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Lanai, the mystery CPU architecture in LLVM

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Re: Lanai, the mystery CPU architecture in LLVM

#42
post #4

I worked for Myricom 2001->2013, and Google 2013->2015. And, wow, I wish I could comment on this thread.. :) EDIT: Scott's Medium blog post linked from this article is fascinating: https://medium.com/swlh/myricom-an-hpc-story-and-lessons-lea...

Interesting - I had never heard of Myricom. I have used Infiniband quite a bit in budget super high performance applications - the old hardware can sometimes be found quite cheaply compared to 40gig/100gig ethernet (or it was at least a few years ago). Much more fiddly to get working but the performance was impressive once it did.

Re: Lanai, the mystery CPU architecture in LLVM

#43
post #4

I worked for Myricom 2001->2013, and Google 2013->2015. And, wow, I wish I could comment on this thread.. :) EDIT: Scott's Medium blog post linked from this article is fascinating: https://medium.com/swlh/myricom-an-hpc-story-and-lessons-lea...

This line in that post is mystifying: they peddled Infiniband, an inferior design based on bus technology, but repositioned as a point to point network

I think that's a confusing reference to the fact that InfiniBand initially was supposed to be also a replacement for system-internal buses (i.e. a PCI replacement), before PCIe took that place instead.

Re: Lanai, the mystery CPU architecture in LLVM

#45
post #4

I worked for Myricom 2001->2013, and Google 2013->2015. And, wow, I wish I could comment on this thread.. :) EDIT: Scott's Medium blog post linked from this article is fascinating: https://medium.com/swlh/myricom-an-hpc-story-and-lessons-lea...

This line in that post is mystifying: they peddled Infiniband, an inferior design based on bus technology, but repositioned as a point to point network

You can use a bus PHY in a p2p configuration.

Re: Lanai, the mystery CPU architecture in LLVM

#46
post #4

I worked for Myricom 2001->2013, and Google 2013->2015. And, wow, I wish I could comment on this thread.. :) EDIT: Scott's Medium blog post linked from this article is fascinating: https://medium.com/swlh/myricom-an-hpc-story-and-lessons-lea...

This line in that post is mystifying: they peddled Infiniband, an inferior design based on bus technology, but repositioned as a point to point network

Yeah that makes no sense.

Re: Lanai, the mystery CPU architecture in LLVM

#47

I gotta say, if I was the BDFL of llvm, I would kick this out of tree without a second thought. Why on earth should a foss project support a private architecture? How many man-hours have been wasted waiting for the Lanai backend to compile? Not to mention applying project-wide refactoring to the Lanai code.

> How many man-hours have been wasted waiting for the Lanai backend to compile? Probably zero? Is it compiled by default?

Yes. Run `strings /usr/lib/libLLVM.so| grep -i Lanai` to check on your version ; mine has all the relevant symbols

Re: Lanai, the mystery CPU architecture in LLVM

#48

Earlier quoted context omitted.

This line in that post is mystifying: they peddled Infiniband, an inferior design based on bus technology, but repositioned as a point to point network

You can use a bus PHY in a p2p configuration.

But Infiniband didn't do that.

Re: Lanai, the mystery CPU architecture in LLVM

#49
post #4

I worked for Myricom 2001->2013, and Google 2013->2015. And, wow, I wish I could comment on this thread.. :) EDIT: Scott's Medium blog post linked from this article is fascinating: https://medium.com/swlh/myricom-an-hpc-story-and-lessons-lea...

Regarding the blog post: "Why did Myricom’s second CEO fail so fast, lack of experience, and loss of respect? If one were to attempt to explain the plummeting fortunes of Myricom during the term of the second CEO, two characteristics suggest themselves:"

It seems to me the second CEO didn't care about the company, the product or the risk the previous CEO wanted to take (more investment to bring out the new chip). Instead they proposed (and got) another round of dividends for the investors, a promotion to CEO, and ultimately an aqui-hire to Google. To me this reads very simply as putting profit and self-interest ahead of the product. Understandable, and it happens all the time. If you have a vision, the best way to achieve it is to remain in control. Somehow the CEO lost that control.

Re: Lanai, the mystery CPU architecture in LLVM

#50

Earlier quoted context omitted.

> The CEO capped the full time headcount at 49 people so he wouldn’t be subject to California law requiring him to provide his employees with a health plan. Can you imagine being this stingy and short sighted? The employees are largely PhDs and he is willing to cripple his company to avoid paying benefits.

It’s not even that hard or expensive to offer 401k, health, life insurance in a startup. Been there, done that.

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