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Qwen 3.8 27B available on Cerebras at 1500 tokens/s

inference-docs.cerebras.ai

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Re: Qwen 3.8 27B available on Cerebras at 1500 tokens/s

#151

I have a self hosted Qwen 3.8 27B and I find it to be unusably bad. Using it agentically, it will spin around in circles on even small tasks talking to itself until it loses context and starts again. I even had it say "I've forgotten the users initial question"

Check sampling parameters and chat template, make sure you have adequate context window, turn reasoning effort down. It should be able to one shot a small app without intervention.

Re: Qwen 3.8 27B available on Cerebras at 1500 tokens/s

#152

150k TPM limit on public endpoint means that it's likely unusable for many coding tasks. When we've tried Cerebras in the past, our problem has always been rates. We'd love to not deal with dedicated and to have access to a more flexible rate pool. Even trying it out, it seems like our account has gotten moved to some limbo where we can no longer add billing information. ``` Billing access restricted Self-serve billi…

What kind of coding tasks would you expect to hit that limit? In my setup, on a very large codebase, it takes each agent 3-4 minutes at minimum to go past 100k tokens. (note it's 150k uncached tokens , the total limit is 450k/min)

So that’s about 400 tok/sec. Times that by 3, you get 100k in under a minute. That’s doing nothing special and just using your current setup.

Re: Qwen 3.8 27B available on Cerebras at 1500 tokens/s

#154

150k TPM limit on public endpoint means that it's likely unusable for many coding tasks. When we've tried Cerebras in the past, our problem has always been rates. We'd love to not deal with dedicated and to have access to a more flexible rate pool. Even trying it out, it seems like our account has gotten moved to some limbo where we can no longer add billing information. ``` Billing access restricted Self-serve billi…

all the above. They just simply do not care about non enterprise customers. Today they announced qwen, guess what - it's also the same day they pulled Gemma off their shared tier. No migration notice and all developers are scrambling as we speak trying to migrate. They gave a soft head-ups on discord a week ago and when folks complained about zero-day migration they started saying 'you aren't suppose to build production app on shared tier'.

Re: Qwen 3.8 27B available on Cerebras at 1500 tokens/s

#155
post #132

Earlier quoted context omitted.

Is this the chatjimmy asic approach with a bigger model?

No, the asic could only ever run one model/set of weights, no updates possible, ever. These are general purpose processors that can have their models updated. But the chips are enormous, with a substantial amount of on-die memory alongside the execution units, for a relatively insane amount of memory bandwidth.

I thought from what I read about the Taalas approach, the model architecture and overall size couldn't be changed, but model weight values could be updated after for further tuning.

Not as flexible as Cerebras though. And I'd love for someone who knows more to clue me in to the truth.

Re: Qwen 3.8 27B available on Cerebras at 1500 tokens/s

#156
post #66

Earlier quoted context omitted.

They have cache, but it costs the same indeed, no idea what the point of the cache is

They don't have cache (e.g. KV cache). But they write down what you sent earlier to say they cached it! To still bill the same as uncached later (because they didn't actually cache it)!

More precisely they can't cache it.

Re: Qwen 3.8 27B available on Cerebras at 1500 tokens/s

#157
post #50

Just tried it on a medium size coding/debug problem on an existing codebase, observations: - Input doesn't look faster than other models, it spends a lot of time reading Read about 5M tokens - Output is awesome, super fast as you expect from the 1500t/sec I think that's correct - Tool call is failing more than say DS4, which leads to time wasted on retries (complex tools like browser control for example) - Shell comm…

I can't believe this situation has not improved in years. Is cerebras' main business selling the hardware, then?

they have exactly two customers, both of whom are also investors.

Re: Qwen 3.8 27B available on Cerebras at 1500 tokens/s

#158
post #76
post #70

Earlier quoted context omitted.

> There is a limit of 450,000 tokens per minute. I hit this limit in about 90 seconds I'm confused. If it's 1500t/s, isn't that only 90k per minute? How do you hit a 450k/minute limit?

Cached tokens count towards the limit as well. For example, if your context window is 50,000 tokens, it takes 9 requests to reach that limit without generating a single token.

Cached tokens counting toward the limit is ridiculous.

Re: Qwen 3.8 27B available on Cerebras at 1500 tokens/s

#159

Earlier quoted context omitted.

It's a limit on input tokens. So that's 3 50k requests per minute. At Cerebras speeds, that's about 5 seconds of usage per minute. I was very excited last year for their coding plan but seeing a burst of requests pulse and then sitting there watching the cooldown reset is really not a great time. Even though each individual request was fast, the sessions were only maybe 10% faster on wall clock time since there was s…

They made the coding plan a bit better toward the end, but it was pretty tough to use throughout. Seems like an Amdahl’s law of inference economics? there’s so much compute relative to SRAM on the chip and shoreline bandwidth onto the chip that caching buys ~nothing? The contended resource is SRAM and a given token of context needs just as much as another.

That’s not what caching is for. Caching lets you resume with a pre computed KV cache saving you from having to ingest everything in the chat history as input on every single round trip. You still need caching regardless of SRAM or not as it saves a huge amount (and ever growing) of compute ingesting the preceding history every time you want a completion.

I don’t know why they don’t give a price discount. Maybe their hardware is incapable for some reason of saving/restoring the state? Or maybe they just haven’t built the infrastructure to do it?

Re: Qwen 3.8 27B available on Cerebras at 1500 tokens/s

#160
post #48

Just a couple days ago I learned about ninfer ( https://github.com/Neroued/ninfer ) and on RTX 5090 I can now get ~200 tok/s and over 400 tok/s on concurrent requests which is plenty fast for a local model of this strength.

Ok, I need to try that. I'm getting 45tok/s with vLLM on my 6000. >600tok/s concurrent, but 45tok/s single request.

Even without ninfer I would get over 80 on LM studio with default settings, so it should be noticeably more on 6000. You might want to try different a different inference engine or settings.
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