Re: 720 Memory Bandwidth

From: Craig Gleason (
Date: Thu Jan 23 1992 - 11:24:13 CST

> Just out of curiosity, I have one application that runs faster than
> expected on the HP. It happens to have a scalar bottleneck that is
> dominated by divides (solving lots of tridiagonal systems without
> factoring them first). On the IBM RS/6000, 64-bit FP divides take
> about 20 cycles --- How fast are they on the Snakes?
> --

They take 12 cycles, so they should be quite a bit faster, given the
higher frequency. The divides will also be put in the FP execution
queue, executed when the units are free and their operands are available,
and can overlap with integer instructions. So if you have enough integer
stuff going on, there could be quite a lot of work done while waiting for
the divides to complete.


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