++) {
> +			nn = &env->numa_nodes[i];
> +			nr = max(nr, perf_cpu_map__max(nn->map));
> +		}
> +
> +		nr++;
> +		env->numa_map = zalloc(nr * sizeof(int));

Why do you use zalloc()...

> +		if (!env->numa_map)
> +			return -1;

Only to right after allocating it set all entries to -1?

That zalloc() should be downgraded to a plain malloc(), right?

The setting to -1 is because we may have holes in the array, right? I
think this deserves a comment here as well.

> +		for (i = 0; i < nr; i++)
> +			env->numa_map[i] = -1;
> +
> +		env->nr_numa_map = nr;
> +
> +		for (i = 0; i < env->nr_numa_nodes; i++) {
> +			int tmp, j;
> +
> +			nn = &env->numa_nodes[i];
> +			perf_cpu_map__for_each_cpu(j, tmp, nn->map)
> +				env->numa_map[j] = i;
> +		}
> +	}
> +
> +	return cpu >= 0 && cpu < env->nr_numa_map ? env->numa_map[cpu] : -1;
> +}
> diff --git a/tools/perf/util/env.h b/tools/perf/util/env.h
> index d8e083d42610..777008f8007a 100644
> --- a/tools/perf/util/env.h
> +++ b/tools/perf/util/env.h
> @@ -86,6 +86,10 @@ struct perf_env {
>  		struct rb_root		btfs;
>  		u32			btfs_cnt;
>  	} bpf_progs;
> +
> +	/* For fast cpu to numa node lookup via perf_env__numa_node */
> +	int			*numa_map;
> +	int			 nr_numa_map;
>  };
>  
>  enum perf_compress_type {
> @@ -118,4 +122,6 @@ struct bpf_prog_info_node *perf_env__find_bpf_prog_info(struct perf_env *env,
>  							__u32 prog_id);
>  void perf_env__insert_btf(struct perf_env *env, struct btf_node *btf_node);
>  struct btf_node *perf_env__find_btf(struct perf_env *env, __u32 btf_id);
> +
> +int perf_env__numa_node(struct perf_env *env, int cpu);
>  #endif /* __PERF_ENV_H */
> -- 
> 2.21.0

-- 

- Arnaldo