Re: Asus A8N-SLI & Athlon X2 Dual Core

><snipped>
> Ok cheched device manager and there are 2 cpus there does windows use
> them both or just one and then the app/game has to be made to use the
> other, i had a 3200 64 bit and a mate asked me to swap for his 4200 x2
> to which i nearly bit his arm off for, at the moment is there any use
> for the duel cores.
>
> Graham
You need to understand 'tasks', and 'multi-threading'. Now start at the
beginning,and visualise a single simple program, that does one linear
'thread' of operations. As such, the OS, can do nothing with this to use
the second processor core. This is a 'single threaded' application.
However if the application uses 'OS' resources (calling things like disk
I/O operations), _these_ can be split onto the second chip. In such cases,
there is a small useage of the second chip/core (perhaps 10 to 15%). If
however you launch a second program, this can be run on the second core.
If instead the program is written as 'multi-threaded', then jobs that it
does, are split off into seperate 'threads', which complete independantly
of the main program. Some programs (like Photoshop), correctly do this.
Now there is a small 'cost' associated with running a multi CPU kernel
(since code has to be added to decide which CPU to send a task to). This
is small, but may be as much as 5%. Conversely though, there is a small
gain in the same situation for most programs, from the ability of the
system tasks to execute on the second core. This gives the typical overall
gain in these circumstances of 10% mentioned above. However as soon as
multiple tasks are running (whether multiple programs, or a multi-threaded
application), the gains 'shoot' up, and may reach perhaps 80% (The OS
overhead, and the fact that the I/O and memory, are shared, prevent 100%
gain ever really being seen). Typical gains for normal application mixes
average out at about 40 to 45% over a single cpu at the same speed. As
such, AMD, are very 'honest' in their speed rating figures for the dual
core units. Your 4200+, clocks at the same rate, as the single core 3400+,
and for most application mixes, should give processor performance very
much better than it's 'rating' suggests. They err on the side of the lower
figure, since it is unlikely that anyone will do 'worse' than their
rating,while most people will be amazed at just how much better stuff
works. :-)
The other really lovely thing that happens with an SMP system, is the
reduction in 'hogging' problems. With Windows, some applications
(paticularly older W9x applications), can sit 'polling' events, and
effectively hogging the system. When this happens on a single core/CPU,
getting keyboard/mouse responses to stop the application, can be really
slow. However with the SMP systems, the second core can respond to you,
making the whole responsiveness of the system, vastly better.

Best Wishes


.

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