Re: [PATCH v12 13/16] perf record: Extend --threads command line option

[Jiri Olsa <jolsa@redhat.com>]

On Tue, Nov 23, 2021 at 05:08:09PM +0300, Alexey Bayduraev wrote:

SNIP

>  
> +static int record__init_thread_masks_spec(struct record *rec, struct perf_cpu_map *cpus,
> +					  const char **maps_spec, const char **affinity_spec,
> +					  u32 nr_spec)
> +{
> +	u32 s;
> +	int ret = 0, t = 0;
> +	struct mmap_cpu_mask cpus_mask;
> +	struct thread_mask thread_mask, full_mask, *prev_masks;
> +
> +	ret = record__mmap_cpu_mask_alloc(&cpus_mask, cpu__max_cpu());
> +	if (ret)
> +		goto out;
> +	record__mmap_cpu_mask_init(&cpus_mask, cpus);
> +	ret = record__thread_mask_alloc(&thread_mask, cpu__max_cpu());
> +	if (ret)
> +		goto out_free_cpu_mask;
> +	ret = record__thread_mask_alloc(&full_mask, cpu__max_cpu());
> +	if (ret)
> +		goto out_free_thread_mask;
> +	record__thread_mask_clear(&full_mask);
> +
> +	for (s = 0; s < nr_spec; s++) {
> +		record__thread_mask_clear(&thread_mask);
> +
> +		record__mmap_cpu_mask_init_spec(&thread_mask.maps, maps_spec[s]);
> +		record__mmap_cpu_mask_init_spec(&thread_mask.affinity, affinity_spec[s]);
> +
> +		if (!bitmap_and(thread_mask.maps.bits, thread_mask.maps.bits,
> +				cpus_mask.bits, thread_mask.maps.nbits) ||
> +		    !bitmap_and(thread_mask.affinity.bits, thread_mask.affinity.bits,
> +				cpus_mask.bits, thread_mask.affinity.nbits))
> +			continue;
> +
> +		ret = record__thread_mask_intersects(&thread_mask, &full_mask);
> +		if (ret)
> +			goto out_free_full_mask;
> +		record__thread_mask_or(&full_mask, &full_mask, &thread_mask);


please put some explanation to comment on the intersection checks,
like what's allowed and what's not.. and also some info about that
to documentation

thanks,
jirka

> +
> +		prev_masks = rec->thread_masks;
> +		rec->thread_masks = realloc(rec->thread_masks,
> +					    (t + 1) * sizeof(struct thread_mask));
> +		if (!rec->thread_masks) {
> +			pr_err("Failed to allocate thread masks\n");
> +			rec->thread_masks = prev_masks;
> +			ret = -ENOMEM;
> +			goto out_free_full_mask;
> +		}
> +		rec->thread_masks[t] = thread_mask;
> +		if (verbose) {
> +			pr_debug("thread_masks[%d]: ", t);
> +			mmap_cpu_mask__scnprintf(&rec->thread_masks[t].maps, "maps");
> +			pr_debug("thread_masks[%d]: ", t);
> +			mmap_cpu_mask__scnprintf(&rec->thread_masks[t].affinity, "affinity");
> +		}
> +		t++;
> +		ret = record__thread_mask_alloc(&thread_mask, cpu__max_cpu());
> +		if (ret)
> +			goto out_free_full_mask;
> +	}

SNIP