From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f171.google.com (mail-pl1-f171.google.com [209.85.214.171]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DD76B2ECD09; Wed, 16 Jul 2025 21:42:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.171 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752702152; cv=none; b=FGWiBZxyzFhHxpxj9B3119BlkbJkMZ+9PsZcVnQPYwYwI3RitBl60jC4xOF9EkVZKNgDU+R53u0DbC+VGotJIvuB/HI1INEixXdCUxsPpTMoD321w73Q6Eak2OiINKpqjq3Bi/g2p+31FI/Cy2Y1A0+jE+h+S1FvujBp0MOTPE8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752702152; c=relaxed/simple; bh=YC3X17Wf+csd/abWzZ5qjcI79F0DUo2/TywSiQuyw4o=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=GXDDHp8TlJonOV43i2ZCZaP9T917YXtPnQ0vHSMVLF3HAV1sVwMf/BbTD/iwJguIne/e56ZAeD0/iKwRfp4PDgGjPIhKKXQO0vSQcN8TJMa+GsHfB3fhaACouitR+jRPWL/eVv1pQEfkDt2RkzJ66ysKxxO5XutYwSNgis6Odgk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=D2DgX48O; arc=none smtp.client-ip=209.85.214.171 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="D2DgX48O" Received: by mail-pl1-f171.google.com with SMTP id d9443c01a7336-235d6de331fso2887875ad.3; Wed, 16 Jul 2025 14:42:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1752702150; x=1753306950; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=5zk8pfJjm8yU++V7Grl8fR5lNUFOH1+ZINWxCMY+UwQ=; b=D2DgX48Oq9DgEx8iBTz7PZxkP6UGH2Eyj7W5N8JGudPGOegzqL2hLAKXr0nveCOBTw lk07/P3jeZ8nG9eYx+u6cizFE+aOzBHBsP/FjcmmeDj5bWsjf+SC/rOJxPgbvvWyYVPy Epsd/c5XoYrXN40kizKL/2NZh+jWmERJnHR1o801XUxOLvn8OBfHzUphptN/G0rpFiVK +bas8Kb2nFaePEFgio0JK9DeWA4fzb+o3xHI+6hPPAD8Xw9y9S/Ecub/s73H0WVz3lIS wDUxkkaDqvFmohJdtJKx364TvTlVPU7a4XnbU5I+BTb64n3nCbxuu+HQHgjfRzFfdYfz 6xOQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1752702150; x=1753306950; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=5zk8pfJjm8yU++V7Grl8fR5lNUFOH1+ZINWxCMY+UwQ=; b=dXOHOYtE9LtYyRexUuVFmb+sPd7APtyFgjvMbtgvK2NFxABZMHMYSu9uuIpEy1AET7 rQ9LtaEcNB7LPDrkylNCZhOoEEtatiVPOw9U/LTPAgNzi9jswFSE1qjcbKugD1ysXH6B Wm2TNWjN+igYgDTneWLdPfOR1ABo048lgLNpjizTL/jzjogYfMIlqWLy9EC4CChv+BfP D943LqEMmyQD5F92VhwTP/kgvezMxCoWCOhd1DzXF1A+EeGBnRhmyC/ygueiAYLFMwV1 yjdzxPenXuXx2UAG2uJwp7dj+kn0ZWixQR5l/01iZg2xVvxb+/zGGFKxbJ0abtiYXIgp FtTQ== X-Forwarded-Encrypted: i=1; AJvYcCUuGbFEWs+ndmmS0oOkV8FAlCECU53HzTgJAPv6u0rzKtb+rMIZ1E6n8Le+4MAkbTqey6A=@vger.kernel.org, AJvYcCXRj/5OcXGoBcob0fBT1hYGRlmB7GUT8ZJDoNYK+jZK4jkmxva0yudVsXT70DfviZNTdMoaCXOD@vger.kernel.org X-Gm-Message-State: AOJu0YyCueDQtm+OjRoqyLH9sRJk76+KdjpqUMwAXC12tRIJTe/mVoNj 039Is8jmMGoSzl/PNf4+ZfnYf3bGiuUc6/jtsZzIp3BWxPceS7zISxs= X-Gm-Gg: ASbGnctdCvtOKKybs8M5fE17wYof/aGXEcjjSubmS0l22HYJB+kzWX655mxZa4XMCBu SktI6rPRe7N0Pv58U/veHpxPKFLCTfS/HqmIvUHfxOya8hCb6vfgwTefw43mDDyBvB823/rJCq3 dsxywAG7NCxQWIzsY8Ultujeo3iBRO/TrgpZYs+ELJ8kTM+FLWK5UMwL0Sl9HvQsE7IVQofUhbQ /2iAyOGYJh+J/PaPkhpwtg8lKaCq2lq1fYaZvI/lmvRkpqcKrAm7KvaAGoZOxWZUAgXaaTyvMh7 Sj0iFq2SPaLX1zqi3famuzWipJ6mswl0BdPT+6RZfiM/fXtBgc1sE2zNkfwD6MDuIK/7y3x9tmW wH/yR7yG0YegDi9DD1aoRHxBEhJ/L6g96iNiz+zSX7LxVMvvd4AAIzobKvDs= X-Google-Smtp-Source: AGHT+IFE973SAu58kAdtLmrGz3o8tMHbYIvR6pDDPnSLsjIP0CNR/mjTXFZnzFDqirzKm3wyAKUb+g== X-Received: by 2002:a17:903:1249:b0:234:bfcb:5c1d with SMTP id d9443c01a7336-23e2576c215mr72034195ad.40.1752702150069; Wed, 16 Jul 2025 14:42:30 -0700 (PDT) Received: from localhost (c-73-158-218-242.hsd1.ca.comcast.net. [73.158.218.242]) by smtp.gmail.com with UTF8SMTPSA id d9443c01a7336-23de432278csm134783785ad.121.2025.07.16.14.42.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Jul 2025 14:42:29 -0700 (PDT) Date: Wed, 16 Jul 2025 14:42:29 -0700 From: Stanislav Fomichev To: Jason Xing Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, bjorn@kernel.org, magnus.karlsson@intel.com, maciej.fijalkowski@intel.com, jonathan.lemon@gmail.com, sdf@fomichev.me, ast@kernel.org, daniel@iogearbox.net, hawk@kernel.org, john.fastabend@gmail.com, joe@dama.to, willemdebruijn.kernel@gmail.com, bpf@vger.kernel.org, netdev@vger.kernel.org, Jason Xing Subject: Re: [PATCH net-next v2] xsk: skip validating skb list in xmit path Message-ID: References: <20250716122725.6088-1-kerneljasonxing@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20250716122725.6088-1-kerneljasonxing@gmail.com> On 07/16, Jason Xing wrote: > From: Jason Xing > > This patch only does one thing that removes validate_xmit_skb_list() > for xsk. > > For xsk, it's not needed to validate and check the skb in > validate_xmit_skb_list() in copy mode because xsk_build_skb() doesn't > and doesn't need to prepare those requisites to validate. Xsk is just > responsible for delivering raw data from userspace to the driver. > > The __dev_direct_xmit was taken out of af_packet in commit 865b03f21162 > ("dev: packet: make packet_direct_xmit a common function"). And a call > to validate_xmit_skb_list was added in commit 104ba78c9880 ("packet: on > direct_xmit, limit tso and csum to supported devices") to support TSO. > Since we don't support tso/vlan offloads in xsk_build_skb, we can remove > validate_xmit_skb_list for xsk. Skipping numerous checks somehow > contributes to the transmission especially in the extremely hot path. > > Performance-wise, I used './xdpsock -i enp2s0f0np0 -t -S -s 64' to verify > the guess and then measured on the machine with ixgbe driver. It stably > goes up by 5.48%, which can be seen in the shown below: > Before: > sock0@enp2s0f0np0:0 txonly xdp-skb > pps pkts 1.00 > rx 0 0 > tx 1,187,410 3,513,536 > After: > sock0@enp2s0f0np0:0 txonly xdp-skb > pps pkts 1.00 > rx 0 0 > tx 1,252,590 2,459,456 > > This patch also removes total ~4% consumption which can be observed > by perf: > |--2.97%--validate_xmit_skb > | | > | --1.76%--netif_skb_features > | | > | --0.65%--skb_network_protocol > | > |--1.06%--validate_xmit_xfrm > > Signed-off-by: Jason Xing > --- > V2 > Link: https://lore.kernel.org/all/20250713025756.24601-1-kerneljasonxing@gmail.com/ > 1. avoid adding a new flag > 2. add more descriptions from Stan Acked-by: Stanislav Fomichev LGTM, but would be nice if Willem or Magnus can chime in to confirm that it's safe.