why win limits CPU usage to 50%?

[xavmdq]

In 2 computers with Pentium 4 540 3.2Ghz / 1GB RAM and P4 3GHz / 2GB RAM
the other, with Windows XP Sp2 in both computers, any process (I probe
Rhino and PET) uses only 50% of CPU in any priority (I set normal and
high). In my computer (Athlon XP 2000 with the same OS) I don't have
this problem.

 

[Shenan Stanley]

In 2 computers with Pentium 4 540 3.2Ghz / 1GB RAM and P4 3GHz / 2GB
RAM the other, with Windows XP Sp2 in both computers, any process (I
probe Rhino and PET) uses only 50% of CPU in any priority (I set
normal and high). In my computer (Athlon XP 2000 with the same OS) I
don't have this problem.

Seems to be unique to you.
I frequently get over 50% of CPU usage on a CPU, dependent on the
application.

Get "HeavyLoad" from here and try running it..
http://www.jam-software.com/freeware/index.shtml

 

[bxf]

In 2 computers with Pentium 4 540 3.2Ghz / 1GB RAM and P4 3GHz / 2GB RAM
the other, with Windows XP Sp2 in both computers, any process (I probe
Rhino and PET) uses only 50% of CPU in any priority (I set normal and
high).

I suppose you've dismissed the idea that your CPUs are so powerful that
they perform any task without exerting themselves beyond 50%?

 

[Michael W. Ryder]

In 2 computers with Pentium 4 540 3.2Ghz / 1GB RAM and P4 3GHz / 2GB RAM
the other, with Windows XP Sp2 in both computers, any process (I probe
Rhino and PET) uses only 50% of CPU in any priority (I set normal and
high). In my computer (Athlon XP 2000 with the same OS) I don't have
this problem.

The 540 is a hyperthreading processor so most single jobs will only use
half of the CPU's power. I only use 50% on my 3.4 GHz processor with
most jobs. But if I am running a large data import in Excel and a large
data conversion in a DOS program at the same time then the processor
goes to 100%.

 

[bxf]

The 540 is a hyperthreading processor so most single jobs will only use
half of the CPU's power. I only use 50% on my 3.4 GHz processor with
most jobs. But if I am running a large data import in Excel and a large
data conversion in a DOS program at the same time then the processor
goes to 100%.

So are we saying that with a HT processor, if we are running only one
task, we can only get 50% of available processing power? Surely that
would be a deficiency in too many circumstances. Is this really the way
it works?

 

[Dr Teeth]

So are we saying that with a HT processor, if we are running only one
task, we can only get 50% of available processing power?

But that is 100% of one (of two) CPUs (albeit virtual ones).

--
Cheers,

Guy

** Stress - the condition brought about by having to
** resist the temptation to beat the living daylights
** out of someone who richly deserves it.

 

[Michael W. Ryder]

Michael W. Ryder wrote:




So are we saying that with a HT processor, if we are running only one
task, we can only get 50% of available processing power? Surely that
would be a deficiency in too many circumstances. Is this really the way
it works?

The advantage in Hyperthreading is that with my Northwood P4 I could
only run one of the jobs at a time. Now I can run both of them at the
same time without any apparent difference in run time. This can save a
lot of time if you have multiple jobs to run together.

 

[bxf]

But that is 100% of one (of two) CPUs (albeit virtual ones).

I'd done just a bit of reading on the subject of HT in the past, and I
understood that, given the right mix of work, a HT processor can
slightly outperform a non-HT one. I cannot translate this to mean that
each CPU of a HT processor is the equivalent of a comparable speed
non-HT processor.

So, if you mean to say that 100% of one (of two) is the equivalent of
100% of one (of one), that would conflict with the above. On the other
hand, if a HT processor can only use half the total power when running
only a single task, then the processor is being under-utilized much of
the time, and I'd find that hard to believe.

Ths does not mean that there isn't some anomaly in the reported CPU
usage for HT processors. But then again, the OP says 50% all the time -
no more, no less.

 

[Bert Kinney]

Hi,

Hyper-Threading allows the processor to execute 2 different software threads
simultaneously on each physical processor. As i see it, the processor executes what's
delivered to it. And i found nothing that suggests that the processor behaves any
differently in terms of % weather it receives single or multiple threads. The "How
Hyper-Threading Technology Works" demo explains the process nicely.

Intel® Hyper-Threading Technology (HT Technology) Demo for Servers
http://www.intel.com/business/bss/products/hyperthreading/server/demo/index.htm

Hyper-Threading Technology
http://www.intel.com/technology/hyperthread/