linux-kernel - Re: [PATCH v2 4/4] sock: Remove redundant cond of memcg pressure

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Message-ID: <ZGtmH/0ytVZkkmCP@corigine.com>
Date:   Mon, 22 May 2023 14:54:55 +0200
From:   Simon Horman <simon.horman@...igine.com>
To:     Abel Wu <wuyun.abel@...edance.com>
Cc:     "David S . Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Glauber Costa <glommer@...allels.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 4/4] sock: Remove redundant cond of memcg pressure

On Mon, May 22, 2023 at 03:01:22PM +0800, Abel Wu wrote:
> Now with the preivous patch, __sk_mem_raise_allocated() considers

nit: s/preivous/previous/

> the memory pressure of both global and the socket's memcg on a func-
> wide level, making the condition of memcg's pressure in question
> redundant.
> 
> Signed-off-by: Abel Wu <wuyun.abel@...edance.com>
> ---
>  net/core/sock.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/net/core/sock.c b/net/core/sock.c
> index 7641d64293af..baccbb58a11a 100644
> --- a/net/core/sock.c
> +++ b/net/core/sock.c
> @@ -3029,9 +3029,14 @@ int __sk_mem_raise_allocated(struct sock *sk, int size, int amt, int kind)
>  	if (sk_has_memory_pressure(sk)) {
>  		u64 alloc;
>  
> -		if (!sk_under_memory_pressure(sk))
> +		if (!sk_under_global_memory_pressure(sk))
>  			return 1;
>  		alloc = sk_sockets_allocated_read_positive(sk);
> +		/*
> +		 * If under global pressure, allow the sockets that are below
> +		 * average memory usage to raise, trying to be fair among all
> +		 * the sockets under global constrains.
> +		 */

nit:
		/* Multi-line comments in networking code
		 * look like this.
		 */

>  		if (sk_prot_mem_limits(sk, 2) > alloc *
>  		    sk_mem_pages(sk->sk_wmem_queued +
>  				 atomic_read(&sk->sk_rmem_alloc) +
> -- 
> 2.37.3
> 
>