A Noticeably Cooler Continental Climate

Nicolas Leterrier, chief representative of the Minalogic coordination unit, whose job is to oversee the “innovation cluster” in Grenoble, France, sat down with Low-Power Engineering to discuss the changes under way in Europe, what’s driving it and where researchers in Grenoble see the future challenges. What follows are excerpts of that interview.

By Ed Sperling

LPE: Is the impetus for reducing power consumption in Europe from the government or the consumers?
Leterrier: It’s a general focus for everyone, from people who want to manage their energy consumption to industry to government. You cannot even buy an incandescent light bulb anymore. People are challenging everything. They want to know where energy is going and they are extremely conscious about the power consumption of everything they buy, from washing machines to air conditioners. It’s also an industry focus. When it came to process development at Grenoble, we had three areas of special focus. One was around low power, the second was around imaging and the third was around RF. Put these together and it leads to low power consumption in systems. On top of that, the European Community is trying to get more efficiency in everything. For TVs or set-top boxes, they have asked for 50% power reduction in standby mode over three years. People are trying to reduce energy consumption not only in cooling and heating, but in their day-to-day lives.

LPE: For a long time, faster and more powerful was the most important. Has that changed?
Leterrier: Yes. There was a gigahertz race in the past. Now we are dealing with current leakage even when the chip isn’t being used. Increasing the speed of the processor uses more energy, but so does increasing the size of the program. We have an enormous amount of memory, which is consuming power, as well. It’s pretty difficult to get performance and lower power consumption at the same time. But it’s doubtful when you are using a word processing program that you need a 3GHz processor with 5 gigabytes of memory. If the software is smart enough to tell what you are doing, it can tell the processor to reduce the speed, the amount of memory used, and maybe you can turn off part of the chip. You are not using the graphical accelerator when you are doing word processing. Turn that off and you will decrease the power where it’s not needed. The second area for change is idle mode where you need it to wake up extremely fast. If it’s a set-top box you don’t want to sit around waiting for it to warm up. And if it’s voice over IP, you don’t want to wait one or two minutes to place a call. The third area is power down mode, where you are trying to reduce power consumption as much as possible. You keep the date, an alarm, but it may require a milliwatt to do that. Now there is a tradeoff so you can scale the use of the processor as it’s needed.

LPE: Verification of these chips becomes incredibly complex. Have we hit a point where it is no longer an option?
Leterrier: There was a point where the design tools were not smart enough to do power optimization, so it was up to the designer to understand the entire system and include power domains and clock gating and so on. It caused a lot of issues in the design flow. The tools have increased in performance. A lot of tools have appeared for validation of systems and in co-verification of hardware and software. We can simulate or emulate part of the hardware with the real software. And we can verify part of the hardware or software with automatic test generation. So we can do much more than we could before. But where we need one engineer to design, we still need three or four to test and validate.

LPE: We’ve reached an inflection point where the old way of doing things doesn’t work anymore. Where is Europe placing its bets?
Leterrier: It’s on how you can optimize the overall power consumption from a system point of view. In a system where you can get part of the chip working at any time but not other parts, that is important to mobile applications. A lot of companies are trying to reduce the power consumption. That is a big race. There are companies like Nokia and Ericsson working on this, but it’s also happening in the automotive industry. There are more electronics in the car but the battery is the same. They are starting to face some power consumption issues. We are also seeing changes in the data center, where some servers are idle most of the day but still consume 80% of the power as when they are completely loaded. You have plenty of clocks running, plenty of memory loaded and processors that are enabled. You need to be able to wake up the system on demand and refresh, but if you are running everything and have to cool it, that uses a lot of energy. A lot of people are working on this right now. It’s how to optimize a full system to get better power consumption.

LPE: In the United States, one solution is simply to outsource everything to more efficient architectures. Is that happening in Europe?
Leterrier: It’s different. First, we are using much less cooling than in the United States, particularly in the summer. The peak of consumption in the United States is summer, but in Europe it is in the winter. Second, there is a willingness of all the actors to reduce the power consumption. This is also linked to the demand of the user to understand how much power they are using when they are making a Google request. And graphics people are extremely cautious.

LPE: As we go down the Moore’s Law road map, we run into other problems. Delivering power is a problem, some components don’t work. Is there a feeling you don’t have to race to the next node?
Leterrier: We are doing some intelligent integration. The processor may need to get smaller, but the memory may not. Instead of manufacturing everything at the same process, there may be a mix. In addition, there needs to be more integration between hardware and software. The hardware cannot make the decision alone to reduce the voltage or frequency. Most of the electronics today are synchronous, so if you reduce the frequency you need to adapt your whole system to a new voltage. In the new chips, you want to run part of the chip at 200MHz and another part at only 50MHz. The issue of how you can manage the power is changing the functional behavior of the chip.

LPE: It sounds as if you’re talking about combining software prototyping with low-power engineering. Is that correct?
Leterrier: Yes. People were thinking you have a hardware flow and a software flow, and at some point it will meet. Now that approach has changed. Because we have an integrated system on chip, we need a good design between both. It’s a very big change in mindset, and now both are concerned with where the power is being consumed. You also need to think about the software at the architecture stage so you can simulate as early as possible your operating mode, estimate your power consumption, and optimize that.

LPE: There are very few people that understand all these pieces. Is there a push to train these people?
Leterrier: There is a major effort by the companies to train people. It started about 2-1/2 years ago. A lot of people in Grenoble are now creating tools that are interesting from a system point of view. And for a lot of companies, there has been a problem creating IP early enough to be able to develop software that works with that IP. If you don’t have the IP early enough, you will not be able to get functional software on top of it. The people developing IP now are increasing their effort to be ahead of the demand in the market.

LPE: We’re seeing a consolidation in the IP market. Is that the same in Europe?
Leterrier: Yes, but we’re seeing new tools to allow you to check the system so it will work at the end of the design process. The CAD tools still have a lead on the hardware side. But we are seeing standards for plugging in the IP, and this community is working fast to develop new tools around this.

LPE: Is Europe is optimistic about these changes?
Leterrier: Absolutely. There is a real market need around low power. Everyone is starting to see that energy is not something that will last forever, and they need to be very conscious of that. There’s also a real change in the enterprise, too, because it is starting to be driven by customer demand.