Discussion RISC V Latest Developments Discussion [No Politics]

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DisEnchantment

Golden Member
Mar 3, 2017
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Some background on my experience with RISC V...
Five years ago, we were developing a CI/CD pipeline for arm64 SoC in some cloud and we add tests to execute the binaries in there as well.
We actually used some real HW instances using an ARM server chip of that era, unfortunately the vendor quickly dumped us, exited the market and leaving us with some amount of frustration.
We shifted work to Qemu which turns out to be as good as the actual chips themselves, but the emulation is buggy and slow and in the end we end up with qemu-user-static docker images which work quite well for us. We were running arm64 ubuntu cloud images of the time before moving on to docker multi arch qemu images.

Lately, we were approached by many vendors now with upcoming RISC-V chips and out of curiosity I revisited the topic above.
To my pleasant surprise, running RISC-V Qemu is smooth as butter. Emulation is fast, and images from Debian, Ubuntu, Fedora are available out of the box.
I was running ubuntu cloud images problem free. Granted it was headless but I guess with the likes of Imagination Tech offering up their IP for integration, it is only a matter of time.

What is even more interesting is that Yocto/Open Embedded already have a meta layer for RISC-V and apparently T Head already got the kernel packages and manifest for Android 10 working with RISC-V.
Very very impressive for a CPU in such a short span of time. What's more, I see active LLVM, GCC and Kernel development happening.

From latest conferences I saw this slide, I can't help but think that it looks like they are eating somebody's lunch starting from MCUs and moving to Application Processors.


And based on many developments around the world, this trend seems to be accelerating greatly.
Many high profile national and multi national (e.g. EU's EPI ) projects with RISC V are popping up left and right.
Intel is now a premium member of the consortium, with the likes of Google, Alibaba, Huawei etc..
NVDA and soon AMD seems to be doing RISC-V in their GPUs. Xilinx, Infineon, Siemens, Microchip, ST, AD, Renesas etc., already having products in the pipe or already launched.
It will be a matter of time before all these companies start replacing their proprietary Arch with something from RISC V. Tools support, compiler, debugger, OS etc., are taken care by the community.
Interesting as well is that there are lots of performant implementation of RISC V in github as well, XuanTie C910 from T Head/Alibaba, SWerV from WD, and many more.
Embedded Industry already replaced a ton of traditional MCUs with RISC V ones. AI tailored CPUs from Tenstorrent's Jim Keller also seems to be in the spotlight.

Most importantly a bunch of specs got ratified end of last year, mainly accelerated by developments around the world. Interesting times.
 

DZero

Senior member
Jun 20, 2024
992
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Chips & Cheese benchmarked SiFive P550 and T-HEAD C910: https://chipsandcheese.com/p/a-risc-v-progress-check-benchmarking

Due to low clocks (1.4GHz and 1.85GHz) these 2 OoO cores have roughly the same performance as a well implemented IoO Cortex-A55 at 2GHz.
Also to note is the lack of support for x264.
Indeed, even more, the SiFive is far better with lower clocks than the C910, implying that the latter had an awful implementation.

I expected them on the tier of the Intel Core 2 Duo tier, but SiFive is on par with Pentium D and the C910 is on the level of Pentium 4!

However what I wanted is seeing how the A55 fares against Huawei's small Taishan.... spoiler: got wrecked in floating point. And consider that Huawei uses a subpar process with SMIC N+2. That explains why the A510 is subpar too.

 

MS_AT

Senior member
Jul 15, 2024
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I've not heard of either being in something the average Joe could buy.
Not that I would like to buy one, but I thought that Veyron was targeting mainstream servers and with Ascalon I was in general curious about the capabilities. So I would expect some whitepapers to appear, maybe some benchmarks scores in the wild. If we are lucky a C&C article. But it's awfully quiet. I mean at least a press info they were already launched and found some customers would be something
 

Nothingness

Diamond Member
Jul 3, 2013
3,292
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Not that I would like to buy one, but I thought that Veyron was targeting mainstream servers and with Ascalon I was in general curious about the capabilities. So I would expect some whitepapers to appear, maybe some benchmarks scores in the wild. If we are lucky a C&C article. But it's awfully quiet. I mean at least a press info they were already launched and found some customers would be something
It looks like average Joe can only buy Tensix machines with what they call "baby RISC-V cores".

EDIT: https://tenstorrent.com/hardware/wormhole
 

soresu

Diamond Member
Dec 19, 2014
3,708
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It looks like average Joe can only buy Tensix machines with what they call "baby RISC-V cores".

EDIT: https://tenstorrent.com/hardware/wormhole
Those are accelerator cards.

The RISC-V CPU cores are just there to pull everything else together, sort of like the async compute silicon part of GCN/RDNA/CDNA I think.

IMHO I do think that there is definitely some mileage in offloading drivers to an onboard processor, I wonder if AMD have looked into this at all.
 

Nothingness

Diamond Member
Jul 3, 2013
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Huh. What is Keller's position then? Front man for recognition? Keller's got the rep, but for all we know, Wei-Han may be an absolute genius. Or not.
Keller is the CEO, he has better things to do than leading the team designing a core, especially given that the core isn't the main product of the company. Which doesn't mean he does not provide inputs for the CPU design.
 

soresu

Diamond Member
Dec 19, 2014
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Yeah so he's basically the frontman trading on his rep
Given what happened with the last smol company (PA Semi) he was part of I can imagine it's definitely not a rep he minds having.

Plus he's spent the rest of his career on lower if important rungs of the corporate ladder.

I imagine he's appreciating the new experiences in organisational structure, while also the potentially greater financial benefits a CEO is likely to reap.
 
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NostaSeronx

Diamond Member
Sep 18, 2011
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The C930 is listed on the Xuantie website: https://www.xrvm.cn/product/xuantie/C930
512-bit -> 256-bit on Vector Registers. (Could be like C910/C920 where VLEN=2 is single-cycle)
Supports WMO(weakly-ordered memory) and TSO(total store order).
Additional stuff, that isn't fully complete:
- RISC-V Zalasr (Atomic, Load-Acquire Store-Release)
- Confidential VM Extension (CoVE) confidential computing architecture for RISC-V application-processor platforms
- smmtt -- Supervisor Domain Access Protection - RISC-V privileged architecture extension to support physical address space (memory and devices) isolation for more than one supervisor domain use cases for RISC-V platforms. Use cases may use supervisor domains to reduce the supervisor Trusted Computing Base (TCB), with differential access to memory and other platform resources e.g. Confidential Computing (CoVE), Security Services, Secure Devices etc.
Additional Matrix Cache unit.

Also, Athena Chiplet from Tenstorrent;

35-score N-total is about 8c/16t Zen3.
 
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NostaSeronx

Diamond Member
Sep 18, 2011
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I expected more than equivalence to a 4+ yr old 4 wide µArch like from an 8 wide design like Ascalon.
If based on Ascalon Cluster/Aegis numbers it should be 8-cores @ 2.1 GHz around 6W TDP.

128 cores @ 2.1 GHz = 95W/107 mm2 on N4 or based on the HPC Superchip slide on N3E = 2x128 (3 GHz?) at ~300 mm2
8 cores @ 2.1 GHz = ~5.94W/6.69 mm2

However, we have to wait till samples(2025)/products(2026) to actually get the specs. Tone done the expectations it isn't a core chasing 6 GHz.
 

camel-cdr

Member
Feb 23, 2024
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This graph is actually the biggest source of SPEC2006/GHz estimates for newer processors I've seen so far.
Since RISC-V companies still mostly publish SPEC2006/GHz, I added some additional cores into the graph (without release date):
 
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soresu

Diamond Member
Dec 19, 2014
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As to the CPU core naming convention of Tenstorrent:

From what I can find Callandor seems to be a reference to a magical power up called a sa'angreal in the form of a sword from the Wheel of Time saga.

Ascalon on the other hand shows up as a sword in numerous Final Fantasy games.

So I would assume that fantasy swords are their naming convention for the time being.
 
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Nothingness

Diamond Member
Jul 3, 2013
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This graph is actually the biggest source of SPEC2006/GHz estimates for newer processors I've seen so far.
No one uses SPEC2006 anymore except RISC-V CPU makers. The excuse of compiler immaturity has lived long enough; if compilers still are not mature enough to properly compile SPEC2017, then the RISC-V ecosystem has other troubles than trying to gain the performance crown. I wouldn't be surprised to see SPEC2025, at which point R-V CPU makers will use a 20 yo benchmark.

That being said, Tenstorrent are making huge claims here. Saying I'm doubtul would be an understatement. Especially given that, as far I know, no one has public access to Ascalon.
 
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DrMrLordX

Lifer
Apr 27, 2000
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@soresu


Ascalon/Ashkelon is in modern Israel.

This graph is actually the biggest source of SPEC2006/GHz estimates for newer processors I've seen so far.
Since RISC-V companies still mostly publish SPEC2006/GHz, I added some additional cores into the graph (without release date):
Speaking of release dates, when can we expect P870 dev boards to be commercially-available? P550 has been available for awhile, but it's not as interesting a product.
 
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soresu

Diamond Member
Dec 19, 2014
3,708
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@soresu


Ascalon/Ashkelon is in modern Israel.
I noticed as much while trawling for correlations between the 2 different codenames.

TT's codename nomenclature is definitely fantasy swords related though.

Callandor is basically WoT's version of Excalibur (WoT is heavily Arthur/Vulgate cycle influenced, the "dragon reborn" is pretty much Arthur in yet another reincarnation after many before).

If not for Google I definitely wouldn't have seen the correlation, as the Ascalon sword isn't in pre FF10 games, and I've not played any >FF10 games beyond the intro to FF10.
 
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