Re: [ANNOUNCE] Interbench v0.20 - Interactivity benchmark

[Con Kolivas <kernel@kolivas.org>]

On Thu, 14 Jul 2005 03:54, Bill Davidsen wrote:
> Con Kolivas wrote:
> > On Tue, 12 Jul 2005 21:57, David Lang wrote:
> >>for audio and video this would seem to be a fairly simple scaleing factor
> >>(or just doing a fixed amount of work rather then a fixed percentage of
> >>the CPU worth of work), however for X it is probably much more
> >> complicated (is the X load really linearly random in how much work it
> >> does, or is it weighted towards small amounts with occasional large
> >> amounts hitting? I would guess that at least beyond a certin point the
> >> liklyhood of that much work being needed would be lower)
> >
> > Actually I don't disagree. What I mean by hardware changes is more along
> > the lines of changing the hard disk type in the same setup. That's what I
> > mean by careful with the benchmarking. Taking the results from an athlon
> > XP and comparing it to an altix is silly for example.
>
> I'm going to cautiously disagree. If the CPU needed was scaled so it
> represented a fixed number of cycles (operations, work units) then the
> effect of faster CPU would be shown. And the total power of all attached
> CPUs should be taken into account, using HT or SMP does have an effect
> of feel.

That is rather hard to do because each architecture's interpretation of fixed 
number of cycles is different and this doesn't represent their speed in the 
real world. The calculation when interbench is first run to see how many 
"loops per ms" took quite a bit of effort to find just how many loops each 
different cpu would do per ms and then find a way to make that not change 
through compiler optimised code. The "loops per ms" parameter did not end up 
being proportional to cpu Mhz except on the same cpu type.

> Disk tests should be at a fixed rate, not all you can do. That's NOT
> realistic.

Not true; what you suggest is another thing to check entirely, and that would 
be a valid benchmark too. What I'm interested in is what happens if you read 
or write a DVD ISO image for example to your hard disk and what this does to 
interactivity. This sort of reading or writing is not throttled in real life.

Cheers,
Con

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