Does Pentium D need Win XP Pro?

[dazz williams]

I read on Microsoft's website that "Scalable processor support – up to two-way multi-processor support." is only available with WinXP Pro, not home. Since Intel Pentium D is a multicore processor, does it need WinXP Pro in order to take full advantage of this? Or is it not truly two separate processors?
dazz.

[SeyelentEco]

Ack. I'm not sure, have you ever seen if Windows sees a Pentium D as two processors? Or if it sees it as one? Usually you can go to the "Task Manager" or right click on the computer icon on the desktop and go to properties.

[DJMaze]

a dual-core processor is like 2 processors.
Windows 9x, ME and XP Home only support one processor.
Windows 2000, XP Pro, 2003 and Vista support multiple processors.

So yes Microsoft docs are correct here but ofcourse lack to tell that an old 2000 will also work and you can guess why.
No problem though XP Home will just run on one of the processors.

Don't start to complain why they ship dual-core with XP Home, it's a selling argument and to reduce costs. 80% of the computer buyers has no clue anyway.

[SeyelentEco]

I just looked it up, and as of SP2, WinXP Home supports dual core processors and uses both cores.

"Windows XP Professional can support up to two processors regardless of the number of cores on the processor. Microsoft Windows XP Home supports one processor."

http://www.microsoft.com/licensing/h...multicore.mspx

So it seems you'll be fine with Win XP Home on a Pentium D processor, as long as you have SP2.

[Belisarius]

As near as I can tell, that document only covers licensing, not the technical aspects. Being that to the OS, dual-core basically means dual-proc, they would have needed to modify the code to allow it, and I'm not sure that was an included change in SP2.

I have always been under the impression that XP Pro was required for dual-core/proc.

[SeyelentEco]

From everything I read in response to the request. SP2 changes how the OS handles dual core processors. The XP Home OS is still multi-threaded and has been able to be run on HyperThreaded processors fine. XP Home has limitations as far as Physical processors and that is just a licensing thing (just just ignore the other processor), but for Dual Core, it treats it as a physical processor, and uses both the cores. I can't find more information from MS than what I gave, so I can't really provide more information. However, the XP Home limitation is not a physical limitation of the OS, its a licensing issue.

[Belisarius]

I konw it's a licensing limitation, but I don't think it's just a registry hack to allow it.

If you go to Task Manager->Performance under XP Home, does it display two CPU Usage Histories?

[AssKoala]

Pentium D's are truly two separate processors. However, Microsoft licenses Windows XP and greater on a "per-socket" level. That means if I have a 64 processor system but its all on one socket (e.g. multi-core), then Windows XP Home's licensing will support it just fine (the 32-bit kernel used by XP is limited to 32 processors, though, but that's a different story).

So, Windows XP Pro supports two processors, but I can have a dual dual core Opteron box running Windows XP Pro without problems.

There is no registry hack to allow more processors than the OS is licensed for. It's a kernel level hard setting.

As far as how XP Home/Pro manages processors, it treats dual core processors the same as Hyperthreaded processors. It keeps multithreaded processes on the same "node" (e.g. socket) and balances processes between physical processes (e.g. between nodes).

In other words, if you have 4 cores on two processors and are running 2 programs 1 program will go on physical processor 0 the other on physical processor 1. The way Intel maps the physical processors is the same as in HT, afaik. For example, processor 0 has two cores, processor 1 has two cores. Windows CPU0 is processor 0 core 0, CPU1 is processor 1 core 0, CPU2 is processor 0 core 1, CPU2 is processor 1 core 1. They do that to ensure both sockets are being used on a Windows 2000 system that doesn't support the scheduling the way Windows XP does.

Hope that helps

[Belisarius]

Originally Posted by AssKoala

So, Windows XP Pro supports two processors, but I can have a dual dual core Opteron box running Windows XP Pro without problems.

You could have six processors, I believe, and it would work fine, but it wouldn't recognize past two. The question is, does Windows, technically, recognize dual cores as two processors, and, also technically, is that a maximum?

[AssKoala]

Originally Posted by Belisarius

You could have six processors, I believe, and it would work fine, but it wouldn't recognize past two. The question is, does Windows, technically, recognize dual cores as two processors, and, also technically, is that a maximum?

No, like I said, Windows is licensed on a "per-socket" basis. Windows XP Pro supports two "sockets".

That is, it sees dual-cores as two processors, but they are only 1 socket. So as far as Windows XP is concerned, if you have a Dual Core processor, to the kernel you have two processors to the licensing you have one.

So, Dual Dual-Core Opterons is OK with Windows XP. Four Single-Core Opterons and you'll need Win2k3. In terms of physical power, the Four Single-Core Opterons will be unquantifiably faster (e.g. they will be faster, but so marginally faster that it isn't even measurable. Bus overhead is where dual-cores can fare better than classical SMP systems, for all else separate processors generally wins out).

On a side note, it's important to note that RedHat, IBM, and others license on a per core basis (or did).

[Belisarius]

You seem to be assuming technical implementation and licensing are the same thing. I'm wondering if anyone has actually confirmed that Windows XP will recognize multiple cores in excess of the socket licensing limitations.

As for the claims that Redhat et al. licensed on a per-core basis, I'm going to say you need to provide documentation for that claim - the only major holdout I knew of in this regards was Oracle (and technically IBM, but only in regards to their PowerPC chips, so it doesn't affect 99% of the market).

[AssKoala]

Originally Posted by Belisarius

You seem to be assuming technical implementation and licensing are the same thing. I'm wondering if anyone has actually confirmed that Windows XP will recognize multiple cores in excess of the socket licensing limitations.

Ok, now I have to be a bit mean, but, can you read? Do not make the assumption that I've made a mistake without taking the time to perform a quick google search.

I specifically said that TECHNICALLY the OS sees the two cores as two separate processors (though schedules them like Hyperthreaded Processors). To licensing (that is, to the difference between XP Home/Pro in terms of # of processors), it is just a single processor.

I'm going to say this one last time, link you to Microsoft's docs, and you should be on your way.

1 processor 1 core = XP Home
1 processor 2 cores = XP Home
1 processor n cores = XP Home
2 processors 1 coreperproc = XP Pro
2 processors 2 coresperproc = XP Pro
2 processors n coresperproc = XP Pro

I don't believe this can be any clearer. Read this to read exactly what I just said.

Here's the google search that will turn up just what I said. Someone should write an article on google searches.

Originally Posted by Belisarius

As for the claims that Redhat et al. licensed on a per-core basis, I'm going to say you need to provide documentation for that claim - the only major holdout I knew of in this regards was Oracle (and technically IBM, but only in regards to their PowerPC chips, so it doesn't affect 99% of the market).

I said:

Originally Posted by AssKoala

On a side note, it's important to note that RedHat, IBM, and others license on a per core basis (or did).

See that "or did"? I was not saying they are currently per core, but they most certainly were almost 2 years ago. Windows 2000 is technically per core licensed since the kernel cannot make a distinction between a physical processor and a core (Linux had the same issue when multicore processors were hitting the market, support had to be added).

Link on Oracle licensing

According to that link, RedHat and Novell follow the same system as Microsoft.

If you want empirical evidence, head over to 2cpu.com's forums and look at the people running dual dual-core opteron boxes on Windows XP Pro.

The answer to the Original Question is No, Windows XP Home will run a Pentium D just fine and utilize both cores.

[Belisarius]

Originally Posted by AssKoala

can you read

Well, this is what I read.

Originally Posted by AssKoala

Microsoft licenses Windows XP. . .

Originally Posted by AssKoala

No, like I said, Windows is licensed on a "per-socket" basis . . .

Emphasis mine.

From those statements, all your techincal discussion followed. I assumed (reasonably) that all your techincal comments were based off the assumption that the licensing was the same as the technical specs. I requested (twice) for clarification - had you simply said "Yes, I've seen dual CPU-Usage on an XP Home box" or pointed to an article talking about it, I would have said "Hmm, learn something new every day".

As to RedHat, IBM, et all, first off, why is it "important" to note that (because it felt like you were trying to make some sort of point)? The impression you gave off was that RedHat, IBM and others were somehow behind the curve to Mircosoft in regards to multi-core licensing. When I saw you included RedHat in that list, it piqued my interest, so I did do a google search, and turned up that very same article about Oracle as you did. I had also found this article that indicated that RedHat had a licensing model that treated dual-core processors as a single processor from *before* the launch of dual-core chips (as did IBM - and this article indicates RedHat had that model *before* Microsoft adopted it). So, rather than simply be an ass and throw your argument back in your face, making some snide comments about learning how to google before making such odd statements, I was simply going to ask for documentation. Because who knows, I might have missed something and ended up looking like a fool.

[AssKoala]

Originally Posted by Belisarius

From those statements, all your techincal discussion followed. I assumed (reasonably) that all your techincal comments were based off the assumption that the licensing was the same as the technical specs. I requested (twice) for clarification - had you simply said "Yes, I've seen dual CPU-Usage on an XP Home box" or pointed to an article talking about it, I would have said "Hmm, learn something new every day".

I fail to see how that was a reasonable assumption. Based on the technical discussion, XP Home would not be able to use more than a single core.

Regardless of that, I stated exactly what I just said a total of three times, including my last post.

Originally Posted by AssKoala's first response

However, Microsoft licenses Windows XP and greater on a "per-socket" level. That means if I have a 64 processor system but its all on one socket (e.g. multi-core), then Windows XP Home's licensing will support it just fine

Originally Posted by AssKoala's second response

No, like I said, Windows is licensed on a "per-socket" basis. Windows XP Pro supports two "sockets".

That is, it sees dual-cores as two processors, but they are only 1 socket. So as far as Windows XP is concerned, if you have a Dual Core processor, to the kernel you have two processors to the licensing you have one.

Originally Posted by Belisarius

As to RedHat, IBM, et all, first off, why is it "important" to note that (because it felt like you were trying to make some sort of point)? The impression you gave off was that RedHat, IBM and others were somehow behind the curve to Mircosoft in regards to multi-core licensing. When I saw you included RedHat in that list, it piqued my interest, so I did do a google search, and turned up that very same article about Oracle as you did. I had also found this article that indicated that RedHat had a licensing model that treated dual-core processors as a single processor from *before* the launch of dual-core chips (as did IBM - and this article indicates RedHat had that model *before* Microsoft adopted it). So, rather than simply be an ass and throw your argument back in your face, making some snide comments about learning how to google before making such odd statements, I was simply going to ask for documentation. Because who knows, I might have missed something and ended up looking like a fool.

You actually got me there. I had originally read that IBM and RedHat were going with per core models initially (though I recall that being on theinq).

I said "it's important to note" not because it's backwards in any way (really, it's backwards to license on a per socket model, this will likely change as processors head towards the 16 core models Intel has on their roadmaps), but because I felt it important to note that not all vendors use a per-socket model.