Re: [PATCH v2 9/9] mm: vmalloc: Set nr_nodes/node_size based on CPU-cores

Baoquan He
2023-09-15T13:04:29Z

On 08/29/23 at 10:11am, Uladzislau Rezki (Sony) wrote:
......
> real 1m28.382s
> user 0m0.014s
> sys 0m0.026s
> urezki@pc638:~$
>
> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
> ---
> mm/vmalloc.c | 26 ++++++++++++++++++++++++++
> 1 file changed, 26 insertions(+)

LGTM,

Reviewed-by: Baoquan He <bhe@redhat.com>

>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 9cce012aecdb..08990f630c21 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -796,6 +796,9 @@ struct vmap_node {
> atomic_t fill_in_progress;
> };
>
> +#define MAX_NODES U8_MAX
> +#define MAX_NODE_SIZE SZ_4M
> +
> static struct vmap_node *nodes, snode;
> static __read_mostly unsigned int nr_nodes = 1;
> static __read_mostly unsigned int node_size = 1;
> @@ -4803,11 +4806,24 @@ static void vmap_init_free_space(void)
> }
> }
>
> +static unsigned int calculate_nr_nodes(void)
> +{
> + unsigned int nr_cpus;
> +
> + nr_cpus = num_present_cpus();
> + if (nr_cpus <= 1)
> + nr_cpus = num_possible_cpus();
> +
> + /* Density factor. Two users per a node. */
> + return clamp_t(unsigned int, nr_cpus >> 1, 1, MAX_NODES);
> +}
> +
> static void vmap_init_nodes(void)
> {
> struct vmap_node *vn;
> int i;
>
> + nr_nodes = calculate_nr_nodes();
> nodes = &snode;
>
> if (nr_nodes > 1) {
> @@ -4830,6 +4846,16 @@ static void vmap_init_nodes(void)
> INIT_LIST_HEAD(&vn->free.head);
> spin_lock_init(&vn->free.lock);
> }
> +
> + /*
> + * Scale a node size to number of CPUs. Each power of two
> + * value doubles a node size. A high-threshold limit is set
> + * to 4M.
> + */
> +#if BITS_PER_LONG == 64
> + if (nr_nodes > 1)
> + node_size = min(SZ_64K << fls(num_possible_cpus()), SZ_4M);
> +#endif
> }
>
> void __init vmalloc_init(void)
> --
> 2.30.2
>