From: lithgow@usl.com (Malcolm Lithgow)
Newsgroups: comp.sys.acorn
Subject: Re: Heia guys: (ok, let's do it civilized...)
Date: 16 Oct 92 01:37:36 GMT
Article-I.D.: ucbvax.9210160419.AA15496

Well, Greg, I carefully considered whether to mail or post this. I
decided to post it, because I think that you are quite probably not the
only person confused about what performance is.

And, of course, I don't like being publicly put down. ;-)

[In message "Re: Heia guys: (ok, let's do it civilized...)", sgitokyo!VNET.IBM.COM!nicho writes:]
>In <9210150224.AA22858@ucbvax.Berkeley.EDU> Malcolm Lithgow writes:
>>Therefore the performance of the Alpha is unimpressive,
>  Oh good grief. How on earth did you make this spectacular leap of
>logic ?? That's like saying a Panda's performance isn't impressive,
>ergo a Ferarri's isn't either, because an F1 can beat both.

Well, if you bothered to read the rest of the sentence...

>Therefore the performance of the Alpha is unimpressive, since the new
>Crays are quite a bit faster at almost everything.

You would notice that I am making exactly the same 'spectacular leap of
logic' that you did when you said:

>> The performance is not amazing. The price/performance ratio is.
>>There is a not so sublte difference between the two.

Since, to spell it out, you are stating that the performance of the ARM
is not impressive because in terms of 'performance' the ARM is beaten
by other machines. My statement, using the same premise, states that
the Alpha's performance is also not amazing, and is in fact
unimpressive, since such beasties as Cray's, Fujitsu Supers, etc.  are
all far faster (ie. have far better 'performance').

So, to go back to your counter-example:

>That's like saying a Panda's performance isn't impressive,
>ergo a Ferarri's isn't either, because an F1 can beat both.

Quite so. If someone comes up to and says, 'A Panda has pretty good
performance considering it's price.'

And you say, 'It has poor performance -- a Ferrari is far faster.'

Then the first person is quite correct in saying, 'a Ferrari's
performance is not particularly impressive, if we're doing this sort of
comparison, because an F1 is far faster.'

Do you understand my meaning now?

>>If you had done a bit of engineering, ..
> Don't try and teach your grandma to suck eggs boy, you just look stupid.

Well, my apologies, grandma, but you were spilling those eggs all over
your dress. ;-)

To be specific about the spilt eggs: you corrected someone's judgement
of 'performance' by stating that the ARM's 'performance' wasn't great,
but it's 'price/performance' was.

>> The performance is not amazing. The price/performance ratio is.
>>There is a not so sublte difference between the two.

Unfortunately, from an engineering point of view, this statement
doesn't make any sense, since 'performance', without any
qualifications, has no inherent meaning (performance of/at what?
compared to what?). Now, if you had bothered to read the previous
poster's argument further, you would have found that he actually
qualified his use of the word performance, giving it meaning.

>>>I would also debate that the performance is no longer amazing.  I was
>>>looking through some data sheets, and I was unable to find another
>>>RISC chip that gives the same performance per pound (that's especially
				 ^^^^^^^^^^^^^^^^^^^^^
>>>true for ARM2 - and ARM250 is INCREDIBLE value for money, if only
					    ^^^^^^^^^^^^^^^
>>>sample quantities were readily available).

Then, along you came and made the meaningless statement:

>>There is a not so sublte difference between the two [performance and
>>price/performance ratio].

In fact, even though I used the ratio 'price/performance' in my
refutation, it is a meaningless phrase in itself -- what is the
performance herein referred to? You will notice, however, that I
corrected myself later in my argument:

> For example, the ARM6 has an incredible MIPS/Watt performance
>ratio, as well as a good cost/integer speed performance ratio.

And I finally wrap up my summary with a statement that I don't think
you read at all, so I'll repeat it:

>Anyway, remember: performance is in the eye of the beholder -- almost
>every chip is the best performer in the market, in some fashion. It is
>up to the designer to decide which area of performance is the most
>important for their current design.

So, to summarize my summary, performance is one of those words that
needs qualification when it is bandied about, and the qualification
cannot refer to performance itself, since you end up with a recursive
definition.

>>-Malcolm.  lithgow@usl.com  These are merely my opinions.
> And exceedingly poorly thought out ones at that.

Why, thank you, dear sir, for obliging me by reading and responding to
my signature. I am forever in your debt. I will now return the favour.

>               ** Of course I don't speak for IBM **

Neither do I.

-Malcolm.  lithgow@usl.com  These are merely my opinions -- take with water.