[RC5] Speed

dan carter motion at es.co.nz
Wed Apr 22 23:26:23 EDT 1998


On Tue, 21 Apr 1998 08:01:46 -0500, Skip Huffman wrote:

>In my garden I can shovel about a cubic meter of soil in an hour into
>a wheelbarrow, move it across the yard and dump it somewhere else. 
>Does this mean that me and my shovel and my wheelbarrow can move a
>cubic meter of water the same distance in the same time?  No,
>obviously, I am using the wrong tool, and the wrong measurement.

This is not how the calculations work.

To use your analogy;
In a one hour period:
The Smiths have 150 cubic meters of dirt in a pile, We know that John "Intel" Smith can pile 50 cubic meters of dirt per hour, therefore we know there are 3 equivelent Johns in the Smith household.
We know that John "Intel" Smith can shift 2 Cubic meters of water per hour. Therefore we have 6 Cubic Meter of Water Movements per Hour (CMWMH)  in the Smith household.

But wait, this 50 dirt = 2 water doesn't hold for the Joneses, so we calculate:

The Jones have a 250 cubic meter pile of dirt in their back yard, we know Mary "Alpha" Jones can pile 125 cubic meters of dirt per hour, therefore we know there are 2 equivelent Marys in the Jones household.
We know that Mary "Alpha" Jones can shift 25 Cubic meters of water per hour, Therefore we have 50 CMWMHs  in the Jones household.

Therefore we have a total of 56 CMWMHs.

We are not saying, we have completed 15Gigkeys/s therefore we could complete 15GigaFLOPS, just as above i am not saying 400dirt=400water.

Rather we are saying 16.5GigaKeys/s=~3324265 MFLOPS3, just as above i said 400dirt=56water.

Of course it is approximate because the dirt to water ratio that holds for John "intel" Smith will not hold for Janis "Cyrix" Smith. But the differences within the Jones should not be radical, after all an i586-150 is just a i586-75, only running at 
a higher MHz, the FLOPS should scale exactly the same as does the integer (shouldn't it?). In contrast, the ratios between the Smiths and the Joneses will be "radically" different, but this is accounted for. 

As to how approximate it is, only a detailed comparison of i586 Keys per second/ i586 FLOPS with K6 Keys per second/ K6 Flops and Cyrix..... will tell us, who wants to volunteer?






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