Thank you for coming to the Neutron quality of service features and future roadmap talk. I'm Victor Howard. I'm a principal engineer at Comcast Hello, I'm Suavek. I'm working in OVH company as developer operator and developer of OpenStack I'm Miguel Angel Ajo. I work at Red Hat in the Neutron team and I'm going to talk about the first about the agenda that we have for today. We're going to talk a little bit about what we did in in liberty and where QS for Neutron started and What we did in Mitaka and what we planned for Neutron and beyond so during Sorry, let me close that During liberty we built a model for QS in Neutron That it's based in policies and Policies are built by rules at that time. We only had one rule with It was one with limit, but the idea is that you can You can build quality of service policies With rules and then attach those policies to networks If you attach a policy to a network all the ports on that network that belong to instances are going to be configured with the specific Quality of service policy tails if you modify Any rule of the policy those ports Will be updated in in real time and You could also attach specific ports to a specific policy Policies as long as your tenant had access to that policy, or if you are the administrator that That was also a lot so as we go aside In liberty liberty was the first release with quality of service in Neutron It was on there was only one type of rule Available it was egress bandwidth limit It was supported only by ML to plug-in and two of three main L2 agents It was supported by open-v-switch and SR IOV agent. There was no support for Linux breach agent for QoS in liberty Short-remind at the beginning how in Neutron how quality of service works in overall first if you want to use quality of service first you need to create You need to create policy policy is kind of container for rules Second step is to create band rule for example band with limit rule To band with limit rule you need to provide max bandwidth limit value with kilo bits per second and optionally max boost in kilo bits and The third parameter here is policy to which rule should be associated and Last step is to apply this policy with rule with rules to port or network if it's applied to network It will be automatically applied to all ports in this network so on this picture there is let's say in general how open-v-switch is connecting virtual machine to the network and in such case open-v-switch agent will Apply band with limit rule policy by execute by executing two commands on OVS vs CTL tool first command will Apply will configure a band with limit and second command will create a configure boost value if it's provided by user and Now as I said before in Mitaka. We provided also support for in Linux bridge agent for this quality of service rules and Now now I want to tell a little bit more about how it was how it was done so Linux bridge agent is using traffic control mechanism from Linux Directly because for example open-v-switch is also underneath using traffic control, but It's kind of wrapper for TC API in Linux bridge agent. We are using the traffic control directly and We are using Policing on ingress Q disk Q disk is Kind of kind of queue for packets Whenever packets kernel wants to send packets to the network the packets are and Q in this Q disk and Some algorithm is deciding which and how many packets can be sent There is plenty of algorithm available in traffic control for Q disks. There are classless classful algorithm with different configuration options and so on One thing which can be confusing and in fact was for me at the beginning when I started working on it why for when we want to provide support for limiting outgoing traffic we are using ingress ingress Q disk for that an answer is Quite simple. It depends of point of view traffic Which is outgoing from virtual machine from virtual machine point of view is in fact incoming to tap interface From bridge point of view and if we are talking about traffic control in Linux, we need to look on it from bridge perspective that's That's why it's there is this change of directions. Let's say and it's quite important to remember Because I made this mistake and first version was was made in wrong direction. In fact as I said, there is many Q disk algorithm available, but for Policing ingress on ingress Q disk this traffic control is using TBF so token bucket filter Q disk It's one of the simplest classless algorithm how it works In general, there is some kind of bucket which is collecting tokens tokens and are produced by Kernel in each tick There is also Q of packets packets which kernel want to send our and Q in this this line and Packet can be sent to the network Packet if packet want to Will be must be sent to the network it Need to obtain packets Tokens from from this bucket if there is not enough tokens for to send packet packet is waiting in this this line After it can wait after some configured time and after this time packets if they are not sent still they are just dropped The size of this bucket of tokens is defined by parameter called burst It's quite important because to To configure it in proper proper value for this parameter Because if it will be too low Then band with one band with limit will never be achieved. It will be real band with limit will be always lower then wanted one if burst will be too high then too many packets will have available tokens and Real band with limit can be higher than expected Example how Linux bridge agent is applying such rule band with limit rule on host For rule configurating neutron in with command like on this slide Linux bridge agent will execute two commands in TC on TC first command will enable ingress Qdisk and second command will call configure filter to match all protocols and with and policy to with rate given by given in notron API and burst given in Notron API API Third parameter here. It's MTU. It's max Size of packets which can be handled by this filter bigger packets will be will be automatically dropped so Finally, as I said in mitaka quality of service Has got egress band with limit Supported by all three agent open L2 agents from ML to plug-ins open with switch agent SRIV agent and also in which agent now supports band with limit rule at the end I want to say about two let's say side effects which we achieved during working on this Band with limiting for Linux bridge agent first of them was provide support for L2 extension drivers for Linux bridge agent its Mechanism introduced in Liberty also, but it it was supported by open V-switch and SRIV in Liberty now as QoS is implemented as Search driver we need to provide support for these Extensions also for Linux bridge agent and second thing is that we provide also support for Linux bridge agent in full stack tests because there was also tests only for open V-switch Now there are some tests for Linux bridge agent also so new in mitaka is the role-based access control in the Liberty release policies were shared across all tenants What role-based access control allows you to do in mitaka is to assign? Cross policy to a specific project There's also a few things new and neutron that are coming up We're going to talk about DSCP marking rules and ingress bandwidth limiting we wanted to add DSCP markings for Comcast because we We want to prioritize traffic and mark traffic so that certain types of traffic get more attention than others And also for security reasons sometimes we want to only allow certain types of traffic into various spots on the network To implement DSCP marking we modified the Neutron client also we modified the API. This is the Neutron client creating a policy then creating a marking rule and Assigning it to that policy and then assigning the policy to a port This is kind of what happens behind the scenes here a user through the client or through the API will request that a DSCP mark be added Then the OVS driver will send an RPC message to the compute They've received the RPC message then through the OVS agent The the mark is added to the port This is kind of a view of how DSCP sits alongside of the bandwidth marketing band with marking rule So they both both are attached to policy The the rule of the policy can have multiple rules and the policy can also be associated with multiple ports okay, so Another feature that is being working on For Newton actually the one taking it is the dangerous bandwidth limiting we in liberty we introduce the The bandwidth limit rules, but they were all egress because it seemed to be the most common case but in in other cases you can have applications that behave us that the consumers from the network so you may want to limit the amount of bandwidth that they that they consume from the network this is the The the proposal implementation Will probably look like this we have to short out a few details like SRIOV for example as far as we know is not able to to limit on ingress To to the policy now on ingress so we will have to see how to do that another option is to introduce another type of rule, but I Don't know from the usability point of view. I don't like that we'll see and These are other RFes that are Proposal currently for for For QS We have minimum bandwidth support And and I will explain that in more detail, but it's like two parts and we also have Requests for traffic traffic classification rate limiting bilanta villain priority marking and Some more stuff. I will talk more detail in the next slides, but let me start with the minimum bandwidth limit The idea behind minimum bandwidth limit is that if you have Competing data flows in the same hypervisor to start You can Let's see this start point the left bar is one port for an instance in in the supervisor that has 10g interface and Right bar here down is another interface from another instance and This other one is is not pushing packets. So if you have no policy and both Start pushing packets at the same moon, right depending on the protocol, but eventually they Will convert to do something like this if if you Express a minimum bandwidth guarantee on the port a and you say I want this port to have a minimum bandwidth of eight gigabits When they both are pushing packets at the same Rate the port a is going to be prioritized. So this is What happens in the hypervisor, but you cool if if you don't involve a schedule in in this equation You cool End up having ports that have minimum bandwidth guarantees that are that the total sum of them are above the the link bandwidth so you can over subscribe your your hypervisor, so this is an example of three three hypervisors and For instances one has eight Eight gigabit Minimum another one has a seven gigabit Minimum and another one has a three gigabit minimum. So if we start scheduling those We we need to coordinate with the with the novice scheduler to make sure that if we want an Strict bandwidth guarantee they don't always subscribe any hypervisor. So The first one could go to the first node that there's another bandwidth there If we schedule the the next one that has seven gigabit that one can go to to to any of the of the other three nodes and If we schedule the third one that had a requirement of three gigabits It could then go to this node, but it could go to this one because there's still enough bandwidth or it could have landed this one and Finally, I will show the case where But there's an instance with a port with no With no requested guarantee. So this instance could go in in any of them Because it really doesn't matter As long as it doesn't have a minimum bandwidth request One limitation of this is that once From from our point of view is that when the Instances are already scheduled to to a hypervisor. We won't be able to To modify the policy at least for for first for a first for an initial version because if you If The scheduling details and and the amount of resources are in control by Nova We will then know if modifying our policy to to raise Bangwith limit is going to over subscribe and out. So we We should at least prevent adding more minimum bandwidth to to a policy and So, yes, this is what it was saying. We are on working with the with the Nova community and the The work that they are doing in the scheduler with the generic resource pools To introduce a new resource that it will be tracked by the by the scheduler and that new throne will be reporting So this is the proposal about minimum bandwidth guarantees and We have another proposal about traffic class classification this one probably will take Will take more time because some of it it has more moving parts, but The idea is that eventually we could be able to Create rules in a policy that are attached to a to an specific Traffic classifier. So you could put on a higher priority your control traffic in this example is the SSH traffic. So if your Instances overloaded by requests of other types or other types of traffic you will be able to to control it yet and So this is How it will look like in the higher level we have to to sort out the details about how to To do this specific part because it's something that it's shared across different Across different projects and we don't want to implement the same thing in different ways is better to Do it just once From the feedback that I'm having During the summit and we are open to more to more feedback I had this this proposal that I want to discuss upstream of Setting a default Policy for a tenant so when you create your tenant you set up This is your default policy any resource that you create is going to be attached to that policy by default and the Tenant of course will be able to change that policy if it has access to two other policies to that one there's another proposal to to do To talk the priority on the villain packets So instead of doing L3 like the Dstp work does we could do it on level two that could be liberated in your data center for example to to prioritize the traffic at the Tenant level if you are using villain Tagging for providing sorry for tenant networks, but initially the idea is to use it for provider networks and There is another proposal that it's More pluri yet, but we are looking at it is to to limit to have some way to To limit the total external man with that Tenant is is using you can do that now if you Go to your router port and set policies on on the on the router ports But maybe it could be interesting to have some higher level abstraction to do that and not to handle the low-level details and Finally there is another one We are looking at that. It's using the easy and congestive notification to to do things more softer than Policing that's what we are doing now and maybe the detecting a congestion situations or depending on how you set rules to Notify the the other side that you are congested and it has to slow down, but that's still quite blurry and That's it you have the Another presentation about the HCP policing that Colleagues from Comcast did the the last day and you have fell into this presentation and Thank you very much for coming and if you have any questions speak back You are we are really glad to hear thank you for presentation just a question of clarification you mentioned in the first set of slides rate limiting you know between the the guests and Then later in these last sets you were talking about policing and dropping Is your intention to rate limit meaning kind of like a hard fix set and then you start to throw packets away once that once a Once there's congestion or are you talking more about shaping and kind of queuing up that excess Waiting until there's a little space wait. We have different. That's something also that has been mentioned and we will look at it Yeah, currently we are doing policing. It is we are just dropping packets when they are it's the simplest way to do it and Especially we have some technical limitations on the new external to do that because you cannot you can only do it on Bridge egress, but in this case is bridge ingress so Eventually we will get there. I think that the kernel now has support for that, but we have to Keep putting the pieces together So eventually we would be able to to queue instead of Police but the easy and thing is using Protocol that works with a type P level and tcp to notify the other side to slow down Okay, okay second. I'm sorry second second question. You mentioned the complexities of setting these minimum bandwidth limits and the relationship to scheduling in other Resource management models for other types of resource similar There's the idea of been packing that you know as your VMs are being Deployed they're arriving in a certain sequence and that you know as you know the second one shows up You have to deal with what's available at that particular point in time, but then there's an optimization cycle It says hey if we could actually Reorganize based on yeah today. We can actually get a better density or better collection. Yeah. Yeah That's controlled by the Nova scheduler at this point. Yeah, you have those two settings to spread or to pack Do you know if there's work on that on that on that problem? Is there an open? Is there I think proposal or any kind of work being done? You can once that we have I Mean it will work together with the Nova scheduler So I think that that's a setting that you have currently in the Nova scheduler You you can I don't know the details because I don't work too much with that, but I know that you can set it for Packing because maybe you want to optimize your data center and set of nodes that you are not using and say power And so this proposal will kind of just naturally inherit that capability. Yeah, it will go together with with all that I don't know if we'll have something like to spread bang we in particular But okay. Yeah, thank you very much. Thank you So the trade limiting or the bandwidth guarantee is that only on the hypervisor switch or do you actually try and do something with the infrastructure Because your destination could be outside your open stack cloud for instance or even within the cloud But it maybe is doing yeah, and well, so how do you actually make sure that the entire bandwidth is guaranteed from an end-to-end perspective? Yeah, yeah, this is I expected that question Yeah We're we're taking baby steps I think this is the first step is to do it on the hypervisor level at this point in time Neutron doesn't have any knowledge about the architecture of your network. I mean Yeah, it doesn't know the topology of your network, so it's not able to take any decision based on that This is the first baby step then when This works we can look further and see how to how to handle that I Guess that eventually We could be able to do that with the same framework that they are using that they are creating in Nova for the generic resource pools you could maybe specify Resource pools of external traffic or traffic on the switch and make sure that when the Instance is scheduled with a specific amount of minimum traffic that traffic is counted to the Top of rack switch and the other dependent switches or the external connectivity You know we'll have to look at that. Well, the other proposal I had in mind is these are apis and it's a service plug-in architecture Right, why could you not write plugins with the physical infrastructure against these? Minimum bandwidth guarantee and that makes sure that the physical infrastructure that the plug-in can configure does that as well for you Right yeah Eventually you could that you could do that in your plug-in if your plug-in is a way is aware of your topology Yeah, but they do have it will have to integrate also with the Nova scheduling to make sure that that happens Okay, so thanks Yeah, in fact, it was Because we when we compare we had these problems with direction of traffic. It was implemented first Wrong way later. We try to implement it Properly, let's say with this policy and we have some we had some problems with Difference between the same a rule configured for open V-switch agent and applied by open V-switch agent and Linux Bleach agent Finally we found that there is some bug with setting boost value for in open V-switch and That was a reason of real bond with limit difference But this rule is in fact exactly the same it's made exactly the same way like open V-switch is doing that and This In fact, I don't know exactly Yeah, it's a good question I didn't notice it before so maybe we have to look at why we have this or maybe when you set that rule in the In the in the filters you have to just give any priority So if there are other packets that match other filters, they are going to be taken in order So we only have one filter. I think the priority really doesn't matter We have to put any No, no, no, I think it's I Not sure but I think that it's the the priority that the filters are going to be evaluated But I know we will look at it for just in case Yeah, with that with with the with the current model and once that we have the villain The billion priority you will be able to define a policy and set both Do you mean with the with the villain or with yeah, so we maybe we have to document Yeah, thank you. I have two questions about the scheduler Do you have any blueprint aspect already in Nova or are you going to write it from yeah, yeah, there are I then if you go If you go to this link and You go to the Okay, I cannot show it there, but if you go to that link You will find the minimum bandwidth guarantee proposal for Neutron and from that There is a link to the Nova one. Yeah, look for something called a genetic resource pool Okay That's the name for it. Okay. It's it's made not only for this It's made for other use cases like storage and Routed networks. So my second question was do we have to wait for this generic resource full discussion settle in the Nova Yeah, I think that the discussion is quite We just have to wait for the work I think that we can work on the first part that it's Configuring everything on the hypervisor level so that's what we call the best effort Minimum bandwidth guarantee. So if you have you know done within the nick Your guarantees are going to work, but so we have two steps there. So thank you very much for coming


What's up guys, I'm Brian Sacawa you're watching he spoke style and today we are talking about watch winders Watch winders So the biggest question I get on this topic is do I need a watch winder? The answer is that it depends and it honestly depends on you. So what is a watch winder? Well, a watch winder is a device that is used to keep an automatic watch running when it is not being worn Now what is an automatic watch an automatic watch is a watch with a movement that is self-winding now Inside there's an oscillating weight called a rotor and as you wear the watch and move around this causes the rotor to pivot and spin That movement is then transferred to the mainspring of the watch which as a result winds the watch Manual winding watches as the name suggests do not have this mechanism You actually need to physically wind the watch to keep it powered So if you have a manually winding watch a watch winder is not going to help you out at all But if your watch has an automatic movement a watch winder could be for you as the watch winder spins every so often It keeps the rotor moving which keeps the watch wound Now back to the original question Do you need a watch winder as I said? It depends if you are someone who likes to set and forget as they say and Rotate through a few different watches over a week or so a watch winder could be a good idea If you have a perpetual calendar with moon phase that you don't wear all the time I would probably consider you getting a watch winder if you're someone who likes gadgets a watch winder is Definitely a good idea, but if you're someone who likes the actual act of winding and setting your watch Then maybe a watch winder is not for you. So I actually fall into that last category I really love the experience of winding and setting my watch However, I do have one watch that is kind of a pain and time-consuming to set especially if it has not been running for a Couple weeks or so. I'm talking about my Rolex GMT master reference one six seven five This watch has a date window, but it does not have a quick set for the date So in order to change the date, I have to move the hands all the way around the dial to advance it one day So if I'm gonna have to advance it more than like just a few days It really starts to take a good bit of time Which is annoying especially if I want to wear the watch and I'm in a hurry to get out the door So this watch made a watch winder sound like a very good idea to me The watch winder I have here is by Barrington It was generously sent to me by them to try out just to clarify Barrington is not sponsoring this video And this is not a review I just have not had enough experience with other watch winders to kind of put this one in perspective But what I can say is that it does its job and that has made me very happy I went away for a month and I did not bring my GMT master I left it home on the watch winder to kind of try it out and see if it would perform And I can report that it did indeed and now I keep my GMT master on it all of the time It's very beautiful piece. I love the wood and I also want to point out that on the back There are two different knobs here one controls the rotation settings You can set it to go clockwise counterclockwise or to alternate between the two which is what I usually have it set to and the other knob is To control the number of turns per day, so you can have it turn anywhere from 650 To 1,950 times per day You can use batteries, but I would recommend using a power adapter So you don't have to worry about the batteries ever running out And you could connect multiple watch winders together if you want to just so you only have to use one power source So there are other watch winders out there. The ones I am most familiar with are by Wolf Again, I really don't have any experience with Wolf watch winders. So I can't really compare You can also get watch winders that will wind multiple watches at once I've seen two Three four six or even these like ridiculous 24 or 32 count cabinets which retail Anywhere between 18 to 25 thousand dollars Obviously there must be a market for it So in conclusion, I can't answer the question of whether you need a watch winder It's something that is definitely a personal choice and depends a lot on you Um, I'll put links to a few watch winders down below in the description including this one right here by Barrington That I showed you guys here in this video A couple from wolf and I will also try to find some other brands that look decent as well If you guys have recommendations, please leave those down in the comments for the benefit of all If you like this video thumbs up don't forget to subscribe to the channel and until next time. Thanks for watching and stay tailed


Okay, so thanks a lot for inviting me to this conference. I love being in ICDP, I was here for the first time almost 40 years ago, so it tells you something. Okay, now, today what I'm going to discuss is kind of a continuation of a talk by Arinata and bringing it more close to, well, cosmology. So first of all, our goal is to find some inflationary models which feed the data and, well, but then also, we would like to do it in a nice and interesting way, so it should be done in some models which at least for today considered to be most interesting and realistic. And then in addition to that, we would like also to solve a couple of other problems to describe not only inflation, but also dark energy and supersymmetry breaking. It's just when you have something seeming, like seems to work, the appetite grows and you want to get more and more. First of all, about this quadratic inflationary model which was explained as to be newly ruled out, well, practically dead. Okay, so this is however a very, very elegant model which was one of the large family of quadratic inflation models proposed long time ago. And the main idea of this set of models was not that this quadratic, but at the time when it was proposed, the dominant ideology was that inflation appears after the cosmological phase transitions with symmetry restoration at high temperature and the deviation from this paradigm to switch to something like quadratic initial conditions and suddenly have inflation was a very unexpected step. So now, Plank data suggests that this model probably is ruled out, but let's try to, well, to see what is actually necessary and how much should be changed in this model in order to get the coincidence with agreement with the data. And what is interesting, this is Plank results and pay attention to these two yellow lines, these are so-called alpha tractors. When alpha some parameter is equal to, well, infinity, it gives you M squared for squared model. When alpha becomes smaller and smaller, it comes to describe this point which is sometimes associated with Strabinski model or with Hicks inflation or some, what was surprising during this set of years, the two years after the first day, a large data release of Plank is that we have discovered a very, very large class of models where the property that almost independently on the structure of the potential of the theory, they all in some limit zoom down to this area which fits Plank data very well. So what is the meaning of alpha tractors and alpha tractors is one of the most general and representative, well, families of these cosmological tractors which you found. So we start with M squared by squared and here is the kinetic term and now we want to modify it a little and that is the only modification which is required. You may leave here this M squared by squared, but in this place we have, well, kinetic term for the scalar field. We make a change. So when this parameter alpha is very large, then this term is very small, so no change. When alpha becomes smaller, then what happens is that this field phi exists only when this field phi is small enough and that is something which actually quite often happens in theories like supergravity, but at the moment let's just consider this phenomenologically. What does it mean? Well, the only thing that we did so far, we just changed kinetic terms, kinetic term, but one can always restore from this complicated kinetic term, one can always go to canonical. So you just write equation d phi over this, well, square root of this. So it is equal to d nu phi, so this is the curly phi will be. So in terms of this new field, well, curly phi, you will have normal canonical kinetic term, but the potential will change and the shape of the potential in these new variables looks like that. M squared as before and here comes hyperbolic tanche. So how does it look? Well, this is for different alpha. So when alpha is very large, the shape becomes quadratic as it was before. When alpha is not very large, you have potential which approaches constant and it approaches constant exponentially fast and now these are predictions for this class of models, at least for sufficiently small alpha. What you have is ns equal one minus two divided by n and r is equal to alpha 12 divided by n squared and if we rewind all of this back to this data, this just as a function of alpha give you all of this line. So if you are in this region and this region correspond to alpha about maybe less than 30, well, then you feed all experimental data perfectly and if you compare it with some other models, well, this one, for example, is a very good describing experimental data. This actually is very similar with the potential to new inflation which was again one of the first models. It's just a hilltop model with quartic potential on top and that was essentially new inflation. It feeds data okay, but the motivation of this model is not very clear. And all others, if you consider this five to the end which is like monetary models, they're just going in this direction. Natural inflation goes in that direction but this one cuts straight. It does not tell you that this is the experimental proof for the theory because there are many, many models which can be fit to fit the data but what is the meaning of this attractors? Okay, well, this was done and here is the funny historical fact. When we discovered all of these sort of models, I start looking whether anything like that was ever well discussed before and then I discovered my own beeper with Goncharov of 84 which at that time, of course, we did not know that this is alpha attractor. This looks like a strange model with the potential going to a constant who cares about this and that it was the shape of this potential and it was actually, this was the first example of a chaotic inflation model in supergravity. We tried this, we tried that and then finally we did something and this was this model and then forgot about it. Okay, so now this is Strabinski model. This is another example of the theory which has this exponential potential. In fact, it took quite a lot of time to realize that Strabinski model is a theory with exponential potential. First it was not even written in this way. It was written like R plus, well, some quantum corrections. Then three years later Strabinski have replaced it in this way but he did it in such a way that nobody even noticed the replacement and it is extremely difficult to understand in his papers. Then in 85 in our paper with Kofman and Strabinski we represented it in this way and then independently we have represented it this theory in this way except for he did not know that he is representing Strabinski model because it was not written in that way and then it was identified with Strabinski model in 88. So that's an interesting story, but never mind. Here is the set of predictions for these alpha attractor models. So starting from this, it goes here. This is your original theory and you modify only kinetic terms. If you modify only kinetic terms this is the way how it looks and the potentials are symmetric and we call it T-model because they look like letter T and because it is tunch, okay? But then if you take potential, modify also potential not only this and modify it in a very specific way then for alpha equal one it exactly coincides with Strabinski model also. And if you change parameter alpha the prediction of the model change like that so it also cuts very nicely through the area of observations. Simplest T-models have potential looking like that and that is just tunch and these E-models, E-models which appear in this asymmetric way somehow and they are parameterized by parameter alpha. So then the potentials look this way. Interestingly, there is another set of models which is related to what was done by this author, Berger-Sikoli and Kiveda. It is here, it is called fiber inflation and predicts something which with R just two times larger approximately than the Strabinski model. This is a prediction of this GL model which is my paper with Goncharov. It corresponds strangely to this alpha equal one ninth and it prediction is here for R and it also perfectly fits experimental data with Planck. So now in order to understand what does it mean and why we call it attractors. So the main property of this set of models because of the structure of kinetic terms it is defined only for phi smaller than square root of six alpha. So this is a limit and this is a limit so your modular space is bounded, okay? Now let's draw any arbitrary potential that's a fun of it. They would just draw by hand arbitrary potential which exists in this area and then you turn from these non-canonically normalised variables to canonical and normalised variables. And what happens? It adds small phi, the difference canonical, non-canonical is not important because this term is small but near the boundary when this term becomes close to zero then the change is very large and what happens is that this boundary goes to infinity. This is a relation between phi and tunch of other function. So this boundary goes to infinity and then what does it mean? You take this line and this line, this small segment here is stretched to infinitely large length and that determines your shape of the potential. So what can be shown that independently of what is going on here, the shape of the potential is constant minus certain exponent. And that is why predictions of all of these models are universal because the only thing that needed to have a prediction is what is the derivative and the value of the potential in this place and everything else is subdominant. So that is why you have universality of predictions here. And all of these models have this universal prediction.   So when you have here this yellow place is the desicciter, almost desicciter plateau and then the field slowly rolls in this direction, falls down here, you have the same predictions. If you are here in this place too bad because it's anti-desicciter, the universe rapidly collapses. So in 50% chance you are in one of these desicciter valleys and independently of what was this totally chaotic shape of the potential. It could be really very uneven. Normally you would look at the potential like that you say okay, let me generate a potential for supergravity and random potential typically does not lead to inflation whatsoever. Then suddenly if you have this non-minimal kinetic terms you generate random potential. That's what I did here. I just pushed the button and produced me garbage. But then after expansion you have potential which leads to inflation automatically. So and the same predictions independently of the initial place. And then this theory was even further simplified when it was possible to reduce the wisdom to the following. You take arbitrary potential and you have near the boundary of the model space. This green function, sorry, this kinetic term behaves approximately like that. You have something becoming zero at the minimum and there is second order. And then the rule is that for all of the theories you have asymptotically exponential even you go to canonical variable. You have this kind of potential and you have universal prediction. So this universality is something which buys us. So here is the basic rule. The basic rule is that this spectral index depends on the order of the pole and the tensor to scalar ratio depends on the dcd of the pole. So you have pretty general phenomenological description of many of these models. The question is however can we get it from something reasonable or I'm just postulating it without any reason. So here are several different ways to approach it in super gravity. So these kind of killer potentials in super gravity are very, very often met. And if I make a change of variables I can represent this killer potential in that way. This field S is a second field which is added to the theory. One can write this type of killer potential or this type of killer potential. They all of them eventually lead to have a possibility to lead to these attractors. Now, example of that. Let's consider killer potential of this type and this is one of the way of introducing alpha attractors to the theory. And let's take this super potential which is, I hope you agree, pretty simple. So this is the potential which produces our model with Goncharov with this alpha equal one nine and the potential is shown by this red line. So it fits experimental data very well. Now we want to make the second step and in this very simple model also to explain, well, to describe cosmological constant meaning dark energy and supersymmetry breaking. So this is super potential for the simple model and we are adding here something which everybody who studied phenomenology easily recognize this is Polonia super potential. This is just linear super potential plus a constant. And we know that by tuning parameter here we're tuning constant here. We can tune cosmological constant in the theory. So what you do, you just write down one thing and another thing and then plug it into your mathematical file, push the button and check what happens. And what happens, you reproduce almost exactly the same potential as we had before. So the same experimental data, the same fit to plank but simultaneously you have supersymmetry breaking which is given by M divided by B and B is approximately square root of three. And then you have a vacuum energy in the minimum of the potential which is proportional to the supersymmetry breaking which is kind of interesting. Cosmological constant appears only if you have supersymmetry breaking here. And then this is the difference of two parameters. That's what Renato was talking yesterday. There are two contributions. One of the contributions is coming to minus gravity in a mass squared and another from this term. And what is important that previously when we were studying models like that we were writing terms like that and then we thought, oh, how do we do consistent cosmology with that? Because usually if this M is sufficiently small then it leads to a famous Poloni cosmological problem because lots of energy is stored in oscillating Poloni field and whatever that's the headache for 30 years. Here this field does not appear if it is nil-potent field that has zero energy sitting in its kinetic energy so no cosmological model or problem. Now the general rule how to work with this nil-potent field which you did not describe is that you do all of your calculations as you do previously. So you have killer potential, super potential. You do all your math and only in the end of calculations if everything is consistent though you just put here S equal to zero. So S equal to zero should not even coincide with the naively calculated minimum of your potential as a function of S. You just declare S equal to zero if this field S belongs to the nil-potent chiral multiplet. Okay and what Renate told you about is that these kind of fields they may have some interesting interpretation in terms of string theory. So we got it but we want it to be more beautiful at least in some respects. So one way of making things beautiful is to make them more complicated first. Okay so you take this killer potential and you add some other terms here which look like why did I do so? Okay well apparently if you do so your original symmetries of what Renate was talking about some punk or a disc, et cetera become more manifest in this representation and this theory in this way is equivalent to the theory with original killer potential just with different super potentials. So it's the same thing but we want killer potential to be as precise as possible for describing geometry of space and this one is better describing geometry. Alternatively also when we previously had killer potential the function of t plus t bar if we divided by t t bar then it also have some nice properties. And yet another possibility is to represent t or z as some functions of field phi and then you have very strange looking killer potential and yet it is extremely, it's all equivalent but it is just very convenient for describing what happens here. So some examples. Let's take absolutely basic killer s s bar and super potential square root of lambda s. Now if s is and we are not talking even about attractors because at this time we have just one field and even this field is nilpot and that's what Renate was talking about yesterday about uplifting and deceit or super gravity. So after all math is done you have theory with cosmological constant lambda. No scalars. Now we want to have scalars because in the end we want to have inflation. So we have, this is just an example of the scalar potential and this is super potential, super potential again a function only of the field s. What we have, we have v equal to constant but then we have also this extra field z and z is just a massless field but it is uplifted already. It lives in the center space. So that's how it looks. And now some explanations are in order. This is this manifold which has this boundary which is in fact at infinity in canonical variables but in original it is well this is something which leads to this boundary singularity and this is Poincare disc and this is Escher picture illustrating it. So you have all of these angels and devils and the physical size of each of them is the same everywhere but here more and more and more of them look like they are near the boundary. In fact the physical size is the same it's just original coordinate system is inadequate but it has some interesting symmetry in it. And then you can go one further step and write a slightly more complicated silver potential which is as before s and then multiply it by something which will be responsible for inflation and finally get your potential which is like Tange which is a promised land. So in these variables and I was specifically running mathematical projecting Escher's picture into my m squared potential to make it clear that most angels and devils live at this place here near the top and then if you go to canonical variables that's what you get. So what was the boundary becomes in fact infinite desitor plateau and that is the potential here and it becomes absolutely clear that inflation is practically inevitable here. So you start with whatever initial conditions you fall down to the desitor space and then you slowly roll down to this place and well you get what you get here. Now the question however is whether we can do it with natural initial conditions for inflation in the original m squared by squared model things were relatively simple. You start at the Planckian density and the Planckian density one Planckian domain was already enough for you to start inflation and you do not really care about the rest of the universe. So you study initial conditions in the smallest possible domain of space and if well your potential dominates the energy there then you have inflation. But in this class of models the height of the plateau if you want to satisfy Planck data is approximately 10 orders of magnitude below. So nevertheless what happens is that you start with expanding universe that is a non-trivial condition. You start with an expanding universe and then eventually when the universe continue expanding you do not have any other choice but drop down to this area and then inflate. What is non-trivial here is that if the universe is well closed then it may collapse before you drop that here. So these closed universe essentially do not even exist because they exist only the time 10 to the minus 29 seconds. Therefore there is no observers living there and asking the questions why our universe is so big. But for all parts of the universe which continue expanding they all naturally belong to this area. We can go to slightly more complicated theories and I'm already well must be fast here. So if we study Keller potential like that very similar to your potential just different Keller then we have in our original coordinates we have a potential which looks like a small boat and you wonder where at all I can have inflation there. So I can go to canonical variable with respect to real part of the field Z and what I have first I have this boat with a very, very infinitely actually long valley here but this valley looks like a gorge with increasingly sharp boundaries and you think oh how I can even fit in this direction but then you calculate the invariant mass in this direction and you feel that something is strange because the invariant mass squared you calculated taking into account all non-minimalities of kinetic terms and you see that the curvature here and here is actually going to be constant and then you choose a proper coordinates and in the proper coordinates that's how it looks. So what happens is that you have infinite desiter valley here and then you fall to the desiter valley you oscillate, you relax here and then you slowly roll down here and again you have inflation here and again the potential in this direction is given by this touch it looks more complicated because of the two field case but eventually this second field becomes equal to zero and you have the same touch potential same experimental consequences but then of course why would we trust our intuition if we have so many fields here and the interactions are complicated and the kinetic terms interact with each other so we run simulations and that's what you get you start with whatever value of the field with whatever kinetic energy and I just roll down to the valley and then I start slowly, slowly, slowly moving down towards this minimum so yeah everything seemed to work. Can we start even in this class of models can we start at plunk and density and still have inflation and our original expectation was that no, of course not because we have this steep valley and whatever however interestingly if alpha this parameter okay it's written like A but who cares. Everything else in the talk is right. Okay so if alpha is sufficiently small then the potential in this direction is also smooth it actually not kind of smooth in normal sense it's exponentially growing perpendicular to in float on direction, exponentially growing but it grows with small exponent and if alpha is smaller than one, whatever it is, third yeah then this exponent is small and as a result you can start inflation at whatever density originally and then you slowly, slowly grow so I can start inflation just like in chaotic inflation in this scenario without absolutely M squared by squared scenario without any problem you roll down and then you slowly move down to the minimum so many different ways of solving it and finally I am returning to once again just a different representation of how you in addition to inflation how you explain well the cosmological constant and supersymmetry breaking this is just another example of the super potential with different parameters this parameter tells you what is the inflaton mass scale this parameter tells you what is the gravitino mass scale and S is an important super field so in the end of the calculation I should put here S equals zero and no Poloni field, no anything and then you have description of supersymmetry breaking cosmological constant and inflation all in one model all with one, effectively one scale of field so you have its real part and imaginary part but imaginary part disappears so one scale of field takes care of all of these issues because it has a hidden friend who cares about cosmological constant and then dies so it's very convenient now the conclusion is the following because of the stimulating pressure from observations which we all really appreciate even sometimes it becomes very painful but then in the end you are very happy if you follow the indication from the sky so we were able to discover a new class of theories which have a very strange and interesting properties their prediction are stable with respect to even strong bending of the potential you can have inflation there even if the potential in a regional coordinates really weird and nevertheless you get the same predictions and you can describe dark energy and super breaking there for it actually leads to some change of our paradigm for looking for inflation theory because for 30 years the main goal of observations as applied to inflation theory was to find a cosmological potential which feeds experimental data and now we see that if we change the potential but the theory has this non-minimal minimal kinetic terms it does not change much so what we are looking for what we are studying is the structure of kinetic terms here and the structure of kinetic terms in super gravity is a structure of your Keller manifold so this is the main conclusion the investigation of geometry of space time these are our cosmological observations can tell you possibly hopefully something about geometry of the model space in the underlying physics thank you so much can we really have some embedding consistent compactifications from string theory or it's just super gravity well one thing about nilpotent field it is a part of string theory and there is an ongoing investigation which is pushed even further by Renate Kveda and also by Oranga so they are studying this question right now but this part is okay as for effective super gravity description of cosmological attractors no we do not have it yet anything else can we connect when when the pole in front of a kinetic term so can you give just example in UV theory or because you said modular space when the actually physical intuition of when the pole in front of a kinetic term happens well I don't know about physical intuition but this is the Keller potential look at this it's log one minus z squared and one minus z squared at some moment when z squared becomes equal one the argument of log becomes zero that's the source of the pole if you go back to the simpler original Keller potentials okay let's go all the way here okay this one this potential is well used all the time everywhere there so you know that when t becomes zero you have the same story it's log of zero and when you write down kinetic terms you just get this dt divided by t in that case it's like a radius typically this is a radium radius field is volume field take this form and then in that case volume goes to zero that's kind of the thing I asked also when it goes to infinity there is kind of dual singularity there are one over t okay there's nothing else let's have another again


Hello and welcome to the International Daily Roundup by People's Dispatch, where we bring you major news developments from around the world. Our headlines, teachers in Haiti announced strike to protest increasing gang violence, COVID-19 cases soared in India amid shortages of oxygen and ICU beds, Syrian parliament announced presidential elections to be held in May, and protests in the US following fatal police shooting of 13-year-old Adam Toledo, which is our video section. In our first story, teachers in Haiti are called for a strike from April 19 to 23. These are members of a group of fundamental teachers for renovated education through new and solidarity actions or referents. The call for the strike has been issued to protest against armed gang violence in the country. This follows reports of the murder of a teacher who was on his way to work near the capital Port-au-Prince. At least a dozen people including Catholic clergymen and nuns were also abducted on April 11. References demanded that the government put adequate security measures in place. The strike action starting Monday will affect classes in national schools. Haiti has been witnessing a surge of gang-related kidnappings, extortion rackets and killings. An integrated office in the country recorded 234 reported cases of kidnapping in 2020. It also noted a 20% increase in reported killings. UNICEF reported that there had been an increase in women and children over victims of violence attributed to gangs. Between September 2020 and February 2021, the numbers increased from 45 to 73. According to the Haitian Brigade for the Protection of Miners, at least 31 children were abducted between 2020 and 2021. Other forms of attack have also included rape and murder. At least 13 people were killed in Belar between March 31 and April 1. According to local reports, the attacks were carried out by the G9 and Spitfire gangs in the attempt to take over the neighborhood. As reported by the Haitian Times, residents stated that police forces did not report to the scene. Activists have also claimed that the government has ordered police forces not to respond to such threats. Protests have been taking place across Haiti for the past several months and response to moves by the president Joanal Moyes to unconstitutionally extend his mandate in office. People across all sectors in the country have demanded his immediate resignation and the introduction of a transitional government to address the pressing political institutional crisis in the country and to take measures to address violence and insecurity. We now go to India, which recorded over 273,000 new cases of COVID-19 in the span of 24 hours. The Health Ministry also reported over 1,600 deaths as of the morning of April 19. Ten states including Delhi and Maharashtra have accounted for over 78% of the new cases. The national COVID recovery rate has also dropped to 86%. India has been witnessing consistent record surges during the second wave. Doctors have also stated that this wave is characterized by greater transferability of the virus. There is also a higher requirement for oxygen in the country. As cases grow, several hospitals have reported severe shortages of oxygen supplies and ICU beds. A news organization's scroll has revealed that several oxygen generation plants commissioned by the government have not been set up. The government had floated tenders for the plants in October 2020. The Health Ministry announced on April 18 that 33 of the 162 plants had been installed. While the case fatality rate is reduced to 1.19%, crematoriums and symmetries in the country have been overwhelmed. Several states have been urging the central government to increase vaccine and oxygen supplies. In the meantime, the government's life insurance scheme for front-line healthcare workers has also been cancelled. The Health Ministry has stated that it is in talks with another insurance company for new dispensations. Only 287 claims have been processed under the existing scheme as of March 24. There is no official data on the number of frontline workers who have died due to COVID-19. However, the Indian Medical Association has estimated that 747 doctors have died so far. In our next story, Syria's parliament has announced that presidential elections will be held on May 26. Speaker Hamouda Sabha announced the opening of nominations on April 18. The process will continue to April 28. Incumbent President Bashar al-Assad won the election held in 2014 with over 88% of the votes. Assad's Bach party also won the majority in the parliamentary elections held in 2020. The United States and its allies have called for a boycott of the elections. They have stated that the elections are in violation of Resolution 2254 of the UN Security Council. The resolution calls for a political solution to the war in Syria and was passed in 2015. It stated that fresh elections should be held in accordance to a new constitution and under UN supervision within 18 months. Syrian rebel groups have also rejected the elections as being legitimate. The internationally backed rebels have been at war with the Syrian government since 2011. The decade-long conflict is a destroyed civilian infrastructure including the country's healthcare system. Over 400,000 people have been killed and nearly half of the population has been displaced. The conditions in the country have also worsened due to wide-ranging sanctions imposed by the United States and the European Union. The UN had warned late last year that these sanctions were hampering reconstruction efforts in Syria. The country is also witnessing a severe economic crisis including sharp devaluation of the currency. The UN has estimated that more than 60% of the population cannot access enough food with 13 million people being dependent on it. And in our final video section, we go to the U.S. where fresh protests have broken out following the police shooting of a child. 13-year-old Adam Toledo is fatally shot by an officer in the city of Chicago on March 29th. Body Camp footage released last week shows Toledo standing with his arms raised in the air before he was shot. Here is a video feature of the circumstances of his death and the protests that followed. So we're here recognizing that what happened to Dante Wright, what happened to Adam Toledo is not disconnected from the 400-plus year undeclared war that has been going on against Black people. In the PSO we have a slogan that goes, stop the war on Black America. Can you all say, stop the war on Black America? Stop the war. On Black America. Stop the war. For the rich and powerful, for the police. And then there's the America for the Black, the Puerto Rican, the Mexican-American, the working class, the poor and colonized people, the oppressed people, right? So we're now fighting for justice within their system. We're fighting for justice which means a new system, right? So it's all we have time for today. We'll be back tomorrow with more news from around the world. Until then, keep watching People's Dispatch.