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Isn’t RISC-V still trying to catch up to A55, which is a 10 year old architecture?
by manuelabeledo 3y ago
Isn’t RISC-V still trying to catch up to A55, which is a 10 year old architecture?
- speed_spread 3y agoIMO The first market RISC-V will be competitive in is microcontrollers. Cortex-M is very popular but it wouldn't take that much for it to start being replaced by home-growned Chinese MCUs.
- snvzz 3y agoSiFive U74 > A55. Smaller, less power, faster. It has also been available for a while (years). Today, it is found in the cheap VisionFive 2, Star64 and Milk-V SBCs.
- manuelabeledo 3y agoThe only comparison between these two I could find [0] gives an advantage to the U74 in a synthetic benchmark, but also clarifies that it does not have vector instruction support. It is nice to see competition to ARM in the embedded market, but it is still far behind. [0] https://www.elektroniknet.de/international/from-microcontroller-to-multicore-processor.191302/seite-3.html https://www.elektroniknet.de/international/from-microcontrol...
- snvzz 3y agoFor U74 with vector support, look at X280 instead. It's pretty much the U74 microarchitecture with an added vector unit. Google is one of the X280 licensees, already using the resulting chips, where they paired the X280 with a specialized accelerator, using a very tight interface between accelerator and cpu, co-designed with SiFive. P670 and P470 are newer, vector-enabled higher performance designs.
- manuelabeledo 3y agoSo higher power draw? This all reads like moving goalposts to me.
- snvzz 3y agoCortex A53/A55 are less efficient than the U74.
- manuelabeledo 3y agoYet you haven’t provided any proof of this. Best I could find is that boards based on either A55 or U74 have a power draw to wall of ~5W under load, with negligible differences in performance.
- snvzz 3y ago>Yet you haven’t provided any proof of this. I learned about it from press releases back when it launched. Here's the first one I found with 15 seconds of Google effort[0]. Relevant page is 5. SiFive has since revised U74's design multiple times providing even higher performance on the same envelope[1]. >Best I could find is that boards based on either A55 or U74 have a power draw to wall of ~5W under load, with negligible differences in performance. SBCs typically have hardware besides the SoC, and the CPUs themselves constitute a small part of the draw of the SoCs used, which in the first place could be fabbed on different nodes. They do not make for very useful comparisons, e.g. my pi4 and VisionFive2 have virtually the same power draw, but the VF2 has a M.2 SSD mounted, whereas the RPi4 does not support USB-PD, so there should be further losses in voltage conversion. Too many variables hide CPU power efficiency. 0. https://c.a.segger.com/fileadmin/documents/Press_Articles/2021/211110_EN_Press_elektroniknet_SEGGER_RISC_V_Processors_new.pdf https://c.a.segger.com/fileadmin/documents/Press_Articles/20... 1. https://linuxgizmos.com/sifive-speeds-up-risc-v-u74-cores-as-canaan-unveils-a-3-tops-kendryte-k510/ https://linuxgizmos.com/sifive-speeds-up-risc-v-u74-cores-as...
- manuelabeledo 3y agoSo the link contents are essentially marketing material coming from SiFive? Alright then.