Why does the mobile eight core still card?

A lot of people look at smartphones, they have to look at the core number. Think the core more performance, not lag. But when they buy a eight core cell phone will still feel the card immediately, will complain: "Eight-core how still card", why? The machine nets for you to answer.

One, what processor does not card?

In fact, the smoothness of the system and a few core relationships are small. What we call fluency consists of two parts.

First, the system itself is fluent, is actually "starter" this application of fluency.

Second, is the application of fluency, is the flow of various applications running.

The impact of these two fluency is not the core of how much, but the single core performance and memory bandwidth.

Our "starter" and various applications can only take advantage of the previous or two cores, and the four cores can be used very rarely, and can take advantage of the rarity of the eight cores.

So the decision to speed is not a few core, but the performance of the single core?

Now on the market processor, there are A7, A9, A15, the various versions of the Ring snake, as well as Intel, the performance difference is very large.

If you use A7, the eight cores are not as good as the two cores of A15. From a fluent point of view, the frequency and type of a single core is more important, the core number of more useless.

Second, memory bandwidth is actually more critical

For smartphones or tablets, it is SOC, which means that the display core is integrated, and the CPU shares the memory bandwidth without the independent video memory. and mobile phone, tablet, resolution are more and more high, this has put a high demand for memory bandwidth.

The program needs to run in memory, the processor is fast, the memory access speed is not keeping up, and the system will be stuck. The higher the resolution, the higher the memory bandwidth requirement.

In situations where the memory bandwidth is not sufficient and the resolution is too high, the system will card regardless of how fast the processor is.

In the early days of Android, WVGA had a resolution of only 800*600=48 pixels, with little pressure on memory bandwidth.

But with the spike in Android resolution, bandwidth becomes a problem. So how much bandwidth is appropriate? Apple products can be a reference.

The New ipad is an interesting short-lived product that uses the processor and resolution to make a reference. A5X processor is really just a dual-core A9 processor, the frequency is not high, and MT6577 a grade.

and the ability to support the New ipad running smoothly is a5x's powerful graphics performance and memory bandwidth, a5x memory bandwidth up to 12.8gb/s.

The New ipad has a resolution of 2048*1536=314 pixels, meaning that Apple believes that providing 4gb/s bandwidth per 1 million megapixels guarantees basic fluency.

With a5x, the A9 four-core processor bandwidth is only 4.2gb/s,6.4gb/s. They use 1280*720=92 megapixel resolution, every 1 million pixels can provide more than 4gb/s bandwidth, basic can also guarantee smooth.

When it comes to 1920*1080=207 pixels, only 8064 of the 8.3g/s bandwidth can be supported.

That's why the first-generation 1080P smartphones are used APQ8064.

The latest Dragon 801 (8974AC) memory bandwidth of up to 14.9gb/s, support 2560*1440=368 megapixel resolution, just over the 4gb/s every 1 million pixels of the bottom line, but also has a smooth foundation. This is why the latest several phones dare to support this resolution base.

However, the other processors on the market is not optimistic, MT6592 bandwidth is about 5.3GB/S, support 720P is not a problem, but support 1080P, every 1 million pixels only 2.56gb/s. No matter how the starter optimizer is difficult to smooth, this is the eight core is the reason for the lag.

Similarly, Huawei HiSilicon's K910 bandwidth is 6.4gb/s, better than MT6592, but with 1080P.

I recently tested an Intel ATOM z3735d tablet, 3.14 million pixels only 10.6gb/s bandwidth, is also the sense of lag.

Memory bandwidth is actually more critical than the processor.