Hyper-Threading Technology and SW

I just bought a new system. A Shuttle with a intel 3 Ghz, 1 gig ram a(hyperx ddr433) a FX500 with a Zippy keyboard. The system has
Hyper-threading technology, which simulate a second cpu by software. Since SW doesn't support multi cpu my assumption is that turning off this capability will speed up the system. When I rebuild, the cpu never exceed 50%. Now with the hyper-threading off the cpu goes to 100%. Anyone has seen this?
--
Robin B
Mech Eng, Montral, Canada
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"Robin" wrote:

software.
I posted this here some time ago (thread was "Hyper-Threading Technology"):

So your 50% / 100% measures are perfectly consistent with Intel's marketing, and with the planned future processors that will actually have 2 processing units on the chip. My guess is you should keep hyper-threading on if your computer runs other software in parallel with SW.
Besides, some people argued that SW actually does support multiprocessors, or rather that Parasolid uses it in a parallelizable jobs such as the (dreaded) shells, but I could never verify it on my dual AMD machine...
I also suggested once that recent stability problems in SW *could* be related to *possible* work to rewrite it (thread-safe...) to take advantage of multiprocessing in the future. Time will tell...
--
Philippe Guglielmetti - www.dynabits.com



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Hyperthreading simulates multiple CPUs in the hardware, not software. When enabled, Windows thinks there are 2 CPUs. Since SW can only run on a single CPU, the total CPU usage never goes above 50% because 1 CPU is 50% of 2 CPUs. SW will accomplish any task in about the same time, either way.
One way or the other will be slightly faster. Maybe someone here can advise which way to go. With HT on, other tasks should be more responsive. If that's important, leave it on.
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single
advise
I vaguely remember someone reporting about a 5-10% slowdown running SW (or maybe it was PW) when running with HT on.
Jerry Steiger Tripod Data Systems
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I remember that post and it was slower. PW is supposedly a little faster but the only way to benchmark PW, AFAIK, is to use a stopwatch and that's a little subjective. Since we're talking about the speed "processing" here, maybe Mike's Ship in the Bottle benchmark could shed some light on it. If there's no difference or an improvement, leave HT on. If it rebuilds slower then leave it off.
- Eddy

When
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Hi
I posted just before christmas after I did a benchmarktest which showed that Hyper-Threading is faster. Therefore I worked for a while with hyper-threading enabled. But I disabled it a month ago and it feels faster. I write feels because I have nothing that proves it.
Klaus
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Yes, I remember. I know your HT test showed otherwise but the conclusion in the thread was that it's slower. Or maybe there was no conclusion depending how you look at it :)
- Eddy

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Several years ago I was working on a dual celeron machine with SW2001+ and NT4. PW was _always_ running at 100% (both cpu full speed), rebuilds were running like three seconds at 50% - three seconds at 100%, alternately. Enough memory to ensure that was not system processes. Elsa video card with mulithreaded drivers. Did the SW really degrade not to use mutltithreading anymore?
Konrad
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Ok, I did my own test.
First test is a rebuild on arraying a hole for a 38*27 holes. I just click ok and look at the watch. Hyper-threading on take 33 sec and HT off takes 29 sec.
Second test is archiving in rar format (best compression) a directory of pictures (including many sub-directories). Result: 46 sec in both cases.
I'll leave it off since it seems equal or faster and I don't have to bother with a dual cpu in the task manager that never reach 100%.
Robin

Since
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