From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 782C423EA90; Tue, 13 Jan 2026 01:21:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768267308; cv=none; b=auXtid194nHyVbv/vCleCNK6F+s2BYR2In4pL33YDJdHdPpqkHHz6qAQxp/2HKMKbTJqkpXkArVVaDKMZLSreB8lJSHvi0u4o4NaCp79ePMzQ0jzXbKhjZJRDHHa/mGRj/Sm+Bvh3rWAWMDU/n6V2xYz6btGe5i9IGUX6Lncyfs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768267308; c=relaxed/simple; bh=SAvQgfZ3g0imNFz3RoHhZxQwiYs2ZbrGTmH7ZJbUlM0=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=XYzSAR8TTP5sP5aOb+zXg8q3hivaAziiPQ38VUzWTrbqqOcfR5qyiR4Utb72tDvhWDdrIy4eCCbaj9JT6vhJSvkKfNhpzvx7yOZHYD/c1JfVwBHwF/VTh2xGUuCLFqEk6iAyrNhSl9sQpM46lFzi+4LU5hl5HiLpx22k/QpqamE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=a3Eua3hx; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="a3Eua3hx" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1EB08C116D0; Tue, 13 Jan 2026 01:21:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1768267308; bh=SAvQgfZ3g0imNFz3RoHhZxQwiYs2ZbrGTmH7ZJbUlM0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=a3Eua3hxdTh3Se9uPtpgJAW+DFPwbJZWVPBEUksLrl63oqvSRGvI+EmSZOzqApwMo ugYv/pPUwbObzvOHNTnI0wpsRk1ZJo1e1dv4I4cGKij6yaeeYZKxEJ3RA5thr89FFo lc7w4nLdV5/Yy0r9OILkMgb/yBKaMTAf4iB7zzrO1MU4ab1lRQGHvfcmj4wFBqDN52 gtY6pkjNNkEYiRzufiLSlGsoLf/mi4G/imdhE/8fkxBXsjIWbNAnbZmBlwrZ1y1+qO LLSIMhASUr/q5uaAPj/dGMN8H/PLnGpCcqxp8yE2LtuLmJIJn4kK/GZdCduZKfv7A/ 02OUaS8o3kgNQ== Date: Mon, 12 Jan 2026 17:21:46 -0800 From: Jakub Kicinski To: Haiyang Zhang Cc: Haiyang Zhang , "linux-hyperv@vger.kernel.org" , "netdev@vger.kernel.org" , KY Srinivasan , Wei Liu , Dexuan Cui , Long Li , Andrew Lunn , "David S. Miller" , Eric Dumazet , Paolo Abeni , Konstantin Taranov , Simon Horman , Erni Sri Satya Vennela , Shradha Gupta , Saurabh Sengar , Aditya Garg , Dipayaan Roy , Shiraz Saleem , "linux-kernel@vger.kernel.org" , "linux-rdma@vger.kernel.org" , Paul Rosswurm Subject: Re: [EXTERNAL] Re: [PATCH V2,net-next, 1/2] net: mana: Add support for coalesced RX packets on CQE Message-ID: <20260112172146.04b4a70f@kernel.org> In-Reply-To: References: <1767732407-12389-1-git-send-email-haiyangz@linux.microsoft.com> <1767732407-12389-2-git-send-email-haiyangz@linux.microsoft.com> <20260109175610.0eb69acb@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 12 Jan 2026 21:01:59 +0000 Haiyang Zhang wrote: > > > Our NIC can have up to 4 RX packets on 1 CQE. To support this feature, > > > check and process the type CQE_RX_COALESCED_4. The default setting is > > > disabled, to avoid possible regression on latency. > > > > > > And add ethtool handler to switch this feature. To turn it on, run: > > > ethtool -C rx-frames 4 > > > To turn it off: > > > ethtool -C rx-frames 1 > > > > Exposing just rx frame count, and only two values is quite unusual. > > Please explain in more detail the coalescing logic of the device. > Our NIC device only supports coalescing on RX. And when it's disabled each > RX CQE indicates 1 RX packet; when enabled each RX CQE indicates up to 4 packets. I get that. What is the logic for combining 4 packets into a single completion? How does it work? Your commit message mentions "regression on latency" - what is the bound on that regression?