linux-kernel - Re: [PATCH] net: skbuff: allocate the fclone in the current NUMA node

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Message-ID: <CANn89iJoHDzfYfhcwVvR4m7DiVG-UfFNqm+D1WD-2wjOttk6ew@mail.gmail.com>
Date: Tue, 20 Feb 2024 06:32:15 +0100
From: Eric Dumazet <edumazet@...gle.com>
To: Huang Shijie <shijie@...amperecomputing.com>
Cc: kuba@...nel.org, patches@...erecomputing.com, davem@...emloft.net, 
	horms@...nel.org, ast@...nel.org, dhowells@...hat.com, linyunsheng@...wei.com, 
	aleksander.lobakin@...el.com, linux-kernel@...r.kernel.org, 
	netdev@...r.kernel.org, cl@...amperecomputing.com
Subject: Re: [PATCH] net: skbuff: allocate the fclone in the current NUMA node

On Tue, Feb 20, 2024 at 3:18 AM Huang Shijie
<shijie@...amperecomputing.com> wrote:
>
> The current code passes NUMA_NO_NODE to __alloc_skb(), we found
> it may creates fclone SKB in remote NUMA node.

This is intended (WAI)

What about the NUMA policies of the current thread ?

Has NUMA_NO_NODE behavior changed recently?

What means : "it may creates" ? Please be more specific.

>
> So use numa_node_id() to limit the allocation to current NUMA node.

We prefer the allocation to succeed, instead of failing if the current
NUMA node has no available memory.

Please check:

grep . /sys/devices/system/node/node*/numastat

Are you going to change ~700 uses of  NUMA_NO_NODE in the kernel ?

Just curious.

>
> Signed-off-by: Huang Shijie <shijie@...amperecomputing.com>
> ---
>  include/linux/skbuff.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index 2dde34c29203..ebc42b2604ad 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -1343,7 +1343,7 @@ static inline bool skb_fclone_busy(const struct sock *sk,
>  static inline struct sk_buff *alloc_skb_fclone(unsigned int size,
>                                                gfp_t priority)
>  {
> -       return __alloc_skb(size, priority, SKB_ALLOC_FCLONE, NUMA_NO_NODE);
> +       return __alloc_skb(size, priority, SKB_ALLOC_FCLONE, numa_node_id());
>  }
>
>  struct sk_buff *skb_morph(struct sk_buff *dst, struct sk_buff *src);
> --
> 2.40.1
>