Re: [PATCH v2 3/3] perf record: adapt affinity to machines with #CPUs > 1K

From: Jiri Olsa
Date: Mon Nov 25 2019 - 04:42:28 EST


On Mon, Nov 25, 2019 at 09:08:57AM +0300, Alexey Budankov wrote:

SNIP

> -static void perf_mmap__setup_affinity_mask(struct mmap *map, struct mmap_params *mp)
> +static int perf_mmap__setup_affinity_mask(struct mmap *map, struct mmap_params *mp)
> {
> - CPU_ZERO(&map->affinity_mask);
> + map->affinity_mask.nbits = cpu__max_cpu();
> + map->affinity_mask.bits = bitmap_alloc(map->affinity_mask.nbits);
> + if (!map->affinity_mask.bits)
> + return -1;
> +
> if (mp->affinity == PERF_AFFINITY_NODE && cpu__max_node() > 1)
> build_node_mask(cpu__get_node(map->core.cpu), &map->affinity_mask);
> else if (mp->affinity == PERF_AFFINITY_CPU)
> - CPU_SET(map->core.cpu, &map->affinity_mask);
> + set_bit(map->core.cpu, map->affinity_mask.bits);
> +
> + return 0;
> }
>
> +#define MASK_SIZE 1023
> int mmap__mmap(struct mmap *map, struct mmap_params *mp, int fd, int cpu)
> {
> + char mask[MASK_SIZE + 1] = {0};

does this need to be initialized?

> +
> if (perf_mmap__mmap(&map->core, &mp->core, fd, cpu)) {
> pr_debug2("failed to mmap perf event ring buffer, error %d\n",
> errno);
> return -1;
> }
>
> - perf_mmap__setup_affinity_mask(map, mp);
> + if (perf_mmap__setup_affinity_mask(map, mp)) {
> + pr_debug2("failed to alloc mmap affinity mask, error %d\n",
> + errno);
> + return -1;
> + }
> + bitmap_scnprintf(map->affinity_mask.bits, map->affinity_mask.nbits, mask, MASK_SIZE);
> + pr_debug2("%p: mmap mask[%ld]: %s\n", map, map->affinity_mask.nbits, mask);

the bitmap_scnprintf could be called only for debug case, right?

if (version >= 2) {
bitmap_scnprintf(map->affinity_mask.bits, map->affinity_mask.nbits, mask, MASK_SIZE);
pr_debug2("%p: mmap mask[%ld]: %s\n", map, map->affinity_mask.nbits, mask);
}

ditto int the record__adjust_affinity function

jirka