CPUs Supported


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In general, for some of the main variants of Linux/Unix/etc., how many processors are supported? I'm trying to collect some info for a project I'm working on. Thanks.

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All of the various linux distributions share the same kernel (well, different versions and slight tweaks but basicly the same)

threads.h Limits the linux kernel to a maximum of 32 processors per node. You can string multiple nodes together in a cluster for an "unlimited" number of processors - the hardware and your ability to write parallel code will be the limit here, not Linux.

Mac OS X's kernel supports a maximum of two processors as shipped from Apple however you can download the source code and try for more. I've read reports of people having success with 4-way and 8-way systems, the availability of hardware is probably the only thing stopping people form trying for more. Again you can cluster your systems and support "unlimited" processors. The "big mac" super computer cluster was 1,100 Dual-processor G5s (2,200 processors) running OS X and is currently the #3 super computer in the world.

OpenBSD supports only single processor systems. There is a project to improve that situation, but it's not in the release code. You can check out the CVS and try for yourself, but I'm not sure what success you'll have. I know people who have run FreeBSD on 8-way systems with success so the lack of SMP is an OpenBSD quirk (they're goal is security over all else so this isn't surprising) and not an inherent limitation of the BSD kernels.

As for OS's that I don't use:

Solaris 9 supports up to 106 ultrasparc processors

HP has a sells "compute blocks" that you can build servers from. They list the SC45 as supporting up to 4096 processors in some configurations, though really that's just a cluster of 1024, 4-way alpha severs. The integrity servers have up to 64 itanium II per node. I believe 64 processors is the limit for both AIX, HP-UX and most other modern UNIXs today. HP-UX 11i will support 128-way system like the HP 9000 Superdome but IIRC it's won't ship until this summer.

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I'm sure Kernel 2.6 can do more than 32. Anyway, I think by the time you got to 32 CPUs you should just cluster them.

BTW: Apple's xgrid (http://www.apple.com/acg/xgrid/) is a very nice app that can use all your macs on a network to do distrubuted computing. It finds them via rendezvous (no need to type IP in), you select a job and then volia you have your own cluster. Shame about the prices of Apple's hardware though ;).

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In general, for some of the main variants of Linux/Unix/etc., how many processors are supported? I'm trying to collect some info for a project I'm working on. Thanks.

In addition to the Multi-Processor options already given, Linux supports many types of processors (where Windows only supports the x86 series).

SPARC, ALPHA, RISC, and more! I think http://kernel.org has better info.

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From menuconfig's (kernel 2.6) help:

Maximum number of CPUs (2-255) NR_CPUS

This allows you to specify the maximum number of CPUs which this

kernel will support.  The maximum supported value is 255 and the

minimum value which makes sense is 2.

This is purely to save memory - each supported CPU adds

approximately eight kilobytes to the kernel image.

Based on that I would say it supports 255.

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In addition to the Multi-Processor options already given, Linux supports many types of processors (where Windows only supports the x86 series).

SPARC, ALPHA, RISC, and more!  I think http://kernel.org has better info.

That's not entirely true. I'm pretty sure there are versions of Windows that will run on Itaniums, which are not x86 :)

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That's not entirely true. I'm pretty sure there are versions of Windows that will run on Itaniums, which are not x86 :)

Same processor family, like Opteron, just 64-bit.

[EDIT: By this, I mean that there isn't any more difference in this than there was from 16-bit WIndows to 32-bit Windows.]

Edited by markjensen
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Itanium EPIC instruction set is about as different from i386 as PowerPC is. Give credit where it's due: Windows runs on two major architectures, one high-end, and one commodity.

Maybe you were thinking of the Intel chips with the reverse-engineered x86-64 extentions that should ship Real Soon Now[tm] (they may even be shipping already, but I don't follow the Intel world very closely to know one way or the other). Those chips are plain old 32 bit pentium-class processors with 64-bit capabilities bolted on, much like Opteron/Athlon64.

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I believe that you would be hard pressed to find a processor that you would want to run linux on that you can't, and if you could I bet that somebody is in the process of making it work.

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My error.

I confused instruction sets (particularly Opteron) and backward compatibility with processor archetectures. Not sure if Itanium even offers any backward compatibility, like Opteron does. :unsure:

One thing is for sure, though... Although Windows may support two processor types for a brief moment, it will soon pass. As 64-bit computing replaces 32-bit, there will be no more support for the older CPUs. Windows is hopping from CPU lilypad to CPU lilypad.

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where Windows only supports the x86 series.

Windows NT 4.0 shipped for DEC Alpha CPUs and Motorola PowerPC CPUs.

http://en.wikipedia.org/wiki/DEC_Alpha

http://www.microsoft.com/presspass/press/1...98/DIGALLPR.asp

http://www.microsoft.com/presspass/press/1...b97/PowerPr.asp

There were beta editions of Windows 2000 for Alpha but they never saw the (official) light of day. - http://www.gnsconsulting.com/Newsletters/G...%202%201999.htm

You could also argue that Windows for Itanium counts as a non-x86 CPU. The Itanium is not natively x86 compatible but it does have hardware x86 emulation.

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itanium doesn't offer backwards compatibility to x86 afaik. that is one of the reasons intel is replacing it I believe

It has hardware-assisted emulation but it's SLOOOWWW....

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I don't see any problem with Windows only supporting one architecture (two for certain versions, but I'm thinking about the mainstream, 32-bit version). It's not as if 99.9% of Microsoft's customer base is going to try to run an Alpha or RISC processor with their copy of Windows (let alone know that there are different CPU architectures). In fact Windows sticking to one "CPU lillypad" probably increases stability, since the fewer different hardware types it needs to support, the more stable it is (this, in fact, is my theory as to why Mac's are generally a tad more stable than Windows PC's, as Apple strictly controls what hardware can be made for their OS). I, for one, have never felt the need to run a CPU with a different archicture; if I did, I probably wouldn't be running Windows XP Home Edition :laugh:

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Writting code for one platform makes your code more stable by the same amount that only reading one book will make you more literate. Supporting as many platforms as possible increases the chances that you will discover bugs caused by stupid assumptions that you make (ie: that all ints are 4 bytes). OpenBSD supports many platforms: M68K, i386, PPC, AMD64Sparc, Alpha,PA-RISC and is extremely reliable. Don't make excuses: if windows has stability problems it's because someone in the loop is making bad software - you should be demanding they fix it.

Also, Apple doesn't control who makes hardware for their machines. They only ship half-a-dozen motherboards and maybe a dozen CPU combinations but there are plenty of people out there making add-on cards, processor upgrades, external USB/Firewire devices, and PCMCIA toys. The documentation and tools you need to write drivers for your hardware are on the Apple website and are free for anyone to download. Aside from the motherboard, if there is a lack of 3rd party hardware: it's not for Apple's lack of support.

And that ignores the fact that Apple's core technologies run on systems other than PPC. The Mach kernel, Rendezvous, Darwin including the whole BSD layer, QuickTime, and OpenStep (the basis for Cocoa) all run on x86 systems just fine. If your premise is that Mac OS X is more stable than Windows is true, then your conclusion "because it only supports a limited hardware set" is false, because many of the technologies that make up OS X are known to work well on many platforms and the remainder like Quartz and Carbon are rumored to work on other platforms as well (though for the purposes of this debate that doesn't amount to the damning evidence I would like it to).

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