Re: [PATCH 14/19] mm: Create/affine kswapd to its preferred node

[Michal Hocko <mhocko@suse.com>]

On Tue 17-09-24 00:49:18, Frederic Weisbecker wrote:
> kswapd is dedicated to a specific node. As such it wants to be
> preferrably affine to it, memory and CPUs-wise.
> 
> Use the proper kthread API to achieve that. As a bonus it takes care of
> CPU-hotplug events and CPU-isolation on its behalf.
> 
> Acked-by: Vlastimil Babka <vbabka@suse.cz>
> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>

Acked-by: Michal Hocko <mhocko@suse.com>

> ---
>  mm/vmscan.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index bd489c1af228..00a7f1e92447 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -7139,10 +7139,6 @@ static int kswapd(void *p)
>  	unsigned int highest_zoneidx = MAX_NR_ZONES - 1;
>  	pg_data_t *pgdat = (pg_data_t *)p;
>  	struct task_struct *tsk = current;
> -	const struct cpumask *cpumask = cpumask_of_node(pgdat->node_id);
> -
> -	if (!cpumask_empty(cpumask))
> -		set_cpus_allowed_ptr(tsk, cpumask);
>  
>  	/*
>  	 * Tell the memory management that we're a "memory allocator",
> @@ -7311,13 +7307,15 @@ void __meminit kswapd_run(int nid)
>  
>  	pgdat_kswapd_lock(pgdat);
>  	if (!pgdat->kswapd) {
> -		pgdat->kswapd = kthread_run(kswapd, pgdat, "kswapd%d", nid);
> +		pgdat->kswapd = kthread_create_on_node(kswapd, pgdat, nid, "kswapd%d", nid);
>  		if (IS_ERR(pgdat->kswapd)) {
>  			/* failure at boot is fatal */
>  			pr_err("Failed to start kswapd on node %d，ret=%ld\n",
>  				   nid, PTR_ERR(pgdat->kswapd));
>  			BUG_ON(system_state < SYSTEM_RUNNING);
>  			pgdat->kswapd = NULL;
> +		} else {
> +			wake_up_process(pgdat->kswapd);
>  		}
>  	}
>  	pgdat_kswapd_unlock(pgdat);
> -- 
> 2.46.0

-- 
Michal Hocko
SUSE Labs