If disable hyperthread do i need to reinstall?

[Ghosthunter]

I have been reading that some people are having perforamnce increases by not using HT while playing EQ2

I was thinking of trying that..but wasnt sure If I need to reinsatll XP to fix the HAL?

Has anyone tried this in bios?

[Chris]

Ive switched back and forth a couple of times, havn't had an issue yet.
Might want to waite for a few more peeps to answer though.

[YARDofSTUF]

No it'll do fine, just will see 1 chip, u can turn it back on too like chris said.

i switch to encode movies cuz the progam only uses 1 chip. another thign u could do is set teh affinity to most little apps to cpu1 and have the windows services and eq2 on cp0. but the fastes solution for an app that will see only one cpu is to disable HT.

[zooner]

No it'll do fine, just will see 1 chip, u can turn it back on too like chris said.

i switch to encode movies cuz the progam only uses 1 chip. another thign u could do is set teh affinity to most little apps to cpu1 and have the windows services and eq2 on cp0. but the fastes solution for an app that will see only one cpu is to disable HT.

exactly.

it's done through the bios, so shouldn't have any real affect on windows.

how much faster is video encoding with the ht'ing disabled?

[YARDofSTUF]

exactly.

it's done through the bios, so shouldn't have any real affect on windows.

how much faster is video encoding with the ht'ing disabled?


not alot but enough to notice on a mpeg 2 at 720x480 res vid

[Ghosthunter]

thanks all going to give it a try now

[Grimson]

the correct answer is no. I have ppl turn it off all the time b/c older programs don't like it.

I had a guy installing win2k sp4 on 4 inspiron xps machines and everyone would get really slow when setting up control panel or something, they all slowed down at the same point of the install. Turned off HT and everything was cool.


Anyho, you can turn it off and on as much as you want.

[YeOldeStonecat]

Having problems with a reindexing function on a Xeon server once....Microsoft had me disable HT in the servers BIOS, to check to see if that was an issue, which it wasn't. But I asked about that affecting the OS, they said no.

Back with NT 4, if you went from one to dual, or visa versa, you'd had to go through many steps in reconfiguring the OS.

But since 2K came out, the OS pretty much treats multi procs as plug 'n play...you can add/remove processors with ease.

[alanore]

Hyper threading is only benifical for programs that are SMP enabled, most new vidoe editing packages are, as to is the likes of folding@home. Having it enabled with programs that arent SMP aware will have a decreased performance by a few percent because of overheads. This is only really noticed if youare doing something really intestive like encoding video with a program that isn't SMP aware. Or if you have a 3.06Ghz P4 with the 533Mhz FSB that will have more of a effect on crippling perfomance as it has HT revision 1. It also can cause strange noises if you have a Creative Sound card.

[YeOldeStonecat]

Hyper threading is only benifical for programs that are SMP enabled, Having it enabled with programs that arent SMP aware will have a decreased performance by a few percent because of overheads.

Depends on the application, some apps even if single threaded still benefit because an HT compliant OS can have more resources free on that 2nd virtual processor to give to the app.

[zooner]

Depends on the application, some apps even if single threaded still benefit because an HT compliant OS can have more resources free on that 2nd virtual processor to give to the app.

it's not so much about single apps, but about multitasking it is priceless!!!

I went from a p4 2.53 to a p4 2.4c and I was shocked at the difference.

[Ghosthunter]

btw just to let you all know..i disabled HT..and it worked...EQ2 is now running much better.

I think for games it is best to keep it off.

[Rivas]

btw just to let you all know..i disabled HT..and it worked...EQ2 is now running much better.

I think for games it is best to keep it off.

i have np with EQ2 at all with HT turned ON
playing it at 1280x1024 with most of the details on maximum (not all of them) and its sooo smooth

[Ghosthunter]

i have np with EQ2 at all with HT turned ON
playing it at 1280x1024 with most of the details on maximum (not all of them) and its sooo smooth


outside i am fine..it the cities

[YARDofSTUF]

outside i am fine..it the cities


Must be your video card :D

[cyberskye]

It's the difference between buying a fast car vs. two econmic cars for the same money. The former is only useful when you need to go really fast in one direction. The latter is nice because there is twice the chance of a car being available when you need it. When you're gaming I'd imagine that is all you are doing, so I'd turn it off. When I am browsing and burning and downloading and IMing all at the same time, I'd rather have it on.

[YeOldeStonecat]

The analogy wants to sound good...but...it's not like the CPU is split in half, which the analogy suggests. The analogy suggests, say you have a 3.0 and you enable HT...it would mean you really only have a pair of 1.5 GHz CPUs, which isn't true. You can still hit 3.0 with a single threaded app.

What HT does, to sum it up very briefly, is utilize un-used CPU cycles which normally would remain unused (even under full load) just due to the design of the core, and free them up for other purposes. There are a LOT of wasted clock cycles in the design of a chip, and what HT does, is reclaim those, and sort of create a second virtual CPU out of them.

Now, if you take 2x apps which are single threaded, and they demand 100% of the CPU, run them at the same time (lets take Folding for example)...you will not get 2x 3.0GHz jobs out of it. Your analogy begins to ring true here...but it's still not taking a single 3.0 and making a pair of 1.5s out of it. How HT is utilized is also up to the software, what areas of the CPU it demands the most from. Hence....difference performance under HT from different apps.

An old article, but still illustrates HT very well, has some graphs showing CPU architecture with and without HT, and lotsa benchmarks across various apps, with and without HT on the same CPU.

http://www.gamepc.com/labs/view_content.asp?id=p4306ht&page=1

[cyberskye]

Many apps that do large I/O will lock (disk writes are blocking) and only use one cpu regardless. Needed to figure a way to incorporate thread-synch overhead into the equation. You lose effeciency with HT.