From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f44.google.com (mail-wm1-f44.google.com [209.85.128.44]) (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 1CCE1280CFB; Fri, 8 Aug 2025 14:53:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.44 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754664816; cv=none; b=Ywg1kKg3Fo40Ce9BPcTb2Ao+A/P1qXsLRZNP+kaVuHuUXENm90++YKp0ViDoiSYYCk/A5+wuuVF8fAD5CNflTscQZ31+cCGMvogBiNJqAj62FsCn5494F55qrKW/WbmzFIZRhNHsT3g77OLSFfcj3zUKqSqzyQfHJOw6wHNzIB8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754664816; c=relaxed/simple; bh=HrrAxyj61SLnsN3GJ6LjWToWuINFN/Kn5UpaU740itM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kDkZT7zuUyFlhnnodPq6TQTLFyNsfn62Oemdk5SjdD/XpIRXIXE0nQ3GSncKzqmkFD9LzdmsTPePk82HEReo9arvbPsZQkPavo1dPXjhRH2UXfezEKkvZL4X/J+njeQE5mVzppQm2DxI0JtL3cR2oFTIWH/lQbpWJ5x7hPuAj3E= 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=Bioy5tLK; arc=none smtp.client-ip=209.85.128.44 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="Bioy5tLK" Received: by mail-wm1-f44.google.com with SMTP id 5b1f17b1804b1-45994a72356so17481565e9.0; Fri, 08 Aug 2025 07:53:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1754664813; x=1755269613; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=hBAG0Fay451JgNwYj7hM+/kGoelDE4FVCawIWFGrRP8=; b=Bioy5tLK0G+/ooEjmnwi7W1RylWvm6Li1FC9I2Mag8RcAyleAQ1e1dm2etL77/Bx6X Cnf0M63Dt5ipOtKcUDyvNvJiQvsKCMibrz3jYxhzXQkFZ4HpD1he3YZvRIffz05XrlRi SZDA01JDNyJZBW0c8Pc9Nix88iHKVPpLNQPJXABpunrR4NHx9UsiLcHgsLAhocLkUiPF OZAhq3s37OysiC3t7nMqcgT7BfDFy4RzMjdsTjyRHqm73vkq+HhWOK6Pem167vXO++2X vp7TOMhMbffYOxNJeF/XortxyAietivcvODaSMtDkkry0RqpfeGHkw8uykL5YoJmT6JA VImw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1754664813; x=1755269613; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=hBAG0Fay451JgNwYj7hM+/kGoelDE4FVCawIWFGrRP8=; b=lMfpG8xO0d9GOfPRcTlFiyMkVUxKCirsfWWoFyztrCXqbSHnn6H3nzr0fNca/ByCNn NaCsQrrEzp2tTEVypHoJ/ubBngakp+q4k41UZ05RaW+NYDsiAf/tiCz6rQ0oJaSKK94j JieOrvpqhuZGHtgm7G8QZ7mEtkn/H1EoQkrJ/U18PKwhKRu4I0I4c5EEaS69bRpjalWJ cSiji6DMcZCilyyqzIz2gtM0oQjMqolYHXwsG/TKfwtLM7pZg5ZmzwCOxpIYQFCqd1K6 6WXwS7u9IdGAKfEUwkj/gr5m3xkEALHks4Sk9Z2GQZsSGf9URzcM/2/W+tsI4WRj2Yrg jMyQ== X-Forwarded-Encrypted: i=1; AJvYcCUTqetzokDus/Tcbshq1uVCh8bjXMzxniNXRr8HnVRPThlMxv7sK+dLvJC/Kp7omAL2XnbIMLwu@vger.kernel.org, AJvYcCXYeAPqFHVcOZVquhcHI5H8NaugvaMDJ30pTqdQyE1aTsiBjaBW4tDeINe1Z83GE0ZqGfmP009UruPjRoU=@vger.kernel.org X-Gm-Message-State: AOJu0YzrBM5JOOiwjyLP4sWTXtpaZaCl6AI/JcekiT0wbB7xEXKTd5eN s4U6M2KWi/AwgjveiguuE3w7FcW7bdrdMZQOcTAH+j8UJOYdb9HbhXKc X-Gm-Gg: ASbGncuzGT/S2JMRBHj9MqhJ/EIwcwmzGZtzJdrG6a5nJB7tTEaoogCCFPR5jY9OVJ8 H012mUDXWfgSJ3c7ZYhw/JS4/bgRP5jplKhh8LkrzdaA7W3d5uikXPP+Wefz8gssdHSRAaAlpia RMg4v1p5piM5PBG0hJ7QsuWN5biygsLB3Sq9f6rjTnQyu8c7mLtrLvV9GLSSBcQ7VU0ip+sRoAS +RSQqAlUCJ/HsdoFW54x6/ymvEMcfQdHICti5Qm1hLZDyciQ1fmQnK9K5YSdMZEDkLlb979aHUX XzM2GYFT4EWAf295UvMEXTNObCEC3RvjqLat4ifwJ/clfeM6xQyppyozpqCyM9FsnNtQe7BAnxF StJFOuQ== X-Google-Smtp-Source: AGHT+IGIE/V2TFfwpLX9Kp68vXYpHcqhncYC0VGIT255SexcmlI4pvh7uyxY+NaPTEunv/QmvlvIjA== X-Received: by 2002:a05:600c:a111:b0:459:db88:c4ca with SMTP id 5b1f17b1804b1-459ede6c0aamr65385875e9.3.1754664813325; Fri, 08 Aug 2025 07:53:33 -0700 (PDT) Received: from 127.com ([2620:10d:c092:600::1:a360]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-459e58400f5sm135106725e9.2.2025.08.08.07.53.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 08 Aug 2025 07:53:32 -0700 (PDT) From: Pavel Begunkov To: Jakub Kicinski , netdev@vger.kernel.org Cc: asml.silence@gmail.com, Eric Dumazet , Willem de Bruijn , Paolo Abeni , andrew+netdev@lunn.ch, horms@kernel.org, davem@davemloft.net, sdf@fomichev.me, almasrymina@google.com, dw@davidwei.uk, michael.chan@broadcom.com, dtatulea@nvidia.com, ap420073@gmail.com, linux-kernel@vger.kernel.org Subject: [RFC v2 02/24] docs: ethtool: document that rx_buf_len must control payload lengths Date: Fri, 8 Aug 2025 15:54:25 +0100 Message-ID: <327e21d7afe67bbdf39d01b17aeab76a7d60fad1.1754657711.git.asml.silence@gmail.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Jakub Kicinski Document the semantics of the rx_buf_len ethtool ring param. Clarify its meaning in case of HDS, where driver may have two separate buffer pools. The various zero-copy TCP Rx schemes we have suffer from memory management overhead. Specifically applications aren't too impressed with the number of 4kB buffers they have to juggle. Zero-copy TCP makes most sense with larger memory transfers so using 16kB or 32kB buffers (with the help of HW-GRO) feels more natural. Signed-off-by: Jakub Kicinski Signed-off-by: Pavel Begunkov --- Documentation/networking/ethtool-netlink.rst | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/Documentation/networking/ethtool-netlink.rst b/Documentation/networking/ethtool-netlink.rst index ab20c644af24..cae372f719d1 100644 --- a/Documentation/networking/ethtool-netlink.rst +++ b/Documentation/networking/ethtool-netlink.rst @@ -966,7 +966,6 @@ Kernel checks that requested ring sizes do not exceed limits reported by driver. Driver may impose additional constraints and may not support all attributes. - ``ETHTOOL_A_RINGS_CQE_SIZE`` specifies the completion queue event size. Completion queue events (CQE) are the events posted by NIC to indicate the completion status of a packet when the packet is sent (like send success or @@ -980,6 +979,11 @@ completion queue size can be adjusted in the driver if CQE size is modified. header / data split feature. If a received packet size is larger than this threshold value, header and data will be split. +``ETHTOOL_A_RINGS_RX_BUF_LEN`` controls the size of the buffers driver +uses to receive packets. If the device uses different buffer pools for +headers and payload (due to HDS, HW-GRO etc.) this setting must +control the size of the payload buffers. + CHANNELS_GET ============ -- 2.49.0