Is HT a waste of cpu time

[Michael C]

I was running a single threaded long process on a HT P4 last night and
noticed that it only used effectively one fake cpu. The result was the
actual usage sat at 50% which looked like a big waste of cpu time to me.
Would it be better to have HT turned off? Is it any use in general?

 

[Noozer]

I was running a single threaded long process on a HT P4 last night and
noticed that it only used effectively one fake cpu. The result was the
actual usage sat at 50% which looked like a big waste of cpu time to me.
Would it be better to have HT turned off? Is it any use in general?

If your computer is just sitting there working on a single process, then
hyperthreading is not helpful.

If you have multiple processes then hyperthreading will balance out the wait
time amongst them. It really helps when a user is accessing the PC at the
same time a heavy process is running.

 

[kony]

I was running a single threaded long process on a HT P4 last night and
noticed that it only used effectively one fake cpu. The result was the
actual usage sat at 50% which looked like a big waste of cpu time to me.
Would it be better to have HT turned off? Is it any use in general?

Yes if your performance needs fall around use of a singe
threaded process, the performance can easily improve with it
off.

 

[ElJerid]

I was running a single threaded long process on a HT P4 last night and
noticed that it only used effectively one fake cpu. The result was the
actual usage sat at 50% which looked like a big waste of cpu time to me.
Would it be better to have HT turned off? Is it any use in general?

I experienced the same "problem", and still wonder why a single process is
only using 50% of total cpu power. In my opinion, HT was used dynamically,
depending of the processes. I also wonder what Intel means by "50%". Are
there any measurements about single task processing with HT enabled and
disabled? Could be interesting !

 

[Michael C]

I experienced the same "problem", and still wonder why a single process is
only using 50% of total cpu power.

This is the way dual processor machines have always work, a single thread
can only use a single processor so will only use 50%. I'm not sure why the
CPU usage varies between the processors though.

Michael

In my opinion, HT was used dynamically, depending of the processes. I
also wonder what Intel means by "50%".

50% in this case means 1 cpu is being used 100% and the other 0%.

Michael

 

[Quaoar]

I was running a single threaded long process on a HT P4 last night and
noticed that it only used effectively one fake cpu. The result was the
actual usage sat at 50% which looked like a big waste of cpu time to
me. Would it be better to have HT turned off? Is it any use in
general?

I don't know the answer, but the question is "what applications or
processes are known to be hyperthreaded?" I'm of the opinion, until
proved wrong, that there are very few hyperthreaded apps and processes
running around loose. I've done searches on the word "hyperthread" and
come up empty handed in terms of much that advertises that coding has
been done to enable the process in any application. This is especially
true if one's applications suite is more than one or two years old.

I thusly believe that there is nothing much more than "hype" in
hyperthreading.

You can verify for yourself; Google "hyperthreading application" for
some interesting reading.

Q

 

[ElJerid]

I don't know the answer, but the question is "what applications or
processes are known to be hyperthreaded?" I'm of the opinion, until
proved wrong, that there are very few hyperthreaded apps and processes
running around loose. I've done searches on the word "hyperthread" and
come up empty handed in terms of much that advertises that coding has been
done to enable the process in any application. This is especially true if
one's applications suite is more than one or two years old.

I thusly believe that there is nothing much more than "hype" in
hyperthreading.

You can verify for yourself; Google "hyperthreading application" for some
interesting reading.

Q

You're right, but do you need specific HT apps in order to benefit from HT?
What about multiple applications running in parallel on your PC? Like
working in Excel, while listening to music and downloading some Windows
updates?

 

[Mike Walsh]

You're right, but do you need specific HT apps in order to benefit from HT?
No

What about multiple applications running in parallel on your PC? Like
working in Excel, while listening to music and downloading some Windows
updates?

Multiple applications running at the same time will use both virtual processors.

 

[kony]

You're right, but do you need specific HT apps in order to benefit from HT?

No, but you need apps that have multiple threads doing a
*lot*. If (as is often the case) you had a single thread
doing most of the CPU intensive stuff and another(s) doing
very little, there is little gain from HT.

What about multiple applications running in parallel on your PC? Like
working in Excel, while listening to music and downloading some Windows
updates?

Yes that would alleviate some of the penalty and boost
performance as HT was meant to- but then again, a single
modern CPU (without HT) should be loafing along doing so
little as Excell, an MP3 and file downloads.

The issue is more one of what needs done in realtime, and
whether the apps have the correct priorities to do so. Most
apps don't need high priority but in the case you mentioned,
it would be good for audio to have it even though audio is
usually a pretty undemanding unless you were using some kind
of player that had DSP effects.

 

[DaveW]

You noticed one of the flaws of HT. I also have run into the problem of
having two heavy applications running on the HT CPU and having it overheat
because it couldn't handle the load.
I now leave HT Off.

 

[HankG]

You noticed one of the flaws of HT. I also have run into the problem of
having two heavy applications running on the HT CPU and having it overheat
because it couldn't handle the load.
I now leave HT Off.

I also feel that there is more hype than fact. I would like to experiment
for myself. Can you (anyone) tell me how to check/set HT on/off? I checked
my bios--found nothing related to HT.

HankG

 

[HankG]

I also feel that there is more hype than fact. I would like to experiment
for myself. Can you (anyone) tell me how to check/set HT on/off? I checked
my bios--found nothing related to HT. >
HankG

My computer is an HP 3.06 Ghz w/1 GB of ram. At times it doesn't seem to
run that fast, but I think it's due more to its 5400 RPM hard drive. I've
looked at Google, but didn't find anything definitive.


HankG

 

[Synapse Syndrome]

If you have multiple processes then hyperthreading will balance out the
wait
time amongst them. It really helps when a user is accessing the PC at the
same time a heavy process is running.

When I have my Athlon64 doing some 3D rendering, I just put the rendering
process on Low Priority in Windows Task Manager. Then I can use the
computer to surf the net or check the newsgroups just as normal.

ss.

 

[Mark]

If you have multiple processes then hyperthreading will balance out the
wait time amongst them.

Will it? Correct me if I'm wrong (seriously), but I do not think WIN XP can,
of its own, 'distribute' threads over processes. Or, at least, you cannot
manually assign threads to single processes (say, to give the MySQL server
its own virtual CPU).

Regards,

- Mark

 

[Michael C]

My computer is an HP 3.06 Ghz w/1 GB of ram. At times it doesn't seem to
run that fast, but I think it's due more to its 5400 RPM hard drive. I've
looked at Google, but didn't find anything definitive.

It should be in the bios somewhere there, I don't think it would be anywhere
else.

 

[Michael C]

I don't know the answer, but the question is "what applications or
processes are known to be hyperthreaded?" I'm of the opinion, until
proved wrong, that there are very few hyperthreaded apps and processes
running around loose. I've done searches on the word "hyperthread" and
come up empty handed in terms of much that advertises that coding has been
done to enable the process in any application. This is especially true if
one's applications suite is more than one or two years old.

I thusly believe that there is nothing much more than "hype" in
hyperthreading.

You can verify for yourself; Google "hyperthreading application" for some
interesting reading.

That's because apps don't have to written for hyperthreading in fact you
can't technically write a hyperthreaded app. You can write a multithreaded
app though which is what people have been doing for years and this will take
advantage of hypertheading, although I don't see how it would be any quicker
than a single threaded app working on a non HT machine.

The problem is very few apps create 2 threads to run the same process. For
example a paint program could create 2 threads, one to modify the top of an
image and one to modify the bottom but most would just do it in a single
thread.

Michael

 

[ElJerid]

I was running a single threaded long process on a HT P4 last night and
noticed that it only used effectively one fake cpu. The result was the
actual usage sat at 50% which looked like a big waste of cpu time to me.
Would it be better to have HT turned off? Is it any use in general?
Because I find this trend very intersting and controversial (and still not
have a definitive opinion), I ran some Sandra benchmarks with and without
HT enabled.As the benchmarks are synthetic, they should give a good idea of
"pure hardware" performance.

HT enabled:
CPU: 9668 - 4030 / 7047
MM: 24883 - 35044
Mem: 5297 - 5286

HT disabled:
CPU: 8585 - 2358 / 4347
MM: 20043 - 25142
Mem: 5290 - 5254

Any comments ???

 

[Noozer]

HT enabled:
CPU: 9668 - 4030 / 7047
MM: 24883 - 35044
Mem: 5297 - 5286

HT disabled:
CPU: 8585 - 2358 / 4347
MM: 20043 - 25142
Mem: 5290 - 5254

Any comments ???

Ya... what does any of that mean?

 

[GT]

This is the way dual processor machines have always work, a single thread
can only use a single processor so will only use 50%. I'm not sure why the
CPU usage varies between the processors though.

Michael


50% in this case means 1 cpu is being used 100% and the other 0%.

But hyperthreading is 1 CPU divided in two, not a dual core CPU! A dual core
PC with HT will appear to have 4 processors. A single core CPU with HT will
'appear' to have 2 CPUs. With a single core, HT CPU shouldn't the work be
split evenly between its two halves and if one half is idle and the other
has a busy thread, then the busy half should be allowed more priority?

 

[GT]

Multiple applications running at the same time will use both virtual
processors.

Doing anything at all in Windows is effectivily multi-threaded as the
operating system itself has tasks running and if you look at the process
list you will see 30+ processes running before you even open what we
consider to be an application.