Re: [PATCH v3 2/2] perf header: Support HYBRID_CPU_PMU_CAPS feature

[Jiri Olsa]

On Tue, May 11, 2021 at 01:30:03PM +0800, Jin Yao wrote:

SNIP

> diff --git a/tools/perf/Documentation/perf.data-file-format.txt b/tools/perf/Documentation/perf.data-file-format.txt
> index fbee9e580ee4..e6ff8c898ada 100644
> --- a/tools/perf/Documentation/perf.data-file-format.txt
> +++ b/tools/perf/Documentation/perf.data-file-format.txt
> @@ -419,6 +419,22 @@ Example:
>    cpu_core cpu list : 0-15
>    cpu_atom cpu list : 16-23
>  
> +	HEADER_HYBRID_CPU_PMU_CAPS = 31,
> +
> +	A list of hybrid CPU PMU capabilities.
> +
> +struct {
> +	u32 nr_pmu;
> +	struct {
> +		u32 nr_cpu_pmu_caps;
> +		{
> +			char	name[];
> +			char	value[];
> +		} [nr_cpu_pmu_caps];
> +		char pmu_name[];
> +	} [nr_pmu];
> +};

when I saw it's similar to the previous one I thought we could have
one big hybrid feature.. but that would be probably more complex and
we might not be able to reuse the code as much as you did


>  free_value:
> @@ -3142,6 +3208,64 @@ static int process_cpu_pmu_caps(struct feat_fd *ff,
>  	return -1;
>  }
>  
> +static int process_cpu_pmu_caps(struct feat_fd *ff,
> +				void *data __maybe_unused)
> +{
> +	int ret;
> +
> +	ret = process_per_cpu_pmu_caps(ff, &ff->ph->env.nr_cpu_pmu_caps,
> +				       &ff->ph->env.cpu_pmu_caps,
> +				       &ff->ph->env.max_branches);
> +	return ret;

why the 'ret' var? could be just:

   return process_per_cpu_pmu_caps(...

> +}
> +
> +static int process_hybrid_cpu_pmu_caps(struct feat_fd *ff,
> +				       void *data __maybe_unused)
> +{
> +	struct hybrid_cpc_node *nodes;
> +	u32 nr_pmu, i;
> +	int ret;
> +
> +	if (do_read_u32(ff, &nr_pmu))
> +		return -1;
> +
> +	if (!nr_pmu) {
> +		pr_debug("hybrid cpu pmu capabilities not available\n");
> +		return 0;
> +	}
> +
> +	nodes = zalloc(sizeof(*nodes) * nr_pmu);
> +	if (!nodes)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < nr_pmu; i++) {
> +		struct hybrid_cpc_node *n = &nodes[i];
> +
> +		ret = process_per_cpu_pmu_caps(ff, &n->nr_cpu_pmu_caps,
> +					       &n->cpu_pmu_caps,
> +					       &n->max_branches);
> +		if (ret)
> +			goto err;
> +
> +		n->pmu_name = do_read_string(ff);
> +		if (!n->pmu_name)

should you set 'ret = -1' in here?

other than this both patches look good to me

thanks,
jirka

> +			goto err;
> +	}
> +
> +	ff->ph->env.nr_hybrid_cpc_nodes = nr_pmu;
> +	ff->ph->env.hybrid_cpc_nodes = nodes;
> +	return 0;
> +
> +err:
> +	for (i = 0; i < nr_pmu; i++) {
> +		free(nodes[i].cpu_pmu_caps);

SNIP