Hi, Johannes,
Johannes Weiner <hannes@xxxxxxxxxxx> writes:
> +static struct swap_cluster_info *setup_clusters(struct swap_info_struct *p,
> + unsigned char *swap_map)
> +{
> + unsigned long nr_clusters = DIV_ROUND_UP(p->max, SWAPFILE_CLUSTER);
> + unsigned long col = p->cluster_next / SWAPFILE_CLUSTER % SWAP_CLUSTER_COLS;
> + struct swap_cluster_info *cluster_info;
> + unsigned long i, j, k, idx;
> + int cpu, err = -ENOMEM;
> +
> + cluster_info = kvcalloc(nr_clusters, sizeof(*cluster_info), GFP_KERNEL);
> if (!cluster_info)
> - return nr_extents;
> + goto err;
> +
> + for (i = 0; i < nr_clusters; i++)
> + spin_lock_init(&cluster_info[i].lock);
>
> + p->cluster_next_cpu = alloc_percpu(unsigned int);
> + if (!p->cluster_next_cpu)
> + goto err_free;
> +
> + /* Random start position to help with wear leveling */
> + for_each_possible_cpu(cpu)
> + per_cpu(*p->cluster_next_cpu, cpu) =
> + get_random_u32_inclusive(1, p->highest_bit);
> +
> + p->percpu_cluster = alloc_percpu(struct percpu_cluster);
> + if (!p->percpu_cluster)
> + goto err_free;
> +
> + for_each_possible_cpu(cpu) {
> + struct percpu_cluster *cluster;
> +
> + cluster = per_cpu_ptr(p->percpu_cluster, cpu);
> + cluster_set_null(&cluster->index);
> + }
> +
> + /*
> + * Mark unusable pages as unavailable. The clusters aren't
> + * marked free yet, so no list operations are involved yet.
> + */
> + for (i = 0; i < round_up(p->max, SWAPFILE_CLUSTER); i++)
> + if (i >= p->max || swap_map[i] == SWAP_MAP_BAD)
> + inc_cluster_info_page(p, cluster_info, i);
If p->max is large, it seems better to use an loop like below?
for (i = 0; i < swap_header->info.nr_badpages; i++) {
/* check i and inc_cluster_info_page() */
}
in most cases, swap_header->info.nr_badpages should be much smaller than
p->max.
> +
> + cluster_list_init(&p->free_clusters);
> + cluster_list_init(&p->discard_clusters);
>
> /*
> * Reduce false cache line sharing between cluster_info and
> @@ -2994,7 +3019,13 @@ static int setup_swap_map_and_extents(struct swap_info_struct *p,
> idx);
> }
> }
> - return nr_extents;
> +
> + return cluster_info;
> +
> +err_free:
> + kvfree(cluster_info);
> +err:
> + return ERR_PTR(err);
> }
>
[snip]
--
Best Regards,
Huang, Ying
