Author: Christophe Theron
Date: 01:01:45 10/27/01
Go up one level in this thread
On October 26, 2001 at 19:08:29, Thorsten Czub wrote:
>On October 26, 2001 at 17:06:20, Christophe Theron wrote:
>>No it is just because the machine thinks that the time passes extremely slowly.
>>
>>It believes it can compute 10000 nodes per second because its seconds last much
>>much longer than a real second.
>>
>>That is why I ask you to check Chess Tiger's clock with an external stopwatch.
>
>ok. again. i am stopping with an external clock.
>using 30 mhz.
>
>ct makes xyz nodes .
>
>doing the same in the same time with 54 mhz.
>
>ct makes xyz + difference nodes.
>
>
>now : how can ct make more (difference) nodes when it is slower,
>or not faster ???
>
>it seems you don't understand what i am doing.
Say that at 30MHz CT can compute 1000 nodes per second (just an example).
Say that at 30MHz, CT's clock is accurate (it follows closely your stopwatch).
Now you set the device to 54MHz. But the PLL cannot reach 54MHZ. It reaches
32MHz and cannot go higher.
BUT the device believes it is running at 54MHz. It will count one second every
time the internal clock ticks 54 million times. But in one REAL second, the
clock ticks only 32 million times.
One second measured by the device is going to last almost two REAL seconds (the
time needed to count up to 54 million).
During these two REAL seconds, Chess Tiger is going to compute something like
2000 positions.
From his point of view, he believes that it can compute 2000 position per
second, hence the incredible performance index.
In reality, it took almost two REAL seconds to compute those 2000 positions, so
you are still close to 1000 positions per second.
There is no big gain because the PLL cannot exceed 32MHz, but if you believe the
performance index without checking it you are going to believe that the device
is twice as fast...
Christophe
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