Pentium 4 3ghz ... enable or disable HYPER-THREADING ?

[stvn]

The reason i ask is that when i encode with most of the software i have only uses 50% of my resourses, This leaves the pc still very responsive to veiw the web or burn cd'd/dvd's but is hyper-threading worth all the effort has anyone tryed encoding times on the same setup / files with the only diffrence hyperthreading enabled and disabled ? The results would be very intersting if i could half the time of my encoding it might be worth it.

[mujahid7ia]

In TMPGEnc you can enable multi-threading. probably helps but I wouldn't know, I don't have HT.

[Ripper2860]

Use it if you got it !! Of course it may cause the events in your forum "Sig" to actually happen!

As far as I know there is no "down-side" to enabling HT. The option is only there in BIOS to accomodate CPU's that do and do not support HT, otherwise it would be automatically enabled all of the time.

HT basically sets up the equivalent of a 2nd "VIRTUAL" processor to handle instruction threads concurrently. In fact some diagnostic and benchmark software shows it as 2 CPU's !!

Software does not have to be compiled for HT support. As far as I know all processor intesive tasks will benefit w/ any software.

TMPGEnc will benefit from 2 aspects of your processor -- HT and SSE2. Video encoding GOODNESS !!!

[Piccoro]

There is a downside to HT but in video encoding you will not see it. Enable.

[Ripper2860]

Piccoro,

What is it? Other than an increase in heat production, I have not heard of one and would definitely like to know. I am sincere in my question, so please do not interpret it as my being facetious.

Oh -- and I was wrong about all software benefiting. Software needs to support SMP.

Thanks !!

[BJ_M]

MANY programs run slower with HT enabled is the downside ,,,,, if they are not SMB aware -- there is no advantage .. there are some other reasons also ....

[Ripper2860]

Yeah -- I forgot that the application and O/S must support Symmetrical Multi-Proccessing.

Also, in true physical multi-processor systems, you would not want to enable HT, as the ideal would be to have an application place program threads on seperate physical processors. Unfortunately w/ HT, 2 physical processors would appear as 4 and the threads could end-up on the same processor (actual and virtual) rather than being placed on the real 2nd processor.

[Piccoro]

Hyperthreading Performance Explored 30-09-2002
Take 2: Hyperthreading Performance Explored (Part 1) 07-01-2004
I'm guessing they have Part 2 coming up.

[Ripper2860]

Picorro,

Thank you. I scanned them and they seem very thorough. I will read them in greater detail.

Thanks !!

[rallynavvie]

To my knowledge neither the Xeons or the MPs have HT. They don't really need to.

I compared a 3.06 P4 with HT to my machine. In SMP-aware apps I smoked the Pentium, but in non-SMP apps (like games) I was outmatched. Both do well multi-tasking typical office apps. Interestingly, between these two system it was the AMD that was more expensive than the Pentium for a change

[Ripper2860]

Current Xeons and Xeon MP's support HyperThreading. However, there are no SMP capable P4's.

Xeon spec's at Intel: http://www.intel.com/products/server/processors/server/xeon/index.htm?iid=ipp_srvr+proc_xeonwrkstn&

Xeon MP: http://www.intel.com/products/server/processors/server/xeon_mp/index.htm?iid=ipp_srvr+proc_xeonmp&

[BJ_M]

yep - my dual xeon machines all have HT and i keep it off (selectable in bios)

[mujahid7ia]

yep - my dual xeon machines all have HT and i keep it off (selectable in bios)

Isn't there a WinXP special edition for HT?? I think it comes w/ PCs from big companies that have P4s w/ HT.

If you run XP HT, the performance will be hurt by disabling HT, right?

Test Center: Notes From the Lab
For optimum single-application performance, you must do more than disable hyperthreading in your new system's BIOS: You must remove the Windows XP multiprocessor files. One way to do this is to turn the PC off and then reinstall Windows XP from scratch. That's because the multithreaded version of Windows XP loads more files and uses more resources than the standard version, and so imposes a performance penalty from the get-go--when you switch off hyperthreading, those files are still loaded.

Here's the article link: http://www.pcworld.com/news/article/0,aid,107492,00.asp
(2nd page)

[Ripper2860]

WinXP Pro supports SMP (upto 2 processors). There are other versions that support even more (Datacenter, Enterprise, etc). In order for WinXP Pro to support HT or a physical 2nd processor, the multi-processor HAL (Hardware Abstract Layer) must be installed. If you have a single HT processor and the MP HAL installed, and then decide that HT is not worth it, you should definitely re-configure XP for single processor in addtion to disabling HT in BIOS.

If you are already running 2 processors (as is the case with the dual Xeon referenced above), even when HT is disabled there is a 2 physical processor configuration, so re-configuring Windows should be un-necessary. Disabling in BIOS should suffice.

[stvn]

[quote="Ripper2860"]Current Xeons and Xeon MP's support HyperThreading. However, there are no SMP capable P4's.

http://www.intel.com/products/desktop/processors/pentium4/

Well i got one MSI 875p Neo board and one P4 3ghz with HT and two virtual processors in task manager

My original question was more of a guide to see the diffrence in times between an identical setup with HT enabled and disabled processing the same task. Im not new to smp but just to encoding and wanted to compare times to see if its worth the time disabling HT

[Ripper2860]

OK -- I guess my statement could be mis-interpreted as it was clear as mud.

Clarification:

There are no Intel desktop P4's that support TRUE multi-processing (i.e. more than 1 physical processor). Only Intel Xeons and Itaniums support MP.

Desktop P4's "emulate" multi-processing via HT, and present 2 "virtual" processors where 1 physical processor exists. This is not truly multi-processing in that 2 physical desktop P4's can not be installed in dual processor mobo and work. In fact -- there are no dual non-Xeon/non-Itanium Intel processor-based P4 mobo's.

[stvn]

Yeah maybe ripper , got the lines crossed a little

long gone are the days when you could dual a pIII or celeron and athlons run to hot for my liking without dualing them and dispersing all that heat

[Hardcoreruss]

HT basically sets up the equivalent of a 2nd "VIRTUAL" processor to handle instruction threads concurrently. In fact some diagnostic and benchmark software shows it as 2 CPU's !!

Checked mine last night and it does show as 2 cpu's !!!!

[stvn]

Checked mine last night and it does show as 2 cpu's !!!!

so hardcoreruss you'll have the same problem as myself with lots of software only using 50% of the cpu cycles for encoding with most software

tmpgenc dvd is the only software ive come across so far that is smp aware
But my favorite is nero vison express for menu creation but having it recode no matter what seams teadious even if the source is a compliant

any other software smp aware ...?

[BJ_M]

lots of pro software is .... autocad , CCE , main concept , Pro-E , vegas , maya , softimage, photoshop and many more ....

[Ripper2860]

BTW -- HT on a desktop P4 only adds approx 15-20% increase in benefit for SMP aware applications -- not 50%.

Unlike true SMP architected systems (2 physical processors), the HT virtual CPU's must share the memory and memory bus. True SMP systems have memory and interface/bus dedicated to each processor.

[rallynavvie]

Most apps that utilize SMP start at ~$300 from what I've seen. They go way up from there. A lot of Adobe apps use both CPUs. What I'd like to find out is if Acrobat 6 finally included SMP support. All previous versions only use a single processor and I get some huge distilling projects that would go a lot faster if both processors were involved

[tdowning]

I may be wrong, but I thought that HT would produce significant benefits like the 15-20% for apps optimized for HT, and more like 10-15% inprovement for Multithreaded, and SMP aware applications, not optimized for HT.

By defenition, an SMP capable OS and app must be multithreaded. threads are single tasks that usually do one single thing.

A standard CPU, from an 8080 on up, (theoretically anyway, I don't think there was multitasking untill the 286, and no multithreading untill windows 95) can only process one thread at a time.

Threads started out as a way to make multi-tasking more effecient, (making the computer seem to run faster, and be more responsive) At some point in the devellopment of the P4 the engineers at Intel realized that any given thread would only consume about half to three-quarters of the logically independant sections of the CPU, that theoretically could all be working. Hyperthreading allows more threads to be prosessed in a given period of time, by making more efficient use of the chip's resources. But not just any two threads could run at the same time. this scheduling process is the cause of the performance hit, (Usually only a few percent IIRC) for non SMP aware apps, (The hit is minimal when multitasking because system threads can sometimes run concurrently with the non threaded application's processes)

Again, IIRC, Dual processor systems all had a Shared memory bus, because there was only one pool of system memory.

The AMD Opteron chips each have thir own seperate pool of memory, and a HyperTransport (A very high speed, serial connection, in the multi gigabit range IIRC) path to each of the other processors in the system, and supposedly this only introduces a little bit more latency when the CPU asks for data from another CPU's System memory.

Lastly, Even SMP does not double performance, per se, because there are additional scheduling tasks that must take place to insure that data in the seperate caches is written back to RAM before the other CPU does something with that data, and dividing the workload.

[stvn]

This has just proved a little frustrating thats all building this pc and finallly trying my hand at making my own dvds ...

Then sitting here watching task manager @ 50%, just ticking over while encoding with 50% just going to waste, Disabling HT might give me a 20%-30% decrease in encoding times but i can still use the pc for other things such as downloads or the net even burning discs without a performance hit on the encoding times.

But when i just want a film on a dvd asap to slip into dvd player with a beer or two feet up you get the picture IS HT worth all the effort ???

[BJ_M]

be done with it and get either a Pentium 4 3.2GHz Extreme Edition 2.5MB 800MHz FSB system or a dual Opteron 248 system or a single Athlon64 FX-51 system or a nice 3.2 dual xeon system (though only at 533fsb)

[Piccoro]

This was a interesting review I stumbled into.
Video encoding only and it breaks down what programs like what at the end.
Link

At first I was thinking they disabled HT but that would be crazy.
But I came across this and then I checked the marks again.

But users wouldn't restart the PC and turn off Hyper-Threading in BIOS Setup every time before encoding because of preferences of a single application, that is why we tested Intel's CPUs as is: those which supported virtual SMP were tested with Hyper-Threading enabled, those which did not were tested without it.

be done with it and get either a Pentium 4 3.2GHz Extreme Edition 2.5MB 800MHz FSB system or a dual Opteron 248 system or a single Athlon64 FX-51 system or a nice 3.2 dual xeon system (though only at 533fsb)

Now you are making me wish I had a SMP system.
In due time I suppose.

[stvn]

be done with it and get either a Pentium 4 3.2GHz Extreme Edition 2.5MB 800MHz FSB system or a dual Opteron 248 system or a single Athlon64 FX-51 system or a nice 3.2 dual xeon system (though only at 533fsb)

Well i got the P4 3ghz 800fsb just missing the L2 cache ov the extreme but i got it O/C to 3675 (245/15) temps just topping out @ 58c under loads so need some better cooling before the push for 3800
http://www.thermalright.com. SP-94 anyone know where this is in stock in the uk cant find one anywhere

just wanted to get the best outta this puppy. as the old dual P3 system has been passed onto the kids

[rallynavvie]

On my HT system at work I'm multi-tasking so I leave HT enabled. This allows me to export something to PDF while working on an entirely different project. If I were to have one at home I'd leave HT disabled because then you'd be using one 3.2 GHz CPU instead of two smaller ones, thus single apps that are not SMP aware would run faster. So basically you have the choice: enable HT so you can do two things at once but get less performance in non-SMP apps, or disable HT and have one fast CPU running all apps to its full potential.

[susie]

So when purchasing a PC, should one choose a CPU with HT or without ?

[BJ_M]

the question now would be to get a p4 or a amd .. most p4 's now have HT