From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 567DAC4332F for ; Thu, 17 Nov 2022 20:34:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240575AbiKQUeM (ORCPT ); Thu, 17 Nov 2022 15:34:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36736 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240606AbiKQUeE (ORCPT ); Thu, 17 Nov 2022 15:34:04 -0500 Received: from vps0.lunn.ch (vps0.lunn.ch [156.67.10.101]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2484CDEBE for ; Thu, 17 Nov 2022 12:33:58 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lunn.ch; s=20171124; h=In-Reply-To:Content-Disposition:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:From:Sender:Reply-To:Subject: Date:Message-ID:To:Cc:MIME-Version:Content-Type:Content-Transfer-Encoding: Content-ID:Content-Description:Content-Disposition:In-Reply-To:References; bh=gYFKGLWxfaDIsV9sv+tzomRDBoThosPZ/XulOk/3N3I=; b=loZVncdTnKtkNrxa3K6Saf0dZ7 6SzT8Er+Rm+4SBmPa1/dmXvo6ozHIr/bUFlxtooJUn3fTNqdIKvhwWsQU0NC5cQ1leCPCMxzanHIf TXYoNOPU+wht7RIl9XmPK+iKLZs7v+p1IYGYNYcEX9tRwjapghtVDL44eMNuBtfz2ZnA=; Received: from andrew by vps0.lunn.ch with local (Exim 4.94.2) (envelope-from ) id 1ovla8-002j9A-Hx; Thu, 17 Nov 2022 21:33:56 +0100 Date: Thu, 17 Nov 2022 21:33:56 +0100 From: Andrew Lunn To: Gerhard Engleder Cc: netdev@vger.kernel.org, davem@davemloft.net, kuba@kernel.org, edumazet@google.com, pabeni@redhat.com Subject: Re: [PATCH net-next 1/4] tsnep: Throttle interrupts Message-ID: References: <20221117201440.21183-1-gerhard@engleder-embedded.com> <20221117201440.21183-2-gerhard@engleder-embedded.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221117201440.21183-2-gerhard@engleder-embedded.com> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, Nov 17, 2022 at 09:14:37PM +0100, Gerhard Engleder wrote: > Without interrupt throttling, iperf server mode generates a CPU load of > 100% (A53 1.2GHz). Also the throughput suffers with less than 900Mbit/s > on a 1Gbit/s link. The reason is a high interrupt load with interrupts > every ~20us. Not my area of expertise, but is NAPI working correctly? It should be that you disable interrupts while NAPI is polling, and only re-enable interrupts when polling has stopped. If you are receiving at near line rate at 100% load, i would of thought that NAPI would be polling most of the time and interrupts would be mostly disabled? Interrupt coalescence makes a lot of sense thought, so the patch itself is useful. Andrew