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Does the seemingly powerful PCIe 4.0 really work? Why does AMD blow up Intel but don't care?

via:CnBeta     time:2019/6/15 20:32:04     readed:120

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The standardization of PCIe is not good when PCIe 4.0 appears.

The full name of PCIe is Peripheral Component Interconnect Express, which can be translated into high-speed connection standard for peripheral devices. This is the PC connection standard proposed in 2003. The PCIe channel contains two data channels to ensure the efficiency of data reception and transmission. Each device has an independently allocated bandwidth and does not occupy the total bandwidth.

At present, the PCIe 3.0 standard is commonly used in our computers, which is the standard that was established 9 years ago. In 2003, PCIe 1.0 was released, with a speed of 2.5GT/s. Then PCIe 2.0 (5.0GT/s) was released in 2006 and PCIe 3.0 (8GT/s) was released in 2010. PCIe will set new standards in about three to four years. However, PCIe 4.0 waited for 7 years and did not release PCIe 4.0 (16GT/s) until 2017. When 4.0 was not yet applied, PCIe 5.0 (32GT/s) was released early in 2019.

Since the beginning of the 2011 HD 7000 series of graphics cards using PCIe 3.0, PCIe 3.0 has been popular for 8 years. The emergence of PCIe 4.0 does not seem to be a good time.

Just over a year after the release of PCIe 3.0 in 2017, the PCI-SIG, which manages and defines the PCIe standard in January 2019, released version 0.9 of the latest PCIe 5.0 specification, while PCIe 5.0 is also backward compatible with 3.0 and 4.0 devices, which caused many vendors to directly skip the PCIe 4.0 direct development of PCIe 5.0 specification devices.

Take the first step? AMD Releases First PCIe 4.0 Consumer Level Processor

AMD was the first to announce a new generation of Acer processors supporting PCIe 4.0 interface at the Taipei Computer Show at the end of May this year. In addition to the 7nm process and high frequency, Intel's support for PCIe 4.0 has become the highlight of this conference. Compared with the buff buckling that doubles the bandwidth of PCIe 3.0, the overall performance of the A platform has also been greatly improved.

At the Taipei Computer Show, many manufacturers introduced AMD's new CPU motherboard. We may see that the motherboard has a small on the South Bridge chip.fanThere is also one more noise source in the chassis. The appearance of this small fan is also related to the application of PCIe 4.0. Because the data processing task is aggravated, the South Bridge has become a small stove. There is no way to add a small cooling fan to the South Bridge.

At the same time, we also saw the ultra-super high speed based on PCIe 4.0 at the Taipei Computer Show.SSDstorage. At the Taipei Computer Show, Gigabyte introduced the world's fastest and largest PCI-e 4.0 AIC SSD. This is still the world's strongest SSD read and write speed has reached 15000MB / s, see clearly is 5 digits! And its capacity has reached 8TB, I can't imagine how high its price is, and I don't know if it will really push to the consumer market. The group E16 master is used, wherein the AIC version consists of four M.2 SSDs, RAID 0, each disk is PCIe 4.0X4, and the four disk groups are PCIe4.0 X16.

A huge boost from PCIe 4.0

CPU has only 16 PCIe channels

Even the current PCIe 4.0 device, the, AMD Ryzen 9 3900X, has only 16 PCIe channels. On the motherboard, the nearest PCIe slot to the CPU is only 16 channels. At present, this slot is plugged in video card, can reach PCIe × 16 full speed. Only 8 8 channels can be realized when two video cards are SLI, and 8 4 4 channels are allocated when three PCIe devices are connected, that is to say, PCIe channels are limited. This is the division of PCIe channels of CPU on the mainstream platform at present, there are only 16 directly connected CPU, because of the limitation of the number of channels, the speed of multi-device connection will be reduced, and the full performance of multiple high-performance PCIe devices will not be brought into full play. When PCIe 4.0 doubles the bandwidth, the communication speed between multiple PCIe devices and CPU will be more beneficial to the performance of each hardware.

New possibilities brought by high-speed data transmission

With the popularity of 5G technology, we have found that high-speed data transmission will change the industry and even spawn new industries. 5G's requirements for hardware bandwidth are actually turned over several times, and high-frequency signals and signal coverage are good. It is really necessary to have a huge upgrade in the industry to achieve such performance. And in 2-3 years, the number of devices that enable data interconnection in the home use scenario will increase dramatically, and the PC industry may usher in new changes, and PCs may become individuals.serverAnd the existence of a data processing center.

Today's smart connection devices do not require high data connection, of course, the degree of interconnection and data exchange between the overall devices is not high. This is because personal data processing is currently based entirely on cloud devices, but not reliable enough. With the development of real personal intelligent assistant intelligent devices, the demand of personal PC data processing center will gradually emerge. The safest way to do this is to match the local server cloud data processing, and PCIe 4.0 already meets the basic needs of the personal data processing center.

However, PCIe 4.0 seems to be just beautiful.

High upgrade cost, blocking the popularity of new equipment

However, PCIe 4.0 looks very good at present. The current cost of PCIe 4.0 is still quite high, because the faster the data transmission speed, the corresponding signal attenuation will increase, and the requirements for components and materials will be corresponding. The higher. According to previous news, the complete 16-channel PCIe 4.0 retimer chip needs $15-25, the motherboard upgrade costs about $100, and the high-end top-level motherboard may cost more. Previously, some users broke the news that msi's top X570 Super God motherboard is priced at 777 euros (about 6,000 yuan), which is really more expensive than the CPU.

The demand in the consumer market is not obvious.

In the past two years since the launch of PCIe 4.0, apart from the enterprise market, there has been no movement in the consumer market at all, in addition to the high cost, there is also a reason that consumer video cards, processors and the network have little demand for PCIe 4.0, which has doubled in speed. This is also the reason for the delay in the launch of PCIe 4.0. As early as the PCI3.0 era, the performance loss of today's graphics card is not obvious, even if it uses PCIe 2.0 × 16 channels.

Moreover, at present, there are not many devices in the consumer market that require high PCIe channels. Currently, devices that require high-speed PCIe channels in the consumer market are graphics cards and full-speed SSDs. Take SSD, the speed of 16 PCIe channel SSD does not reach the PCIe bandwidth limit, but the number of channels is full, and the price is still expensive, it is not a product for the consumer market.

The enterprise market begins to abandon PCIe

The high demand for PCIe is the high-speed data processing requirements environment, but PCIe has its own flaws in the data processing environment.

PCIe in home computers is indeed a very fast and practical connection technology because there are fewer devices connected to the motherboard and there is little need to extend the application across multiple computers. In the data center, each PCIe device has its own isolated memory pool, and communication between different devices becomes very inefficient due to bandwidth and latency. NVIDIA and AMD have developed NVLink and InfintyFabric technologies to deal with this problem, CXL isIntelTake out the countermeasures.

In March 2019, Intel launched a new data device interconnection protocol CXL (Compute EXpress Link) for data center, high-performance computing, and AI. The technology is built on the physical and electrical implementation of the complete PCIe 5.0, but it does not require a specially designed interface, which simplifies the design of the server hardware and reduces the cost of the overall system. Intel announced with Alibaba, Dell EMC, Facebook, Google, HPE,Huawei,MicrosoftA joint alliance was formed to develop this protocol to eliminate bottlenecks in compute-intensive workloads such as CPUs and accelerators. The role played by Intel is the same as its role in USB and PCIe development. It shares the technical achievements with the Alliance members and continues to develop together.

The timing is wrong 尴尬 from PCIe 5.0

Since PCIe 5.0 is backward compatible with 3.0/4.0, the status of 4.0 is somewhat embarrassing. Of course, the root cause is that the 4.0 standard is too late. It is seven years away from the 3.0 specification in 2010, and the PCI-SIG organization is eager to restore the established rhythm of the eight-year standard.

The bandwidth of PCIe 4.0 is doubled directly compared to 32GB/s (x16) of PCIe 3.0, and it has reached 64GB/s (x16), and this time PCIe 5.0 doubled on this basis. It is 128GB/s (x16). They are also using the 128b/130b encoding of PCIe 3.0, but the PCIe 4.0 transfer rate is up to 16GT/s, and PCIe 5.0 is up to 32GT/s.

The planning of the PCI-SIG is,PCIe 4.0 and 5.0 specification products will coexist in the market for a long time, of which 5.0 will be used only for high performance computing, while the consumer side is all 4.0.At present, Intel's enterprise-class SLC solid-state disk, the Ruler SSD, is designed directly for PCIe 5.0.

to sum up

At present, PCIe 3.0 is indeed enough to meet the consumer market. From all aspects, PCIe 4.0 is a bit out of reach due to various reasons such as cost, timing, market, etc. Perhaps because of these various reasons, Intel does not seem to care about PCIe 4.0 at present, and the CPU has always seemed to have no new plans. The news is that Intel will directly develop PCIe 5.0 devices beyond PCIe 4.0, and PCIe 5.0 devices will be directly backward compatible with 3.0 and 4.0 devices. Is this the legendary dimension reduction strike? For consumers, the upgrade cost of PCIe 5.0 will be very high, but the compatibility will reduce the upgrade cost, and the consumer market can be upgraded gradually.

However, it is better to buy new ones than to buy old ones. Yes, my explanation and analysis above are based on the current hardware equipment and software requirements, analyzing the current PCIe 4.0尴尬 situation, but with the increasing demand for personal PC data throughput, several years later software and hardware Development will certainly keep up, and after the scale effect, the corresponding costs will gradually decline. After all, our mainstream memory capacity is from 1GB to now 16GB. Whenever we have encountered all the memory consumed by the software, the desire of players and manufacturers for the device to be "higher, faster and stronger" should not stop.

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