CPU two cores or one core

[Gabriel Knight]

Hi all

I have this CPU here :

http://www.cpu-world.com/sspec/SL/SL7Z9.html

I have installed one in a pc before and it came up as a two core, as in when
I look in "task manager" then "performance" there are two cubes for the "CPU
Usage History"... Is this CPU a Dual Core? as far as I know its a P4 single
core CPU.

Thanks
GK

 

[DerekBaker]

Hi all

I have this CPU here :

http://www.cpu-world.com/sspec/SL/SL7Z9.html

I have installed one in a pc before and it came up as a two core, as in when
I look in "task manager" then "performance" there are two cubes for the "CPU
Usage History"... Is this CPU a Dual Core? as far as I know its a P4 single
core CPU.

Thanks
GK

http://en.wikipedia.org/wiki/HyperThreading

 

[TVeblen]

Hi all

I have this CPU here :

http://www.cpu-world.com/sspec/SL/SL7Z9.html

I have installed one in a pc before and it came up as a two core, as in when
I look in "task manager" then "performance" there are two cubes for the "CPU
Usage History"... Is this CPU a Dual Core? as far as I know its a P4 single
core CPU.

Thanks
GK

You don't say what P4 processor you are using, but most Pentium 4
processors are dual core: 2 processor cores on one die. The OS sees it
as 2 processors because that is how it can utilize it.

 

[TVeblen]

P4s only have single cores. Pentium Ds are dual core. Starting with
the Prescott series, P4s have hyperthreading, (HT). There is one
physical core and a virtual core. This appears as 2 CPUs in Task
Manager. For an OS and apps that can utilize HT, this allows for
more efficient thread scheduling as there are 2 processing paths,
although the individual threads are still processed sequentially.
In a true multicore CPU the threads can be processed simultaneously.

I think you are right, but this article:
http://en.wikipedia.org/wiki/Pentium_Dual-Core
Is what I was thinking of. I should have said "some" and not "most".
I've got a Wolfdale box kicking around here.

 

[shegeek72]

P4s only have single cores.  Pentium Ds are dual core.  Starting with
the Prescott series, P4s have hyperthreading, (HT).  There is one
physical core and a virtual core.  This appears as 2 CPUs in Task
Manager.  For an OS and apps that can utilize HT, this allows for
more efficient thread scheduling as there are 2 processing paths,
although the individual threads are still processed sequentially.
In a true multicore CPU the threads can be processed simultaneously.

What's interesting is Intel brought back hyperthreading in its i7
series. If you have a CPU monitor that can display multiple cores
you'll see 8 cores!

 

[Paul]

Hi all

I have this CPU here :

http://www.cpu-world.com/sspec/SL/SL7Z9.html

I have installed one in a pc before and it came up as a two core, as in when
I look in "task manager" then "performance" there are two cubes for the "CPU
Usage History"... Is this CPU a Dual Core? as far as I know its a P4 single
core CPU.

Thanks
GK

A Hyperthreaded processor has one physical core and one virtual core.
The virtual core gets to run, if the physical core is blocked. As such,
you get 1.1x performance than if the virtual core is turned off. So
Hyperthreading, at the best of times, gives 10% more performance.
The main benefit, may be a slightly smoother desktop, due to less
blocking of running tasks (i.e. you can feel a difference between
a single core AthlonXP and a hyperthreaded P4, when both have the
same performance level).

http://processorfinder.intel.com/Details.aspx?sSpec=SL7Z9

A Pentium D by comparison, has two physical cores and you get 2.0x
performance.

http://processorfinder.intel.com/details.aspx?sSpec=SL88S

Both processors (the hyperthreaded single core and the true dual core)
would have two graphs in Task Manager. If you were to turn off Hyperthreading
in the BIOS, then the next time the OS boots, there would be one graph.

Paul

 

[TVeblen]

What's interesting is Intel brought back hyperthreading in its i7
series. If you have a CPU monitor that can display multiple cores
you'll see 8 cores!

In Windows 7 there is an advanced boot feature that allows you to tell
the OS how many "processors" it can work with to speed boot time. So for
an i7-920 machine should this setting be 4 or 8?

 

[DevilsPGD]

In message <[email protected]> TVeblen

In Windows 7 there is an advanced boot feature that allows you to tell
the OS how many "processors" it can work with to speed boot time. So for
an i7-920 machine should this setting be 4 or 8?

Unless you have specific needs, you're probably best off leaving it
alone.

Defaulting to all processors logical processors is generally the way to
go, and this is the default.

 

[TVeblen]

In message<[email protected]> TVeblen


Unless you have specific needs, you're probably best off leaving it
alone.

Defaulting to all processors logical processors is generally the way to
go, and this is the default.

The default setting is one processor. Regardless, it doesn't make any
noticeable difference either way.

 

[DevilsPGD]

In message <[email protected]> TVeblen

The default setting is one processor. Regardless, it doesn't make any
noticeable difference either way.

No, it doesn't default to one processor. It defaults to "undefined",
which tells the OS to use all available processors.

http://www.edbott.com/weblog/?p=2476

Limiting to one causes a measurable (although insignificant) slowdown.

 

[TVeblen]

In message<[email protected]> TVeblen


No, it doesn't default to one processor. It defaults to "undefined",
which tells the OS to use all available processors.

http://www.edbott.com/weblog/?p=2476

Limiting to one causes a measurable (although insignificant) slowdown.

Thanks for that info. I unchecked "Number of Processors". So now it will
use all available processors.
If you check the box the only options are 1 through 8.
That's not obvious, which is why it's an advanced setting!

 

[DevilsPGD]

In message <[email protected]> TVeblen

Thanks for that info. I unchecked "Number of Processors". So now it will
use all available processors.
If you check the box the only options are 1 through 8.

It will show you all options appropriate for the number of logical
processors. On a Q6600 you'll see 1 through 4, since anything over 4
wouldn't be appropriate.

That's not obvious, which is why it's an advanced setting!

It's an advanced setting because using less than the total number of
logical processors on your system is an extremely rare configuration.

 

[DevilsPGD]

In message <[email protected]> TVeblen

I wonder what possible reason someone would have for doing so?

Usually troubleshooting or diagnostics of some sort.