Wednesday , January 27 2021

The only test like this on the MacBook Air M1: you ask, we check

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Piotr Urbaniak

The new MacBook Air is like an emotionally unstable family: once you’re a perfect companion, other times you want to get out the door, but then you’ll regret it. However, this is only my initial opinion. The conclusion may be completely different, and why you will learn more in reading.

I admit that, unlike much of the industry, I wasn’t an uncritical fan of the transition from x86 to Arm. It’s not that I wouldn’t trust Apple’s engineers because they show a class in the smartphone segment every year or have a special love for Intel, but changing the software model is always an earthquake.

We are talking about the situation of overturning the entire hardware layer. Everything changes. Based on the list of instructions and data types, addressing exceptions and interruptions through addressing modes and records.

It’s as if the traffic arrangement is changing from day to day, forcing everyone to drive on the left. Or, by analogy, the average American was given a car with a manual transmission. Either way, science wouldn’t be rocket engineering, but it would take some time to change habits.

RISC and CISC – let’s explain

Despite being an expert in technology, you’ve probably heard that x86 is a CISC-type architecture while Arm Arm is a member of the RISC team. But that is archaism.

At the beginning of time, CISC and RISC were antonyms and meant a computer that had a set of instructions with complex and reduced instructions. However, it comes from the English extensions of these two readings that are read directly: Complex Instruction Set Computer and Reduced Instruction Set Computer.

Today, the original division has almost lost its meaning. Although the base of all X86 instructions defines more than 1.5 miles. there are positions, but some of them are examples of chips that they literally use and are then classified as CISC. There are even RISC processors with dozens or even hundreds of instructions, such as the latest PowerPC.

The main pointer is different. That is, RISC circuits, unlike the CISC type, must change a set of operands to registers in arithmetic operations. In other words, they have no statement linking it to the execution of the payment.

However, it has once again devalued somewhat. In the 1980s, when the concept of RISC was crystallizing, the speed differences between CPU registers and operating memory were similar from here to California. The simplicity of the instruction set, in addition to acting solely on the records, can be predicted by execution time and addressing.

Only, now the processors are not as sequential and serial as before, and subsequent cache levels have greatly accelerated the memory subsystem.

Since Pentium Pro, it is common to divide complex instructions into smaller ones that often run at the same time by multiplying the number of arithmetic and logic units. To this, let’s add the out-of-order execution, which is the ability to sort instructions so that the chip can use resources in the best way possible. So there has been no significant stop waiting for the data.

In short, it doesn’t matter what happens to backend operands. Even for a programmer who doesn’t usually use machine code. The compiler will do most of the work, so switching from x86 to Arm seems the worst thing on paper.

Apple M1 in macroarchitecture

Unfortunately, not much is known about the Apple M1 itself, as the manufacturer usually goes through the details through a dense sieve. But something slipped there.

The new Apple chip is created in the 5 nm TSMC lithography process. It has eight cores, four of which are high-performance “Firestorm” and four energy-saving “Ice Storm”. This concept resembles big.LITTLE, but in the case of M1 it is completely heterogeneous, so that two clusters can work simultaneously.

The Cupertino-based company said energy-saving cores are happy with one-tenth the power of basic cores.

It is worth paying special attention to the organization of the memory subsystem. Each high-performance core has a 192 KB cache for instructions and 128 KB for data, and a power-saving core of 128 and 64 KB, respectively. L2 memory, on the other hand, is shared within clusters. “Firestorm” has 12 MB available, “Icestorm” – 4 MB.

The thick line should emphasize that the Apple M1 has not received a 3rd level cache. However, depending on the configuration, the LPDDR4X-4266 has 8 or 16 GB of operating memory directly embedded in the chip.

Instead of reducing the latency of accessing RAM through the Apple L3, they placed all the memory as close to the CPU as possible. This increases the chances of not being hit. cache andrea), which is waiting to enter a block from the main inactive memory, but minimizing the negative effects of this phenomenon. Because RAM itself has a much shorter access time and apparently someone thought it was a profitable compromise.

Other interesting data: The clock speed of the high-performance cluster is between 0.6 and 2.064 GHz and the energy-saving cluster is between 0.6 and 3.204 GHz. In turn, the power limit is 13.8 and 1.3 W, respectively.

The peak power value is therefore similar to low-voltage x86 chips, such as the “Tiger Lake-U” or “Renoir,” but the asymmetrical configuration allows for significantly reduced power consumption in moderate load scenarios, which is, let’s say, more of a notebook that it is used part of the time.

What else? The M1 offers an 8-core graphics chip (7 cores on some models) for processing, and Apple believes it can last up to 25,000. threads at a time. There is also a 16-core neural motor; A co-processor for AI-related tasks, it performs 11 trillion operations per second, according to official data. Finally, the rest of the specs include a signal processor, Thunderbolt 4 and NVMe controller or an isolated security enclave.

Complete this review with us

It doesn’t make any sense to put too much of what is in the physical aspect of the MacBook Air M1. It’s what it was in the previous generation: it surprises with its aesthetic and finish quality, it irritates only two USB-C ports and a 720p webcam.

A positive change in terms of design, as you know, is the suspension of the fan. As a result, the team is silent. This time literally.

The revolution is happening inland, of course. That’s why we’re going to end this review together. Please write in the comments what I need to check on my MacBook Air M1. Maybe it’s compatibility with specific applications? Performance in a particular reference? Or maybe the comfort of work in a specific setting?

I look forward to suggestions until Friday. I don’t promise to satisfy everyone’s curiosity, but I will do everything I can to do so. It will continue …

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