linux-kernel - Re: [patch] mm, slab: periodically resched in drain

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Message-ID: <7fb9b7cc-5c07-4b30-fa5e-6146b402f73f@suse.cz>
Date:   Mon, 2 Jan 2023 09:32:15 +0100
From:   Vlastimil Babka <vbabka@...e.cz>
To:     David Rientjes <rientjes@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        Joonsoo Kim <iamjoonsoo.kim@....com>
Cc:     Roman Gushchin <roman.gushchin@...ux.dev>,
        Hyeonggon Yoo <42.hyeyoo@...il.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [patch] mm, slab: periodically resched in drain_freelist()

On 12/28/22 07:05, David Rientjes wrote:
> drain_freelist() can be called with a very large number of slabs to free,
> such as for kmem_cache_shrink(), or depending on various settings of the
> slab cache when doing periodic reaping.
> 
> If there is a potentially long list of slabs to drain, periodically
> schedule to ensure we aren't saturating the cpu for too long.
> 
> Signed-off-by: David Rientjes <rientjes@...gle.com>

Thanks, added to slab/for-6.2-rc3/fixes

> ---
>  mm/slab.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/mm/slab.c b/mm/slab.c
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -2211,6 +2211,8 @@ static int drain_freelist(struct kmem_cache *cache,
>  		raw_spin_unlock_irq(&n->list_lock);
>  		slab_destroy(cache, slab);
>  		nr_freed++;
> +
> +		cond_resched();
>  	}
>  out:
>  	return nr_freed;