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The new Raspberry Pi 4 is out and they are moving from Amazon distribution centers and distribution sites to desktops and desks around the world. Before connecting a new USB C cable and connecting these PIS, it is useful to know what you are engaging in. The all new Raspberry Pi is fast. Not only that, but because of the new System on Chip, it's now a viable platform for a cheap homebrew NAS, a streaming server or any other solution requiring considerable bandwidth. This is the Pi of the future.
The Raspberry Pi 4 includes a system-on-a-chip BCM2711B0, a quad-core Cortex-A72 processor running at 1.5 GHz, with up to 4GB of RAM (with guidance on an upcoming 8GB version). The previous Pi incarnation, the 3 B + model, used a SoC BCM2837B0, a quad-core Cortex A53 clocked at 1.4 GHz. Compared to 3 B +, the Pi 4 does not use an "efficient" kernel, we are deeply in the field of "performance" with a larger cache. But what do these figures mean in real terms? That's what we are here to know.
Pi 4 is a very different material
The standard for evaluating a Raspberry Pi and other single-card computers is Roy Longbottom's Raspberry Pi reference. Yes, you must compile them. When we released the Raspberry Pi 3 model B +, we could ignore many of these tests because the memory chip and graphics processor were identical to the Raspberry Pi 2; There would simply be no significant difference outside clock speed, which was not very significant at first. This time it's different. The Pi 4 brings a brand new SoC, a new graphics processor, a new RAM and a brand new. The question is, does it matter? These tests will compare the Raspberry Pi 4 Model B + with Raspberry Pi 3 Model B +
Processor performance
The LINPACK test simply solves the linear equations and is a sufficient test to evaluate the raw performance of the processor. The test is available in two variants, single and double precision. The considerable increase observed in the Linpack reference points is a direct result of the SoC change. The Raspberry Pi 3 featured a quad-core Cortex-A53, the "efficient" core of the family. The Cortex-A72 present in the Raspberry Pi 4 has a larger cache and the Linpack measurement is in part a measure of the size of the cache.
The results show a significant gain over the Raspberry Pi 3. This is just a test of how quickly a computer can multiply, and there is much more that goes into the speed of a system. Memory bandwidth, for example.
Memory bandwidth
For years, the Pi has a 32-bit memory bus, which does not matter, because you can only get a Raspberry Pi 3 with 1GB of RAM. Years ago, RAM was soldered directly to the SoC, which meant that the production of this model would stop when the production of that RAM chip stopped. RAM has always been the limiting factor for the Pi. This has changed with the Pi 4. We now have a SoC with more data lines and addresses going to the RAM. Oh, and we have more than 1GB of RAM now. How it works?
The Pi 4 shows a significant increase in memory bandwidth, but that's what buries the lede. You can now get a Pi with 4GB of RAM, and the 8GB version has been unofficially announced in the official specifications. If I had to guess, I would say we can expect the 8GB version in about a year. Regarding the memory bandwidth? Who cares – we have four times the RAM now.
Networking far exceeds Pi 3 in wired and wireless performance
Since 2012, the architecture of the Raspberry Pi is a problem, especially that of model B, very common: USB and Ethernet ports all rely on a single USB hub. From the first Raspberry Pi Model B to last month's Raspberry Pi 3 Model B +, USB and Ethernet ports were controlled via a LAN7500 serial chip. This chip transforms a simple USB connection (on the SoC) into a few USB ports and into an Ethernet controller. It is certainly worth adding ports to a system-on-a-chip, but the bandwidth is limited: everything must go through a USB 2.0 connection. The maximum combined rate will be 480 Mbps. Regardless of the content of the LAN7500 data sheet, Gigabit Ethernet was impossible, and any use of USB connections would reduce the bandwidth of the Ethernet.
The good news is that the new SoC of the Raspberry Pi 4 is equipped with an Ethernet controller:
The Ethernet connection is saturated by all accounts. This was a ping test, download and download from speedtest.net. I'm lucky to have a fast (and economical) fiber and, in all respects, the Raspberry Pi 4 pulls your feet as fast as my router allows. However, the Raspberry Pi 3 is bothered by the USB to Ethernet controller. The Raspberry Pi 4 is now a competent 4K broadcast box, and not only because it's the Raspberry Pi that supports 4K HDMI technology.
But what about WiFi? The Raspberry 3B + includes a Wi-Fi and Bluetooth thanks to CYW43455, the Cypress chipset hidden under the magnificent RF shield with the Raspberry Pi logo. The Raspberry Pi 4 loses the RF tank in relief, but it works better than the 3B +?
The wireless in the Raspberry Pi 4 is better. Although the cable connections are always better, the Raspberry Pi 4 is not left behind, pulling at 85 Mbps from the router in the room. The Raspberry Pi 3 could only handle between 20 and 30 Mbps in the same environment.
Conclusion: Reactive enough to be used as a daily driver
The Raspberry Pi was originally designed as a small, inexpensive Linux computer and intended for education. The idea is that if you give a computer to a child, this one will learn STEM, or something similar. Computer education mainly consists of osmosis; you can not tell someone how to code, there must be practical time. You can not teach someone to use a spreadsheet, you need practical time. Until now, the Raspberry Pi platform was lagging behind traditional desktops, laptops and Chromebooks in terms of power and speed. This reduces the impact of the pi on education.
Now the Raspberry Pi is comparable to any office experience. If the Raspberry Pi 3 is a computer able to go under your bench when you need to quickly find something, the Raspberry Pi 4 is a powerful daily driver. You can very well use a Raspberry Pi 4 as the main computer. It's fast enough, there is enough memory, the networking is excellent and it will do everything you want, with the same responsiveness as a thousand dollar office.
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