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[goodcow]

I got a P4 3.0C with HyperThreading enabled in the BIOS, and WinXP Pro.

There are some applications however, such as Grid.org, and DOSBox, which will only use 100% of "one CPU," effectively meaning it's only using 50% of the CPU. Why?

 

[myzhi]

I got a P4 3.0C with HyperThreading enabled in the BIOS, and WinXP Pro.

There are some applications however, such as Grid.org, and DOSBox, which will only use 100% of "one CPU," effectively meaning it's only using 50% of the CPU. Why?

1) Hyper-Threading Technology enables multi-threaded software applications to execute threads in parallel. If a program is not design to run in multi-threads (most don't), HT does nothing for them. Thus, to take advantage of HT, you need to run 2 or more instances of same / different software.

2) Since processors with HT are really just one CPU, Windows does not show correct cpu usage. Thus, even though it may say 50+%, it could be the same as 90+% on a non HT system.

 

[rc213]

If a program is not design to run in multi-threads (most don't), HT does nothing for them.

 

[Phoenix]

1) Hyper-Threading Technology enables multi-threaded software applications to execute threads in parallel. If a program is not design to run in multi-threads (most don't), HT does nothing for them. Thus, to take advantage of HT, you need to run 2 or more instances of same / different software.

Add to that - most programs are not constantly multi-threaded. Unless you're monitoring a webserver or similar that spawns a thread on request and would thusly have lots of threads open, many multithreaded applications spawn off threads that are not always active or are short-lived. The Windows CPU monitor is pretty crappy at effectively displaying that behavior, but if you put the application under a microscope (profiler) you would see the result.

MANY applications simply aren't multithreaded and by nature aren't problems that require multiple threads. Hyperthreading is a great thing for cheap servers - but is only of marginal benefit for the average user.

 

[maharg]

And it bears repeating that if what you're seeing is multiple heavy processes running and only using 100% of one cpu, it is likely that one of them is CPU bound and thus isn't actually allowing enough room in the pipeline for the virtual cpu to run. Hyperthreading is a hack, you don't really have two cpus.

 

[Mr Gump]

Does this only work on xp pro or is it the same for home?

 

[myzhi]

Does this only work on xp pro or is it the same for home?

Since Home edition supports 1 cpu / 2 virtual cpu, it supports HT.

 

[DaCocoBrova]

What about video encoding? Does it speed things up?

 

[CueTheMusic]

It should speed up most video encoding programs a little. It doesn't usually give the performance to two cpu's, but it usually does help a little bit in threaded applications.