LLVM Patches Confirm Google Has Its Own In-House Processor

http://www.phoronix.com/scan.php?page=news_item&px=Google-Lanai-Architecture

by buserror • 10 years ago

165 55 10 years ago

TheCoreh• 10 years ago

Now, would it even make sense to merge into the mainline codebase of LLVM backend code targeting a platform that noone else can test or use?

Is Google planning on eventually releasing this architecture publicly or maybe licensing it to third party manufacturers, a-la ARM?

lhecker• 10 years ago

Maybe they just don't want to backport their backend code again and again for every LLVM snapshot they do, because that can be a tedious thing to do compared to just having it in origin/master forever for free.

iainmerrick3• 10 years ago

What makes that tedious? And can't it be fixed?

jacquesm• 10 years ago

Without the ability to test though they will still have to do a bunch of work in order to be able to use a new release. Possibly the release breaks their backend but nobody will know until google tries to use it.

usrusr• 10 years ago

For Google, sure. Everybody working with the in-house hardware could do so without hunting for a version of the internal patch/fork. Using the fork would surely be easy enough when directly using LLVM, but the deeper it is hidden within a dependency tree, the more friction it adds to whatever the user at the root of that tree is doing.

Everybody else pays a small "maintenance tax" when working on the codebase or relying on work being done on that codebase.

Being by no means a compiler expert I do suspect however, that this "tax" is tiny and likely to be dwarfed by other contributions from Google, so letting them solve distribution of their private backend by piggybacking on the public release is most likely the right course of action.

tyingq4• 10 years ago

It appears to be for the Myricom LanAI processor, which is available to others. It's an older 32 bit RISC processor, used as the offload engine for their NIC cards.

Here's gcc for it: https://github.com/myri/lanai-gcc

Sounds like it's not particularly interesting unless you want to write your own network offload code.

Edit: Probably just the offload processor they are choosing for their in-house routers/switches/servers. And, probably they want their own firmware either for security/nsa reasons, or performance, or both.

mikecb• 10 years ago

I thought this too, but someone in the email thread explicitly mentioned the myricom, and the _response_ to that message was that it was purely internal hardware, not useful for others...so it may just be a coincidence.

JabavuAdams• 10 years ago

Didn't know what an offload engine was, so I looked up TCP offload engine (TOE) on Wikipedia: https://en.wikipedia.org/wiki/TCP_offload_engine

The page states: """ A generally accepted rule of thumb is that 1 hertz of CPU processing is required to send or receive 1 bit/s of TCP/IP.[3] For example, 5 Gbit/s (625 MB/s) of network traffic requires 5 GHz of CPU processing. """

Question for people in this line of work: is this accurate / reasonable?

Thanks

Sir_Cmpwn• 10 years ago

No, I don't think it really makes sense for LLVM to mainline an architecture no one can use. I doubt they'll be on board with this.

verbatim• 10 years ago

It's not exactly unprecedented. GCC supports mmix, which hardware doesn't even exist for. (An educational platform from TAOCP.)

https://gcc.gnu.org/backends.html

kenferry• 10 years ago

Looks like there's consensus to accept it as an "experimental" backend. I think that means the code is in tree, but other people changing LLVM aren't obligated to keep it working.

It may be accepted as a full backend in the future, but that discussion is deferred since people are happy with it being experimental for now.

jakejake• 10 years ago

Ordinarily I'd agree with you. Except the tradeoff of having Google's other contributions to the main branch is probably worth it for a little bit of code that isn't harming anyone else.

It's perhaps not fair, but just a reality that a company like Google has a lot to offer so they can sometimes get special treatment.

DannyBee2• 10 years ago

GCC has done it for years. For LLVM mainline, often for small and simple architectures, the people contributing to mainline is much more valuable than the cost of having to make mechanical API changes in that backend when codegen api's are changed.

(Once you have > ~5 backends, which LLVM does the cost of doing the latter just doesn't really change much).

If you want to build a real community, turning away contributions likely to lead to an overall net positive for the community tends not to be a good approach :)

(I await the arguments about corporations having no care about communities or whatever else)

maaku• 10 years ago

Having been in this position before, I can tell you that maintaining large patch sets increases friction against submitting anything upstream. Even if this was a Google-only CPU (it's not), that'd still be an argument for merging upstream.

desdiv• 10 years ago

This story has a little more info, including the chip's origin from Myricom:

http://www.theregister.co.uk/2016/02/09/google_processor/

rurban• 10 years ago

This LANai v11 RISC chip seems to be the successor of the LANai v7 and LANai v9 chips described here: https://www.myricom.com/scs/myrinet/...ogramming.html for which the gcc toolchain already exists: https://github.com/myri Porting this to LLVM makes more sense.

Nothing too interesting, as it doesn't use IBM's 7nm or Intel's 10nm chip tech. Just a simple but parallel high-speed network chip, as used in the Myrinet network cards. The old ones ran with 33MHz but very low latency.

Really exciting would be the Power8 based on IBM's new 7nm, which would finally blow away Intel advantages on an fully open (and unbackdoored) design.

pgeorgi• 10 years ago

Really exciting would be the Power8 based on IBM's new 7nm, which would finally blow away Intel advantages on an fully open (and unbackdoored) design.

Sounds like you read https://raptorengineeringinc.com/TALOS/prerelease.php :-)

cmrx643• 10 years ago

Nothing about the POWER8 or IBM's process technology implies unbackdoored. I can't inspect the factories, or their supply chain, or the HDL they used, or the tools that processed the HDL. The only thing more "open" about POWER8 is firmware in some deployments, and maybe licensing the ISA (if you have enough clout/money to join the foundation, I can't find any licensing information at all). RISC-V is more interesting in every way, with respect to openness.

userbinator• 10 years ago

Lanai is a simple in-order 32-bit processor with 32 x 32-bit registers, two registers with fixed values, four used for program state tracking, and two reserved for explicit usage by user, and no floating point support.

Might as well be a MIPS. The fact that Google has suppoedly developed its own CPU is interesting, but the architecture itself seems quite mundane.

Edit: comments on the article suggest it's the Myricom LANai, a NIC embedded processor. Google may just happen have these NICs in their machines and want to write firmware for them.

vmorgulis• 10 years ago

http://www.phoronix.com/forums/forum/phoronix/latest-phoroni...

It could be lanAI too...

eternalban• 10 years ago

OT(?): reverse(Lanai) // todo: see if copying XXX cpu is OK

ZenoArrow• 10 years ago

I wonder if they'll be using RISC-V for the same purposes in the near future.

http://www.eetimes.com/document.asp?doc_id=1328561

PeCaN• 10 years ago

Seeing as Google partially sponsored RISC-V[1], it wouldn't really surprise me.

1. Indirectly, via ASPIRE Lab.

cmrx643• 10 years ago

Google is also a member of the OpenPOWER Foundation (though they've done much more with that). I don't think sponsorship is necessarily endorsement or deployment plans -- it'd be nice if that were the case though!

pyvpx• 10 years ago

perhaps folks will now take 'intelligent' NICs more seriously than "we tried offloading once and it went poorly so thanks but no thanks"

koder2016• 10 years ago

If you are serious about your software...

at-fates-hands• 10 years ago

but at least for Lanai it looks like a CPU used just internally and isn't something that is going to power the next generation of Android devices;

How many times have we seen a huge corporation do something in house, then release it for public consumption several years later? At this time, it will probably stay in house, but if there is a revenue opportunity, trust me, they'll release it.

mpu• 10 years ago

Hurray, no floating points!

Nano2rad2• 10 years ago

First part is lan second part is ai. It could be something to do with artificial intelligence.

Nano2rad2• 10 years ago

Maybe there is no chip, could be they are implementing on FPGA or virtual machines.

WestCoastJustin• 10 years ago

Must be funny working at Google and knowing the inside scoop (watching people speculate). So, here is my wild speculation about a similar secret project. There was a talk given by Dick Sites (from Google) [1, 2], where he talks about performance monitoring across the Google fleet. Very technical and useful if you are into monitoring (highly recommend it). A large part of his talk is dedicated to issues and limitations with off-the-shelf CPUs. Given that AWS has custom chips (talked about at Invent a few years back), why wouldn't Google solve this issue too, they have the talent and money.

[1] http://www.pdl.cmu.edu/SDI/2015/slides/DatacenterComputers.p...

[2] https://vimeo.com/121396406

wmf2• 10 years ago

It's already been posted in this thread that it's just a smart NIC evolved from existing Myricom NICs. (Of course, my coworker was just telling me a story about how John Cocke hid his RISC processor in a printer project.)

And Amazon's "custom" CPUs are 100 MHz faster Xeons.

LLVM Patches Confirm Google Has Its Own In-House Processor

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