婆罗门
精华
|
战斗力 鹅
|
回帖 0
注册时间 2007-8-17
|
本帖最后由 归蝶 于 2020-4-4 07:09 编辑
顶楼的机翻完全没有谈到点上。 原文在 https://www.eurogamer.net/articl ... erny-tech-deep-dive
几个要点：
- 频率和功耗并不完全相关 - 根据执行的代码不同，在同样频率上的处理器也会有不同的功耗
- 索尼为PS5的CPU和GPU分别预先设定了功耗上限，这个上限是与PS5的散热能力相匹配的
- 功耗上限和频率上限(也就是3.5GHz/2.23GHz)不是一回事。例如，CPU达到3.5GHz时可能并没有达到功耗上限，这时AMD SmartShift技术可以将多余的电力分给GPU以保证更稳定的图形性能。
- 设定的功耗上限足以让CPU和GPU同时运行在最高频率，开发者无需在这个方面做取舍。
- PS5的调度算法会尽量保证处理器不在高频率空转(idle)，例如停下来等待v-sync的同步。换句话说，会尽可能保证CPU和GPU的频率得到充分利用。Boost frequencies are designed to be maintained by load across full frame processing。在满负荷的情况下，大部分时间CPU和GPU都可以在接近或达到最高的频率运行。
- 围绕功耗上限来调整性能，这么做的核心目的是保证一致性，使得PS5的表现不会因为个体因素（如环境温度）而变化。 换句话说，开发者在开发机上看到的效果和每一台零售机器都是一致的
- 开发者可以实时观察的CPU与GPU功耗，并以此为依据来优化游戏代码
- 数毛社采访的开发者反映他们的游戏难以充分利用CPU的功率配额，因为这些游戏的引擎还在兼顾上世代的Jaguar。他们观察到CPU的频率被降低而GPU得以稳定运行在最高频率上
"We don't use the actual temperature of the die, as that would cause two types of variance between PS5s," explains Mark Cerny. "One is variance caused by differences in ambient temperature; the console could be in a hotter or cooler location in the room. The other is variance caused by the individual custom chip in the console, some chips run hotter and some chips run cooler. So instead of using the temperature of the die, we use an algorithm in which the frequency depends on CPU and GPU activity information. That keeps behaviour between PS5s consistent."
Inside the processor is a power control unit, constantly measuring the activity of the CPU, the GPU and the memory interface, assessing the nature of the tasks they are undertaking. Rather than judging power draw based on the nature of your specific PS5 processor, a more general 'model SoC' is used instead. Think of it as a simulation of how the processor is likely to behave, and that same simulation is used at the heart of the power monitor within every PlayStation 5, ensuring consistency in every unit.
"The behaviour of all PS5s is the same," says Cerny. "If you play the same game and go to the same location in the game, it doesn't matter which custom chip you have and what its transistors are like. It doesn't matter if you put it in your stereo cabinet or your refrigerator, your PS5 will get the same frequencies for CPU and GPU as any other PS5."
.......
Mark Cerny sees a time where developers will begin to optimise their game engines in a different way - to achieve optimal performance for the given power level. "Power plays a role when optimising. If you optimise and keep the power the same you see all of the benefit of the optimisation. If you optimise and increase the power then you're giving a bit of the performance back. What's most interesting here is optimisation for power consumption, if you can modify your code so that it has the same absolute performance but reduced power then that is a win. "
In short, the idea is that developers may learn to optimise in a different way, by achieving identical results from the GPU but doing it faster via increased clocks delivered by optimising for power consumption. "The CPU and GPU each have a power budget, of course the GPU power budget is the larger of the two," adds Cerny. "If the CPU doesn't use its power budget - for example, if it is capped at 3.5GHz - then the unused portion of the budget goes to the GPU. That's what AMD calls SmartShift. There's enough power that both CPU and GPU can potentially run at their limits of 3.5GHz and 2.23GHz, it isn't the case that the developer has to choose to run one of them slower."
"So, when I made the statement that the GPU will spend most of its time at or near its top frequency, that is with 'race to idle' taken out of the equation - we were looking at PlayStation 5 games in situations where the whole frame was being used productively. The same is true for the CPU, based on examination of situations where it has high utilisation throughout the frame, we have concluded that the CPU will spend most of its time at its peak frequency."
Put simply, with race to idle out of the equation and both CPU and GPU fully used, the boost clock system should still see both components running near to or at peak frequency most of the time. Cerny also stresses that power consumption and clock speeds don't have a linear relationship. Dropping frequency by 10 per cent reduces power consumption by around 27 per cent. "In general, a 10 per cent power reduction is just a few per cent reduction in frequency," Cerny emphasises.
There's likely more to discover about how boost will influence game design. Several developers speaking to Digital Foundry have stated that their current PS5 work sees them throttling back the CPU in order to ensure a sustained 2.23GHz clock on the graphics core. It makes perfect sense as most game engines right now are architected with the low performance Jaguar in mind - even a doubling of throughput (ie 60fps vs 30fps) would hardly tax PS5's Zen 2 cores. However, this doesn't sound like a boost solution, but rather performance profiles similar to what we've seen on Nintendo Switch. "Regarding locked profiles, we support those on our dev kits, it can be helpful not to have variable clocks when optimising. Released PS5 games always get boosted frequencies so that they can take advantage of the additional power," explains Cerny.
|
评分
-
查看全部评分
|
楼主: 医生狼多
沪公网安备 31010702007642号 )
发表于 2020-4-3 14:55
所以说温度不测吗 不怕爆？
风扇起飞的话直接就是毁灭打击。
