From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.10]) (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 A2F0E30FC26 for ; Thu, 5 Mar 2026 09:06:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.10 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772701578; cv=none; b=imt8/TjYaV9NaXPRgrcG/0b3xonbDO9Vdqm/gMOqbhebLT3iPRhwOFsp+3Q8RqB7F8qf38hrM+gBvRb6CobcuymVPVoRi85t2Yp0lNCfLP1rdAUlQ+lSFI1wX/Of4doAoL5eEpD8nEVbEC4B+zokTBc4x27GOSlKgYCj1iwxk7Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772701578; c=relaxed/simple; bh=TPAo2N+ZE9bD65+PlCU4V9OBA/W1OYT3t5+awZA8BH4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=jWyGKXExBREx7wp5iQU2nosW5yGUwBMU6l9mhfMU1tb/XN+xKmbB9T7Jo8wITRv6I7uNTI89Huiq8o1HA4JOpgWQOZHcMTjg4pAdajZmZjXRcMdgYn4u9pfNXRQ+EyARb4Wms2I7ekzGA+eWSRxwAtJ7/87EZAgSHg6mF/v/hEY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=TMYy5MEc; arc=none smtp.client-ip=198.175.65.10 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="TMYy5MEc" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1772701578; x=1804237578; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=TPAo2N+ZE9bD65+PlCU4V9OBA/W1OYT3t5+awZA8BH4=; b=TMYy5MEcgCOISYEqZITzAkdE9100STbI3DhiFaE0nqrU6Mdkrf+kTVuT poCOZR+VJWeR8ZEV8gq+4+ppkZcSe6JU9EKVd27pTwoMnCzLB1PaWd2Gc C0hUgMdSVWOgIv24RLp5n51UZCa2MUzaFQEhdp5oRT0UE45BJGv52+rsq 07UPc9W7k7RAM+GFnDVZxNBO3ytXx02cKHMgqpd+86weR7RG8JoyaFktK OkDnJIM5b/JyPPRL23PPl7+SWJTkj9UrG/L286ft+qCCXcF+6VOEus8Z+ +e9yo9XcWWrdfmlXkVCZpL6K3fjqVMmG0DqZPHLToZ7x4HY6mlYnMThZG g==; X-CSE-ConnectionGUID: 6oApGk8ZRGC6FmkHaKZXTg== X-CSE-MsgGUID: AWm3KxQhTdG3EFV6vebaNg== X-IronPort-AV: E=McAfee;i="6800,10657,11719"; a="91171129" X-IronPort-AV: E=Sophos;i="6.23,325,1770624000"; d="scan'208";a="91171129" Received: from fmviesa001.fm.intel.com ([10.60.135.141]) by orvoesa102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Mar 2026 01:06:17 -0800 X-CSE-ConnectionGUID: MBQ+cH/KT62XBVZD0W0Zxg== X-CSE-MsgGUID: 0D1ncnbzQ9+WE6oMGFBtLg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.23,325,1770624000"; d="scan'208";a="245122572" Received: from black.igk.intel.com ([10.91.253.5]) by fmviesa001.fm.intel.com with ESMTP; 05 Mar 2026 01:06:16 -0800 Received: by black.igk.intel.com (Postfix, from userid 1001) id 9053895; Thu, 05 Mar 2026 10:06:14 +0100 (CET) Date: Thu, 5 Mar 2026 10:06:14 +0100 From: Mika Westerberg To: =?utf-8?B?T2RkYmrDuHJu?= Kvalsund Cc: netdev@vger.kernel.org, Mika Westerberg Subject: Re: thunderbolt_net performance and receive-side-scaling (RSS) Message-ID: <20260305090614.GZ2275908@black.igk.intel.com> References: 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 Content-Transfer-Encoding: 8bit In-Reply-To: Hi, On Thu, Mar 05, 2026 at 09:56:26AM +0100, Oddbjørn Kvalsund wrote: > Hi, > > I am seeing fairly good network performance between a 2018 Dell XPS15 laptop > and a 2021 MacBook using Thunderbolt and the thunderbolt_net driver, with jumbo > frames enabled on both machines (iperf3 results below). However, while iperf3 > is running, one core on the XPS15 is at 100% utilization due to the ksoftirqd > process. This makes me wonder whether additional performance could be achieved > if the load were distributed across multiple cores. > > From what I can tell, this might relate to receive-side scaling (RSS), which > does not appear to be implemented in the thunderbolt_net driver. Would adding > RSS support be worthwhile, or are there architectural limitations that would > make such an optimization ineffective? I'm not familiar with that but feel free to experiment and if you find that it provides better throughput please provide patches :) USB4NET spec can be downloaded from USB-IF, it's part of USB4 spec.