Why is Intel HT tech bad for corporate users?

[Zstream]

I work at a corporation which uses quite a few Xterm windows and unix applications within windows XP. The thing that bothers me though is that none of these apps are multithreaded or even use the HT tech efficently. My question to you all is why would they have HT on when they could just as easily turn it off and make 99% of the terminals faster?

 

[StrangerGuy]

Don't know about corporate servers, but I must say that HT improves multitasking performance quite a lot from my experience.

 

[Zstream]

Originally posted by: StrangerGuy
Don't know about corporate servers, but I must say that HT improves multitasking performance quite a lot from my experience.

I am just talking about workstations now though. My main question though is why HT is active when half of the applications are unix based using a port for windows XP.

My understanding of HT is that for every 6 cycles with HT on it divides the cycles into 3 x 3 one for each software core since HT is not hardware. When you are using non multithreading applications the HT is pretty much disabled and it goes 3 x 3 even though large chunks of data is being sent through so would not 6 then another 6 be better then 3x3 3x3 ?

 

[zephyrprime]

Originally posted by: Zstream

Originally posted by: StrangerGuy
Don't know about corporate servers, but I must say that HT improves multitasking performance quite a lot from my experience.

I am just talking about workstations now though. My main question though is why HT is active when half of the applications are unix based using a port for windows XP.

My understanding of HT is that for every 6 cycles with HT on it divides the cycles into 3 x 3 one for each software core since HT is not hardware. When you are using non multithreading applications the HT is pretty much disabled and it goes 3 x 3 even though large chunks of data is being sent through so would not 6 then another 6 be better then 3x3 3x3 ?

That is a totally wrong description of how hyperthreading works.
explanation

You won't see more than a few percentage drop in performance with HT on in your situation. You may see a speed up if more than one teminal is using the processor simultaneously.
office software benches

 

[TuxDave]

You should not see a significant performance hit with HT on for non-multitasking enviroments.

 

[Zstream]

Originally posted by: zephyrprime

Originally posted by: Zstream

Originally posted by: StrangerGuy
Don't know about corporate servers, but I must say that HT improves multitasking performance quite a lot from my experience.

I am just talking about workstations now though. My main question though is why HT is active when half of the applications are unix based using a port for windows XP.

My understanding of HT is that for every 6 cycles with HT on it divides the cycles into 3 x 3 one for each software core since HT is not hardware. When you are using non multithreading applications the HT is pretty much disabled and it goes 3 x 3 even though large chunks of data is being sent through so would not 6 then another 6 be better then 3x3 3x3 ?

That is a totally wrong description of how hyperthreading works.
explanation

You won't see more than a few percentage drop in performance with HT on in your situation. You may see a speed up if more than one teminal is using the processor simultaneously.
office software benches

Umm Intel HT in windows XP is software based not hardware. Linky

 

[Accord99]

Originally posted by: Zstream
Umm Intel HT in windows XP is software based not hardware. Linky

Too bad that article doesn't know what it's talking about. You should read the previous link by zephyr.

 

[sonoran]

Originally posted by: Zstream
Umm Intel HT in windows XP is software based not hardware. Linky

Zstream, it seems your understanding of hyperthreading is grossly off base (probably because that FAQ you linked to is just plain wrong on some counts). The implementation of hyperthreading consumed about an extra 5% of die space on the chip - that's extra hardware circuitry. And as zephyrprime already tried to explain to you, there should be little to no performance degradation in general workstation usage. In fact the main thing users should notice is a smoother computing experience, as their machine should hang less frequently if one app wants to hog the CPU at 100%. Also note that even if your apps aren't multithreaded - your OS is.

In a nutshell, a more accurate description of what's going on is this: "Hyper-Threading Technology enables thread-level parallelism (TLP) by duplicating the architectural state on each processor while sharing one set of processor execution resources". You can find a complete article on hyperthreading here: Hyper-Threading Technology

* Not speaking for Intel Corp *

 

[dexvx]

HT is not software based. It is hardware based, it's just Intel's version of SMT.

Using Linux, it significantly speeds up uses with multiple terminals and processes.

 

[F1shF4t]

Actually this is straight from intel but it pretty much shows the diff between single core, HT and dual core, graphically.

Diff between single core,HT and dual.

Click on the dual core demo.

There is no amd bias in that demo, so its safe to watch

Edit: also another thing to remeber is that there is not only one program running at a time, ie windows has many small progs running all the time, so any multithreaded capability helps as they can be assigned to different cores (or logical core).

There was some benchmarks i saw before, and that was pretty much comparing the northwoods with HT with the early athlons 64's, now when encoding one file (mp3) after waiting till it finished then another the athlon 64 was faster, while doing both files at the same time the northwood was faster.

 

[Gamingphreek]

Originally posted by: dexvx
HT is not software based. It is hardware based, it's just Intel's version of SMT.

Using Linux, it significantly speeds up uses with multiple terminals and processes.

Its not even hardware based. There is not a dedicated chip on the processor called "The Hyperthreading Chip".

All hyperthreading does is compensate for the Pentium's insanely long instruction pipeline. A cache miss or a branch misprediction stalls out the entire pipeline. Even if all the tasks make it through OK only a small fragment of the Instruction Pipeline is used since it is so large.

HT counters this by staggering sending 2 threads at once. It keeps the Instruction Pipeline running at much closer to a theoretical maximum than it otherwise would. Additionally, the fact that it sends 2 threads at once ESSENTIALLY makes it like a virtual processor.

No where near the benefit that a Dual Core/SMT system will give you but definitely a nice thing to compensate for a long pipeline.

-Kevin

 

[TuxDave]

Originally posted by: Gamingphreek

Originally posted by: dexvx
HT is not software based. It is hardware based, it's just Intel's version of SMT.

Using Linux, it significantly speeds up uses with multiple terminals and processes.

Its not even hardware based. There is not a dedicated chip on the processor called "The Hyperthreading Chip".

-Kevin

And the scheduler for hyperthreading is done on the chip. So doesn't that make it hardware?

 

[sonoran]

Originally posted by: Gamingphreek
Its not even hardware based. There is not a dedicated chip on the processor called "The Hyperthreading Chip".

Wrong on the first count - right on the second one (sort of). It's an integral part of the die, and increased die size about 5% when it was introduced. You're also correct in that it is not tantamount to having two complete cores. It's a duplication of much of the logic that prepares instructions for execution, but there is still only one set of execution units on a hyperthreaded single core chip.

* Not speaking for Intel Corp *

 

[dmens]

And the scheduler for hyperthreading is done on the chip. So doesn't that make it hardware?

No it isn't

 

[TuxDave]

Originally posted by: dmens

And the scheduler for hyperthreading is done on the chip. So doesn't that make it hardware?

No it isn't

 

[Zstream]

Originally posted by: Gamingphreek

Originally posted by: dexvx
HT is not software based. It is hardware based, it's just Intel's version of SMT.

Using Linux, it significantly speeds up uses with multiple terminals and processes.

Its not even hardware based. There is not a dedicated chip on the processor called "The Hyperthreading Chip".

All hyperthreading does is compensate for the Pentium's insanely long instruction pipeline. A cache miss or a branch misprediction stalls out the entire pipeline. Even if all the tasks make it through OK only a small fragment of the Instruction Pipeline is used since it is so large.

HT counters this by staggering sending 2 threads at once. It keeps the Instruction Pipeline running at much closer to a theoretical maximum than it otherwise would. Additionally, the fact that it sends 2 threads at once ESSENTIALLY makes it like a virtual processor.

No where near the benefit that a Dual Core/SMT system will give you but definitely a nice thing to compensate for a long pipeline.

-Kevin

Ok cool that us what I thought, I knew that true dual core acted much different from single core with HT enabled.