Crusoe As Server CPU

rxmd writes "Heise has an article on Transmeta's Crusoe processor being used as a x86-compatible server CPU by companies such as rebel.com and RLX (read their press release on the project), supporting Linux as well as other "established operating systems". Basically, it's about the Crusoe's lower power consumption and temperatures enabling server manufacturers to put more processing power into the same amount of space than with Intel or AMD cpus. Interesting that a CPU designed for mobile applications should find its way into the server market."

Comments

Not this again...

[slothbait]

> Seems to me that it'd be pretty cool to write to the native Crusoe architecture rather than going through the x86 ``emulation''. Does anyone know if it's even possible to bypass the emulation at all, and write native machine code

Just about every Crusoe posts comes standard with one or two of these questions. Actually, I don't know the answer, but I expect it is *not* possible to write to the "native" ISA of the Crusoe chips. In so doing, you would be circumventing important architectural features of the chip, which operate in their ultra-low-level ISA emulation software.

But most importantly, even if you could, they do not *want* you to. Their code-morphing software also performs some optimizations, which would be thrown out the window if you went "native". More importantly, though, native could would be irrevocably tied to *that implementation* of the Crusoe. Transmeta is under no obligation to build the next Crusoe with the same ISA, and probably won't. Since they are emulating another ISA, the physical architecture is only seen by their software, thus they can tweak the architecture as much as they like between revs without having to worry about breaking binary compatibility. As any design engineer knows, this is a Thing of Beauty, and a luxury no other company is allowed. If people started programming native, they would lose that luxury.

So, while writing straight to the Crusoe silicon (if possible) may be fun as a hack, it would not result in maintainable software. Moreover, it is in Transmeta's best interests to discourage such behavior

--Lenny

Re:Not this again...

[Mr Z]

Transmeta is under no obligation to build the next Crusoe with the same ISA, and probably won't.

...and already haven't. Their existing two part families (the TM3200 and TM5400/TM5600) have different ISAs under the hood. Apparently, the TM3200 doesn't handle legacy 16-bit code as well, so they went back and improved that with extra functionality found only in the TM5xxx families.

Now what would be interesting is if Transmeta offered a better "meta-assembly language" that was both easier for them to decode and translate, and simultaneously served as a better compiler target. That's perhaps asking too much. At least the "Transmeta running x86-64/AMD-Hammer" thing sounds interesting...

On a different note, another reason they don't want you coding to the native ISA is that not only are the x86 instructions emulated, but also some of the legacy x86 peripherals are emulated as well. It makes perfect sense to at least partially swallow up some things, like timers and interrupt controllers and emulate them in software, avoiding unneeded bus traffic. It speeds up the CPU and reduces power.

--Joe
--

Why not PowerPC?

[TWR]

Using Crusoe strikes me as silly when there's another CPU out there which uses a heck of a lot less juice than x86: the PowerPC. Granted, it won't help the WinNT people, but for those running Linux servers in server farms, it's ideal. Low power, low heat (iMacs, iBooks, and Cubes don't even have fans), and a lot faster than Crusoe.

I've been waiting for Apple to start running ads in California trumpeting how much less power Macs use, compared to PCs. This might be a good place for Apple to start; G3/G4 rack-mount, anyone?

-jon

pretty much a first

[po_boy]

at least someone is using it.

Nop, it makes sense

[The Fanfan]

It all depends on the application, but most servers "require" :

1 - small code (always the same app running)
2 - mucho data, not so mucho processing.
3 - mucho I/O

For a good design server, a kick-ass bus and lots of CPUs is way more important than having the latest 5.3 zillion Hz processor. The speed and width of the bus/switch fabric sets the upper limit on how much data you can move around. Having a lot of processors is good so you can max out your bandwidth, some processors using the bus while others stall on I/O or locks. In a data server, a CPU spends most of its time doing strictly nothing but wait for the rest of the world.

There are some applications that would prove me wrong : web server with very complex / sophisticated / bloated dynamic pages may be, scientific computing definitely. But the above is more or less the rule of thumb when looking at a data server.

My $0.02