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sakras | 1 year ago
This is needlessly aggressive. I specialize in writing SIMD code. That is my job. I am very eager to get my hands on a RVV chip so that I can play with a new SIMD ISA. So obviously a non-SIMD chip is useless to me.
> Why would you expect it to have vector extensions?
Because it has "Performance" in the name. I double-checked the ISA and saw that it did not have V, and was disappointed.
> If you don't need RISC-V this year then
Why would anybody _need_ RISC-V? RISC-V is exciting because it has the possibility of giving the end user higher performance per dollar. Until it does that, it will relegated to enthusiasts who just like playing with new ISAs.
brucehoult|1 year ago
I apologise.
> I specialize in writing SIMD code. That is my job. I am very eager to get my hands on a RVV chip
The P550 core was announced in June 2021, 2 1/2 years ago. It was stated at the time that it doesn't have RVV.
The X270, announced the same day, is a dual-issue in-order core that DOES have RVV.
https://www.sifive.com/press/sifive-performance-p550-core-se...
I've also been eagerly waiting for RVV 1.0 hardware (and programmed RVV 0.7.1 hardware in the meantime, as a very close proxy ... and the C910 has a quite high performance implementation as an OoO core with dual vector pipelines) so I follow the news, mostly on Reddit's /r/riscv.
Boards with in-order cores implementing RVV 1.0 have been shipping since November 2023.
Those of us who follow the news have been eagerly awaiting the SG2380 SoC and Milk-V Oasis (and other) boards with it. Sixteen 2.5 GHz OoO SiFive P670 cores with RVV, plus 8 SiFive X280 cores with RVV as an NPU.
This was originally announced in October 2023 with predicted delivery in September 2024 (which tbh was never believable, and I expressed that at the time), then January 2025, and then late 2025 (which probably should have been the target in the first place), and now it may be cancelled because of US government sanctions.
> Because it has "Performance" in the name.
That comes from marketers, not engineers.
But it is indeed the fastest RISC-V available today, per core, on real-world scalar code, by a factor of 2. (The C910 is close on code that runs from L1 cache, maybe L2).
> Why would anybody _need_ RISC-V?
At the moment because they want to develop software to be ready when the machines competitive with the top end of Arm and/or x86 do arrive. Or if the current performance and price level already meets their needs e.g. Samsung with their future line of TVs (prototype already demonstrated at a show) using the P470 core. Samsung has had a team porting and optimising their Tizen OS and Microsoft's CoreCLR JIT for about two years now. No doubt similar activity is happening at LG, who have also announced switching to RISC-V.
> has the possibility of giving the end user higher performance per dollar. Until it does that
We are already more than half way from ratification of the base ISA in mid 2019 to that date. Probably 2/3 of the way. The SoCs that will do that are already on the drawing boards. Time is short and there is much to do.