3 ms·

Lichee Pi 4A: Serious RISC-V Desktop Computing [video]

11 points by snvzz 3y ago

gardenfelder 3y ago
https://liliputing.com/sipeed-lichee-pi-4a-is-a-modular-risc-v-mini-pc-with-up-to-16gb-ram/ https://liliputing.com/sipeed-lichee-pi-4a-is-a-modular-risc...
camel-cdr 3y ago
Here is the source code* for the CPU: https://github.com/T-head-Semi/openc910 https://github.com/T-head-Semi/openc910 * AFAIK they didn't opensource the pre ratification vector extension implementation they ship with the taped out chip.
- deleted 3y ago
  [deleted]
imtringued 3y ago
I want to correct a recent post I made about the Vision Star Five. That board is only competitive against the Raspberry Pi 3. This one here actually is on a level playing field as the Raspberry Pi 4. https://sipeed.com/licheepi4a https://sipeed.com/licheepi4a In practice, the lack of vector instructions significantly limits the performance of the processors. So they tend to perform poorly in Geekbench or the Phoronix benchmarks. Anyway. The reason why RISC-V will beat ARM has little to do with the merits of RISC-V really. The reason is that ARM is a sclerotic company that is falling behind the competition and RISC-V as an architecture itself does nothing to beat ARM, it is the fact that everyone has become an ARM competitor that will finish off ARM. x86 is still a significant threat to both ARM and RISC-V in the datacenter, for instance because there is a semblance of competition between Intel and AMD.
- RetroTechie 3y ago
  Performance issues are 2-fold: a) As mentioned, vector extensions. If missing, big performance hit in some benchmarks. b) General software optimizations (compilers & GPU drivers in particular). A lot of these are still on the table. And thus situation should improve as software support matures further. Getting boards out there helps a lot. Developers can't fix software support without hardware to test on.
- brucehoult 3y ago
  Note that this board, the Lichee Pi 4A, has pretty good vector units, though they implement the current draft version of RVV (0.7.1) as at the time the core was designed in 2019. Significant incompatible changes were made before RVV 1.0 was ratified in November 2021 -- the general design is the same, most instructions and binary opcodes are the same, but both source code and binary incompatibilities exist. But at the same time, much useful library code such as memcpy(), strlen(), strcpy(), strcmp() etc can be binary compatible (and optimal) for both. Most toolchain and library effort is going into 1.0, of course, but if you buy one of these and want to write vectorised code you can do so using assembly language, which is much easier than using typical SIMD ISAs. For example, here is an optimised memcpy (dst, src, len in a0, a1, a2): 0000000000000000 <memcpy>: 0: 86aa mv a3,a0 0000000000000002 <.L1^B1>: 2: 00267757 vsetvli a4,a2,e8,m4,d1 6: 12058007 vlb.v v0,(a1) a: 95ba add a1,a1,a4 c: 8e19 sub a2,a2,a4 e: 02068027 vsb.v v0,(a3) 12: 96ba add a3,a3,a4 14: f67d bnez a2,2 <.L1^B1> 16: 8082 ret
RetroTechie 3y ago
Nice to see more RISC-V boards in the wild! Just the other day obtained a VisionFive 2. :-)) In comparison: Lichee Pi should be faster (+50%? 2x? 3x?). And max. 16 GB RAM vs. 4/8 GB on the VF2. Requires a carrier board. More flexible but if you only get/use 1 of that, module+carrier is more expensive than single board. VF2 GPU: IMG BXE-4-32 Lichee Pi: ?? Anyone? Much will depend on driver support though. No (working) driver for feature X, then feature X might as well be absent.
- brucehoult 3y ago
  TH1520 (Lichee Pi 4A, OoO cores similar to Arm A72) beats JH7110 (VisionFive 2 and others, in-order cores similar to Arm A55) on all micro-benchmarks. e.g. by about 40% on my branchy primes benchmark, which exercises the CPU and L1 cache only: https://hoult.org/primes.txt https://hoult.org/primes.txt 10.430 sec Sipeed LM4A TH1520 4x C910 @1.848 GHz 216 bytes 19.3 billion clocks 10.851 sec Sophon SG2042 64x C910 RV64 @1.8? GHz 216 bytes 19.3 billion clocks 12.115 sec Pi4 Cortex A72 @ 1.5 GHz A64 300 bytes 18.2 billion clocks 14.885 sec VisionFive 2 U74 _zba_zbb @ 1.5 GHz 214 bytes 22.3 billion clocks 19.500 sec Odroid C2 A53 @ 1.536 GHz A64 276 bytes 30.0 billion clocks The TH1520 has much faster memcpy speeds at every level of cache and DRAM. https://hoult.org/JH7110_memcpy.txt https://hoult.org/JH7110_memcpy.txt https://hoult.org/JH7110_memcpy.txt https://hoult.org/JH7110_memcpy.txt And yet ... both Richard Jones at Fedora and I have found that the VisionFive 2 is actually slightly faster at building software packages! My result was that building the same binutils + gcc + newlib snapshot (an old one with RVV 0.7.1 support)... https://github.com/brucehoult/riscv-gnu-toolchain https://github.com/brucehoult/riscv-gnu-toolchain ... the VisionFive 2 takes 108 minutes while the Lichee Pi 4A takes 122 minutes. That's with the supplied fan on the LPi4A (and confirmed it's not throttling) and no cooling at all on the VisionFive 2. I used the same Samsung external USB3 SSD on both -- the VisionFive 2 gets slightly faster transfer speeds (IIRC 190 MB/s vs 160) with that, but that's not enough to matter: just 12s difference on the time to tar up the source directory, compared to a 14 minute build time difference. Both have enough RAM to cache everything anyway. > VF2 GPU: IMG BXE-4-32 Lichee Pi: ?? Anyone? BXM-4-64
  - mycall 3y ago
fithisux 3y ago
Is it serious to use non-standard vector extensions? Unless you can upgrade your cpu :-)

11 points by snvzz 3y ago

https://liliputing.com/sipeed-lichee-pi-4a-is-a-modular-risc-v-mini-pc-with-up-to-16gb-ram/ https://liliputing.com/sipeed-lichee-pi-4a-is-a-modular-risc...

camel-cdr 3y ago

Here is the source code* for the CPU: https://github.com/T-head-Semi/openc910 https://github.com/T-head-Semi/openc910 * AFAIK they didn't opensource the pre ratification vector extension implementation they ship with the taped out chip.

deleted 3y ago
[deleted]

imtringued 3y ago

I want to correct a recent post I made about the Vision Star Five. That board is only competitive against the Raspberry Pi 3. This one here actually is on a level playing field as the Raspberry Pi 4. https://sipeed.com/licheepi4a https://sipeed.com/licheepi4a In practice, the lack of vector instructions significantly limits the performance of the processors. So they tend to perform poorly in Geekbench or the Phoronix benchmarks. Anyway. The reason why RISC-V will beat ARM has little to do with the merits of RISC-V really. The reason is that ARM is a sclerotic company that is falling behind the competition and RISC-V as an architecture itself does nothing to beat ARM, it is the fact that everyone has become an ARM competitor that will finish off ARM. x86 is still a significant threat to both ARM and RISC-V in the datacenter, for instance because there is a semblance of competition between Intel and AMD.

RetroTechie 3y ago
Performance issues are 2-fold: a) As mentioned, vector extensions. If missing, big performance hit in some benchmarks. b) General software optimizations (compilers & GPU drivers in particular). A lot of these are still on the table. And thus situation should improve as software support matures further. Getting boards out there helps a lot. Developers can't fix software support without hardware to test on.
brucehoult 3y ago
Note that this board, the Lichee Pi 4A, has pretty good vector units, though they implement the current draft version of RVV (0.7.1) as at the time the core was designed in 2019. Significant incompatible changes were made before RVV 1.0 was ratified in November 2021 -- the general design is the same, most instructions and binary opcodes are the same, but both source code and binary incompatibilities exist. But at the same time, much useful library code such as memcpy(), strlen(), strcpy(), strcmp() etc can be binary compatible (and optimal) for both. Most toolchain and library effort is going into 1.0, of course, but if you buy one of these and want to write vectorised code you can do so using assembly language, which is much easier than using typical SIMD ISAs. For example, here is an optimised memcpy (dst, src, len in a0, a1, a2): 0000000000000000 <memcpy>: 0: 86aa mv a3,a0 0000000000000002 <.L1^B1>: 2: 00267757 vsetvli a4,a2,e8,m4,d1 6: 12058007 vlb.v v0,(a1) a: 95ba add a1,a1,a4 c: 8e19 sub a2,a2,a4 e: 02068027 vsb.v v0,(a3) 12: 96ba add a3,a3,a4 14: f67d bnez a2,2 <.L1^B1> 16: 8082 ret

RetroTechie 3y ago

Nice to see more RISC-V boards in the wild! Just the other day obtained a VisionFive 2. :-)) In comparison: Lichee Pi should be faster (+50%? 2x? 3x?). And max. 16 GB RAM vs. 4/8 GB on the VF2. Requires a carrier board. More flexible but if you only get/use 1 of that, module+carrier is more expensive than single board. VF2 GPU: IMG BXE-4-32 Lichee Pi: ?? Anyone? Much will depend on driver support though. No (working) driver for feature X, then feature X might as well be absent.

brucehoult 3y ago
TH1520 (Lichee Pi 4A, OoO cores similar to Arm A72) beats JH7110 (VisionFive 2 and others, in-order cores similar to Arm A55) on all micro-benchmarks. e.g. by about 40% on my branchy primes benchmark, which exercises the CPU and L1 cache only: https://hoult.org/primes.txt https://hoult.org/primes.txt 10.430 sec Sipeed LM4A TH1520 4x C910 @1.848 GHz 216 bytes 19.3 billion clocks 10.851 sec Sophon SG2042 64x C910 RV64 @1.8? GHz 216 bytes 19.3 billion clocks 12.115 sec Pi4 Cortex A72 @ 1.5 GHz A64 300 bytes 18.2 billion clocks 14.885 sec VisionFive 2 U74 _zba_zbb @ 1.5 GHz 214 bytes 22.3 billion clocks 19.500 sec Odroid C2 A53 @ 1.536 GHz A64 276 bytes 30.0 billion clocks The TH1520 has much faster memcpy speeds at every level of cache and DRAM. https://hoult.org/JH7110_memcpy.txt https://hoult.org/JH7110_memcpy.txt https://hoult.org/JH7110_memcpy.txt https://hoult.org/JH7110_memcpy.txt And yet ... both Richard Jones at Fedora and I have found that the VisionFive 2 is actually slightly faster at building software packages! My result was that building the same binutils + gcc + newlib snapshot (an old one with RVV 0.7.1 support)... https://github.com/brucehoult/riscv-gnu-toolchain https://github.com/brucehoult/riscv-gnu-toolchain ... the VisionFive 2 takes 108 minutes while the Lichee Pi 4A takes 122 minutes. That's with the supplied fan on the LPi4A (and confirmed it's not throttling) and no cooling at all on the VisionFive 2. I used the same Samsung external USB3 SSD on both -- the VisionFive 2 gets slightly faster transfer speeds (IIRC 190 MB/s vs 160) with that, but that's not enough to matter: just 12s difference on the time to tar up the source directory, compared to a 14 minute build time difference. Both have enough RAM to cache everything anyway. > VF2 GPU: IMG BXE-4-32 Lichee Pi: ?? Anyone? BXM-4-64
- mycall 3y ago

fithisux 3y ago

Is it serious to use non-standard vector extensions? Unless you can upgrade your cpu :-)