Anthropic's original take home assignment open sourced • Hacker News Board

Re: Anthropic's original take home assignment open sourced

#361

Post by mike_hearn » Thu, Jan 22, 2026, 9:58 AM UTC

HarHarVeryFunny wrote: post #319

fc417fc802 wrote: post #304

Earlier quoted context omitted.

Presumably that is only one of two purposes, with the other being to test your ability to efficiently read, understand, and edit low level code that you didn't write. I imagine you'd regularly run into raw PTX if you worked for them in the relevant capacity. And perhaps a third purpose is to use the simulator to test your ability to reason about hardware that you are only just getting familiar with.

I would assume that anyone optimizing kernels at Anthropic has full documentation and specs for what they are working on, as well as a personal butler attending to their every need. This is big money work - every 1% performance improvement must translate to millions of cost savings. Maybe they specified the challenge in this half-assed way to deliberately test those sorts of skills (even if irrelevant to the job), or…

> as well as a personal butler attending to their every need

I think they do and his name is Claude ;)

Re: Anthropic's original take home assignment open sourced

#362

Post by mike_hearn » Thu, Jan 22, 2026, 9:59 AM UTC

matt_d wrote: post #289

owlbite wrote: post #247

Earlier quoted context omitted.

I think calling VLIW "an adandoned design" is somewhat of an exaggeration, such architectures are pretty common for embedded audio processing.

Worth adding on that note: From JAX to VLIW: Tracing a Computation Through the TPU Compiler Stack, https://patricktoulme.substack.com/p/from-jax-to-vliw-tracin... Google’s Training Chips Revealed: TPUv2 and TPUv3, HotChips 2020, https://hc32.hotchips.org/assets/program/conference/day2/Hot... Ten Lessons From Three Generations Shaped Google’s TPUv4i, ISCA 2021, https://gwern.net/doc/ai/scaling/hardware/2021-jouppi.pdf

Thanks, that JAX writeup was interesting.

Re: Anthropic's original take home assignment open sourced

#363

Post by WithinReason » Thu, Jan 22, 2026, 1:21 PM UTC

amirhirsch wrote: post #293

I'm at 1137 with one hour with opus now... Pipelined vectorized hash, speculation, static code for each stage, epilogues and prologues for each stage-to-stage... I think I'm going to get sub 900 since i just realized i can in-parallel compute whether stage 5 of the hash is odd just by looking at bits 16 and 0 of stage 4 with less delay.....

Submit it to the leaderboard: https://www.kerneloptimization.fun/

Re: Anthropic's original take home assignment open sourced

#364

Post by amirhirsch » Thu, Jan 22, 2026, 2:48 PM UTC

WithinReason wrote: post #363

amirhirsch wrote: post #293

I'm at 1137 with one hour with opus now... Pipelined vectorized hash, speculation, static code for each stage, epilogues and prologues for each stage-to-stage... I think I'm going to get sub 900 since i just realized i can in-parallel compute whether stage 5 of the hash is odd just by looking at bits 16 and 0 of stage 4 with less delay.....

Submit it to the leaderboard: https://www.kerneloptimization.fun/

I think I can hit #1 (current #1 is 1000). sub 900 not possible though.

Let me put down my thought process: You have to start to think of designing a 6-slot x8-len vector pipeline doing 48 hashes in parallel first which needs at least 10 steps —- if you convert three stages to multiply adds and do parallel XORs for the other three) —- the problem with 10 cycle hashing is you need to cram 96 scalar xors along side your vector pipeline, so that will use all 12 ALUs for 8 of those cycles. Leaving you only 24 more scalar ops per hash cycle which isn’t enough for the 48 tree value xors..

so you must use at least 11 steps per hash, with 96 xors (including the tree value xor) done in the scalar alus using 8 steps, and giving 3*12 Alu ops per hash cycle. You need 12 more ops per hash to do odd/even, so you must be 12 stages, and just do all of the hash ops in valu, 4 cycles of 12 alus doing modulo, 8 cycles x 12 alus free

With 12 steps and 48 parallel you’re absolute minimum could be 4096/48 x 12 = 1,024 cycles, since stage 10 can be optimized (you don’t need the odd/even modulo cycle, and can use some of those extra scalar cycles to pre-xor the constant can save you ~10 cycles. 1024 gonna be real hard, but I can imagine shenanigans to get it down to 1014, sub-1000 possible by throwing more xor to the scalar alus.

Re: Anthropic's original take home assignment open sourced

#365

Post by cheikhcheikh » Thu, Jan 22, 2026, 5:33 PM UTC

johnnyanmac wrote: post #350

scottyah wrote: post #295

Earlier quoted context omitted.

I think the job is to be one of the few that's better than LLMs.

And how would one do that these days if they didn't spend their career doing this pre-LLM? Just expect to study and perform such projects as a hobby for a few years on the side? These are specialized problems that you only really do for a few select companies.

I mean yeah... You kind of have to learn this stuff (performance engineering) by yourself (a strong education background helps a lot of course). There are transferable parts of it and there are platform-specific parts where you need to be somewhat familiar with GPUs.

Re: Anthropic's original take home assignment open sourced

#366

Post by 0xffff2 » Thu, Jan 22, 2026, 6:20 PM UTC

WithinReason wrote: post #227

WithinReason wrote: post #185

Earlier quoted context omitted.

After a quick look this is can be seen as a low level GPU/TPU optimization problem where you have to consider the throughput and depth of different arithmetic pipelines. If you want to hire people who understand how to do that you unfortunately have to give them such a convoluted task and emulate the relevant parts of HW. (In reality this is probably more like TPU since it has scalar pipelines, but the optimization m…

This also shows that a performance engineer's job, even at Anthropic, is to be a glorified human compiler, who is often easily beaten by LLMs.

> who is often easily beaten by LLMs

Is that really the case? My experience is fairly limited, but I've found that the LLM's willingness to fill in plausible sounding (but not necessarily at all accurate) numbers where it needs them to be a significant hindrance when asking it to think about performance.

Re: Anthropic's original take home assignment open sourced

#367

Post by nostrademons » Thu, Jan 22, 2026, 6:32 PM UTC

epiccoleman wrote: post #353

nostrademons wrote: post #249

Earlier quoted context omitted.

Also bears all the hallmarks of an ordinary post (by someone fairly educated) on the Internet. This would make sense, because LLMs were trained on lots of ordinary posts on the Internet, plus a fair number of textbooks and scientific papers.

The — character is the biggest cause of suspicion. It's difficult to type manually so most people - myself included - substitute the easily typed hyphen. I know real people do sometimes use it, but it's a smell.

I think some software will automatically substitute "smart quotes" for regular quotes and an em-dash for a double hyphen -- I know MS Word used to do this. Curious if any browsers do. This comment was typed in Brave, which doesn't appear to, but I didn't check if Chrome or IE or Opera does.

Re: Anthropic's original take home assignment open sourced

#368

Post by pclmulqdq » Thu, Jan 22, 2026, 6:40 PM UTC

Aurornis wrote: post #339

pclmulqdq wrote: post #308

Earlier quoted context omitted.

Yeah, I have told HR people this and been rejected. I do say this upfront because I don't want to send you a surprise bill. The main response I get is "OK, that's fine, don't spend more than 4 hours on it." The Anthropic recruiter told me, "no problem, it's a 4-hour test anyway."

> I do say this upfront because I don't want to send you a surprise bill. Sending a company a surprise bill that they didn't agree upon is bad practice. Interviews are customarily not compensated, so it's unreasonable to surprise bill someone for it. If you send a company a surprise bill for the interview, it's going to give the HR people a good laugh as they cross you off the candidates list. Everyone involved is go…

I only mention this because I think some people have done that.

Re: Anthropic's original take home assignment open sourced

#369

Post by bird0861 » Thu, Jan 22, 2026, 7:48 PM UTC

bird0861 wrote: post #68

pvalue005 wrote: post #27

I suspect this was released by Anthropic as a DDOS attack on other AI companies. I prompted 'how do we solve this challenge?' into gemini cli in a cloned repo and it's been running non-stop for 20 minutes :)

Which Gemini model did you use? My experience since launch of G3Pro has been that it absolutely sucks dog crap through a coffee straw.

Hilarious that this got a downvote, hello Satya!

Re: Anthropic's original take home assignment open sourced

#370

Post by johnnyanmac » Thu, Jan 22, 2026, 9:34 PM UTC

cheikhcheikh wrote: post #365

johnnyanmac wrote: post #350

Earlier quoted context omitted.

And how would one do that these days if they didn't spend their career doing this pre-LLM? Just expect to study and perform such projects as a hobby for a few years on the side? These are specialized problems that you only really do for a few select companies.

I mean yeah... You kind of have to learn this stuff (performance engineering) by yourself (a strong education background helps a lot of course). There are transferable parts of it and there are platform-specific parts where you need to be somewhat familiar with GPUs.

Seeks like another catch 22 when companies still care about 3-5 years of experience in industry, even if you work on some hobby projects. I'm not in this sector but I had similar struggles getting noticed in another specific domain despite studying it for a while.