From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-vk0-f45.google.com (mail-vk0-f45.google.com [209.85.213.45]) by dpdk.org (Postfix) with ESMTP id 5561329D2 for ; Wed, 24 Feb 2016 01:55:04 +0100 (CET) Received: by mail-vk0-f45.google.com with SMTP id e6so2916428vkh.2 for ; Tue, 23 Feb 2016 16:55:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=qDee3BlDULmYlsXNvVeZMD5k8xp/CemGSoLoLwBzRHQ=; b=Vb1x1rZrmH8MuPU/yYbEoaqmXm1pgXVtC9zBbQrlFeCNdHkM4CuZTBbf+CYLIctZyg WEI8Z3loXZdeHn8137jK7tfD6KE4jaPayGlyuiiNHkwN9u8THcPTFL5tV8nEUH2FFSBd rWG0RkQnD/j6/MxkrtTH1R/ANn9H3s63fkmouFIVUGhNW+jfEKKVt5wIT9E1YWg1iREu lEV+tfujTfFwEVpEPpSVOQ35RdARHbMDEGtaUyTAsxvviXl+rYldYgFIqL5blCAcUgl2 ywQH2Y4oDtu6fIjM1pia6m62T9zqUNRaIwIyskjr/QUluUIDWDsaEkCOMRbyiT3Mc2SM 44dA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:cc:content-type; bh=qDee3BlDULmYlsXNvVeZMD5k8xp/CemGSoLoLwBzRHQ=; b=FZrEQNFND4Fh2aLWlztup4FHqE0/IK6wNDgOAhSdoPo32RkzNgd8+oBp3NlrnsGSvq 03NC/LCRgzDMXs2hu5dfTF+U3FWCY9BkCQuc2NsYntmSO8nMTvyYYFwcpa33vw2oIRaH H7VJ5ArmyIT9XiZwBw47c6ldlB/GXfgEUcku9IqSYzjbYCYU2K8KtimKJD+lNB33nNCE 7lmD6SLuCv1noj6HcdjQsixbaA8fPgUx8a0KGRGPwZjlFPssrYFO8zghNitPsR4cdXp4 tdqRC7Me3l/oaLtPnhu0xE0waw0u106f1k7kF0B3ck/7H2vkxTU7rRHpZYDm4Jlpb6hQ /nig== X-Gm-Message-State: AG10YOQbgbIv8FCAdpkbrpQVk1kS1wiLvOpXM5xRnCwqwOFU8HFX1iQmUn/hlZvsh9//8JcEMtWug1JrbyxH6Q== MIME-Version: 1.0 X-Received: by 10.31.54.207 with SMTP id d198mr31980636vka.119.1456275303733; Tue, 23 Feb 2016 16:55:03 -0800 (PST) Received: by 10.159.32.45 with HTTP; Tue, 23 Feb 2016 16:55:03 -0800 (PST) In-Reply-To: <3EB4FA525960D640B5BDFFD6A3D89126479536FC@IRSMSX108.ger.corp.intel.com> References: <3EB4FA525960D640B5BDFFD6A3D8912647952060@IRSMSX108.ger.corp.intel.com> <3EB4FA525960D640B5BDFFD6A3D89126479536FC@IRSMSX108.ger.corp.intel.com> Date: Tue, 23 Feb 2016 16:55:03 -0800 Message-ID: From: sreenaath vasudevan To: "Dumitrescu, Cristian" Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Content-Filtered-By: Mailman/MimeDel 2.1.15 Cc: "dev@dpdk.org" Subject: Re: [dpdk-dev] DPDK-QoS - link sharing across classes 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: Wed, 24 Feb 2016 00:55:04 -0000 b) In current DPDK QoS implemention, if C1 has un-used b/w would that get used by C0? Or is it only "lower priority class (C3, more specifically) uses the un-used b/w from higher priority classes (C0,C1,C2) ? [Cristian] Due to strict priority, it does not make sense to think about higher priority classes using whatever is not used by low priority classes: If high priority classes have traffic to send, they will always be picked in the detriment of lower ones; when the high priority classes hit their upper limit rate, then they are not allowed to send more, otherwise the upper limit makes no sense. So the bandwidth reuse concept makes sense only for low prio TCs to reuse whatever is not used from high prio TCs. Usually, this is configured by fully provisioning TC0 .. TC2 and setting TC3 to 100% of pipe rate, so TC3 can use its rate plus whatever gets unused by TC0 .. TC2, so TC3 rate is between: 100% - (rate TC0 + rate TC1 + rate TC2) and 100% of pipe rate. As explained above, this can be applicable to e.g TC1 as well when only TC0 and TC1 are actually used. So the answers to your 2 questions are: no/no. >> Sreenaath - Let's say I have two classes TC0 and TC1 each having a single queue. Let's say I give TC0 60% and TC1 100%. So according to DPDK's implementation, TC1 can use 100% of the bandwidth if TC0 is inactive, while TC0 at any time cannot exceed 60%, even if TC1 is inactive. Is that correct ? And since you mentioned that this is strict priority, according to this implementation, high priority traffic cannot use 100% of the bw even if there is no low priority traffic, but low priority traffic can use 100% of the bw if there is no high priority traffic. Is my understanding correct ? This doesn't make sense. On Fri, Feb 19, 2016 at 7:02 AM, Dumitrescu, Cristian < cristian.dumitrescu@intel.com> wrote: > > > > > *From:* sreenaath vasudevan [mailto:sreenaathkv@gmail.com] > *Sent:* Thursday, February 18, 2016 8:01 PM > *To:* Dumitrescu, Cristian > *Cc:* dev@dpdk.org > *Subject:* Re: [dpdk-dev] DPDK-QoS - link sharing across classes > > > > Hi Cristian > > Thanks for detailed response. > > Your solution works so long as I have four queues in my current > implementation. > > [Cristian] Yes, I was relying on you saying you can actually group Q0 and > Q1 together, as well as Q2 and Q3, Q4 and Q5, Q6 and Q7. > > > > Following are the two issues I have now > > 1. I have 8 queues in the current implementation. This means I need to ma= p > the existing 8 queues to two sets of 4 queues across two different classe= s > (C0 and C1) in DPDK-QOs right? The problem with that approach is that que= ue > weights are not relative across classes. Is there a way to work around th= is? > > [Cristian] You can, of course, change to code to implement 8 queues per > pipe traffic class, but this is not going to be a trivial exercise. With > the current implementation unmodified, you could simply map 4 queues to > e.g. TC0 and 4 queues to e.g. TC1, provided that it makes sense to > prioritize the 4 queues of TC0 as higher priority than those 4 queues > mapped to TC1, so basically you are OK with having strict priority (up to > an upper limit) between the 2 sets of 4 queues. > > > > > > 2. B/w redistribution - > a) The moment I map the current implementation's 8 queues across two > different classes (say C0 and C1), would remaining b/w be distributed > across the two classes C0 and C1? Is it true that in the current DPDK-QoS > implementation, unused b/w gets distributed only to the last class C3? > Would not un-used b/w from C0 come to C1? > > [Cristian] With 4 queues mapped to TC0 and 4 queues mapped to TC1, you ca= n > set TC0 rate to X% of pipe rate and TC1 rate to 100% of pipe rate. This i= s > the idea behind strict priority: the sum of TC rates is usually bigger th= an > 100% of pipe rate, but this is fine, as due to strict priority the lowest > priority TC used (which in this case is TC1, not TC3, as you are not usin= g > TC2 and TC3 at all) only gets 100% of the pipe rate when no traffic from > higher priority TCs exists. In this case, the extremes are: (1) TC0 deman= d > is high, so TC0 uses everything up to X%, so TC1 can use a max of (100 = =E2=80=93 > X)% and (2) TC0 demand is zero, in which case TC1 is free to use up to 10= 0% > of pipe rate. So the answers to your 3 questions are: yes/no/yes. > > > > b) In current DPDK QoS implemention, if C1 has un-used b/w would tha= t > get used by C0? Or is it only "lower priority class (C3, more specificall= y) > uses the un-used b/w from higher priority classes (C0,C1,C2) ? > > [Cristian] Due to strict priority, it does not make sense to think about > higher priority classes using whatever is not used by low priority classe= s: > If high priority classes have traffic to send, they will always be picked > in the detriment of lower ones; when the high priority classes hit their > upper limit rate, then they are not allowed to send more, otherwise the > upper limit makes no sense. So the bandwidth reuse concept makes sense on= ly > for low prio TCs to reuse whatever is not used from high prio TCs. Usuall= y, > this is configured by fully provisioning TC0 .. TC2 and setting TC3 to 10= 0% > of pipe rate, so TC3 can use its rate plus whatever gets unused by TC0 .. > TC2, so TC3 rate is between: 100% - (rate TC0 + rate TC1 + rate TC2) and > 100% of pipe rate. As explained above, this can be applicable to e.g TC1 = as > well when only TC0 and TC1 are actually used. So the answers to your 2 > questions are: no/no. > > > > > > On Tue, Feb 16, 2016 at 2:46 PM, Dumitrescu, Cristian < > cristian.dumitrescu@intel.com> wrote: > > > > > -----Original Message----- > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of sreenaath > > vasudevan > > Sent: Tuesday, February 2, 2016 9:09 PM > > To: dev@dpdk.org > > Subject: [dpdk-dev] DPDK-QoS - link sharing across classes > > > > Hi > > I currently have QoS implemented in hardware and I am thinking of using > > DPDK's QoS feature to move it to software. > > Currently in the hardware,Based on the 4 class per pipe and 4 queues pe= r > > class limitation, I was thinking of using 4 classes in DPDK-QoS and > spread > > out the 8 h/w queues across the 4 classes. > > Let me explain with an example. Currently, this is how the h/w queue is > > represented > > Q0 - 10% b/w > > Q1- 10% b/w > > Q2- 15% b/w > > Q3 - 15% b/w > > Q4 - 15% b/w > > Q5 - 15% b/w > > Q6 - 10% b/w > > Q7 - 10% b/w > > > > Translating the above config to DPDK-QoS, based on my application need, > Q0 > > and Q1 can be logically grouped under class0 with upper b/w =3D 20%; Q2= , > Q3, > > Q4, Q5 can be logically grouped under class2 with upper b/w =3D 60%; Q6= and > > Q7 can be logically grouped under class 3 with super b/w =3D 20%. > > > > However, in the h/w, link sharing is available across all the 8 queues. > > DPDK materials say link sharing "typically" is enabled for last class, = in > > this case class2. However, I also want class 1 or class 0 to use the > > remaining bandwidth when class2 does not have any traffic and so on. Ca= n > > this be done in DPDK ? Do we have a concept of min and max b/w guarante= e > > at > > the class level in DPDK-QoS ? > > Your requirements seem to be: > - minimal rate for each class (with rates fully provisioned, i.e. sum of > rate not exceeding 100%) > - avoid b/w waste by redistributing unused b/w to the traffic classes tha= t > currently have traffic according to their relative weights > > In our implementation, traffic classes are scheduled in strict priority > (with upper limit defined, to avoid starvation), so TC0 traffic is always > prioritized for the current pipe over TC1 .. TC3 traffic (as long as > current pipe has TC0 traffic and pipe TC0 rate is not reached). Therefore= , > the traffic class hierarchy level is not going to help you here. > > On the other hand, if you map all your queues/traffic classes to the > queues of one of our pipe traffic classes (it does not matter which one o= f > TC0 .. TC3 you pick, as long as you pick just one), your requirements > become possible, as we have 4 queues per each pipe traffic class, and the= y > are scheduled using weighted fair queuing (byte-level weighted round > robin). Simply map your class0 to our pipe TC0 queue 0 (weight of 20%), > your class2 to our pipe TC0 queue 1 (weight of 60%) and your class3 to ou= r > pipe TC0 queue 2 (weight of 20%), with our pipe TC0 queue 3 unused, which > should work exactly what you need. Makes sense? > > Regards, > Cristian > > > > > > Thanks ! > > > > -- > > regards > > sreenaath > > > > > -- > > regards > sreenaath > --=20 regards sreenaath