Messages in this thread | | | Date | Fri, 19 May 2006 13:23:49 -0400 | From | John Richard Moser <> | Subject | Re: Stealing ur megahurts (no, really) |
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Dr. David Alan Gilbert wrote: > * John Richard Moser (nigelenki@comcast.net) wrote: > >> Scrambling for an old machine is ridiculous. Down-clocking makes sense >> because you can adjust to varied levels; but it's difficult and usually >> infeasible. Pulling memory and mix and matching is not much better. > > <...> > >> This brings the idea of a cpumhz= parameter to adjust CPU clock rate. >> Obviously we can't do this directly, as convenient as this would be; but >> the idea warrants some thought, and some thought I gave it. What I came >> up with was simple: Adjust time slice length and place a delay between >> time slices so they're evenly spaced. > > <...> > > Hi John, > While cpu downclocking helps a bit, it would be hopelessly inaccurate > for figuring out if your app would run fast enough on the given > ancient machine. A lot else has happened to the world since the days > of the 200MHz CPU: > * Faster memory > * Larger caches > * Faster PCI busses > * Instruction set additions (various more levels of SSE etc) > * Faster discs > * Changes to the CPU architecture/implementation >
Skews and fuzz. Imperfections, but at least we get a general idea. ;)
> Still, it would be interesting to see the difference in performance > of a downclocked modern processor and its 10 year old clock equivalent. >
Yes. Too bad CPUs can't be uniformly underclocked by design; they have at most 3-5 different levels of CPU frequency you can pick from at run time.
> Dave >
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