Re: How are CPU Speed and Overall CPW Related? -- MIDRANGE-L

To focus only on the issue of CPU performance may cause someone to lose site
of the big picture.  If that has occurred for anyone, please accept my
apology.

From my admittedly limited perspective, OS/400 is a hidden treasure.  It
seems to me, that it would be used by more people to do more things if the
supporting hardware offered more bang for the buck.

But I really ought to drop this line of thinking, and let the big players in
the market - the ones who have the bigger picture, decide what's best for
the future of the platform.

Thanks to those who added to my inquiry.

Nathan.


> Date: Thu, 3 May 2001 10:26:21 -0500
> From: "Alexei Pytel" <pytel@us.ibm.com>
> Subject: Re: How are CPU Speed and Overall CPW Related?
>
> I can't understand your obsession with "artificial constraints".
> It's much more complicated than that.
> CPU (any CPU) is so much faster than memory, that however large is the
> cache, CPU always has to waste cycles.
> The only really "unbridled" case will be if cache entirely replaces
memory.
> Next, we were talking about L2 cache. L2 cache is still sufficiently
slower
> than CPU, so any L2 cache always constrains CPU.
> To let CPU run at "unbridled" speed will be to expand L1 cache to the size
> of memory - say 256MB.
> In fact, using your logic, Intel does "artiicially bridle" it's chips,
> because Pentium L1 cache is much smaller than PowerPC L1 cache. However,
> you don't seem to complain about it.
>
> Next, every application has different requirements in terms of cache. Some
> applicatoins benefit more - what you discovered in your test. Some others
> will not so easily benefit from it. Of course, if cache could be made the
> size of memory (or in other words, memory could be made to run at CPU
> speed), then any sort of applications will benefit. But this kind of
> surpasses modern technology.
>
> Also, you found a benchmark, which shows that your laptop is superior in
> performance to iSeries. I totally agree - your laptop runs your test
> faster. So what - do you spend hours and hours round o'clock to run this
> test ?
> I have my doubts. Try to run a banking system with a modest number of say
2
> million accounts on your laptop - a dozen branches, couple of hundreds of
> users, interest calculations, loan validation, credit risk etc. Why not -
> it is so much faster than iSeries, it should be a breeze.
> Again I have my doubts.
>
> Any benchmark shows how well system A runs this particular benchmark. No
> more, no less. Now if you can demonstrate that your real application is
> sufficiently similar to a benchmark, then these results will tell you
> something important. Otherwise, it can be real misleading. This is a
> problem with any becnhmark.
>
> For what it's worth...
>
>     Alexei Pytel
>


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