Orchid Win7 v1 <voi### [at] devnull> wrote:
> If you can get 100 kb/s, and you start a second download, the second 
> download goes at 50 kb/s, and the first one also slows down to 50 kb/s. 
> This is not strange.

> Now imagine you get 100 kb/s, and you start a second download, and this 
> /also/ gets 100 kb/s, so your total download rate is now 200 kb/s. THAT 
> is strange.

You are confusing usage percentage with speed. Windows doesn't tell you how
fast the processes are running (compared to maximum theoretical speed), only
how many (virtual) cores are currently being used (and at which ratio, if
not fully utilized.)

When Windows tells you that 50% of CPU time is in use, that doesn't mean
that the process is running at 50% of the maximum possible speed. In the
case of hyperthreading that's probably closer to 90% or something.

What the number is telling is how many virtual cores are being used at
the moment by that process (assuming that it's using all of the virtual
cores fully).

50% means that it's using half of all the virtual cores. 100% would mean
that it's using all of them. However, the latter doesn't necessarily mean
that the process is now running twice as fast. (With multithreading it
probably means a 10-30% speed increase, depending a lot on the type of
application.)

(Of course this with the caveat that, as said, the process is using the
core fully. If it's using it only partially, then then the system will
calculate how many %'s of the total available time on that virtual core
is being used by the process, and summing up the values from different
cores where the process is running.

Thus if you have for example 4 virtual cores and the process is using 50%
of two of them, then the total CPU time usage will be 25%, ie. the same as
if only one virtual core were fully utilized.)

-- 
                                                          - Warp

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