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Does win2kpro Support Hyperthreading?

"The following desktop operating systems are not recommended for use with Hyper-Threading Technology."

Does that mean it'll still work? Just poorly? or....?

Hex
 
People are always giving incorrect advice around here:

Win2K ALL versions will work with HT. it's just that the OS doesn't have specific support for optimizations, so the os will only see it as 2procs; whereas XP will know that it's only one additional APU (or something) and thread more efficently. You might also want to make sure you put SP3 on ASAP when you install it.

Thank link is only for Intel Brandning, nothing to do if it will work or not (I'm assuming you know Win9x won't see dual procs period), I'm sure if i got bored enough and installed it NT 4.0 would see 2 procs as well.

Win2kPro will see a single HT chip as two procs.

As Proof:
Running a Server on Win2k with dual Xeons (HT enabled) and it works fine.

-Teva24
 
w00ties

That was the answer I had sorta figured upon, it works just maybe not as well.

Thanks

And Now I am going to bed

Night all 😀

Hex
 
The question was:
Does win2kpro Support Hyperthreading? Or do I need to use winXP?
Click to expand...
The answer is that Windows 2000 does not support HT, if you want to make use of that feature you need to run XP. I dont see any incorrect advice here.

Yes Win 2K does see it as 2 seperate CPUs, the *problem* with that is that it will try and run multi threads on the same CPU and they will be fighting for the same resources since your dont really have the two CPUs (this isnt really a problem, just something to keep in mind). If I remember correctly you can actually see better performance with Win 2K if you disable HT (although I dont remember the details on that).

-Spy
 
Running a Server on Win2k with dual Xeons (HT enabled) and it works fine.
Click to expand...

I've heard many stories of things like IIS getting a major performance drop when HT is enabled on Win2K, probably because of the condition spyordie007 mentioned about a multithreaded app competing for the same CPU resources since the OS thinks there's 2 unique CPUs.
 
Originally posted by: Nothinman
Running a Server on Win2k with dual Xeons (HT enabled) and it works fine.
Click to expand...

I've heard many stories of things like IIS getting a major performance drop when HT is enabled on Win2K, probably because of the condition spyordie007 mentioned about a multithreaded app competing for the same CPU resources since the OS thinks there's 2 unique CPUs.
Click to expand...

Exactly, it's not HT aware and you wind up losing performance do to it.
Bill
 
Here is the (my) official answer after doing a small amount of investigating.

Yes, Windows 2000 supports Hyperthreading. Unfortunately, I have to report that Intel does not recommend enabling Hyperthreading on Windows 2000.

http://www.intel.com/support/platform/ht/os.htm

I have two servers at the office that are dual 2.8 xeons with HT enabled. They scream. They are both GSX virtual server servers and they are running without any problems. Would it run faster if I disabled HT? I'll probably never take the time to find out.
 
Originally posted by: bhay
Here is the (my) official answer after doing a small amount of investigating.

Yes, Windows 2000 supports Hyperthreading. Unfortunately, I have to report that Intel does not recommend enabling Hyperthreading on Windows 2000.

http://www.intel.com/support/platform/ht/os.htm

I have two servers at the office that are dual 2.8 xeons with HT enabled. They scream. They are both GSX virtual server servers and they are running without any problems. Would it run faster if I disabled HT? I'll probably never take the time to find out.
Click to expand...
No, Windows 2000 does not support HT.

Windows 2000 will run on a HT enabled CPU however it will believe that it is running on 2 seperate Physical CPUs (which of course is not the case).

Really the answer is NO, Windows 2000 DOES NOT SUPPORT HYPERTHREADING

-Spy
 
Okay, taken right from that Whitepaper:
Windows 2000 Server does not distinguish between physical and logical processors on systems enabled with Hyper-Threading Technology; Windows 2000 simply fills out the license limit using the first processors counted by the BIOS. For example, when you launch Windows 2000 Server (4-CPU limit) on a four-way system enabled with Hyper-Threading Technology, Windows will use the first logical processor on each of the four physical processors, as shown in Figure 2; the second logical processor on each physical processor will be unused, because of the 4-CPU license limit. (This assumes the BIOS was written according to Intel specifications. Windows uses the processor count and sequence indicated by the BIOS.)

However, when you launch Windows 2000 Advanced Server (8-CPU limit) on a four-way system enabled with Hyper-Threading Technology, Windows will use all eight logical processors, as shown in Figure 3.

Although Windows recognizes all eight logical processors in this example, in most cases performance would be better using eight physical processors.
Click to expand...
Maybe you are assuming something that this document doesnt say, but it sure sounds to me like Microsoft is saying that Windows 2000 doesnt support it and it will just assume that the multiple logical processors are really multiple physical processors (which really isnt the case).

-Spy
 
The DELL link also shows the Windows 2003 is slower with HT enabled, what does that prove?

It proves that the tests they were running don't like HT; not that Win2000 can't use it.

I also hope everyone knows that if you are only doing *ONE* thing, enabling HT WILL slow you down.

Thanks,

Teva24
 
Spyordie, Thanks for making me feel welcome with my first post.

I think I would choose my words a little better if I were you. You have several people here proving that HT is supported. You even say it yourself in your last post. Then you contradict yourself. I made my post after doing some investigating and it is clear as water that win2k supports HT. The original question was, "is HT supported". That has clearly been answered. True, we've seen a case where HT showed improvements. Aparently you've shown a case where it does not show improvements. The answer is, it is supported, but Intel doesn't recommend it. My personal answer is that it is completely supported, I love it, I recommend it, and I think you're just jealous you don't have any HT boxes to play with.

Ok this is just fun right? I'm having a good laugh any way.

 
My personal answer is that it is completely supported, I love it, I recommend it, and I think you're just jealous you don't have any HT boxes to play with.
Click to expand...

It's not completely supported. The issue is that if you have a dual xeon box with HT supported (which, btw is what my home machine is, so no jealousy here) what you want is for the OS to schedule tasks on across the two physical CPU's first then across the virtual ones. 2K doesn't know the difference and schedules them all the same. It's a subtle but extremely important detail. This is from Intel, I was involved in the partner review of this a long time ago, and when spent a good deal of time talking thru scheduling issues.

Bill
 
My personal answer is that it is completely supported, I love it, I recommend it, and I think you're just jealous you don't have any HT boxes to play with.
Click to expand...

Then you would be wrong.

Just because it sort-of works doesn't mean it works well or is supported. HT and SMP are totally different, the fact that Win2K treats HT enabled boxes as full SMP boxes is very bad for multithreaded app performance or even concurrent singlethreaded app performance.
 
Spyordie, Thanks for making me feel welcome with my first post.
Click to expand...
Sorry it was not my intention to make you feel unwelcome. Unless you spend your time in Off Topic you should find quite a few people here who have some (if nothing else) interesting things to say. Welcome to the fold.
You have several people here proving that HT is supported.
Click to expand...
No, there are several people here who have proved that Windows 2000 will run on a HT Processor (but we already knew that). The problem is that Windows 2000 cannot distinguish between Physical Processors and Logical Processors so it doesnt know how to schedule threads properly (as bill pointed out).

I think the confusion here is the differance between the question "Will Windows 2000 Run on a HT CPU?" and "Does Windows 2000 Support Hyperthreading?"
Will Windows 2000 Run on a HT CPU:
You bet, the problem is that if you have a single CPU with 2 logical CPUs (HT) Windows 2000 Schedules two seperate threads on the two differant logical processors without knowing that they share the same casche and core, this can cause performance problems in many situations and therefore is not reccomended or supported.
Does Windows 2000 Support Hyperthreading?
Considering that Windows 2000 doesnt even know what it is and the Windows 2000 Kernel doesnt know the differance between a Physical and a Logical CPU it cannot support it.
and I think you're just jealous you don't have any HT boxes to play with.
Click to expand...
Now that is definetly true, I've got a new server that I will be building here soon and it will be my first HT system but up until now I've never actually had one to play on.

-Spy
 
Originally posted by: Teva24
Ok then.

Please tell me how this is slower with HT enabled on Win2000

http://www.infoworld.com/article/02/02/25/020225plxeon_1.html

It shows a 30-45% INCREASE in speed, even for win2k.

Thanks,

Teva24
Click to expand...
That article is rather old, and features just two usage scenarios. To extrapolate those results and say the performance benefits of HT are "undeniable" (as the article concludes) is presumptuous journalism.

In fact, while I can't recall offhand where I saw it and don't pay much attention to x86 server platforms anyway, the general figures I have read of the real-world benefit of HT is between 0-25% with OS support. What spyordie007 is saying, which I totally buy, is that enabling HT on an OS without scheduling support probably gives you a performance wash at best. If per-CPU licensing comes into play at all, then you could well be paying extra for negligible performance benefits.
 
Why doesnt Microsoft just put out a patch for win2k?

I am sure win2k could be patched to support HT properly IF microsoft wanted to.
 
Originally posted by: Budman
Why doesnt Microsoft just put out a patch for win2k?

I am sure win2k could be patched to support HT properly IF microsoft wanted to.
Click to expand...
Now why would they want to do that? It's always been a "buy the next version" and "upgrade now" market, I'm not holding my breath on this one.

sarcasm
I can see their answer now:
"Why dont you just upgrade?"
rolleye.gif

/sarcasm

-Spy
 
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