From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx23lb.world4you.com (mx23lb.world4you.com [81.19.149.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 68BFA3B29D for ; Fri, 18 Nov 2022 01:24:11 -0500 (EST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=engleder-embedded.com; s=dkim11; h=Content-Transfer-Encoding:Content-Type: In-Reply-To:From:References:To:Subject:MIME-Version:Date:Message-ID:Sender: Reply-To:Cc:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=3I3SwrE1ec9Yum6mA/ld4JlVpgmVobKLwcgaFw6IkmQ=; b=c+o4yrj4zvLY4ToK/gSXai1TkJ wILnBSQYzTTd7iBrF6TLXWyUzc8QKYljyVwM69w/fmuv+3/XnETPMQz7xh7EFer4eHPISb1Gl1JaS aGkzpf+RJFExb7vf0R1jkeE0d5OduxJbe3ON+pq0GescSnS2sXm7lv/AHKGPgNmOtNgY=; Received: from [88.117.56.227] (helo=[10.0.0.160]) by mx23lb.world4you.com with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1ovunK-0000XN-3q; Fri, 18 Nov 2022 07:24:10 +0100 Message-ID: <5486a072-c143-d865-8dba-02a8356c9434@engleder-embedded.com> Date: Fri, 18 Nov 2022 07:24:09 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.10.0 Content-Language: en-US To: Dave Taht , libreqos References: <20221117201440.21183-1-gerhard@engleder-embedded.com> From: Gerhard Engleder In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-AV-Do-Run: Yes X-Mailman-Approved-At: Fri, 18 Nov 2022 08:45:10 -0500 Subject: Re: [LibreQoS] Fwd: [PATCH net-next 0/4] tsnep: Throttle irq, rotten pkts, RX buffer alloc and ethtool_get_channels() X-BeenThere: libreqos@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Many ISPs need the kinds of quality shaping cake can do List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 18 Nov 2022 06:24:11 -0000 On 17.11.22 22:02, Dave Taht wrote: > time sensitive networking is a thing. Now less sensitive. At least on > this a53, an interrupt rate of 20us resulted in total cpu usage at a > gbit... > > Taking a 7x hit in latency tho, to reduce the cpu load, strikes me as > a lot. dpdk would just spin-read here, vs a vs xdp. 7x less interrupts does not mean that latency is also 7x higher, but latency will definitely be increased. A balance between CPU load and latency need to be found here. > "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. > > Reduce interrupt load by throttling of interrupts. Interrupt delay is > configured statically to 64us. For iperf server mode the CPU load is > significantly reduced to ~20% and the throughput reaches the maximum of > 941MBit/s. Interrupts are generated every ~140us."