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Meanwhile, I ran right now git clone an open-source high performance out-of-order RISC-V implementation simulate the RTL, and have it out perform my current des

Meanwhile, I ran right now git clone an open-source high performance out-of-order RISC-V implementation simulate the RTL, and have it out perform my current destop cpu (Zen1) on a per cycle basis: https://camel-cdr.github.io/rvv-bench-results/articles/xperm4-utf8-validation.html https://camel-cdr.github.io/rvv-bench-results/articles/xperm... (scroll to bottom and compare scalar performance between Ryzen 1600x and XiangShanV3) You may notice that while scalar is faster, the vector performance is slower, this is because their vector implementation is still quite new, and they are still missing a few optimizations. XiangShan repo: https://github.com/OpenXiangShan/XiangShan https://github.com/OpenXiangShan/XiangShan More micro architectural details: https://www.servethehome.com/xiangshan-high-performance-risc-v-processors-at-hot-chips-2024/ https://www.servethehome.com/xiangshan-high-performance-risc... BTW, XiangShanV2 has already been taped out and will be available in an laptop in the future: https://milkv.io/ruyibook https://milkv.io/ruyibook

adrian_b 2y ago
If what you say is correct about the comparison with Zen 1, you should keep in mind that Zen 1 (of which I also still have one) has an IPC equivalent with that of Intel Broadwell, a CPU launched in 2014, i.e. 10 years ago. (In the following years AMD has reduced then eliminated their initial handicap of 3 years, with Zen 2 matching Skylake in IPC, and then from Zen 3 until now they have always matched in IPC the best contemporaneous Intel cores.) So even such an unusually fast RISC-V core has 10 years of handicap to recover until being able to match modern CPU cores, like the Apple and Qualcomm Arm cores or like the current AMD and Intel cores. Moreover, unless your RTL simulation includes cache memories and slow DRAM memory, the simulated IPC will be far too optimistic. In any real CPU the IPC is diminished a few times from its ideal values by the cache misses that stall the CPU until data is loaded from the main memory.
- phkahler 2y ago
  >> If what you say is correct about the comparison with Zen 1, you should keep in mind that Zen 1 (of which I also still have one) has an IPC equivalent with that of Intel Broadwell, a CPU launched in 2014, i.e. 10 years ago. So I just upgraded my Zen1+ processor (2400G) to a Zen3 (5700G) which doubled the core count and upped single core performance by about 50 percent. My favorite benchmark runs 3x as fast. Now Zen5 AFAICT is not more than 2x the performance of Zen3. So per-core the state of the art AMD is maybe 3x that of Zen1. In the last 10+ years the only significant jump due to an advanced node was with the switch to EUV lithography (TSMC 7nm) and that jump was included between Zen1 and Zen3. All the other node advancements seem to be 10-15 percent performance with new CPUs getting a modest IPC increase on top of that. If there really is a RISC-V chip with Zen1 performance that's really quite good and I'd be happy to have it. Not sure what node it's on either, so there's probably room to "buy" more performance.
- brucehoult 2y ago
  > even such an unusually fast RISC-V core has 10 years of handicap to recover until being able to match modern CPU core Yes. But why do you say this as if it's news, or even bad news? Two years ago the best RISC-V core in the market had 30 years of handicap to x86/PowerPC in IPC. Catching up by 20 years in 2 years is pretty impressive, don't you think? Parity is coming well before 2030, even allowing for x86 advances in that time.

adrian_b 2y ago

If what you say is correct about the comparison with Zen 1, you should keep in mind that Zen 1 (of which I also still have one) has an IPC equivalent with that of Intel Broadwell, a CPU launched in 2014, i.e. 10 years ago. (In the following years AMD has reduced then eliminated their initial handicap of 3 years, with Zen 2 matching Skylake in IPC, and then from Zen 3 until now they have always matched in IPC the best contemporaneous Intel cores.) So even such an unusually fast RISC-V core has 10 years of handicap to recover until being able to match modern CPU cores, like the Apple and Qualcomm Arm cores or like the current AMD and Intel cores. Moreover, unless your RTL simulation includes cache memories and slow DRAM memory, the simulated IPC will be far too optimistic. In any real CPU the IPC is diminished a few times from its ideal values by the cache misses that stall the CPU until data is loaded from the main memory.

phkahler 2y ago
>> If what you say is correct about the comparison with Zen 1, you should keep in mind that Zen 1 (of which I also still have one) has an IPC equivalent with that of Intel Broadwell, a CPU launched in 2014, i.e. 10 years ago. So I just upgraded my Zen1+ processor (2400G) to a Zen3 (5700G) which doubled the core count and upped single core performance by about 50 percent. My favorite benchmark runs 3x as fast. Now Zen5 AFAICT is not more than 2x the performance of Zen3. So per-core the state of the art AMD is maybe 3x that of Zen1. In the last 10+ years the only significant jump due to an advanced node was with the switch to EUV lithography (TSMC 7nm) and that jump was included between Zen1 and Zen3. All the other node advancements seem to be 10-15 percent performance with new CPUs getting a modest IPC increase on top of that. If there really is a RISC-V chip with Zen1 performance that's really quite good and I'd be happy to have it. Not sure what node it's on either, so there's probably room to "buy" more performance.
brucehoult 2y ago
> even such an unusually fast RISC-V core has 10 years of handicap to recover until being able to match modern CPU core Yes. But why do you say this as if it's news, or even bad news? Two years ago the best RISC-V core in the market had 30 years of handicap to x86/PowerPC in IPC. Catching up by 20 years in 2 years is pretty impressive, don't you think? Parity is coming well before 2030, even allowing for x86 advances in that time.