From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by dpdk.org (Postfix) with ESMTP id 4CF7CC338 for ; Fri, 5 Jun 2015 22:50:58 +0200 (CEST) Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga103.fm.intel.com with ESMTP; 05 Jun 2015 13:50:57 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.13,560,1427785200"; d="scan'208";a="721567720" Received: from irsmsx154.ger.corp.intel.com ([163.33.192.96]) by fmsmga001.fm.intel.com with ESMTP; 05 Jun 2015 13:50:56 -0700 Received: from irsmsx108.ger.corp.intel.com ([169.254.11.59]) by IRSMSX154.ger.corp.intel.com ([169.254.12.182]) with mapi id 14.03.0224.002; Fri, 5 Jun 2015 21:50:56 +0100 From: "Dumitrescu, Cristian" To: "Yeddula, Avinash" , "dev@dpdk.org" Thread-Topic: 4 Traffic classes per Pipe limitation Thread-Index: AdCfrtt4Sum93oHARSOGVPPSgMROGgAIWncQ Date: Fri, 5 Jun 2015 20:50:55 +0000 Message-ID: <3EB4FA525960D640B5BDFFD6A3D8912632372F7E@IRSMSX108.ger.corp.intel.com> References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [163.33.239.180] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Subject: Re: [dpdk-dev] 4 Traffic classes per Pipe limitation X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 05 Jun 2015 20:50:58 -0000 Hi Avinash, > -----Original Message----- > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Yeddula, Avinash > Sent: Friday, June 5, 2015 6:06 PM > To: dev@dpdk.org > Subject: [dpdk-dev] 4 Traffic classes per Pipe limitation >=20 > Hi, > This is related to the QOS scheduler functionality provided by dpdk. >=20 > I see a limit on the number of traffic classes to be 4. I'm exploring th= e > available options to increase that limit to 8. Yes, there are 4x traffic classes (scheduled in strict priority), but each = traffic class has 4x queues (scheduled using WFQ); for big weight ratios be= tween queues (e.g. 1:4 or 1:8, etc), WFQ becomes very similar to strict pri= ority, a king of strict priority without starvation. So the 16x queues per = pipe can be considered 16x sub-traffic-classes. You might want to watch this video on DPDK QoS: https://youtu.be/_PPklkWGug= s=20 >=20 > This is what I found when I researched on this topic. > The limitation on number's of TC (and pipes) comes from the number of > bits available. Since the QoS code overloads the 32 bit RSS field in > the mbuf there isn't enough bits to a lot. But then again if you add lots > of pipes or subports the memory footprint gets huge. It is not that simple. The number of 4x traffic classes in deeply built int= o the implementation for performance reasons. Increasing the number of bits= allocated to traffic class in mbuf->sched would not help. >=20 > Any more info or suggestions on increasing the limit to 8 ? Yes, look at the 16x pipe queues as 16x (sub)traffic classes. >=20 > Thanks > -Avinash