Loongson

Loongson () is a family of general-purpose MIPS64 CPUs developed at the "Institute of Computing Technology" (ICT), Chinese Academy of Sciences (CAS) in China. The chief architect is Professor . It was formerly called Godson.
Loongson is the result of a public–private partnership. "BLX IC Design Corporation" was founded in 2002 by ICT and Jiangsu Zhongyi Group. Based in Beijing, BLX focuses on designing the 64-bit Loongson general-purpose and embedded processors, together with developing software tools and reference platforms.
STMicroelectronics fabricates and markets Loongson chips for BLX, which is fabless.
MIPS patent issues.
The current Loongson instruction set is a MIPS64, but the internal microarchitecture is independently developed by ICT. Early implementations of the family lacked four instructions patented by MIPS Technologies (US4814976A, unaligned load-store) to avoid legal issues.
In 2007, a deal was reached by MIPS Technologies and ICT. STMicroelectronics bought a MIPS license for Loongson, and thus the processor can be promoted as "MIPS-based" or "MIPS-compatible" instead of "MIPS-like".
In June 2009, ICT licensed the MIPS32 and MIPS64 architectures directly from "MIPS Technologies".
In August 2011, Loongson Technology Corp. Ltd. licensed the MIPS32 and MIPS64 architectures from MIPS Technologies, Inc. for continued development of MIPS-based Loongson CPU cores.
Microarchitectures.
Loongson has three main families of microarchitectures, some of which are available as IP cores:
All loongson cores are little-endian. They use MIPS EJTAG for debugging.
Chips.
Loongson 1.
The first revision of the Loongson architecture, the Loongson1 (Godson-1) is a pure 32-bit CPU running at a clock speed of 266 MHz. It is fabricated with 0.18 micron CMOS process, has 8 KB of data cache, 8 KB of instruction cache and a 64-bit floating-point unit, capable of 200 double-precision MFLOPS. It is intended for embedded applications, such as point of sale (POS) systems, where a high performance 64-bit architecture is not needed.
Loongson 1 Series.
In April 2010, Loongson Technology Corporation Limited was formally established and settled in Loongson Industrial Park, Zhongguancun Environmental Protection Science and Technology Demonstration Park, Daoxianghu Road, Haidian District, Beijing, China. After the establishment of the company, the Loongson survey market re-established the low-end embedded product line - Loongson 1 Series. Currently known products are Loongson 1A, 1B, 1C300/1C101 (fingerprint biometric application chip), 1D (ultrasonic measurement chip), 1E04/1E300/1E1000 (1E series is Loongson Aerospace special anti-irradiation processor) 1F04/1F300 ( 1F series is 1E series supporting Loongson Aerospace special anti-irradiation bridge), 1G (audio special chip), 1H (oil drilling high temperature resistant chip), 1J (anti-irradiation single-chip chip).
Loongson 2 Series.
The Loongson 2 adds 64-bit ability to the Loongson architecture. Initially running at 500 MHz, later revisions to Godson 2E were produced that run up to 1 GHz. The Godson 2F, released to market in early 2008, ran at 1.2 GHz.
Loongson 3 Series.
This series sees the adoption of 1.0, an expanded instruction set that is a superset of MIPS64 release 2. It can be broken down into:
Loongson 3A1000.
The 65 nm Loongson 3A1000 is able to run at a clock speed near 1 GHz, with 4 CPU cores (~15 W) first and 8 cores later (40 W). In April 2010, Loongson 3A1000 was released with DDR2/3 DRAM support.
Loongson 3B1500.
There are two versions of the Loongson-3B1500 (Godson-3B1500), the first featuring a 32 nm 6-core processor, and the second version having a 28 nm 8-core processor. Each version can be clocked from 1.2 GHz to 1.5 GHz. Loongson-3B has exceptional energy efficiency in terms of performance per watt - executing 192 GFLOPS using 40 watts. Each CPU core has 64 KB L1 cache and 128 KB L2 cache. All the cores share a common 8 MB L3 cache, which helps to reduce the cache miss rate.
ICT has launched a Loongson-3B-based six-core desktop solution. Technical specifications:
This desktop solution uses an optimized version of Fedora 13, with a lot of software ported and available, such as Kingsoft (WPS) office suite. The manufacturer states that the user experience of the desktop solution has been significantly improved over its Loongson-3A based predecessor. Results of a benchmark test, conducted in April 2014, are available
Loongson 3A3000.
In 2017, Loongson released latest version of 3A cpu, 3A3000. As one of the domestic CPU of China, Loongson 3A3000 is being commercialized, and in the recently exhibition in Nanjing (2017), based on the Loongson 3A3000 motherboard developers computer quietly debut.
3A3000 is designed with quad-core 64-bit and clocked at 1.5 GHz, power consumption is only 30 W. 3A3000 single-threaded performance is lower than Intel or AMD products. For comparison, the 3A3000's performance is about one-third of the Intel i5-4460 running at about twice the clock frequency (3.2 GHz/84 W), or a relative performance of roughly 66%.
Loongson 3A4000.
In late-2019, Loongson released latest versions, 3A4000 and 3B4000. The processors are designed with four cores, 8MB of L3 cache and operating clocks between 1.8 GHz to 2 GHz.
A "LoongISA 2.0" was introduced for GS464V R2. Compared to LoongISA 1.0, the DSP module is removed, and a few sets are added:
Hardware-assisted x86 emulation.
The Loongson 3 adds over 200 new "LoongBT" instructions over Loongson 2. Their addition has the specific benefit of speeding up Intel x86 CPU emulation at a cost of 5% of the total die area. The new instructions help with emulation performance, for example QEMU (the only known example). The new instructions reduce the impact of executing x86/CISC-style instructions in the MIPS pipeline. With added improvements in QEMU from ICT, Loongson-3 achieves an average of 70% the performance of executing native binaries when running x86 binaries from nine benchmarks.
Supported software.
Unlike processors from Intel, Advanced Micro Devices or VIA Technologies, Loongson does not directly support the x86 instruction set. The processor's main operating system is Linux, while in theory any OS with MIPS support should also work. For example, Windows CE was ported to a Loongson-based system with minimal effort. In 2010, Lemote ported an Android distribution to the Loongson platform.
Loongson machines are used in the package-building and CI infrastructure of Debian and Golang, respectively. This is partially because of Loongson's status as the only vendor producing application-grade MIPS CPUs for retail.
Many operating systems work on Loongson:
Compiler support.
The GNU Compiler Collection (GCC) is the main compiler for software development on the Loongson platform. LLVM is still inadequate due to missing workarounds for loongson's CPU errata.
ICT also ported Open64 to the Loongson II platform.
User applications.
Open source applications on Linux Platform can be ported with little effort. Most common open-source applications (including OpenOffice.org, Mozilla Firefox, Pidgin, and MPlayer) and applications written for the Java platform are supported. For .NET applications, an unofficial port of the Mono Common Language Runtime is available online.
Loongson-based systems.
In March 2006, a €100 Loongson II computer design called "Longmeng" (Dragon Dream) was announced by Lemote.
In June 2006 at Computex'2006, YellowSheepRiver announced the "Municator YSR-639", a small form factor computer based on the 400 MHz Loongson 2.
Currently, Loongson boxes that come with a 667 MHz Godson 2E processor or an 800 MHz Godson 2F processor are sold in China at CNY 1599 (US$200) or CNY 1800 respectively without monitor, mouse, or keyboard.
, two manufacturers have announced Loongson 2F products for sale outside China.
 the new 8.9" netbook from the Chinese manufacturer Lemote that replaced "mengloong", "Yeeloong" (Portable Dragon), running Debian, is available in Europe from the Dutch company "Tekmote Electronics".
Loongson 3A laptop.
Loongson insiders revealed a new model based on the Loongson 3A quad-core laptop has been developed and is expected to launch in August 2011. With a similar design to the MacBook Pro from Apple Inc., it will carry a Linux operating system by default.
In September 2011, Lemote announced the Yeeloong-8133 13.3" laptop featuring 900 MHz, quad-core Loongson-3A/2GQ CPU.
Supercomputers.
On 26 December 2007, China revealed its first Loongson based supercomputer with performance 1 TFLOPS of peak performance, and about 350 GFLOPS measured by LINPACK in Hefei, designated as KD-50-I. This supercomputer was designed by a joint team led by Chen Guoliang at the computer science technology department of the University of Science and Technology of China and ICT (the secondary contractor). KD-50-I is the first Chinese built supercomputer to utilize domestic Chinese CPUs, with a total of more than 336 Loongson-2F CPUs, and nodes are interconnected by Ethernet. The size of the computer was roughly equivalent to a household refrigerator and the cost was less than RMB800,000 (approximately 120,000, 80,000).
On 20 April 2010, USTC announced successful development of Loongson 3A based KD-60-1. The new supercomputer is a cluster of standard blade servers with a total of over 80 quad-core Loongson processors, providing theoretical peak performance of 1 TFLOPS and reduces power consumption by 56% compared to the KD-50-I system that has similar performance.
On 26 December 2012, USTC announced successful development of Loongson 3B based KD-90-1. The new supercomputer is a cluster of standard blade servers with a total of over 10 octo-core Loongson processors, providing theoretical peak performance of 1 TFLOPS, and reduces power consumption by 62% compared to the KD-60 system that has similar performance.
Dawning 6000.
The high-performance Dawning 6000, which has a projected speed of over one quadrillion operations per second, will incorporate the Loongson processor as its core. Dawning 6000 is currently jointly developed by the Institute of Computing Technology under the Chinese Academy of Sciences and the Dawning Information Industry Company. Li Guojie, chairman of Dawning Information Industry Company and director and academician of the Institute of Computing Technology, said research and development of the Dawning 6000 is expected to be completed in two years.
TopStar ATX.
Topstar has also released a pair of Mini-ATX based motherboards, the TEB-6040M and TEB-5040.
Major events.
Development of the first Loongson chip was started in 2001.
On 25 June 2008, Hu Weiwu (chief designer of Loongson processors) gave a keynote speech at ISCA 2008, held in Beijing. The topic of the speech was "Research and Development of Godson processors".
2010 January, Jiangsu province plans to buy 1.5 million Loongson PCs.