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([2a0d:3344:2712:7e10:4d59:d956:544f:d65c]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7f4eef7101asm58756085a.38.2025.08.25.23.33.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 25 Aug 2025 23:33:53 -0700 (PDT) Message-ID: <6e645155-1d2d-4b64-a19a-a6e90a12b684@redhat.com> Date: Tue, 26 Aug 2025 08:33:50 +0200 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next 3/3] net: add new sk->sk_drops1 field To: Eric Dumazet , "David S . Miller" , Jakub Kicinski Cc: Simon Horman , netdev@vger.kernel.org, eric.dumazet@gmail.com, Willem de Bruijn , Kuniyuki Iwashima References: <20250825195947.4073595-1-edumazet@google.com> <20250825195947.4073595-4-edumazet@google.com> Content-Language: en-US From: Paolo Abeni In-Reply-To: <20250825195947.4073595-4-edumazet@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/25/25 9:59 PM, Eric Dumazet wrote: > sk->sk_drops can be heavily contended when > changed from many cpus. > > Instead using too expensive per-cpu data structure, > add a second sk->sk_drops1 field and change > sk_drops_inc() to be NUMA aware. > > This patch adds 64 bytes per socket. I'm wondering: since the main target for dealing with drops are UDP sockets, have you considered adding sk_drops1 to udp_sock, instead? Plus an additional conditional/casting in sk_drops_{read,inc,reset}. That would save some memory also offer the opportunity to use more memory to deal with NUMA hosts. (I had the crazy idea to keep sk_drop on a contended cacheline and use 2 (or more) cacheline aligned fields for udp_sock only). Thanks, Paolo