This simplifies the internal connections and control logic, lowering the resulting power consumption. As opposed to the Kepler where all of SMX resources were shared, an SMM is divided into several groups of subunits with dedicated control logic.In the Maxwell, there is a separate 64KB block of shared memory while the texture and L1 caches are combined into one. In the Kepler, there was a 64KB L1 cache/shared memory while the texture cache was separate. The system of caches has been revised.Here are the key differences from the Kepler architecture: It means that there is less control logic per each SM. As is typical of Nvidia’s junior solutions, the GM107 has one GPC but this GPC contains five SMMs whereas in the Kepler architecture there were up to three SMXs per each GPC. The key difference of the Maxwell from the Kepler is in the new streaming multiprocessors which are referred to as SMMs rather than SMXs. Besides higher energy efficiency, the cache also boosts the overall performance, by the way. The larger cache can contain more data for reading and writing, reducing memory controller load and increasing the cache hit rate. The L2 cache is 2 MB large, which is 8 times the size of the L2 cache of the previous GK107 chip. But every difference we can spot is actually meant to ensure higher energy efficiency. We can see a GigaThread Engine, an L2 cache, raster operators and a graphics processing cluster (GPC) with five Maxwell streaming multiprocessors (Nvidia calls them “SMMs”). There seem to be no fundamental differences from the previous Kepler architecture. Now that it’s clear why Nvidia tried to make its Maxwell 1.0 architecture as energy-efficient as possible, let’s see how it did so. So, if with the current 28nm tech process Maxwell-based solutions prove to be economical and cold, the upcoming 20nm Maxwell-based chips (with much more transistors) will be just ordinary in these parameters. That will increase transistor density but also heat dissipation. TSMC plans to switch to 3D transistors in its 20nm tech process, too. We can remind you that two years ago Intel released its Ivy Bridge CPUs manufactured on 22nm tech process with 3D tri-gate technology. It is no wonder considering that it was developed with the future 20nm tech process in mind. Nvidia claims that the Maxwell was designed for a record-breaking performance-per-watt ratio. So if the GPU architecture is not optimized, heat dissipation per each square millimeter of the semiconductor chip will be growing until it becomes an obstacle to increasing clock rates and, consequently, performance. Even transitioning to a new tech process is not a solution anymore since transistor density grows faster than power consumption per each transistor. And it would not be possible without optimizing your product designs for better energy efficiency. When it is not possible to quickly switch to a “thinner” tech process, you have to resort to increasing clock rates in order to make your top-end solutions faster. Less advanced power and cooling systems can be used, which translates into better reliability and lower noise level.Įnergy efficiency has been improving for years, becoming even more important after the process of transitioning to new manufacturing technologies has slowed down. Moreover, lower power consumption makes a graphics card with better consumer properties, other factors being the same. The latter chip can be modified to have more computing subunits or higher clock rates and beat the first chip in performance because the 300W chip has no reserves for similar modifications due to its already excessive power draw. For example, suppose we have two chips with the same performance, but one consumes 300 watts whereas the other, 150 watts. The saved watts can be spent to increase clock rates or the number of computing subunits. Some people argue that performance matters more than energy efficiency but it turns out that energy efficiency is actually the key to high performance. There will be some additional modifications in the second-generation Maxwell but, like in the first generation, the focus will be on energy efficiency. The second generation of Maxwell-based GPUs will be rolled out in the second half of this year and will supposedly consist of three chips codenamed GM200, GM204 and GM206 – all manufactured on new 20nm technology.
0 kommentar(er)
